35

CHAPTER II

PREVIOUS WORK AND REGIONAL GEOLOGY

2.1 PREVIOUS WORK

The might of Himalaya has inspired and evoked the awe and wonder of the people of the

world from time immemorial. In order to give the previous geological account of the study

area, the present chapter reviews and summarizes the present state of knowledge. After the

first attempt of systematic examination of Himalaya by Captain Herbert (1842), the then

Deputy Surveyor General of India, he divided the Himalayan terrain into four different

zones right of the line of the watershed between the Indus and the Ganga and the low hills

of Siwaliks.

Malla Johar which lies in Uttarakhand Tethys Himalaya earlier considered as part of the

Tibetan Himalaya. Compared to all other domains of Himalaya this part remain invincible

for decades because of many political and mythological causes. Complication in geological

history of Malla Johar is cleared by the line of Doyen of Himalayan Geology A. Gansser

(1964), “In Kumaun Himalayas, the problematic zone of Exotic Blocks”; and also

suspicious about the new work possibilities in the near future. His possibilities remain true

because till date a very little work has been done on the evolution of this problematic zone

except some work on age and depositional environment on the basis of microbiota and

petrographical description by Mehrotra and Sinha (1978, 1981); Shah and Sinha, (1974);

Sinha and Srivastava (1978, 1986); Sinha and Dmitrenko, (1983); Kumar et al (1978);

Garg et al (1981); Juyal et al (2002).

Sangchamalla Formation, which is a flyschoidal unit, attains the status of formation in

early eighties after the expeditions of Wadia Institute of Himalayan Geology, Dehradun

(WIHG) from 1973 to 1980. First worldwide attraction towards this flyschoidal unit was

because of Heim and Gansser (1939a), they considered it as an upper part of Giumal

Sandstone, which is strikingly similar to some Alpine Flysch deposits. Some geologists

named it Jhangu Formation (Garg et al, 1981) but now from the perusal of the literature on

the geology of Kumaun, it is accepted as Sangchamalla Flysch, because it’s best

development occur at Sangcha Malla which lies below the Kiogad peaks, and considered

as the type locality of the Sangchamalla Formation. The detail of previous work done on

Sangchamalla Formation and associated sequence is given before the stratigraphic details

of Sangchamalla formation.

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2.2 REGIONAL GEOLOGY

The main belt of the Tethys Himalaya lies between the Indus Tsangpo Suture to the north

and the Higher Himalaya zone to the south. In western Himalaya the well developed

sequence of Tethyan zone, also called the Tibetan zone is exposed in Malla Johar,

Northern Kumaun, Spiti and Zanskar regions (Heim and Gansser, 1939a, b; Gansser, 1964;

Valdiya, 1980; Sinha, 1989; Thakur, 1992; Hirn et al., 1984). The Kashmir and Chamba

sequences located south of the main belt as well as south of the higher Himalaya zone of

Zanskar, are included in the Tethys Himalaya zone (Thakur, 1992) (figure 2.1).

Figure 2.1: An outline tectonic map of western Himalaya Showing distribution of the Tethys

Himalaya Zone (Thakur, 1992).

The ‘Tethyan’ facies comprises the fossiliferous Precambrian-Palaeozoic–Mesozoic-

Tertiary sequences resting along the Trans Himadri Fault (THF) (Valdiya, 1987) or South

Tibetan Detachment (STD) on a basement of the Central Crystallines, which in turn

overrides the sediments and metasediments complex of the Lesser Himalaya to the south

along the Main

Central Thrust (MCT) (Gansser, 1964; Valdiya, 1981, Sinha, 1989; Thakur, 1992). In the

older classical concept the Tethyan zone sequences was considered as geosynclinal

deposits. In plate tectonic interpretation the Mesozoic sequence of Tethys Himalaya of

ZANSKARS P I T I

MALLAJOHAR KUMAUN

TSO MORARIK A S H M I R

POTWAR PLATEAUPANJAB PLAINS

MBT

MBT

MM

T

ITS

ITS

PESHAWAR BASIN

LAHAUL

CHAMBA KINNAUR

G A N G A B A S I N

ZANSKAR

Tethys Himalaya

Gilgit

Indus R Leh

Kailash

Kargil

NunKun

Jhel

um R

Che

nab

R

Ravi R

Beas R

Satluj R

Chandigarh

Ambala

Yam

una

R

MussoorieAlmora

Nainital

Ka

li R

Lee Pargil

Gartek

Sarchu

Kishtwar

Shimla

Mandi

RampurDharmsala

Udhampur

Punch

Rawalpindi

Murree

Abbotabad

Islamabad

Peshawar

MBT

Astar

Burzil PassNanga Parbat

Nanda DeviMCT

Indus R

Indus R

Srinagar

350

300

750

800

350

300

750

800

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37

Malla Johar, Kumaun, Kashmir, Zanskar, and Spiti represents the deposits of the southern

Tethys over the north facing Indian margin (Thakur, 1992).

In all the well-developed sequence of Tethyan zone in western Himalaya, Spiti is the best

studied section because of good connectivity and communication, while Malla Johar is less

explored because of poor connectivity and communication. A lithostratigraphic

comparison between Spiti and Malla Johar is given in Table 2.1. The present knowledge

about the Tethyan zone of Malla Johar/ Central Himalaya is provided by the Swiss

expedition in 1936, which was led by late Prof. Arnold Heim. Monograph published in

1939 after this expedition remained till today the authentic literature with the modern

concept of the first half of the twentith century in Geologial sciences. After long time of 50

years another monograph “Geology of the Higher Central Himalaya” by Prof. A. K. Sinha

published in 1989, which is the outcome of a number of post-independence expedition

initiated by the Geological Survey of India (GSI) and Wadia Institute of Himalayan

Geology (WIHG). Preliminary work from GSI was initiated by Mehdi (1966), he was the

first post-independence worker to give the stratigraphical account of Darma Ganga and

Lesser Valley of Tethyan domain, after that Sarvashri Gopendra Kumar, Gyan Prakash and

S. H. Mehdi subsequently published their review of strtigraphy of parts of then known

Uttar Pradesh Tethys Himalaya in 1972. Publication of Sastry et al. (1970), Sastry and

Mamgain (1970, 1975, 1977), and Mamgain and Sastry (1975) was some more work from

GSI on Tethys Himalaya and it was based on account of Cretaceous microflora and

biostratigraphic data from Mesozoic and Paleozoic sediments. After the foundation of

WIHG, the first expedition in Tethys Himalaya was in Kali valley and literature was

published by Valdiya and Gupta (1972), Valdiya et al. (1972), Powar (1972), and Banerjee

(1974).

Lithostratigraphy and trace fossils have been published by Kumar et al. (1977). The

monograph by Sinha (1989) was the outcome of number of expedition organised by WIHG

between 1973 to 1980, and publication came out covering the different aspects of

geological problems from the inaccessible Tethys Himalaya. The problems related to

regional geology, structural, tectonics, biostratigraphy, geochronology, mineralogy-

petrology and metallogeny have been partly covered and touched by many authors like

Shah and Sinha (1974), Banerjee, Tandon, and Sinha (1975), Sinha and Jhingran (1977),

Sinha (1974, 1975, 1977, 1978, 1980, 1981, 1982, 1983, 1984, 1987, 1989), Sinha and

Bagdasarian (1977), Ashgirei et al. (1976, 1977, 1982), Fuchs and Sinha (1974, 1978),

Sinha and Pal (1978), Mehrotra and Sinha (1978, 1981), Sinha and Srivastava (1978, 1979,

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1986), Sharma et al. (1978), Sinha and Nanda (1979), Sinha and Raaben (1979), Sinha and

Mehrotra (1979), Azmi and Sinha (1981), Bist and Sinha (1982), Negi et al. (1982, 1983,

1984), Sinha and Dmitrenko (1983), Khanna et al. (1985), Schwan et al. (1985).

Table 2.1: Stratigraphic correlation between Spiti and Malla Johar Tethys Himalaya (after, Sinha,

1989 and Bhargava, 2008)

SPITI (Bhargava, 2008) MALLA JOHAR (Sinha, 1989)

GROUP FORMATION A G E FORMATION

KANJI DUMBAR Lutetian Mid Eocene

KELCHA Thanetian-Ypresian Late Paleocene to Early Eocene

DISCONFORMITY

LAGUDARSI CHIKKIM Cenomanian-E. Maastrichtian Late Cretaceous SANGCHA MALLA FORMATION

GIUMAL Late Valanginian-Albian Early Cretaceous GIUMAL

SPITI Oxfordian-Early Valanginian Late Jurassic-Early Cretaceous SPITI

DISCONFORMITY

Callovian

Middle Jurassic SULCACTUS THE FERRUGINOUS OOLITE

KIOTO TAGLING Lias Early Jurassic LAPTHAL FORMATION

PARA Late Rhaetian Triassic KIOTO FORMATION

NIMOLOKSA NUNULUKA Late Norian-Early Rhaetian Triassic

KUTI SHALE

ALAROR Late Norian Triassic

HANGRANG Middle Norian Triassic

RANGRIK Early Middle Norian Triassic

SANGLUNG RONGTONG Middle-Late Carnian Triassic

KALAPANI LIMESTONE

RAMA Early Middle Carnian Triassic

TAMBA KURKUR

CHOMULE Ladinian-Early Carnian Triassic

KAGA Ladinian Triassic

MIKIN Induan-Anisian Triassic

DISCONFORMITY

KULING GUNGRI Dzulfian-? E. Dorashamian Late Permian KULING SHALE

DISCONFORMITY

GECHANG Asselian-?Sakamarian Early Permian

DISCONFORMITY

KANAWAR GANMACHIDAM Late Carboniferous Late Carboniferous

PO Visean-Serpukhian Late Early Carboniferous FENESTELLA SHALE

LIPAK Givetian-Tournaisian Mid Devonian

MUTH Early Devonian Early Devonian MUTH QUARTZITE

ANGULAR UNCONFORMITY

SANUGBA TAKCHE Ashgill-?Wenlockian Late Ordovician to Mid Silurian VARIEGATED FORMATION

YONG FORMATION

THANGO Early Ordovician Early Ordovician SHIALA FORMATION

GARBYANG FORMATION

ANGULAR UNCONFORMITY

HAIMANTA KUNZAM LA Early Middle Cambrian Early Middle Cambrian RALAM FORMATION

BATAL Ediacaran-Early Cambrian Ediacaran-Early Cambrian MARTOLI FORMATION

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2.3 TETHYS OF MALLA JOHAR

The Tethys Himalayan sequence of Malla Johar region (figure 2.2) to the south including

the Martoli Formation overlies the Central Crystallines of the Higher Himalaya along the

Trans-Himadri Fault (THF) or South Tibetan Detachment (STD) and extends to the north

upto the Cretaceous and Paleocene-Lower Eocene rocks, which are overlain along a thrust

by the klippen of exotic blocks formation. The stratigraphy of the Tethys Himalayan zone

of Malla Johar is summarized in table 2.2. The account of the regional stratigraphy from

the Vaikrita Group to the Sancha Malla Formation with associated ophiolites and exotic

formation, is mainly based on Kumar et al. (1972), Shah and Sinha (1974), Sinha (1980,

1989); and the environment of deposition is described after Kumar et al. (1977, 1978) and

Valdiya (2010).

2.3.1 VAIKRITA GROUP

It was Griesbach (1891) who introduced the sanskrit word to describe the highly deformed

crystalline complex of rocks of Central Himalaya. In sanskrit, Vaikrita means the

deformed, and the metamorphosed. Subsequent workers have called this unit variously the

Central Crystallines or Basement Complex. Vaikrita delimited at base by the MCT and cut

at the top by the STD or THF fault, the Great Himalaya 6000-10,000m thick lithotectonic

slab squeezed up as a consequence of continued India – Asia convergence (Valdiya, 2010).

Metamorphic rocks of this group show grading from low to high grade catazone

silliminite-kyanite schist with an appreciable thickness of hundreds of meters of quartzite,

sometimes occurring with kyanite – silliminite as well as garnets in the schistose and

gneissose part of the argillaceous sediments. The other components of the crystalline

complex are various grades of gneisses and schists including calc-silicate schistose rocks

and granitic gneisses of different phases (Gansser, 1964; Valdiya, 1988; Sinha, 1989;

Thakur, 1992) (figure 2.2 & 2.3).

The entire Vaikrita Complex is intensely deformed and metamorphosed due to

remobilization and therefore, the role of the Central Crystalline in the palaeogeologic

reconstruction of Himalaya remained an enigma for the workers. This Vaikrita Complex of

uncertain age formed the floor of the Tethys basin in which the Phanerozoic sediments,

ranging in age from the Cambro – Ordovician to the Eocene, were laid down (Valdiya,

2010).

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Figure 2.2: Regional Geological Map of Malla Johar Tethys Himalaya (after Sinha, 1989)

2.3.2 MARTOLI GROUP (ca. 3250 m)

Greisbach (1891) observed that the Vaikrita Complex, which rests conformably on the

granitic gneiss of the southern range along its northern slope, passes gradually into

metamorphosed muddy flysch described by H.H. Hayden in 1904 as the Haimanta (‘snow

–covered’ in Sanskrit) system. Heim and Gansser (1939a) showed the Vaikrita passing

gradually into slightly metamorphosed flysch of the Martoli Formation in NE Kumaun.

The Martoli Formation comprises greywackes showing flute casts and related features and

contain trilobite fossils (Valdiya, 2010). In the entire area of Central Greater Himalaya, the

Martoli group of sediments tectonically and in turn they are unconformably overlain by

Ralam Conglomerate and quartzites. In Malla Johar Pindari, Rilkot and Budhi schists,

represents the locally metamorphosed Martoli sediments at the base (figure 2.3). The

intense tectonic and magmatic activities, and dynamothermal phenomena, caused the

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schistosity of sediment with the development of random growth of porphyritic biotite. The

distribution of Martoli Group is not uniform from the Dhauli valley in the northwest to

Kali gorge in the extreme southeast. The maximum thickness (ca. 6000 m) is attained in

the central part of the arcuate disposition of basin in the region of Nanda Devi and Gori

Ganga gorge; the highest peaks of the Great Himalayan range, viz. Nanda Devi (7820 m),

Api (7140 m), Nanda Kot (6861 m) etc. are all formed by the Martoli Group of

sedimentary rocks (Sinha, 1989).

Table 2.2: Stratigraphic subdivisions and age of the Tethys Himalaya Zone in Malla Johar (after

Shah and Sinha, 1974; Valdiya, 2010) Division Lithology Characteristic Fossils Age

Shah and

Sinha, 1974

Valdiya,

2008

Sangcha Malla Formation

Greenish shales with bands of radiolarian cherts Greenish- grey greywackes and dark shales. Purple marly

shale with foraminiferal ooze Dark greenish shale with greywacke bands

Radiolaria, fucoid, markings,

Globotruncana, Heterohelix, Shackoina, Eouvigerina

Lower Eocene

Upper Cretaceous

Cretaceous Giumal Sandstone

Greenish grey sandstone and sandy shale with thick bands of massive radiolarian cherts

Thick bedded glauconitic sandy shales and sandstones

Not determinable fossil except radiolaria

Spiti Shale

Blach shales with phosphatic, ferruginous and calcareous concretions

Belemnmopsis gerardi, Perisphincts(Virgatosphinctes) fregens,

Lytoceras sp, Hoplites, etc.

Portlandian

Jurassic Sulcactus the ferruginous

Oolite

Ferruginous oolite with coquina Belemnpsis sp., Reineckites sp., Macrocephalites, etc

Callovian

Lapthal Formation

Dark- blue to grey limestone with bands of conquina Pecten sp., Astrate sp., Cardium sp., Trigonia sp., Belemnites sp.

Lias

Kioto Formation

Grey limestone with numerous bands of coquina. Nodular and oolitic limestone. Cross- bedded calcarenite and

arenaceous limestone. Grey and blue dolomitic limestone

Megalodon, Spiriferina, pectin, etc. Rhaetic Rhaetic

Kuti Shale Alternating bands of blach shale and limestone Few pelecypod shells Noric

Upper Triassic

Kalapani Limestone

Nodular limestone, grey massive limestone

Ptychites, Gymnites, halobia, Arcestes, etc.

Carnic- Ladinic

Mid Triassic

Kuling shale Black crumply shale with thin beds of limestone with concretions towards the top

Paramarginifera himalayensis, Cleiothyridium roysii, etc

Upper and Middle

Permian

Late Permian

Muth Quartzite

White sugary orthoquartzite with bands of dirty white quartzite

Chocolate brown quartzite and dolomitic limestone

Schellwienella williami, Leptaena, rhomboidalis, Strophomena sp.

Devonian Silurian

Variegated Formation

Purple limestone and shale with bands of quartzite Atrypa reticularis, Strophonella sp., Orthis (Dalmanella) basalis, Favosites sp.,

Leptaena rhomboidalis

Silurian

Silurian

Yong Formation

Green nodular biohermal and biostromal limestone Calostylis? Dravidiana, Streptaena halo, Favosites sp.? Saffordia sp., Monotrypa

sp. Strophomena sp.,

Shiala Formation

Grey to pinkish sandstone and quartzite with bands of limestone at the top

Alternating bands of sandstone and shale Alternating bands of greenish shale and biostromal

limestone. Green splintery shale with thin bands of arenite

Rafinesquina aranea, R. Muthensis, Triplecia sp., Skendium sp., etc.

Ordovician Late Ordovician

Garbyang Formation

Green needle shales with occasional bands of limestone Alternating bands of sandstone and shale with graded

bedding Cross- bedded calcareous sandstone

Greyish green graded bedded sandy shales, crinoidal and oolitic limestone, brown marl

Brown dolomitic limestone with alternating bands of shale

Eccliotteris kushanesis

Cambrian Mid Ordovician

Ralam Formation

Arenaceous shale Dark coloured quartzite

Conglomerate alternating with quartzite

Precambrian Mid Cambrian

Martoli Formation

Graded bedded grayish black shales, slates and phyllites

Early Cambrian

Vaikrita Group Quartzite, Quartzite schist, calc-silicates, kyanite and silliminite gneisses, migmatites and granites

Proterozoic

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Considering the huge thickness and basal position of the Martoli Group and the

unconformable Ralam Conglomerates at the top, dividing the entire group into four distinct

formations with appreciable thickness and distinct lithological identity. These four

formations, viz. Rilkot, Burphu, Bilju, and Milam, are best exposed in the Gori Ganga

section (figure). On the consideration the age of Garbyang Formation, it could be inferred

that the Martoli Group goes back to Precambrian era (Sinha, 1989)

Figure 2.3: Stratigraphic column of the basal Tethyan sequence with subdivisions of the Martoli

Group (after Sinha, 1989).

VA

IKR

ITA

G

RO

UP

( =

15 K

m)

RIL

KO

T

F

MN

( =

250 m

)

B

UR

PH

U F

MN

( =

2000 m

)

B

ILJU

F

MN

( =

500 m

)

MIL

AM

FM

N (

= 3

500 m

)

RALAM FMN

GA

RB

YA

NG

FM

N

( M

iddle

) >

500m

MA

RT

OL

I G

RO

UP

Greenish Grey Phyll. Calc.

Aren Dolo Phyll.

Dolo Phyllite

Quartzite

Brown Conglomerate

Unconformity

Phyllite, SiltstoneQz Vein + Chloritewith Copper Pyriteminzn.

GreenishSiltstone, Phyllite

Pyrite Quartzite

Graded GreenishSilty Phyllite

Sericite SchistPhyllite

Qz. Ser. Schist

Biotite Porphyry Schist

Tectonic Contact

Kyanite Sill

SchistMica SchistBiotite Schist

Calc. SilicatePgm. Apl.

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43

2.3.3 RALAM FORMATION (ca. 800 m)

The Ralam series, proposed by Heim and Gansser (1939a, b), is exposed in the spur of the

Ralam pass (5500 m). The characteristic lithology is represented by basal conglomerate

and quartzite. The brick- red conglomerate has quartzitic clasts of hand to smaller size,

unsorted, with a hard quartizitic matrix with bands of quartzites, where clasts are absent, or

with a decrease in the number and size of clasts (figure 2.3). The rock imperceptibly grades

into grey to purple and green, very hard, massive quartzite in the upper horizon. The clasts

are almost invariably of quartzite. The upper part of Ralam consist a dolomitic lithology

and transitionally crosses over to the Garbyang horizon. Since it lies conformably below

the Garbyang dolomitic rocks and with a marked unconformity over the Martoli Group, the

age of the Ralam Formation is regarded as Precambrian- Cambrian. The marked

unconformity may represent the hiatus of Baikalian orogeny (Sinha, 1989). In Malla Johar

Tethyan sector, the Early Cambrian is intriguingly absent and the Late Precambrian

metasediments is succeeded directly by the mid Cambrian Ralam Conglomerate (Valdiya

2010).

2.3.4 GARBYANG FORMATION (ca. 1500 m)

Malla Johar sub-basin of Tethys subprovince saw initiation of Paleozoic sedimentation in

the Mid Ordovician time (Valdiya 2010). Garbyang Formation, first studied by Heim and

Gansser (1939a) in the Kali river valley, was named after a flourishing Bhotia village,

‘Garbyang’ functioning as the centre of Indo- Tibetan trade. In the earlier works of

Greisbach (1891, 1893), this was considered to be the upper part of Haimanta system. The

Garbyang Succession of calcilutite, showing rain prints and mud-cracks in ferruginous

slates, was laid down in a shallow platform (Valdiya 2010). The Garbyang zone was

especially studied since the rich barite- polymetallic mineralization has been discovered to

be confined in this zone (Shah and Sinha, 1974; Sinha, 1977). After the expedition of

WIHG in 1973 stratigraphic status of Garbyang was raised to formation with the division

of three A, B, and C members (figure 2.3). The lowermost Member A conformably

overlying the quartzite of Ralam assumes a thickness of ca. 250 m and the characteristic

lithology is shaly dolomitic limestone, dark blue calcareous phyllite and sericite schist.

This Member A is conformably overlain by massive grey dolomitic limestone with marly

bands and intercalated shaly horizon to an insignificant amount in a huge thickness of 200

m. This ‘Member B’ of Garbyang in its lower part is confining barite-pyrite mineralization.

The uppermost Member C of the Garbyang Group, having a thickness of ca. 550 m, is well

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exposed in the Girthi Ganga near Dobala at the confluence of the Girthi Ganga and the

Kiogad. Garbyang is more or less devoid of identifiable fossils except gastropods, viz.

Eccliopteris Kushanensis and doubtful fragments of trilobites and Linguids (Sinha, 1989).

Heim and Gansser (1939a) reported badly preserved Mid Ordovician gastropods from the

Upper part of the Garbyang Formation.

2.3.5 SHIALA FORMATION (ca. 600 m)

The Garbyang imperceptibly passes upwards into the Shiala formation made up of

olivegreen shales and siltstone interbedded with blue-grey crinoidal limestone and marlite,

with maroon and light grey limestone – shale rhythmite (figure 2.4). Towards the top of the

Shiala Succession a biostromal horizon occurs (Valdiya 2010). The Shiala Series is

assigned to the Late Ordovician and was first described by Heim and Gansser (1939a). It

was named after the Shiala Pass. In the gorge of the Kiogad, a few kilometers before the

Sumna campsite, there is a perfect conformity between the Garbyang Formation and Shiala

Formation. The main distinction in lithology between the two formations is the presence of

a biostromal band in the Shiala. It is taken as a distinctive and important criterion to mark

the boundary between the Garbyang and the Shiala Formations. The Shiala Formation

comprises a sequence of green shale with silty bands towards the base. With the gradual

increase in the arenaceous component, the Shiala Formation becomes essentially quartzitic

towards the top. Throughout the formation, more towards bottom, two bands of biostromal

limestone consisting of fragments of arenaceous , calcareous algae, coral and shells of

brachiopods etc. are met with. They vary in thickness from a few centimeters to about 60

cm, and are seldom persistent. Very often they occur as podshaped bodies within the

predominantly shaly rocks, the imperceptible transition zone between the Shiala and the

Garbyang formations characterized by the lithology of green shale with arenite followed by

the Orthis (Dalmanella) testudinaria zone. As a matter of fact, the occurrence of Orthis

should be taken as the first and the best exposed fossils in the Tethyan column of Central

Himalaya.

The Shiala Formation is rich in fauna and can be divided into four biostratigraphic zones.

They are named after the characteristic fossil taxa, from the base, as: Orthis (Dalmanella)

testudinaria zone, Rafinesquina arenea zone, Monotrypa zone and Rafinesquina alternata

zone. The faunal assemblages clearly indicate an age ranging Middle to Upper Ordovician

(Sinha, 1989).

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Figure 2.4: Stratigraphic column of Tethys Himalaya Zone from Garbyang to Kalapani Limestone

(Sinha, 1989)

2.3.6 YONG LIMESTONE FORMATION

The biota consists of calcareous branching algal, stromatoporids, crinoids, corals and

bryozoans. Formation thickness varies in fifties of meters. It is graiesh-green in colour of

and continuously met from Rimkhim to Yong gad. It comprises a series of reefal structure

with dips in all direction of domal shape and interconnected with one another by bedded

reefal debris (Sinha, 1989) (figure 2.4). The formation has been named after the deserted

village of Yong valley where one of the reefs is exposed on the mule track leading to

Rimkhim. Microfaunal studies have revealed that reasonably rich palynological

assemblage, consisting of 11 chitinozoan and scolecodont forms occur. These forms tend

to suggest an upper Ordovician-Lower Silurian, probably Caradocian to Llandoverian age,

to the Yong Limestone and the Ordovician – Silurian boundary lies in the lower half of this

stratigraphic horizon (Khanna et al., 1985). In Malla Johar sub-basin of Tethyan Himalaya,

algal bioherms characterized by Early Silurian stromatoporoids forms a part of the Yong

Limestone (Shah, S.K. and Shina, 1974: Khanna et.al., 1985). The Yong laterally grades

into what Heim and Gansser (1939a) described as the Variegated Silurian.

2.3.7 VARIEGATED FORMATION (33-400 m)

The name of this horizon is derived from the ‘Variegated Silurian’ proposed by Heim and

Gansser (1939a) in the Kumaun Himalaya, and this formation was called ‘Red Crinoidal

KALAPANI L.ST.

KULING SHALEPERMIAN

MUTHFORMATIONDEVONIAN

SILURIAN

ORDOVICIAN

VARIGA. FMN

YONGLIMESTONE

SHIALA FMN

GARBYANG FMN

Greenish Grey Calc-Phyllites

Calc-Sandstone

Greenish-Grey Limestone

Red Calc Shale

Dolomite Brownish Quartzite

White Massive Quartzite

Carbonaceous Mica Calcareous Shale

1000 m

500 m

0 m

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Limestone’ by Griesbach (1891), and was regarded as carboniferous and basal Silurian.

The mistakes were rectified by Hayden (1904), who ascertained that the Spiti

representative of the ‘red crinoidal limestone’ is certainly not younger than upper Silurian.

The Shiala pass exposure of Variegated Formation was estimated by Heim and Gansser

(1939a): (a) 200-300 m red to green and grey shales with layer of white limestone,

characterized by smaller blood red shale and rusty weathered dolomitic in the upper part;

and (b) 500-600 m of shaly lenticular limestone with crinoidal fragments. Somewhat

nodular limestone of about 100 m thickness has also been observed by them and regarded

as special facies of Variegated Silurian sequence. But now it has been established that this

nodular limestone facies is nothing but reefal Yong horizon. The lower part of the

Variegated formation is represented by purplish algal limestone and phyllite, sometimes

arenaceous followed by upper part mainly composed of purplish and green calcareous

quartzite. This formation is separated distinctly on account of colour contrast with the

underlying green Yong Limestone and the overlying white Muth quartzite (figure 2.4). The

formation is poorly fossiliferous but one characteristic assemblage zone was recorded from

Kiogad valley section named as Strophonella Zone. Valdiya and Gupta (1972) recorded in

their intermediate horizon the various forms: Orthis (Dalmanella) bouchardi and Orthis

(Dalmanella) basalis var. muthensis. The upper limestone members have yielded Favosites

spitiensis and poorly preserved Streptelsma and broken blades of Polygnathids.

2.3.8 MUTH FORMATION (400-1000 m, on average ca. 400 m)

A 300-600m thick band of strikingly snow-white quartzite, forms a blanket of

quartzarenite in Kashmir, Zanskar, Spiti, Kumaun and north-western Nepal known as Muth

Quartzite (Valdiya, 2010). The Muth is one of the very conspicuous datum lines in the

stratigraphic history of the Himalaya. This formation was a time-transgressive unit that

ranged in age from Middle to Late Silurian (Shah, S.K., 2005). The sediments were

deposited very rapidly in a short span of time in a costal environment. The Muth sediments

represent offshore elongate bars and a shoal complex (Bagati, 1990; Bagati et al., 1991).

The Muth marks an epoch of tectonic stability during the Later Silurian period, when

practically the whole of the Tethyan domain stretching from west to east became a site of

shallow-water deposition of well-sorted clean sands (Valdiya, 2010).

In the Malla Johar (Yong valley) section, the variegated Formation is overlain by the Muth

quartzite with an angular unconformity (Sinha, 1989) (figure 2.4). Heim and Gansser

(1939a) also mentioned this angular unconformity and regarded it as lithological rather

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than tectonic. The stratigraphic situation reveals that deposition at the bottom of the deep

sea possibly might have been interrupted for a short period because neither the ‘Variegated

Formation’ nor Muth quartzite represents a deep sea deposit. In the upper reaches the Muth

quartzite forms a cliff (Sinha, 1989).

2.3.9 FENESTELLA SHALE

In the Spiti as well as in Kumaun basin, restriction of water circulation caused

development of anoxic conditions as reflected in the accumulation of thick, black

carbonaceous shale and black limestone, described by H. H. Hayden in 1904 as the Lipak

Limestone and the Po shale, respectively. In Uttarakhand Tethys Himalaya, Fenestella

shale was first recorded by Valdiya and Gupta (1972) in the gorge of Kali River in

Kumaun. Pink and grey silicious limestone, dolomite and sandstone contain Lower

Carboniferous Linoproductus and Chonetes (Valdiya et al, 1972; Mamgain and Mishra,

1989). These shales are characterized by Middle Carboniferous bryozoan fauna: Fenestella

plebei, Protoretepora cf. ampla, Spirifer middlemissi and Productus (= Waagenoconcha cf.

scabriculo) along track towards Lipu lekh just climbing up along eastern slope of Teragad

(Valdiya and Gupta, 1972). In Malla Johar Po has been described as the Fenestella Shale

and reported between Gunji and Kalapani (Sinha, 1989).

2.3.10 KULING SHALE (20-100 m)

The original name has been derived from the locality in the Spiti basin which is called

‘Guling’, a name given by F. Stoliczka in 1865. This persistent horizon of euxenic facies of

black silty micaceous shale of ca. 20 to 100 m thickness with well preserved fossils

exhibits contrasting geology by its situation over white sugar competent quartzite of the

Muth formation (figure 2.4). In the Kiogad valleys a 70 m thick band of black friable

Carboniferous shale is continuously present resting on the Muth Quartzite. Within these

shales thin lenticles of limestone are present. This formation is rich in nodules towards

upper part, which on breaking yield fossils. The first fossil horizon immediately over the

Muth Quartzite is the Paramarginifera himalayensis zone, rich in middle to upper Permian

fossils. This indicate that the Carboniferous lower Permian is completely missing from the

section (Sinha, 1989). The trace fossils reported from the Kuling shale are Cochlichnus

(Tandon and Bhatia, 1978). The geological characteristics of the formation point to a

reducing euxinic lagoonal sea environment.

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2.3.11 THE TRIASSIC OF CENTRAL TETHYAN ZONE

The Triassic of the Tethyan zone of Himalaya as a whole has been worked out in much

greater detail in comparison to other geochronostratigraphic horizons. The basic reason for

such special attention was attributed to the resemblance of fossils assemblage from the

Alps. The pioneer work was done by the group of Austro-German geologists who were

engaged by the Geological Survey of India as early as the end of the last century. The

fundamental contributions have been made by Griesbach (1891), Von Kraft (1902), and

Diener (1912). Amongst them the contribution by Diener were the most valuable, starting

in 1895 and culminating in 1912 with the GSI memoir volume 36, part III. Von Kraft made

special studies of the Triassic in Kumaun in 1900. His stratigraphical and tectonics results

have been summarized in the interesting paper (GSI Memoir volume 32, part III). Soon

after finishing his mission he died suddenly on 22 September, 1901, in Calcutta, then his

material, note books, sketches and fossil collection were passed on to Professor Carl

Diener of Vienna University for completion of the publication of the unfinished valuable

research. The early work on the development of lower Trias in the Central Tethyan Zone

has been known through Griesbach (1891) and Diener (1903), and this work summarized

by Diener (1912).

Heim and Gansser (1939a) proposed the following main lithological divisions on the basis

of early recognized nomenclature given by Diener (1912).

1. Chocolate series (= chocolate limestone, Griesbach).

2. Kalapani limestone (after the famous place in Kali River).

3. Kuti shales (after the Kuti village situated in Kuti Yankti).

4. Kioto limestone (name from Spiti adopted from a sketch of the geography and geology

of Himalaya by Burrard and Hayden and revised by Burrard and Heron (1934).

The above- mentioned subdivisions of Triassic remains undisputable, and henceforth the

description of the individual horizon is taken up.

2.3.11.1 CHOCOLATE FORMATION (30-50 m)

Heim and Gansser (1939a) described this as formation with typical chocolate colour due to

the brown weathering. They have observed that it is more shale than limestone. At the

confluence of the Shalshal and the Yong Gad this horizon was spotted with the underlying

Kuling shale and overlying Kalapani limestone. Kumar et al. (1977) referred this horizon

to the lower Triassic on the basis of conodonts found in them. Azmi (Azmi and Sinha,

1981) reported some typical lower Triassic conodonts at the contact horizon between the

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Kuling shale and the Kalapani limestone exposed in the Kiogad on the way to

Rewalibagar. The fossils reported by Azmi from a sample of Kalapani Limestone from the

Unta Dhura Pass in the Malla Johar region, are: Neospathodus triangularis, and forms

transitional to Neogondolella jubata-N. regalae, indicating latest Scythian age. The

Chocolate series is Lower Triassic or Scythian.

2.3.11.2 KALAPANI LIMESTONE (ca. 50 m)

The Kuling shale in the northwestern part of the area is directly overlain by the Kalapani

limestone, a bluish massive limestone towards the lower part and nodular limestone above

(figure 2.5). It appears to be of the nature of algal biostromes. The maximum thickness is

available in the Kiogad valley and in this valley it does not exceed 20 m. The Kalapani

limestone is highly fossiliferous in certain sections, apart from large numbers of

pelecypods, ammonites of typical Carnic affinity are found. These include among other,

species of Gymnites, Arcestes, Ptichites, Griesbachites, Halobia, etc. This has been given

the name Ptychites zone and seems to correspond the Halobia and Tropites beds of Spiti as

also indicated by Heim and Gansser (1939a). Some conodonts have been reported by Azmi

and Sinha (1981). They are Neogondolella excelsa and Himalayalla dropla indicating

Lower Ladinian age.

2.3.11.3 KUTI FORMATION (ca. 500 m)

The name of the formation is derived from Kuti village situated in the bank of the Kuti

Yankti River. The typical alternating horizon with shale and limestone lying over the

Kalapani limestone formation belonging to Kuti shale is exposed throughout Tethyan zone

of Central Himalaya. This typical lithological complex is found to be conformably

overlying the Kalapani limestone (Sinha, 1989). Its thickness varies from 300 to 500 m.

This horizon is being given the status of formation in conformity with the mode of

stratigraphic nomenclature since it represents a consistent, well demarcated, quite thick

horizon throughout the Tethyan zone. Geomorphologically, the Kuti formation is exposed

along the escarpment wall of the steep gorge in the Kiogad valley on the track through the

campsite to the Rewalibagar top. Its geomorphic feature is controlled by the competent

horizons of the Kalapani limestone and the Muth below it and hard massive limestone of

Kioto overlying it. The upper part of Kuti formation is characterized by regular layers of

great limestone. Sometimes folded disharmonically in such a manner that it forms a

vertical wall and a pillar-like feature. In the Kiogad valley, the Kuti formation is

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represented by at least 400 to 500 m suite of disharmonically folded alternating bands of

shale and limestone. The shale is dominated by black micaceous compounds. The

individual limestone bands do not exceed a meter thickness. Numerous tiny gastropods,

pelecypods, and brachiopods are reported to be Noric fauna, characterized by the numerous

Parajuvavites and Steinmannites (Sinha, 1989).

Figure 2.5: Stratigraphic column of Tethys Himalaya Zone from Kioto Formation to Sangchamalla

Formation, (after Sinha, 1989)

2.3.11.4 KIOTO FORMATION (ca. 700 m)

The Kuti shale is conformably overlain by a thick suite of limestone, occasionally having

an arenaceous composition (figure 2.5). Kioto limestone formation forms a continuous

ridge from Rewalibagar to Rim Khim (figure 2.6) separating the Lapthal-Shalshal plateau

Thrust With Ophiolite & Exotic Blocks

Radiolarian Chert

Greenish Shale

Graywacke

Black Silty Shale

Red Shale With ChertyLimestone Bands

Felspathic Sst.Shaly Sst.Radiolarian Chert

Radiolarian Cherty Sst.Graywacke

Glauconitic Sst.

Black Crumpled Shale

Ferrigenous Oolite

Brownish Sandy Lst.

Limestone

SA

NG

CH

AM

AL

LA

FO

RM

AT

ION

(

FL

YS

CH

)

GIU

MA

L

SPITISHALE

SULCACUTUS

LAPTHAL

KIO

TO

FO

RM

AT

ION

KU

TI

FO

RM

AT

ION

KALAPANI LST.

T

R

I A

S

S

I

CJ

U R

A S

S I

CC

R E

T A

C E

O U

S -

E O

C E

N E

Black Shale and LimestoneEstelar

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to the northeast from the deeply dissected rugged to the southwest. The lower part of this

formation, in the escarpment of Rewalibagar climbing from Kiogad valley, contains

characteristic pelecypods and Megalodon in addition to number of other fossils like Pecten,

Spiriferina, and Megalodon, reported earlier from the Spiti region. The arenaceous

limestone bottom is criss-crossed by the secondary hydrothermal activities with barite and

calcite veins of a thickness not exceeding 5 to 10 cm.

2.3.12 LAPTHAL FORMATION (91 m, Middle to Upper Dogger)

Lapthal Formation is a horizon of multiple layers of broken shells deposited in shallow

water stretches west from Kungribingri in Nepal border to Painkhanda in Garhwal

(Valdiya, 2010). The name of this formation was given by Heim and Gansser (1939a) from

the locality of the Lapthal camp site situated on the Spiti shales between Chidamu and

Sangcha Malla in Malla Johar. The thickness exposed in the Kiogad gorge type area of

Lapthal formation is found to be 91 m. It has been found that the main lithological

component is calcareous but it is mixed up with arenaceous (figure 2.5). In the section

from Rewalibagar to the Lapthal camp site; this formation has a total thickness of about 80

to 90 m (figure 2.7). About 10 m from the base of the Rewalibagar camp site, a horizon

bearing pelecypods was found and named as Pecten and Astarte assemblage zone (Sinha,

1989). The topmost part of the Kioto limestone consist of black cherty massive limestone

and oolites at the contact point, transitionally superseded by cherty limestone with calcite

and secondary calcite quartz veins. Grey sandy limestone covers the rest 5 m to 10 m

exposed thickness from the bottom being followed by arenaceous limestone of greenish

colour with shales and in this horizon the typical Lumachelle start appearing (Sinha, 1989)

(figure 2.8). The colour becomes brownish and composition is more sandy. Up to further

30 m the brown sandy limestone continues and at the point 45 m measurement from the top

a horizon of 4 m thickness is characterized by black sandy limestone Estelar

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Figure 2.6: Steep scarp of Kioto Limestone at Rewalibagar en-route to Sangcha Malla

appears with large 7 to 10 cm belemenite. Lumachelle is so characteristic of this horizon

that it assumes the name ‘Lumachelle formation’ in Nepal (Fuchs, 1967, 1977; Fuchs et al.,

1988; Bordet et al., 1971; Bodenhausen and Egeler, 1971; Bassoullet and Mouterde, 1977).

Some of the typical fossils identified from this horizon are: Rhynchonella, Isognomon sp.

The Lapthal bands contain Middle and Upper Dogger fossils. The Lumachelle formation

appears to be a rather consistent horizon in the part of Central Himalaya and it has been

established as Upper Dogger in age by Fuchs (1967, 1977) and also Dogger according to

Bordet et al. (1972).

2.3.13 SULCACTUS THE FERRUGINOUS OOLITE (3m Callovian)

This significant rather thin index bed was discovered in 1895 by Diener in Chirchun area

and is refered to because of its abundant Belemnites as the Sulcactus bed. Lapthal

Formation follows a condensed sequence comprising arenite at the base, and oolitic

limestone forming the bulk of the Ferruginous Oolite Formation (figure 2.5).

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Figure 2.7: Steeply dipping beds of Lapthal Formation at the base of Spiti Shale near Sangcha

Talla base camp

Strikingly golden-reddish in colour and formed in warm water agitated by waves, the oolite

horizon forms one of the most conspicuous and persistent stratigraphic unit in the

Neotethyan domain. Set in iron-rich matrix, the golden oolite and pisolite are seen all along

from southern Tibet, through northern Kumaun, Malla Johar and Spiti to the Quetta region

in Balochistan and then to the Kachchh region in Gujrat (Valdiya, 2010).

Figure 2.8: Lumachelle Beds typical of Lapthal Formation near Sangcha Talla base camp

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2.3.14 SPITI SHALE (250-300 m)

The Upper Jurassic Spiti Shale shows singular geographic persistence without lithological

variation from Hazara in the west to southern Tibet in the east (Valdiya, 2010). It is a shelf

environment in which muds were deposited at a very slow rate, and there were mud flows

occasionally and hard-ground formation frequently (Bhargava et al., 1987). This persistent

horizon of crumpled black shale provides a picture of flat topography between the

competent calcareous Kioto- Lapthal horizons and the sandstone cliffs of Giumal (Sinha,

1989) (figure 2.9 and 2.10). The Spiti shale is highly fossiliferous but a systematic

collection of fossils is not possible from the upper shale because it weathers easily and is

consequently always soil covered. Though the formation is full of fossils, their exact

position within the shale is not determinable, for these are found within the concretions

which are rolled into ravines or mixed with the soil. This fossiliferous horizon was

exploited for a 100 years by orthodox religious Tibetan people and Hindus, treating the

ammonites as ‘Shaligram’, the symbol of ‘Lord Shiva’. The excellent paleontological

script by V. Uhlig (1903-1910) remains as standard work on the ammonites in this

formation. The thickness of soft black carbonaceous clay shale varies greatly, apparently

by stratigraphical and technical causes. Among the rich variety of ammonites forming

Shaligrams are Oerisphinctes, Hoplites, Nacrocephalites, Himalites, Belemnopsis, and

Nucula. The upper part of the Spiti shale has been designated the Perisphinctes- Hoplites

zone (Sinha, 1989).

The Spiti Shale in Malla Johar contains foraminifers of stratigraphic importance (Singh, M.

P., 1979; Singh, M. P. and Kumar, 1978). Upper Jurassic microfauna from the Spiti shale

including foraminifera and ostracods from the exposure at the Lapthal camping ground,

have yielded the Lingulina mallajoharensis (Singh and Kumar, 1978), Bentalina

pseudocommunis, Marginulina batrakiensis, Marginulina sp., Lentinculina variana,

Lenticulina muesteri, Lenticulina sp., Saracenaria reesidei, Shalshalensis, Veginulina

constricta, Pseudonodosaria sp., Involtina sp., Eoqutalina sp., and ostracods: Bythocypris

sp., Monoceratina sp. The microfaunal assemblages correspond well with the Callovian-

Oxfordian microfaunal assemblage.

In the deeper shelf-to-slope faunas of the Spiti Shale in southern Tibet, the ammonite

assemblages comprise (1) Witchellia-Fontannesia assemblage having affinity with the

north-western Australian fauna, and (2) the Oxfordian Graiceras assemblage containing, in

addition to endemic forms, the elements of both the India-Madagascar and the

Mediterranean provinces (Westermann and Yi-gang, 1988).

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The faunal studies infers that ca. 250 m thick Spiti shale sequence near Lapthal represents

a rather continuous succession ranging in age from Oxfordian to Lower Hauterivian.

However, Isocrinids reported by Singh et al. (1980) representing Isocrinus and

Nielsenicrinus from the upper part of the Spiti shale range in age from Cretaceous to

Palaeocene, have revealed a rich assemblage of dinoflagellates and acritarchs along with

some spores and pollen grains.

Fig

ure

2.9

: P

ano

ram

ic v

iew

of

San

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a M

alla

fro

m L

apth

al c

am

p s

ite,

show

ing S

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hal

e, G

ium

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and

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San

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a

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la F

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atio

n (

fles

h c

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ur)

, B

alch

adhura

volc

anic

, ophio

lite

and e

xoti

c blo

cks

of

Mal

la J

oh

ar

Estelar

56

Figure 2.10: Flat topography of Spiti Shale at Lapthal camp site, in background exotic blocks are

sited

2.3.15 GIUMAL SANDSTONE (400 m) (Lower Cretaceous to Upper Neocomian to

Gault)

In Tethyan domain, the Cretaceous succession is a flysch assemblage made up of

rhythmites – glauconitic greywacke interbedded with shale and bedded chert (Valdiya,

2010) known as the Giumal Sandstone. This formation is traceable from Nindam in

Ladakh to Kagbeni and Kampa in southern Tibet (Valdiya, 2010). Spiti Shale upwards

conformably into Giumal, which comprises of moderately sorted, graded to cross-bedded

calcareous sublitharenite interbedded with Belemnites-rich black shale (Valdiya, 2010).

The term Giumal has been derived from a locality in the Spiti basin. Its average thickness

is ca. 400 m. This formation is represented by geomorphologically resistant cliffs

composed of glauconitic sandyshale, sandstone, and chert. The Spiti shale passes

conformably into this thick bedded glauconitic sandstone (figure 2.11). Formerly these

rocks were called ‘Lower Flysch’ by von Kraft (1902). In the Central Himalayan region,

Heim and Gansser (1939a) used this term for the similar rocks of Spiti. Towards the upper

part near Sangchatalla these rocks contain thick bands of radiolarian chert. Sinha and

Nanda (1979) recorded Pseudomontis, Inoceramus, and Gryphea. In the Giumal sandstone

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there are a radiolarian assemblage dominated by Cryptothorecis (Jain et al., 1978),

dinoflagellates, multisegmented Theoperid and Nassellaria, and single-shelled spherical

spumellarians. A few forms referable to speudoaoulaphacid and/or spongodiscid

spumellarians also constitute a significant part of this assemblage. Glauconitization is

conspicuous and age of Giumal Sandstone is Upper Jurassic –Lower Cretaceous (Sinha,

1989). In Zanskar, Giumal Sandstone represents an Early Cretaceous (Valanginian –

Albian) volcanic extensional event, which is indicated by abundant volcanic detritus and

local basaltic lavas of alkaline and tholeiitic suites in a large part of the north Indian

passive margin, from Zanskar in the NW to Nepal in the SE and correlates with the 115 Ma

old Rajmahal Traps of north-eastern India. This magmatism is related to an Early

Cretaceous break up episode that preceded the final opening of the Indian Ocean (Garzanti

et al., 1987; Garzanti, 1993; Gaetani and Garzanti, 1991). In Spiti Valley, Giumal

Sandstone represents sedimentation in shallow marine basin, possibly somewhat deeper

part of the basin experienced occasional turbidity currents (Bhargava, 2008). This

sequence, however, does not look like a proximal turbidite as advocated in its strike

extension in the Zanskar area (Bhargava, 2008).

Figure 2.11: Thinning and fining upward sequence of Giumal Sandstone

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2.4 PREVIOUS WORK ON MALLA JOHAR

We have classified the history of geological investigation of Sangchamalla Flysch and

associated sequences of Malla Johar and adjoining Tibetan region into two epochs: viz. the

Pre-Independence and Post-Independence period of India. On the basis of published

literature an attempt has been made to refold the geodynamic evolution of the Malla Johar

with special emphasis on the Sangchamalla Flysch, especially in context of plate-tectonics.

2.4.1 PRE-INDEPENDENCE WORK ON SANGCHAMALLA FLYSCH AND

ASSOCIATED SEQUENCES

During the Pre-Independence, in the mid Nineteen century, Captain Richard Strachey

(1851) was the pioneer geologist to publish his result on the Kumaun Himalaya and

produced the first maps and sections. With the map, it forms by far the most important

contribution to the geology of this part of Himalaya by distinguishing Azoic to Tertiary

stratigraphic units. More details of the area came through the publications of C. L.

Griesbach (1880, 1891, 1893), who first classified the rocks, recorded the occurrence of a

more or less complete Pre-Cambrian-Paleozoic-Mesozoic sequence, and produced broad

and generalized geologic maps and profiles of the inaccessible part of Kumaun Himalaya,

Sutlej, and Hundes in Tibet. He was the first worker to draw the attention to what is known

as the “Exotic Blocks” of Malla Johar and recognized these Chitichun limestone Blocks as

‘klippen’. According to Greisbach (1893) “this area presents features of structure of

exceptional interest, features which, so far I am aware, have, up to the present, not been

observed in India. There is nothing less than a series of Klippen Zuge as blocs’ exotiques”

(Sinha, 1989).

Diener (1895, 1897, 1898, 1903, 1906, 1912) added further details to the geology of Malla

Johar and explained the mode of occurrence of ‘klippen’ as a result of faulting

accompanied by intrusion of igneous rocks. He further elaborated his work on fauna

collected from Malla Johar and published his work as “The Trias of the Himalaya” in

1912. A few years later Von Kraft (1902) mapped the same region in more detail and came

to the peculiar conclusion that the chaotic block resulted from huge volcanic explosions in

Tibet, and reported the presence of slickenside structures near the contact between the

exotic rocks and the underlying flyschoidal formation. The most of the work on this region

of the central Himalaya was produced by the herculean efforts of Swiss expedition in 1936,

which was led by late Professor Arnold Heim and the Doyen of Himalayan Geology

Professor Augusto Gansser of ETH, Zurich. Monograph entitled “Central Himalaya”

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published in 1939 after Swiss expedition remained until today the only authentic literature

with the modern concept of the first half of the last century in geological sciences. Their

Publications, a travelogue Throne of Gods (1938, 1939b) followed by a monograph

“Central Himalaya” (1939a) mark the advent of systematic geological study of this region

and prepared the geo-traverse map of Kiogad and Southern Tibet exotic region (figure

2.12) (Sinha, 1989).

Heim and Gansser (1939a, b) described that the contact of the Spiti Shale with the

overlying arenaceous Cretaceous, the Giumal Sandstone is gradual. In uppermost Spiti

Shale intercalations of calcareous, glauconitic sandstones grades into the massive

glauconitic Lower Giumal Sandstone. This sandstone is followed by greenish reddish and

black silty shale overlain by a second thick sandstone body- The Upper Giumal Sandstone.

Total thickness of Giumal sandstone section exceeds 500m. Without any sharp break the

Giumal sandstone is followed by argillaceous thick section of red to purplish marly shales,

marly dense limestones with few pelagic foraminifera, black silty shales, slates with thin

partly siliceous sandstone, and a limestone flag with fucoids and top is formed by

characteristic red and green fine siliceous sandstone, red radiolarites and siliceous shales.

This is overthrusted by the exotic thrust sheet with its basic igneous rocks; it represents the

highest section in the Northern Kumaun. Heim and Gansser (1939a) suggested that, the

higher argillaceous silty section of Giumal Sandstone is strikingly similar to some Alpine

Flysch deposits, and it is totally different from the Indus flysch sections. They considered

this flysch like deposits in northern part of the Himalayan range is of special interest, since

flysch sediments are normally missing along the lower Himalayan front and the Siwalik

Molasse. This fact distinguishes the Himalayas from the Alps with their very widespread

Flysch deposits.

Heim & Gansser (1939a) reported the similar exotic blocks in Shib-Chu, Amlang-La,

Raksas anticlinorium and Kailas range in Tibet with characteristics ophiolitic belts and

similar flyschoidal deposits of world-wide importance (Gansser, 1959). Exotic region is

extended to more than 5000 square km upto the south of Kailas range over 100 km to the

ENE (figure 2.12).

2.4.1.1 KIOGAD EXOTIC REGION

Flysch of the Kiogad exotic region of Kumaun Himalayan forms N-S directed structures,

plunging in a northerly direction (figure 2.12). The youngest flysch sediments preserved

locally below the thrust mass are siliceous black, red and green shales and red radiolarites

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of upper Cretaceous age. Exotic blocks are also present within flysch sediments, possibly

related to thrusts connected to larger exotic masses, suggest tectonic complications Exotic

block may not be in their normal position because of the strong solifluction widespread in

region. Contacts of such exotic masses with the flysch are well exposed (Heim and

Gansser, 1939a, Gansser, 1964, Sinha, 1989).

Basic volcanites present in Kiogad form a constant sheet, topped by Kiogad limestone

masses. There volcanites are well exposed in the 5500 m high Balcha Dhura area

northwest of the Kiogad. Volcanite consist of large serpentine sheets with zone of

ophicalcite, some peridotites, diabases, amygdaloidal porphyrites and a variety of basic

tuffs mixed with siliceous flysch sediments.

The exotic mass forming the Kiogad peaks represents a disrupted and highly broken sheet

of dense to fine crystalline massive limestone, 200-300m thick and covering an area of 20

square km, the Kiogad dip regionally to the north and disappear northwards below the

thick quaternary gravel deposits belongs to the Sutlej Basin (Gansser, 1964).

2.4.1.2 AMLANG-LA EXOTIC REGION

Exotic zone of Amlang-La, A more eastern south front of Kiogad exotic zone, present in

southwest of Raksas Lake, at the Amlang-La (figure 2.12). Here the general NW-SE strike

of the Tethys Himalaya, runs from the Kiogad region due east, a strike direction possibly

influenced by the eastward-rising dome-like old crystalline mass of the Gurla Mandhata.

The change in strike is clearly evident in the flysch deposits, forming the core of exotic

zone (Gansser, 1964).

Gansser (1964) divided the flysch section of Amlang-La into a lower and upper section,

each containing a horizon of exotic blocks. The lower flysch begins with shaly sandstones

and intercalated siliceous shales which increases upwards together with argillaceous chert

horizons. Fine, well bedded glauconitic sandstones occur in middle part, which is arkosic

with angular quartz and feldspars grains and contain fragments of ophitic diabase, similar

to the volcanics related to the exotic blocks. Some glauconitic sandstone is unexpectedly

rich in radiolarian and some foraminifera and it contains the exotic blocks of lower level.

They are topped by conspicuous calcite-veined well-bedded foraminiferal limestone,

regarded as upper cretaceous and which separate the lower flysch section from the upper.

The upper flysch section follows with green siliceous shales, locally steeply folded and

200-400m of light yellowish well-bedded sandstone; contains higher exotic blocks. Whole

flysch section is very well bedded, dips regionally at about 300-400 to north.

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Fig

ure

2.1

2:

Geo

-tra

ver

se m

ap o

f ex

oti

c re

gio

n o

f M

alla

Johar

and S

outh

ern T

ibet

(H

eim

an

d G

anss

er,

193

9a)

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62

Compared to the Kiogad, size and amount of the blocks is somewhat reduced, and both

higher and lower level exotic blocks have different composition. The lower blocks consist

predominantly of white fine crystalline limestone, red limestone rich in middle to lower

Triassic cephalopods. These limestones are strikingly similar to “Alpine” Trias of the

Kiogad region (Gansser, 1964). In upper exotic horizons only blocks of a white brittle and

dense limestone were observed. They are quite distinct from the blocks of lower horizon

and somewhat resemble the Kiogad limestone.

Volcanites cover the northwards dipping flysch and its exotic blocks follow a wide

extension of fresh peridotite. It is uniform and locally serpentinized. It extends over 3500

square km. The coarse grained peridotites shows quite fresh olivine (forestrite) and some

enstatite with lamellar inclusions of monoclinic augite, they all form a rhombic variety

indicate that rocks cooled rather slowly. The northern limit of the main peridotite mass lies

near the west shore of the Raksas Lake at Jungbwa, a name suggested for the whole

peridotite mass. The flysch just below the peridotite is rich in red radiolarian chert, with

well preserved radiolarian (Gansser, 1964).

2.4.1.3 SHIB-CHU EXOTIC REGION

Heim and Gansser (1939a) documented another extension of the Kiogad exotic blocks was

found in the Shib-Chu gorge north of the Kiogad region. The Shib-Chu, draining the

Kiogad region, forms a gorge mostly cut through the thick quaternary Sutlej terraces

(figure 2.12). Within this gorge excellent exposures of a strongly reduced flysch to exotic

block are present. On northwest side, the Jungbwa peridotites overly the flysch, while older

rocks of Chilamkurkur Formation crop out to the east. Due to uplift of Chilamkurkur

Formation in the east, the flysch of the Shib-Chu Gorge strikes abnormally northwards and

dips at about 300-40

0 to the west. Calcareous sandstones alternating with black silty shales

compose the flysch section. On the top of the flysch, lenticular remnants of red and white

limestone blocks occur, which are directly covered by the Jungbwa peridotites. Between

the peridotites and the limestone a conspicuous band of ophicalcite are present. This

ophicalcite is not restricted to the limestone contacts alone, but can be observed further to

the north in the same gorge where exotic blocks have disappeared, and Jungbwa peridotites

rest unconformably onto the more strongly folded flysch. These exposures indicate a

reduction of the exotic zone from the south to the north. After Shib-Chu exposures, only

older formations outcrop all along the northern limit of the exotic rocks, and they reappear

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along the south front of Kailas range, in a northwards thrusted flysch zone with tectonised

zone of exotic blocks.

2.4.1.4 KAILAS FLYSCH ZONE

According to Gansser (1964) the northern limit of the Himalaya is possible to find only on

reaching the Kailas Range in the Tran-Himalayas. After the last gently north dipping

outcrops of the deeper Raksas phyllites, an alluvial plain of over 20 km stretches upto the

foothills of the Kailas Range. South of the Kailas the foothills consist of a highly complex

and steeply south dipping flysch zone (the Kailas Flysch) with intercalated ophiolites and

some exotic blocks (figure 2.12). To the west, this flysch zone is cut out, and the

northwards outcropping Kailas conglomerates reach the alluvial plain. Eastwards the

flysch continues, but its extension is unknown. The Kailas flysch represents the last

remnant of the Himalayas; thrust steeply northwards over the autochthonous Kailas

Conglomerates which transgress over the Kailas granite.

The southernmost outcrops of the flysch zone consist of a most complicated schuppen zone

of sandy slates, red sandstone, slates and red radiolarian chert. It is intruded by massive

enstatite bearing serpentine which is associated with lenses of yellowish to white dolomitic

limestones. These limestones are strikingly similar to certain exotic blocks, and the

serpentine is identical to the Jungbwa peridotites, which are younger than the flysch. The

whole section dips steeply to the south. This flysch is slightly metamorphic and thrust

along a well exposed and 300-40

0 south dipping sharp tectonic contact over the thick and

horizontally bedded Kailas conglomerate. The general strike of the flysch mass is eastwest.

There is hardly any doubt that this flysch section with its ultrabasic rocks and included

exotic limestones corresponds to the north directed exotic thrust mass of Kiogad, Amlang-

La, and Jungbwa. This thrust divides the Himalaya from the Trans-Himalaya, the

allochthonous from the autochthonous, along a sharp contact. Heim & Gansser (1939a) and

Gansser (1964) also could not provide any account about the distribution of this North

Himalayan Flysch Basin.

2.4.2 POST-INDEPENDENCE WORK ON SANGCHAMALLA FLYSCH AND

ASSOCIATED SEQUENCES

Post-Independence, zoom in study of Uttarakhand Tethys Himalaya came after the

inception of Wadia Institute of Himalayan Geology (WIHG) in Dehradun. The result of the

first expedition was published by Kumar et al. (1972), Shah and Sinha (1974) ,Valdiya and

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Gupta (1972), Valdiya et al. (1972), Powar (1972), and Banerjee (1974), after this

subsequent expedition of 1973, 1974, 1975, 1976, 1978, 1979, and 1980 provided the

more detail aspect of regional geology, structural and tectonics, biostratigraphy,

geochronology, petrology and metallogeny and the result came out through the publication

of Sastry and Mamgain (1975), Banerjee et al. (1975), Kumar et al.(1977), Sinha and

Nanda (1979), Mehrotra and Sinha (1981), Jain et al. (1978, 1980, 1984), Sinha and

Srivastava (1986). A monograph entitled “Geology of the Higher Central Himalaya”

(1989) published by Sinha have summarized all the previous work on Malla Johar and

provides a strong foundation for further detail work. After a long gap of decades only one

paper on microfauna and age of Sangcha Malla Formation (Juyal et al. 2002) is published.

A more detailed account of Post-Independence work on Sangchamalla Formation and

associated sequences is as follows.

2.4.2.1 SANGCHAMALLA FORMATION

Sangchamalla Formation in Malla Johar (synonyms: Spiti Valley: Chikkim Limestone;

Zanskar: Fatula Limestone; Cenomanian- Campanian) shows the detached nature of basin

during the deposition as there is marked lateral facies changes from Kumaun to Zanskar.

During the Cenomanian, the outer continental terrace was covered by 100m light grey to

multi coloured pelagic foraminiferal limestone that forms the white Chikkim cliff in the

upper Spiti Valley (Stolickza, 1865; Hayden, 1904) and the multicoloured Fatula

Limestone in Zanskar (Gaetani et al., 1985). This early Cretaceous sedimentation marks

the onset of the opening of the Indian Ocean and the north directed drift of India (anomaly

34, 80 Ma, Campanian, Patriat et al., 1982, Patriat and Achache, 1984).

In Spiti, Chikkim Formation is divided into two members, viz. (a) Limestone Member and

(b) Shale Member. According to Fuchs (1981), Giumal Sandstone passes laterally and

conformably into Chikkim Limestone which represents offshore pelitic sediments and has

yielded Hedbergella infracretacea and Globorotalites aptiensis of Gargesian stage

(Colchen et al., 1986). The Chikkim is a succession of pelagic limestone and marlite

developed as a continental slope deposit in a fast subsiding basin (Valdiya, 2010).

According to Bhargava and Bassi (1998), the Limestone Member represents sedimentation

in shelf to off-basinal environment with occasional periods of restricted circulation. The

Shale member was deposited in outer shelf (Bhargava and Bassi, 1998).

In Malla Johar, overlying the Giumal sandstone without any unconformity, a radiolarian

bearing cherty horizon marks the base of flysch (Sinha, 1989). This radiolarian bearing

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local horizon is followed by shaly and feldspathic sandstone, chocolate reddish-shale with

calcareous and cherty lenses, black silty shale, and greenish shale (figure 2.13). According

to Sinha (1989) “from the perusal of the literature on the geology of other areas of

Kumaun, it is clear that this formation has its best development as Sangcha Malla below

Kiogad where complete sequence is exposed, and this is proposed as the type area of the

Sangchamalla Formation”. The details of the lithological sequence of Sangchamalla

Formation is given by Mehrotra and Sinha, 1981, which is modified after Shah and Sinha,

1974 (Table 2.3).

Table 2.3: Distribution of microplankton in the different levels of Sangchamalla formation (After

Mehrotra and Sinha, 1981), thickness and lithological details after Shah and Sinha, 1974. Stratigraphic unit

Exotic blocks

Characteristic fossils

Age

SA

NG

CH

AM

AL

LA

FO

RM

AT

ION

Greenish shales with bands of

chocolate sandstone and dark grey

radiolarian cherts (300 m)

Predominance of Areosphaeridium

diktyoplokus, A. arcuatum, Homotryblium

tenuispinosum; rare representation of

Oligosphaeridium sp. and Hystrichokolpoma

unispinum

Upper Eocene

(?)

To

Middle

Eocene

Greenish grey greywacke and dark

shales bearing fucoid markings,

with bands of radiolarian cherts

towards the top and a band of

brown feldspathic sandstone near

the base (650 m)

Predominance of Oligosphaeridium complex,

O. pulcherrium, Diphyes colligerium,

Cordosphaeridum exilimurum; first appearance

of Areosphaeridium diktyoplokus, A. arcuatum,

and Homotryblium tenuispinosum

Lower

Eocene

To

Palaeocene

Purple marly shale with brown

bands of foraminiferal ooze (70

m)

Abundant and restricted occurrence of

Odontochitina cribropoda and high

representation of Systematophora schindewolfi

Upper

Cretaceous

Dark greenish shale with a few greywacke bands (50 m)

Giumal sandstone

Figure 2.13: Fining upward flyschoidal sequence of Sangchamalla Formation

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Age of the Sangchamalla Formation is dated as Upper Cretaceous by Heim and Gansser

(1939a) on the basis of few globular radiolarians (Spumelliarians) and imperforate

siliceous foraminifera (Ophthalmididal). Shah and Sinha, 1974 also reported some more

foraminiferal genera- Globotruncana, Heterohelix, Plummerita, Shackonia and

Eouvigerine- from the purple shale samples and supports the Upper Cretaceous dating of

Heim and Gansser. A large number of fossil dinoflagellate species were recorded from the

different stratigraphic levels of the formation and found that the upper age limit of the

formation does not end with Upper Cretaceous but extends into Eocene (Mehrotra and

Sinha, 1978, 1981). The lower part of the Sangchamalla Formation consists of dark green

and purple shales with a few bands of foraminiferal oozes and greywacke. The upper

purple shale (70 m) level of the formation is marked by the abundant occurrence of

Odontochitina cribropoda (Deflandre and Cookson, 1955), this species is well known for

its restricted occurrence in Upper Cretaceous age. This is further strengthened by the

presence of high frequencies of Systematophora schindewolfi (Alberti) from the same

horizon. This species has been reported from Germany and England and occurs in large

numbers only in Upper Cretaceous sediments (Davey et al., 1966), these fossil evidences

are suggestive of an Upper Cretaceous lower limit of the Sangchamalla formation. The

typical Eocene forms, Homotryblium tenuispinosum (Davey et al., 1966), Aerosphaeridium

diktyoplokus (Klumpp) (Eaton, 1971) and A. arcuatum (Eaton, 1971), which occurs

abundantly in the 650 m thick sequence of dark green shales associated with radiolarian

chert, which forms the middle part of the formation. The predominant dinoflagellate genera

recorded are Oligosphaeridium pulcherrium (Deflandre and Cookson, 1955; Davey et al.

1966) Cordosphaeridium exillimurum (Klumpp) (Davey et al., 1966), Hystrichokolpoma

unispinum (Williams and Downie, 1966), and Diphyes colligerum (Davey et al., 1966). All

these forms are well known for their abundant occurrence in the Palaeocene-Lower Eocene

sediments of England (Davey et al., 1966) and India. From Indian Oligosphaeridium

pulcherrium, O. complex and Diphyes colligerum are known from the Lower-Middle

Eocene sediments of North Cacher Hills, Assam while Oligosphaeridium complex is quite

common in the Lower Middle Eocene Subathu sequence of Lesser Himalaya (Khanna,

1978). Cordosphaeridium exillimurum and Aerosphaeridium diktyoplokus are the other

stratigraphic species common in the Subathu and Sangchamalla formation. The appearance

of typical Eocene forms like Aerosphaeridium arcuatum, A. diktyoplokus, and

Homotryblium tenuispinosum in this level also supports its being Eocene in age.

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The topmost greenish shale-radiolarian cherts (300 m) sequence is very rich in

Aerosphaeridium diktyoplokus, A. arcuatum, and Homotryblium tenuispinosum. Presence

of Cordosphaeridium exilimurum is very high and absence of typical Lower Eocene forms

further suggests that the level is definitely younger than the Lower Eocene, i.e. Middle

Eocene. Hence, Middle Eocene is the upper age limit of the Sangchamalla Formation.

The predominance of dinoflagellates in the sequence is an indication of shallow marine

depositional environment, within the flysch sedimentational cycle. It infer that flysch

graben with loaded sediments has experienced pulsating vertical movements with

shallowing and deepening of the basin. The study of glauconite appearing with radiolarian

also affirms the shallowing of purple shaly horizon having marked oxidizing environment

(Sinha and Srivastava, 1978, 1986). Thus the dinoflagellates and glauconite appearance are

complementary to each other affirming a pulsationally sinking and rising flysch basin.

It is very interesting that a large number of species are common in the Sangchamalla and in

the London clay microplankton assemblages. This is attributed to the existence of some sea

link between the two regions during Eocene times. Reid and Chandler (1933) indicated the

existence of this sea route which allowed the Indo-Malayan flora to migrate as far as Great

Britain during the deposition of London clay sediments. Further, Sinha (1989) on the basis

of foraminiferal evidence it has been indicated that the Tethys sea might have extended

from the high ranges of Sind-Baluchistan frontier to Iran, Asia Minor, North Africa,

Turkey and Greece to western Europe as far as the Pyrenees. The close similarity between

the microplankton assemblage of the Subathu (Khanna, 1978) and Sangchamalla

Formations with that of London clay has further strengthened the above probability.

Rich assemblages of coccoliths are reported from the flysch sediments by Sinha and

Dmitrenko, (1983). The forms reported are: Watznaueria barnesae (Black) pereb-Nielson,

W. biporta Bukry, Biscutum constans (Gorka) Black; Staurolithites sp; Braarudosphaera

bigelowi (Gran, Braarud) Deflandre, Thoracosphaera sp., Broinsonia sp., Lucianorthabdus

cayeuxi Deflandre, Marthasterites fureatus (Deflandre) Stradner, Lithraphidites

carniolensis Deflandre etc.

Sedimentation study of the flysch and the occurrence of glauconite with radiolarites have

given an important clue to its history of sedimentation and environment of tectonic

phenomena in the flysch graben (Sinha and Srivastava, 1978, 1986). The occurrence of

Liosphaera sp., Staurocaryum sp., and Cyrtocapsa sp. of radiolarites have been found in the

glauconite bearing medium grained, moderately to poorly sorted greywacke units of Lower

Flysch sediments in Malla Johar of Kumaun (Sinha, 1989).

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2.4.2.2 EXOTIC BLOCKS OF MALLA JOHAR

Overlying the Sangchamalla formation, the ophiolitic mélange with associated exotic

blocks are present (figure 2.14). In 1982, Griesbach, Diener, and Middlemiss discovered

some isolated limestone blocks embodying Permo-Carboniferous and Triassic fossils near

Chirchun in the border region of India and Tibet, in the upper Kiogad valley in higher

Kumaun region (earlier known as Malla Johar). Griesbach (1893) and Diener (1895)

recorded their observations in their geological maps. Griesbach believed them to be due to

faulting while Diener left the ‘Klippen’ unexplained. In 1892, Greiesbach near

Sangchatalla discovered loose blocks of a red and white limestone with Jovites and

concluded that the blocks belonged to the Carnic stage of the Upper Trias. In 1900, Von

Kraft systematically mapped the ‘exotic block’ area, and collected numerous fossils,

chiefly ammonites. His conclusion that “The exotic blocks were brought up to the surface

by a violent volcanic outburst and later disturbance having thrust the whole into confusion”

could not hold good in the context of modern concepts. He died prematurely in Calcutta on

22 September 1901. Later on Professor Carl Diener of Vienna University was entrusted to

work over his collection. Diener (1898) commented “In their occurrence amidst much

younger sediments, and without stratigraphical connection with the later, which makes the

structure of the Chitichun area one of the most intricate and most remarkable in the Central

Himalayas”. Swiss geologist Augusto Gansser in 1936 who came to work with his teacher,

the late Professor Arnold Heim, established that the exotic blocks of Kiogar-Chitichun

extended to more than 5000 km2 and infer that the ‘exotic blocks’ could be classified in to

three categories in accordance to the physical association: (1) Exotic blocks associated

with the flysch; (2) Exotic blocks enclosed in the basic volcanites along the thrust plane,

and (3) The exotic humps along the ridge in Kiogad water divide.

(1) Exotic blocks in flysch have been elaborately described by Von Kraft (1902) in the

south of Kiogad peaks, they all occur as exotics. These blocks of Liassic age was initially

studied by von Kraft and again in 1936 Heim made a detailed study with Gansser (Heim

and Gansser, 1939). von Kraft first discovered Arietites and Phylloceras. The presence of

Sponga spicular and radiolarian in the dense limestone prove the deep sea facies. Many

other Liassic exotic blocks in Upper Cretaceous Eocene flysch are known to be embedded

associated with ophiolitic rocks are represented by serpentinites, spillites and amygdaloidal

basic igneous complex.

(2) A large number of exotic blocks have been noticed to be enclosed in ophiolite (Von

Kraft, 1902; Heim and Gansser, 1939a; Gansser, 1964). The exotics in the basic and

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ultrabasic complex from a widespread sheet showing enclosed limestone exotic blocks in

the ophiolite complex.

There is a wide variation in the composition of basic and ultrabasic rocks of ophiolite. The

igneous masses consist of large serpentine sheets with zones of ophicalcite, some

peridotites, diabases, basic, often amygdaloidal porphyrites and spillitic rock, and variation

of basic tuffs intermixed with siliceous flysch sediments. The K/Ar dating recorded age

are: 107.5 Ma

Figure 2.14: Exotic Block of Kiopeak-1 with ophiolite and Sangchamalla Formation

between Lower and Upper Cretaceous), 75 and 73 Ma (Companian-Maestrichtian) (Sinha

and Bagdasarian, 1977), shows that the earlier 107.5 Ma phase of ophiolitic eruption seems

to be followed by 75 Ma and 73 Ma eruptions. The entire range of Kiogad peaks are within

the ophiolitic complex. The other enclosed components are white Kiogad limestones, red

radiolarian cherts, dense brick-red limestones and marls (Gansser, 1964).

(3) In this category comes the Kiogad peaks (1 to 5) exotic mass. At a glance on the ridge

with Kiogad peaks, it looks like a continuous thrust-sheet, but with desiccated and eroded

features disconnecting each broken sheet of dense and fine marbleized limestone. The

average thickness of the mass is 200 to 300 m and the total area covered is 20 km2

(Gansser, 1964). In some places a vague plane of stratification could be observed which

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dips towards the north. The development of ophicalcite at the contact of limestone and

basic igneous rocks is very conspicuous and its thickness varies at different places from a

few metres to tens of metres (Sinha, 1989). The summits formed by these limestone blocks

vary between 5861 m to 5800 m.

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