KIMBERLITE

DIATREMES

AND

VOLCANOS:

SIMILARITIES

AND DIFFERENCES

CONTENT(preliminary version)

• 1. Geography & Tectonics• 2. Geomorphology• 3. Channel of eruption• 4. Petrology & Microstructure• 5. Mineralogy and Mineral resources• 6. Volcanology• 7. Genesis & Conclusions

Part 1

Geography

&

Tectonics

Fact:

Geographical distribution of kimberlites and

volcanoes is different with 100% negative

correlation.

Kimberlites occur within ancient cratons while

volcanoes – within young mobile belts.

Ancient cratons and folded belts are the two main tectonic elements of the Earth’s crust

Kimberlites occur within cratons

(After O.R.Eckstrand et al, 1995, Geology of Canada No. 8, GSC.)

Volcanoes occur within folded belts

Kimberlites vs. volcanoes by region.North & South Americas

Volcanoes (red dots) Kimberlites

No volcanoesin NWT Canada

No volcanoesin Brazil

No kimberlites in Ring of

Fire

Kimberlites vs. volcanoes by region. Yakutia, India and Australia

KimberlitesVolcanoes (red dots)

No volcanoesin Yakutia

No volcanoesin India

No volcanoesin Australia

No kimberlitesin Ring of Fire

India

Kimberlites vs. volcanoes by region. Europe and Africa

Volcanoes (in red) Kimberlites

No kimberlites in Iceland

SouthernAfrica

Iceland

No volcanoes in Southern Africa

N.Tanzaniavolcanoes

W.Tanzaniakimberlites

White Seaprovince

No volcanoesin White Sea

province

N.Tanzaniavolcanoes

Part 2

Geomorphology

Fact: Kimberlites and volcanoes create

diametrically opposite topographic forms:

volcanoes – positive

kimberlites – negative

There are no volcanoes with negative forms,

and there are no kimberlites with positive

forms of relief.

Volcanoes create positive forms of relief (Mt. Mayon, Philippines)

Kimberlite pipes create negative forms of relief (composite sketch)

(After Dr. A.R.Chakhmouradian

Geomorphology

There are no volcanoes without a cone: Klyuchevskoi volcano (left).

There are no diatremes with a cone: model of kimberlite pipe (right). Red dashed line indicates the same level for volcano and for diatreme: the end of a diatreme is a beginning of a volcano

Geomorphology

Simultaneous (?)

accumulation (volcano)

and excavation (pipe),

(386 km between them)

• Kilimanjaro (rhyolite volcano)

Age - 40 Ma

Height (Kibo) = 5,895 m (in air)

Crater size = 2.7 x 1.9 km

• Mwadui (kimberlite pipe)

Age – 41 Ma (C. Jennings, 1990)

Depth of crater 400 m (in granites)

Crater size = 1.5 x 1.2 km

GeomorphologyOl Doinyo Lengai

Part 3

Channel of eruption

Three-dimensional model of the Misery kimberlite complex

5034 kimberlite pipe, Canadaconsists of four lobes

Volcano has a simple pipe-like vent and a rounded crater filled with homogeneous rock (left)

Model of channel of eruption

Kimberlite pipes

have a complex

inner structure(previous slide as well)

Du Toit’s Pan pipe consists of dozen of kimberlite rocks with different grade

Kimberlite pipe walls structure

“Grooves or striae which appear after

mechanical abrasion of the pipe walls by

intruded kimberlite could be inclined or even

horizontal” (C.R.Clement, 1986). That means

that kimberlite magma had different directions

during its eruption which is impossible for

volcanoes.

Petrology…

Part 4

Petrology…

• Diatremes can be composed with rhyolites,

dacites, andesites, basalts, ultrabasic rocks

and carbonatites – the whole range of

effusive / hypabyssal rocks

• Volcanoes are filled up with rhyolites, dacites,

andesites, basalts and carbonatites. There are

no kimberlite rocks were found in volcanoes

Geological contacts between different kimberlites are very graduate. They do not conform to the classic structure of magmatic contacts, which must include zones of endo- and exo-contacts. They rather look like accumulative zones between different portions of the same batch of kimberlite magma.

Classic contact zone between broken and baked siltstone (bottom) and mafic sill with frozen endocontact

…inner structure

Xenoliths in effusive rocks are quite rare, because they were washed away by final batches of ascending lava. There is clear contact reaction rim around xenolith (black arrows)

“Volcaniclastic” kimberlite overfilled with xenoliths. There are no contact rims between xenoliths and cold magma

Xenolith gabbro in basalt. Hawaii. C.Benrley, 2010

Part 5

Mineralogy…

Mineral resources

• Diatremes can contain high quality

deposits of the long list of minerals like

gold, copper, iron, uranium, diamonds,

zinc, lead, etc

• Volcanoes themselves directly produce

mostly breakstone, some perlite, and also

some sulphur.

VolcanologyPart 6

Ol Doinyo Lengai Carbonatite

Kilauea Volcano

Kilauea VolcanoBasalt

Kimberlite should be between them

Types of volcanoes:kimberlite should be close to Hawaiian and Icelandic types,

far from Plinian

Eruption Type

VEI Main Rocks SiO2 (%)

Viscosity

Eruption Mode

VolcanicProducts

PlumeHeight

TroposphericInjection

Plinian 8 Rhyolites

65

Very high Mega-Colossal

Tephra

50 km Substantial

Pelean 7 Dacites 62

High

Colossal

Tephra

> 25 km Substantial

Vesuvian 5-6 Andesites

59

Intermediate

Paroxysmal

Tephra

10-25 km Substantial

Vulcanian 3-4 Rhyolito- Basalt

54

Moderate

Severe

Tephra, minor lava

3-15 km Substantial

Strombolian 1-2 Andesito- Basalt

51

Moderate

Mildly explosive

Tephra, minor lava

1-5 km Minor

Hawaiian 0 Basalt 48

Low

Gentle, Effusive

Lava, very little tephra

0.1-1 km Negligible

Icelandic 0 Basalt 45

Low

Non-ExplosiveMost peaceful

Lava, rare tephra

< 0.1 km Negligible

Kimberlitic Close to zero

Picrite-Carbonatite?

35?

Should be low

Should benon-explosive

Tephra should be rare

About 0.1 km?

Negligible?

Carbonatitic(Ol Doinyo)

0-3 Carbonatite

3-10

Very low Non-Explosive

Lava, rare tephra

0.01-0.1 km Negligible

Types of volcanoes and their main parameters

Blocks, no ash

Lapilli Ash, no blocks

Volcanic ash can’t make a deposit inside its own crater (Natural separation by size & weight)

wind

tephra

Volcanic ash makes deposits a hundreds kilometers away from the crater.

Volcanic ash

Solid, well-rounded kimberlite pellets of the TK- kimberlite, covered by 70 m of granites, 5034N, Canada (left), clearly differ from sharply angular porous pieces of volcanic ash, Brokeoff Volcano, California (right).

Pseudo-pyroclastic TK-kimberlite Volcanic ash

Some important numbers

Kimberlite magma was extremely cold:

below 200 degree (Davidson, 1964) to

400 degree (Dawson, 1980)

Volcanic lava has a temperature

between 1000 -1300 degree.

Tephra which was not found among kimberlites

Ribbon bomb “Bread crust” bomb

Rotation bomb Porous bomb

Autoliths which were not found in tephra

Autolith with stratified structure in the center and concentric structure around. Maliutka pipe, Yakutia. Slab

Concentric-zoned autolith. Dal'naya pipe. Yakutia. Thin section.

“Lapillus”. Victor-North“pyroclastic”kimberlite.Canada. B. vanStraaten et al.

Lapilli (?) unit in the El Guayal KT site.

(Salge and Claeys, 2000)

Which magic force could keep lapilli in suspended condition and protect them against falling down before the solid supporting matrix was created?

The Natural History Museum, 2000.Thin section.

Around - Liquid magma,Fine-grained fully crystallizedgroundmass of hypabyssalrock

Minerals

Kimberlite autolith

To

aut=To

mag

To

aut=3000

Kimberlite “lapillus”

Victor-North “pyroclastic” kimberlite with completelycrystallized groundmass.Ontario, Canada.

B. van Straaten, M. Kopylova, K. Russell, K. Webb, B. Scott Smith

Volcanic tephra

Around - Gases/air,Porous glassy groundmassof volcanic rock

Pores

Volcanic glassT

o

lap>>To

air

To

lap=10000

Minerals Pores

Porous volcanic bomb

Volcanic lapillus

Around - Gases/air,Porous glassy groundmassof volcanic rock

Around - Liquid magma,Fine-grained fully crystallizedgroundmass of hypabyssalrock

Pores

Volcanic glass

Minerals

Kimberlite autolith

To

lap>>To

air To

aut=To

mag

To

lap=10000 To

aut=3000

Minerals

Genesis & Conclusions

Part 7

Genesis.

• During the flight in atmosphere volcanic tephra obtained the

hard crust of the frozen surface (“bread crust”). This crust

has prevented lapilli against their tight junction into solid

magmatic rock. Such crust was never observed in kimberlite

rocks.

• Kimberlite pellets had never left their original magmatic

environment as far as they represent the silicate part of the

initially homogeneous kimberlite magma. These pellets are

cemented by an immiscible carbonatite (Kryvoshlyk, 1976,

2008).

Genesis

1. Volcano was created by eruption of a simple homogeneous magma.

2. Diatreme is a result of eruption of a composite magma, which fragmentation is a product of a liquid immiscibility. Liquid immiscibility is a wide spread natural phenomenon which can be observed by everybody everyday (oil in water).

3. Kimberlite “tuff” (TK, VK,…) is a mixture of picritic melt which was fine-dispersed starting from a molecular level within carbonatitic melt.

Conclusions

1. Natural sequence of volcanic events in modern

theories is broken: tephra must be generated

first, before lava, and lava must appear later,

after tephra. In kimberlite pipes we see lava (HK-

kimberlite) first and tephra (TK-kimberlite) later.

2. If the HK-kimberlite represents kimberlite lava, so

why there are no clear sharp contacts between HK and TK-kimberlites which should represent tephra? The fact is: there are many meters of HKt and TKt kimberlites between TK and HK