GEOLOGIC AND RAtIIOMETRIC SURVEY

OF PART OF THE

MONKTON-STARKSBORO AREA

Diane H. Variecek and Rebecca J. tiorsey

Division of Geolow, and Earth Resources (Vermont Geo1oica1 S'.irve)

Avenev of Erivirorimerita]. Conservation Mor,tpelier, Vermont 0602

1983

Open-File Report No. 1983-3

TABLE OF CONTENTS

Iritrodtctiari ... ... .... . . . .. ... . .. ... 1

hethods of Studs .......................3

Stratirh ........................4

Radioactivity .. ... .. .... .. .. ..... ... 7

Fiure i: Location Map Showinn Field Area ......... 8

Fi'jre 2 Map Showins Locations of Anomalies Found bw

Texas Instruments ................. 9

Fiure 3 Field Area Ma ..... ... ...... .. .

Figure 4 Detailed Map of Part of Field Area ....... . 11

References Cited ........ ... . . ... .... ... 12

INTRODUCTION

The Purpose of this studs was to conduct a around survey

of the radiometric anomalv located in the Moriktori and

Starksharo area (see Fi. Hy where abnormal concentrations

of radioactive material were found to he present bv Texas

Inistrutiterits (1976). They conducted a reconnaissance airborne

Aamma - rav survey of ,a portion of New En].arid for the U. S.

Energy Research and Deve1oment Administration. The obJect

of their survey was to 'define those areas showing surface

indications of a menerallv hiher uranium content.

(uraniferous provinces) where detailed exlorat.:áon for

uranium would most ]. ike].'d he successful. N

In the Lake Champlain 2-degree cuadrarisle (U20000)

Texas Instruments (1976) found 'preferred' and 'suspect'

anomalies (see Fig. 2). 'Preferred' anomalies are 'more

siriificarit anomalies showing 'Jranii'Jrn enrichment over the

mean val'.ies for the geologic map units involved and over the

mean U/Th arid/or U/K ratios for those units. Most of these

suest possibilities for veiri-te uranium Prospectsf but a

few aear to indicate potential itratiform deposits.'

The studs area is Texas Instrument's (1976) Location No.

21 which is a 'preferred' anoma1 (see Fig. 2). They found

the following Ppm eU in the studs area

3.4 Ppm in the Wiruooski, Mallet and tiuriham Dolomite and

Moriktori Quartzite.

2. 5 pp i ri the D ij n ha ii Do 10 m i t e.

2.8 Ppm in the Cheshire Quartzite.

Texas Instruments (1976) states that this occurrence

Smav be a vein-te accumulation, or mav he similar to

anomalies at Locations 5 and 6 (in the Milton area), which is

a radioactive zone in the Milton dolomite alons a mapped

.L'... 14. fi

METHODS OF STUDY

The UpTsefeTTedil anomalv in the Mor,kton-Starkshoro area

(Location No. 21), was studied bv the authors. See Figure 3

for a map of the field area.

A very detailed survey of geology and radioactiviv was

heurt along a predetermied arid system on Hoback Mountain

(see Fig, 4), This detailed work was abndoried when no

appreciable readiris were found using a amma-ra

spectrometer. Instead, a reconnaissance survey was done

covering the whole area (see Fi. 3), trvins to find the hih

concentrations that Texas Instruments (1976) reported.

3

STRATIGRAFHY

The rock units encountered in this studs include the

Late Precanibriari Fairfield Pond ForiTtatior, and the Lower

Cambrian Cheshire and Dunham Formations. The Aeolomw of

these units in western Vermont was compiled by r.ill, et al,

(1961)p and has more recerit].y been described by Tauvers

(1982), Greor (1982), Mrow (1983), and DiPietro (1983).

8iriificar,t radiometric anomalies were not detected in the

studs area, and no contacts between maior rock units were

observed. -

FAIRFIELD PONt' FORMATION

This unit was observed in only one outcrop at the

eastern edge of the reconnaissance survey. It was maed in

this area by Doll, et al, (1961), aspart of the Firinacle

Formation, but was later recon:ied as the Fairfield Pond

Formation by DiPietro (1983). It consists of a honioeneous,

fi.ssjle, trey to wreen chioritic ph1lite with local

occurrences of thin sands. beds.

CHESHIRE FORMATION

Lower Arillaceous Memher The arillaceous member of

the Cheshire Formation occurs locally at the core of a

regional north-plungint anticl inc • The hine of this

structure extends alons the northern flank of Hohack

Mountain where detailed mappins was initially undertaken for

4

this study (see Fi. 4). The ari11aceous Cheshire was also

recariiz.ed in one hill on the east side of Route 116.

This member consists of thint].y initerhedded whitish and

and dark tram ph].litic units. Intense deformation and

chlorite grade metamorphism have heavily overprinted and

obscured Primary features such as bedding and hioturhatiori.

Thus' the aril].aceous member is typically recognized by

alternatint thin bands of fine to medium sand and fine tray

phl].ite oiiented parallel to the dominant reianal

schistosit. Thicker massive sand units occur locally in

beds up to 8 feet thick. Mrow (1983) showed that the lower

Cheshire in the Bristoly Vermont area represents a tidal flat

and restricted basin environment which is overlain by the

trarisressive deeper water uer member,

Upper Massive MembeW The uer member of the Cheshire

Formation was identified in outcrops north of Hoback

Mountain and in samples taken from a drilled water well to

the east of Hoback Mountain. The uer member consists

primarily of massively bedded, l:i.ht brayy coarse trained

cuartzite with only minor thin phllitic partinis.. It was

shown by Myrow (1983) to rereserit hih er,ery subtidal sand

bodies deposited offshore from the lower Cheshire tidal flat

sei_Ierice

DUNHAM FORMATION

The tiuriham Formation was described in detail for

northwestern Vermont by Gregory (19825 who documented a

5

I - - - - - -

trarissressive sewJeruce of Peritidal to subtidal shelf ede

carbonate environments. No environmental ana].ysis was

attempted for this studs. The Dunham is a hilh1v varied unit

consisting of thin to thick bedded dolomite with common zorues

containing vertical and horizontal worm burrows. Sands beds

up to 1 or 2 feet thick and occasional thin shalev partiris

were observedy with colors ranging from dark tray to cream to

pink. One unit of do].omitic sarirjstone (blue color on Fi.

3), was located within the Dunham Formation and was estimated

to he 40 to 80 feet thick. Cleavae and other deformation

features are minimal throuhout the Dunham in this area.

DI 0 A CT ivii Y

No location in the studs area, or Just outside of the

studs area, were appreciable amounts of radioactivity found

(see Fi+ 3),

The highest readins in the area (40--60's) were found an

Hoback Mountain in the euartzites of the lower member of the

Cheshire Formation (see Fig. 4), Most of the readinis in

this litholo5v were uniformly in the 40's with one 50 and one.

60. These two hiher readiris were not associated with an

noticeable variation of the characteristics of the rocks.

The readiris in the other litholoies in the studs area

ranred from 16 to 40, with most,beins in the 20's.

7

8

RichIo7 —

EXPLANATION ke

*Isl,-

' c ' ) / Lwe11 / c Albans / fO,L E p ( I Git.. syesite, bssalt, dunite, peridot-itc,

( f I I q NLnnjo,j ) .,' / 1\ Q \ ' st r

f \ Haven\f e Jifl Stiurtan-Devoman

szwc, timrolonr,quartoite. con- phyllul, ioh on 1. to hat m tn gene phsbo- L. Intruded by granite, and nyemte.

', A M$$ [ E Cai4n f'\

IvJC €ster

EEN Har k CALEDO IA

B LTNGT( / '.,

Ordonian

Tuconic Range—SLaB, geuy,escho, quartzite,harsioar, conglom- - orate, ,nurbte.

far: ' . St. Johnsbury - Champlain-Vecmontvalloyn Shak,dolornito,Zimeolose,quarto-

•c, Green Mountaina—Phylliio, ochiat, q000toite, groraotonc, slate,

0 - I - graywacke, goios, conglomerate, amphtb-olito.

Eastern Vermont—Phyllite, qoortzite, greonotone, sghiul, gee-

Monkto W.A I N T 0 / >-

Intruded

M ELIE

Bar :

Cmbrtv 0

- Bristol I - / J Taconic Range—State, groo-okc, qvortzte, hmestone, phyllite, sandstone. ,00eblc, dolomc,e.

Champlain-Vermont valley.—Qaurlr.doiomilc,slate,phylltte,

/ conglomerate, marble. A D U S ) I

Id b 0 A N co

Green Mountains—Sehisi, phyilile, qoartsite, graywseke, con-glomeeste, /rrennlosr, dolomite, lime- / stone, gneiss, .asphibolilo.

- Lgtke Moreii ( °

Intruded by ultrabanie rocks, basalt.

k. Dunm : '

8

South

La ? Fai

.Strafford to I - Precasnbr.an

Citamplain Volley (smell urea)—Gsniss, quartoite, granulite. Green

Eastern Vermont—Geress, orhiol, quartoite, calotte, and dub-

/ mite marble, omphibolite.

ake Predominant and important rooko in italics. Bo en

st1eton oo tock - .,.er

Earth Mateeiale

(land Ct Taconic Range—Slate, marble.

Went Champlain-Vermont valleys clay, kaolin,

RU — -

Green Mountains—Talc, asbestos, verd antique marble, road- stone.

001 I U OR / lose- ( Eastern Vermont—Granite, talc, eoadstone, copper (now

For uses conanit The Mineral /sdsalra of Vermo

8 1.

a ne Classic Structures U.S. Bureau of Mines, Preprint, tel , rn Superintendent

I Printing Jfllce, Waohingtoo, I) .C.

WesI t - Do Champlain thrust fault Also, use information available from the mineral industries,

D The more detailed Centennial Geologic Rap of Vermont, scale 125q000,avasbabbe from State L,brar,a, Vermont St to

TJ Taconic klippe hot.

llinesburg thrust fault, r .

GENERALIZED

W I N D GEOLOGIC MAP OF VERMONT

1970 Ben -

$ Br tleboro 4 0 4 SCALE

8 12 16 MILES

Adayted from the Centennial Geologic Map of \'ermont by Charles G. Doll, State Geologist.

A S S Figure 1. Location Map Showing Field Area.

S;;--. : I ' • .- , i .- , C

tN : Y12J T I I

/\ 00 \ci- 2i ° J (

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Vfr744_J / Jh'

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VipH L et er

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i 7 .VERMONT

4 5

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o j -

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it

En

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1]oac SeeUedetailed C bV UR

Clem Mount

map of this 211 0 / - Figure 3. Field Area Map area. J;)4 (

N EXPLANATION '

OL

Outline of anomalous area (Texas Inst , 1976)

otic t sandy dolomite

Cheshire Fm Upper Member--Massive, light gray, coarse grained quartzite.

Lower Member--Thinly bedded, highly cleaved argillaceous qzte.

• Fairfield Pond Fm Homogeneous gray to green chioritic phyllite

/Th I 50's cps using spectrometer (average of 5 one second counts)

Lil

I

thone pole

Figure 4. Detailed map of part of the field area (seeFigure 3 for location). All rocks are lower. member of the Cheshire

N Formation.

Scale 1:1,200

20 cps using spectrometer (average of 5 one second counts) ..

12

Is REFERENCES CITED

DiPietroy J. A+f 1983, Geolo of the Starksboro Area, Vermont

Vermont Geo1oical Survey, Special Bu11etiri No. 4,

Doll., C. 6., Cadyy W. M., Thompsony J. B., Jr.Y and Bil1ins, M. compilers and editors, 1961, Centennial eo1oic map of Vermont: Vermont 6eoloica1 Survey, scale 3. 2O,000.

Gre!Jorvy G. J., 19829 Paleoerivirorimerits of the lower Camhr:iani Dunham Dolomitey northwestern Vermont: Master's thesis, University of Vermont, B'.irlintonv VT, 91 P.

Myrow, P.9 1983, A paleoenvironlTiental analysis of the Cheshire Formation in west-central Vermont: Master's thesis, University of Vermont, Burlington, VT, 210 P.

Tauvers, P. R.Y 1982, Bedrock eoio of the Lincoln area, Vermont: Vermont Geological Survey, Special Bulletin, No. 2.

Texas Instruments, Inc., 1976, Airborne sjeophysical survey - of a portion of New Eriland Presared for the U. S.

Enery Research and Development Administrations Grand Junction Officey contract nos. E(05-1)-1666 and E(05-1)-1667, GJO-1666--1.