-7993-MS Informal

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-7993-MS

Informal Report

Thermal Gradients and Heat Flow Data in Colorado and Wyoming:

A Preliminary Report

Post Office Box 1663 Los Alamos. New Mexico 87545

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U N I T E D S T A T E S D E P A R T M E N T O F E N E R G Y C O N T R A C T W-7405-ENG. 3 6

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LA-7993-MS Informal Report Issued: August 1979 UC-66a

Thermal Gradients and Heat Flow Data in Colorado and Wyoming:

A Preliminary Report

E. R. Decker*

G. J. Bucher*

*Department of Geology, University of Wyoming, Casper, WY 82601.

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THERMAL GRADIENTS AND HEAT FLOW DATA A PRELIMINARY REPORT I N COLORADO AND WYOMING:

E. R. Decker and G. J. Bucher ABSTRACT

Temperature g r a d i e n t d a t a and h e a t f l o w d a t a a r e compiled f o r 23 c o r e and r o t a r y d r i l l h o l e s i n t h e Rocky Mountains o f Colorado and Wyoming.

t h e Medicine Bow Mountains, Wyoming, t o 40.1"

C/km i n t h e San Juan Mountains, Colorado. Un- c o r r e c t e d h e a t f l o w ranges from 1.1 t o HFU a t Rawlins, Wyoming t o 6.1 a t Rico, Colorado.

G r a d i e n t s range from 10.7"C/km i n

I. INTRODUCTION

T h i s r e p o r t r e f e r s t o c o n t r a c t s N28-38966-1 and N28-4934H-1 ( d i r e c t e d by E. R. Decker, U n i v e r s i t y o f Wyoming). Research t o d a t e has emphasized tempera- t u r e d e p t h measurements i n 23 c o r e and r o t a r y d r i l l holes i n Colorado and Wyoming.

Thermal g r a d i e n t s and h e a t f l o w v a l u e s have been compiled f o r many o f these h o l e s . t h e San Juan Mountains i n southwestern Colorado.

R e l a t e d f i e l d work i n v o l v e d c o n t r a c t c a s i n g o f a deep ( ~ 6 7 0 m ) c o r e h o l e i n

11. WORK I N PROGRESS

Radiogenic h e a t p r o d u c t i o n v a l u e s a r e b e i n g determined f o r many o f t h e deep h o l e s t h a t p e n e t r a t e d i n t r u s i v e r o c k s i n t h e s o u t h e r n Rocky Mountains (see Table Core and/or c h i p samples

for

thermal c o n d u c t i v i t y measurements f o r many o f these holes w i l l be a v a i l a b l e i n t h e near f u t u r e .

11).

111. DATA

F i g u r e s 1-23 a r e p l o t s o f temperatures and depths i n 23 d r i l l h o l e s t h a t a r e b e i n g analyzed under t h e c o n t r a c t s . T a b l e I i s a c o m p i l a t i o n o f g r a d i e n t s f o r n i n e o f these h o l e s . Observed (qu c ) and c o r r e c t e d (qco ) heat f l o w d a t a f o r 1 2 o f these l o c a l i t i e s a r e l i s t e d i n Pable 11, as a r e h o l e Vocations t o t h e n e a r e s t

1

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minute.

for three-dimensional

topography1.

Each correction

was made f o r t e r r a i n f o r a

lateral

d i s t a n c e

equal t o

20

times t h e

d e p t h o f each hole.

Figures

1-23 and

Tables

I and I 1 represent

the

most r e l i a b l e data t h a t

we have been

a b l e

t o

obtain.

These d a t a

will y i e l d publishable

heat

flow values.

A l t h o u g h many

other s i t e s

(about 20) have been visited

for

temperature-depth

measurements, the d a t a for them

cannot be used f o r r e l i a b l e heat flow calcula-

tions because the holes were

blocked a t

very

shallow d e p t h s .

The

corrected heat flow values d i r e c t l y follow Birch's (1950) correction

TABLE I

SUMMARY OF PRELIMINARY GRADIENT VALUES FOR DRILL HOLES

Colorado E l k h o r n W i

n

f i

el

d Chicago Basin V . Basin

Del Norte

Wyom i

n

g

Sand Lake

(Medicine Bow

Mtns)

Rawlins (Red R i m ) Doug1

a s

(Powder River Basin)

#LCI

#LC2

Grad i en

t

*C/km 24.6 30.3

30.9, 28.8

27.6 40.1

10.7 16.4

34.4 33.8

1 . Francis Birch, "Flow o f heat i n t h e Front Range, Colorado,"

Geol.

SOC. Am.

B u l l .

-

61, 567-630 (1 950).

2

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TABLE 2

SUMMARY OF PRELIMINARY HEAT FLOW VALUES Local i t y

Colorado

Heat Flow H FU L o c a t i o n

W. Long., N. L a t .

qu nc %or

E l khorna Apex

105" 32', 40" 45' 2.13 1.96

105" 33', 39" 52' 105" 34', 39" 52'

1.50 1.79

1.42 1.58

W i n f ie l d 106" 26', 38" 58'

106" 27', 38" 59' 2.88 2.84

2.97 2.74

Chicago Basina 107" 3 7 ' , 37" 36' 2.69 2.45

a, b

V . Basin 107" 35', 37" 34' 1.91

2.44

2.11 2.29 Redwell Basin

R i co

107" 3 ' , 38" 54' 3.26 3.62

108" 1

',

37" 42' 108" 2', 37" 42'

5.2

-

^5.9

5.2

-

^6.1

Del N o r t e S u m m i t v i l l e a

106" 22', 37O47' 2.68 2.69

106" 36', 37" 26' 2.3 2.4

Wyoming Sand Lake A1 ba nya Raw1 i n s

106" 14, 41" 29' 106" ll', 41" 1 2 ' 107" 27', 41" 44'

1.4 1.4

-

^1.5

1.60 1.62

1.1 1.1

~

a R a d i o a c t i v i t y measurements i n progress.

bCased w i t h monies p r o v i d e d by LASL c o n t r a c t .

3

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