A preliminary analysis of ERTS-1 imagery of the Northern Coast Ranges and Sacramento Valley, California, has disclosed a potentially important fracture system which may be one of the controlling factors in the location of known mercury deposits in the Coast Ranges and which appears to be associated with some of the oil and gas fields within the Sacramento Valley. Recognition of this fracture system may prove to be an extremely useful exploration tool, hence careful analysis of subsequent ERTS imagery might delineate areas for field evaluation

Rich, E. I.

English

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Paper G 18 
RELATION OF ERTS-1 DETECTED GEOLOGIC STRUCTURE TO KNOWN 
ECONOMIC ORE DEPOSITS 
Ernest I .  Rich, Department ~f Geology, Stanford University, Stanford, California 
AESTRACT 
A prel iminary ana lys i s  cf ERTS-1 imagery of t he  Northern Coast 
Ranges and Sacramento Valley, Ca l i fo rn i a ,  has  d isc losed  a p o t e n t i a l l y  
important f r a c t u r e  system which ma) Lc o :e of t h e  con t ro l l i ng  fac-  
t o r s  i n  the  loca t ion  of knom mercuty d e p o s i t s  i n  t h e  Coast Ranges 
and which appears  t o  be assoc ia ted  with some of t h e  o i l  and gas  
f i e l d s  wi th in  t h e  Sacramento Valley. Recognition of t h i s  f r a c t u r e  
system may prove to  be an extremely use fu l  explora t ion  t o o l ,  hence 
c a r e f u l  ana lys i s  of subsequent ERTS imagery might d e l i n e a t e  a r e a s  
f o r  f i e l d  eva lua t ion .  
INTRODUCTION 
The i n t e n t  of t h i s  r e p o r t  is t o  armrmarize, i n  a p re lh i . na ry  way, 
t he  reg ional  geologic s t r u c t u r e  of the  Northern Coast Range and Sacramento 
Vnlley, Ca l i fo rn i a  and t o  suggest a poss ib le  r e l a t i o n  between the  geologic 
s t r u c t u r e  and known occurrences of mercury, hot  spr ings  (geothermally 
a c t i v e  a r e a s ) ,  and some of the o i l  and gas  f i e l d s  of nar thern  Cal i forn ia .  
The a rea  covered by t h e  stud.y includes a l l  of northwestern Cal i forn ia ,  
extending from t h e  l a t i t u d e  of San Francisco Bay on t h e  south, t o  t h e  
California-Oregon border on the  north,  and t h e  P a c i f i c  Ocean on the  w e s t ,  
t o  t he  western f o o t h i l l s  of t he  S ie r r a  Nevada on the  e a s t  ( f igure  1 ) .  
The o r i g i n a l  ob jec t ive  f o r  examining t h e  ERTS imagery was t o  determine 
the  f e a s i b i l i t y  of de t ec t ing  g ross  l i t h o l o g i c  and s t r u c t u r a l  da t a  from 
s a t e l l i t e  imagery. In  prepara t ion  f o r  t h e  examination of t h e  a a t e l l i t e  
imagery, ERTS-compatible photographs were obtained from USA, U-2 a i r c r a f t  
underf l i g h t s ,  which were flown i n  conjunction wi th  an  on-going environ- 
mental study of t h e  San Francisco Bay Region by t h e  U.S. Geological Survey. 
These photos were taken a t  varying time i n t e r v a l s  during 1970 t o  1972 and 
under va r ious  c l ima t i c  condit ions.  I n  addi t ion ,  t h e  photographs from a 
s i n g l e  s t e r eo - s t r ip  along t h e  39th p a r a l l e l ,  extending from t h e  P a c i f i c  
Ocean t o  t h e  c r e s t  of t h e  S ie r r a s ,  a d i s t ance  of about 320 h (200 miles), 
were flown f o r  another  ERTS inves t iga to r  and copies  were made a v a i l a b l e  
t o  t he  pro jec t .  From these  va r ious  sets of photographs, v i s u a l  i n t e r -  
p r e t i v e  c r i t e r i a  were developed f o r  each mul t i spec t r a l  bandwidth and, 
395 
Original photography may be purcfiad 
E.;'l; ,h:a Cerller 
1~;;: ?nd Dakota Avenue 
Sioux Falls, SD 571s - 
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https://ntrs.nasa.gov/search.jsp?R=19730019517 2020-03-17T08:43:58+00:00Z
FIGURE I 
OUTLINE MAP OF CALIFORNIA SHOWING PHYSIOGRAPHIC PROVINCES 
wtthin the  l i m i t s  of t he  ava i l ab le  photography, t h e  photo- .charac ter i s t ics  
of t he  var ious  rock types under seasonally d i f f e r e n t  c l ima t i c  condi t ions  
were evaluated and recorded f o r  l a t e r  use.  Data from these  unde r f l i gh t s  
suggested t h a t  t h e  ob jec t ive  of t h e  p ro j ec t  could be bes t  served by 
grouping the  wide v a r i e t y  of l i t h o l o g i c  types wi th in  the  a rea  i n t o  th ree  
broadly defined l i t h o l o g i c  groups: 1 )  ultramaf i c  igneous rock, including 
p e r i d o t i t e ,  se rpent in ized  p e r i d o t i t e ,  and se rpen t in i t e ;  2 )  ex t rus ive  
volcanic rocks,  including andes i t i c -basa l t  contained wi th in  the  l a t e  
Mesozoic Franciscan assemblage, rhyo-daci t ic  flows of t he  Pl iocene t o  
Recent Sonoma-Clear Lake volcanic f i e l d s ,  and Pliocene t o  r ecen t  b a s a l t i c  
volcanic flows of the  Modoc Pla teau  (nor theas tern  Ca l i fo rn i a )  ; and 3)  
sedimentary rocks,  including the  l a t e  Mesozoic m a r h e  sedimentary rocks  
of t he  Great Valley sequence, Te r t i a ry  marine and n o r i i r i n e  sedimentary 
rocks along t h e  m a ~ g i n s  of t h e  Sacramento Valley and p a r t s  of t h e  c o a s t a l  
b e l t ,  and recent  unconsolidated sediments, such as t h e  alluvium wi th in  
the  Sacramento Valley and along t h e  major drainages.  
Rel iab le  l i t h o l o g i c  iden t i f  ;cation depends, t o  a l a r g e  ex ten t ,  on 
r e l a t i n g  the  photogeologic c r i t e r i a  t o  vege ta t ion  cnanges, which occur 
on t h e  var ious  l i t h o l o g i c  groups, during the  annual seasonal  changes 
(wet t o  dry  season and/or dry  t o  wet season). ERTS da ta  f o r  a l l  of 
these  time periods a r e  not present ly  ava i l ab le .  A reg ional  geologic 
s t r u c t u r a l  i n t e r p r e t a t i o n  has  beeu made from the  a v a i l a b l e  ERTS imagery, 
independent of t h e  l i t h o l o g i c  da t a ,  and is  presented here. Undoubtedly 
the  s t r u c t u r a l  i n t e r p r e t a t i o n s  w i l l  need t o  be modified when t h e  l i t h o -  
l o g i c  groups can be more c l e a r l y  iden t i f i ed .  
The regional  geologic s t r u c t u r e  was not  s tudied  i n  d e t a i l  during the  
preliminary preparatory s t age  of t h e  p ro j ec t  a s  i t  was bel ieved t h a t  the  
s t r u c t u r a l  f e a t u r e s  could be independently evaluated. After  r e c e i p t  of 
t h e  f i r s t  ERTS-1 imagery, t h e  frames were c a r e f u l l y  analyzed and the  chief  
geologic s t r u c t u r a l  elemen's were recorded. Each frame was enlarged and 
t h e  geologlc da t a  t r ans fe r r ed  t o  a topographic base map of northern 
Ca l i fo rn i a  (1:500,000 sca l e ) .  Data on the  loca t ions  of mineral  and f u e l  
depos i t s  were obtained from resource maps published by the  Ca l i fo rn i a  
D!.vision of Mines and Geology. 
GEOWGIC STRUCTURES 
The geologic s t r u c t u r e  of t h e  Coast Ranges is  extremely complex and 
poorly understood. Recent ideas  baegd on p l a t e  t ec ton ic s ,  o r  seaf loor  
spreading, a t t r i b u t e  t h e  s t r u c t u r a l  complexity (mhlange-style deformation) 
t o  t h e  piling-up of oceanic--plate n a t e r i a l  along a subduction zone 
associa ted  wi th  a late Mesozoic t r ench  (Ernst,  1970). The coeval marine 
sedimentary rc-ke of t h e  Great Valley sequence are l i t t l e  deformed and 
a r e  thought t o  have been derived from a Sier ran  a r c  and t o  have been 
deposi ted i n  a l a t e  Meeozoic "arch-trench gap" which probably e r i e t e d  
between the  Coaet Range Trench and the  Sier ran  Arc (Dickineon and Rich, 
1972) . 
A prel iminary examination of ERTS imagery d isc losed  th ree  poten t i -  
a l l y  important systems of l i n e a r  f e a t u r e s  within the  Coast Ranges which 
may represent  f a u l t  systems or  shear  zones inasmuch a s  topographic o f f -  
s e t  and s t r a t i g r a p h i c  d i s r u p t i o n  can be seen along some of t h e  l i n e -  
a t i o n s  ( f i gu re  2 ) .  Some of the  l i n e a r  feazures  shown on f i g u r e  2 rep- 
r e sen t  bedding t r a c e s ,  o r  unusual alignment of topographic f e a t u r e s ,  
and s t i l l  o the r s  have no p re sen t ly  know. explanat ion.  
One of the  systems is  subpa ra l l e l  t o  t he  San Andreas f a u l t  and i s  
confined t o  t h e  P a c i f i c  c o a s t a l  b e l t  (Coastal System). Another s e t  of 
l i n e a t i o n s  ( the  Cent ra l  System), which a t  t h e i r  nor thern  terminus acute-  
l y  j o i n  but  do not  t r a n s e c t  t h e  Coastal  System, is confined t n  t he  co re  
of t h e  Coast Ranges. It is l e s s  we l l  defined but  it appears  t o  be t he  
chief  c o n t r o l  f o r  t he  s t r u c t u r a l  and topographic g r a i n  of t h e  t e r r a i n .  
These two systems can be seen on f i g u r e  3 (ERTS-1, Frame No. 1094-18231- 
MSS-6). The t h i r d  s e t  of l i n e a r  f e a t u r e s  ( the  Valley System) has not 
been c l e a r l y  recognized here tofore .  It t rends  no r th  or  no r theas t e r ly ,  
a t  obtuse angles  t o  t h e  Central  System, and one o r  two l i n e a t i o n s  v i t h -  
i n  t h i s  system can be discontinuously t raced  from the  co re  of t h e  Coast 
Range ac ros s  the  a l l u v i a t e d  p a r t  of t h e  Sacramento Valley i n t o  t he  foot-  
h i l l s  of t h e  S i e r r a  Nevada, f i g u r e  4 (ERTS-1, Frame No. 1075-1870-MSS-5). 
S t r a t i g r aph ic  d i s rup t ion  of t h e  l a t e  Mesozoic Great Valley sequence along 
t h e  western margin of t h e  Sacramento Valley ( f i gu re  4 ) ,  is, i n  p a r t ,  
assoc ia ted  with t h e  Valley System. Linear elements subpa ra l l e l  t o  t h e  
Valley System, can be de tec ted  i n  t h e  Coast Ranges and t h e  a l l u v i a t e d  
p a r t  of t h e  Sacramento Valley. Within t h e  Sacramento Valley,  they may 
r e f l e c t  t h e  cont inua t ion  of t h e  Valley System wi th in  t h e  bedrock t h a t  
f l o o r s  t h e  Valley. I n  t h e  nor thern  p a r t  of t h e  a r e a  t h e  Valley System 
is roughly p a r a l l e l  t o  t h e  off-shore Mendocino Escarpment and i t s  land- 
ward extension.  
The ERTS imagery of t h e  Klamath Mountains and Modoc Pla teau  of 
northern Ca l i fo rn i a  and southern Oregon have not  been completely evaluated 
a t  t h i s  time; hence, some of t h e  t r ends  of t h e  l i n e a r  f e a t u r e s  i n  t h e  
northern p a r t  of t h e  Ca l i fo rn i a  Coast Ranges, shown on f i g u r e  2, may 
r e f l e c t  t h e  inf luence  of t he se  two l a r g e  geologic f ea tu re s .  
The l o c a t i o ~ s  of known mercury d e p o s i t s  and nor thern  Ca l i fo rn i a  o i l  
and gas  f i e l d s  have been p lo t t ed  on t h e  map ( f i gu re  2). Some of t h e  
mercury depos i t s ,  r ecen t  volcanism, a s  we l l  a s  some of t h e  geothermally 
a c t i v e  a r e a s  near  Clear Lake, i n  t he  Coast Ranges, a r e  along t h e  Valley 
System o r  a t  t h e  i n t e r s e c t i o n  of t h e  Cent ra l  and Valley systems; however, 
o the r  mercury d e p o s i t s  seep t o  be  more c l e a r l y  r e l a t e d  t o  +he Cent ra l  
Syetcm, o r  appear t o  show no d i r e c t  r e l a t i o n  t o  t h e  l i n e a r  systems. 
This  prel iminary review suggests ,  however, t h a t  r ecogn i t  ion of t h e  
l i n e a r  systems may p r w e  t o  be  an  extremely va luable  explora t ion  t o o l .  
A l l  of the  o i l  and gas f i e l d s  i n  northern California a r e  b e n u t h  
the a l luvia ted  pa r t  of the Sacramento Valley. The locat ionr  of rome 
of there  f i e l d 8  a r e  c losely  associated with some of the l inea r  elamentr 
i n  the  Valley Syrtam and o the r s  with the  l inea r  elemento of the Central 
Syrttm. A thorough ana lys i s  of the  publiehed data  i e  underway i n  order 
t o  determine the  subeurface control  i n  u c h  of the f i e l d s .  If the rm- 
la t ione  reported here prove r e l i a b l e ,  the  ana ly r i r  of ERTS imagery may 
ntggert other areae f o r  mineral f u e l  exploration. 
REFERENCES CITED 
California Divieion of Minee and Geology, 1955, Economic Mineralr Map8 
of California,  Special Bull. 45. 
Dickinron, W.R,, and Rich, E.I.,  1972, Petrologic Ingervalr and Petro- 
f a c i a s  In  the  Great Valley requence, Sacramento Valley, California:  
Geol. Soc. American Bull. v. 83, p. 3007-3024. 
Ernrt , W.G., 1970, Tectonic contact  brtwwrt the Francircan mhlange 
and the  Great Valley requrncr, c r u r t a l  arprerrior. of a l a t e  Pirroroic 
Benioff zone: Jour. Geophyr. Rerearch, v. 75, p ,  886-902. 
FIG. t. MAP OF NORTHERN COAST RANGES AND SACRAWTO VALLEY, 
CALIFORNIA SHOWING ERTS-RECOGNIZED GEOLOGIC STRUCTURES. 
Eigure 3. Part sf N0rtlier.r California Coast Ranges showing prominent l inear 
systems: Coastal System includkng the  San Andreas and related 
Sau!.ts, near coast between Point Reyes (1) and Point Arena (2) ;  
Central System between San Francisco Bay (3) and northwestern 
part of image; and a ~rominent linear of tke  1,'alley System trends 
northeasterly through Clear Lake (4). Masyevflle Butte 
laeco l i th  (5) and topographic depression ( 5 )  within  Sacramento 
Valley (ERTS-1 Frame, 1094-16231-6). 
Figure 4. Part of Sacramento Valley and Sierra Nevada footh i l l  belt showing 
extension of the Central System into the Valley alluvium near Lake 
Berryessa (1) and a prominent iinear of the Valley S y s ~ m  through 
Herysville Buttes laccollth 2 )  Circular topographic deyression- 
caldera? ( 3 ) .  See figure 2 far d e t a i l s  (ERTS-1 Frame, 1075- 


Relation of ERTS-1 detected geologic structure to known economic ore deposits

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