FORMATO DE SCANNEO
INFORMES GEOlAIGICOS Y GEOFlSlCOS
C l T C O I N T E R N A T I O N A LP E T
1 9 00 N O R T H L O O P W E S T
HOUSTON. T E X A S
TELEPHONE: (713) 883-2000
TELEX: 7 6 - 2 0 5 6
C A B L E : ClTEXPET
December 1 8 , 1981
REPLY TO:
"--
M r . L. M. Asbury
Arco International
515 South Flower S t r e e t
Box 2676
Los Angeles, CA 90051
í"
-
Mr. I. H e r r i c k
Amoco International Oil Company
P. O. Box 4381
t
Houston, Texas
77201
Mr, B , Toborda
Ecopetrol
Carrera 13, No, 36-24 P . l l
B O g O t a , Colombia
"La Luna Source Rocks in the Middle Magdalena Valley, Colombia"
by J. E. Zurnberge.
SUBJECT:
, u F Gec L'"
As a result a€ John Zurnberge's presentation t o the 26th International Geological
Congress, Paris, 1980, on t h e correlation of o i l s t o source rocks in Colombia,
he has been asked t o submit a paper for i n c l u s i o n in an AAPG compendium on
carbonate source rocks. This is being compiled by J i m Palacas o f t h e USGS.
-.
!
A first d r a f t of
the proposed paper i s attached for your information. There is
no a d d i t i o n a l material o v e r and above t h a t contained in the 1980 p r e s e n t a t i o n .
On this b a s i s , Cities Service has authorised John Zumberge t o submit t h i s d r a f t
for publication.
If you have any q u e s t i o n , please do not hesitate to c o n t a c t me.
Paul R. Achton
Manager Geology
PñA/dc
Enclosure
CC:
E.
A. Quinones, Bogota
J. Zumberge, Tulsa
"
L A LUNA SOURCE ROCKS IN THE MIDDLE
MAGDALENA VALLEY, C O L O M B ~ A
-~-I
I_-
bY
John E. Zumberge
Cities S e r v i c e Research
P.O. Box 3908
Tulsa, OK 74102
A3 STRAC T
Carbonate-rich o u t c r o p s from t h e Upper Cretaceous La Luna Formation i n
-
the Middle Magdalena Valley, Colombia average 4 . 3 % total
2500 ppm extractable hydrocarbons,
o r g a n i c c a r b o n and
Microscopial and elemental analyses of
w
La turn kerogen suggest t h a t the orgarrlc matter in these La kilns samples is
m a r i n e o r i g i n and a t a maturity l e v e l within t h e o i l generation zone.
-
úf
Biochem-
.-
i c a l fossil distributions a t t e s t t o a n aquatic microorganism source due t o
abundant C27 steranes r e l a t i v e t o C29 steranes, low q u a n t i t i e s o f C1g and C 2 0
tricycl i c di terpanes r e i a t i ve t o extended ( u p t o C30) t r i c y c l i c di terpanes, and
u b i q u i t o u s hopane t r i t e r p a n e s .
INTRODUCTION
,-
The Cretaceous La Luna Formation has long been ascribed t o as t h e source
rock for much of the oil found i n t h e Maracaibo Basin of Venezuela (e.g.,
Hedberg, 1 9 3 1 ; 8ockmeulen e t a l . , 1981).
Valley, Colombia,
Crude oils from t h e Middle Magdalena
r e s e r v o i r e d in T e r t i a r y f l u v i a l . sands, have recently been
shown t o have also been generated, i n p a r t , from the Upper Cretaceous La Luna
Formation based on geochemical corre1 a t i o n techniques such as stable carbon
isotopes and biochemical fossíl d i s t r i b u t i o n s (tumberge, 19801.
of t h i s p r e s e n t study is t o d e s c r i b e i n detail the
widespread and pro’li f i c cal careaus source rock,
The o b j e c t i v e
organic geochemistry o f this
I
8
Outcrop samples were c o l l e c t e d along t h e \
eastern flank of the Nuevo
--------
--i
Mundo Syncl-ine--in
t h e Middle Magdalena B a s i n approximately 20 km west o f
/--
Bucaramanga, Colombia,
Although the samples
are from outcrops, care
was taken
t o c o l l e c t unweathered specimens; however, some o f the observed v a r i a b i l i t y o f
t h e data may be due t o d i f f e r e n t i a l weathering e f f e c t s -
A l l t h r e e members o f
t h e L a Luna formation (Gaiembo, Pujamana, and Salada) were sampled; the o l d e r
S a l a d a member samples were collected - 5 km south o f t h e Galembo and Pujamana
-
.
members sample collection area (Quebrada La Sorda),
t i o n ranges f r o m 150 m t o 600 m.
The thickness o f the forma-
i n general, the La Luna Formation in t h i s
r e g i o n can be lithologically described as c o n s i s t i n g o f dark grey t o
black
calcareous shales w i t h varying amounts of i n t e r b e d d e d 1 irnertanes and some t h i n
chert beds.
i n t h i n section, La Luna samples f r o m t h e Pujamana and Salada
members c o n t a i n abundant calcareous planktonfc forami n i f e r a and other p e l a g i c
c i r c u l a t i o n (M. Longman, personal
comunication).
no evidence o f land-derived m a t e r i a l ,
-
Except f o r a e o l i a n c l a y s ,
such as d e t r i t a l
quartz, was found.
F o r a m i n i f e r a t e s t s which a r e n o t fílled w i t h calcite a r e o f t e n filled w i t h oil
as was determined by fluorescence microscopy in reflected l i g h t { S . Palmer,
personal communication).
These Colombia L a Luna samples are remarkably simi-
lar to La Luna rocks f r o m northwestern Venezuela as described by Hedberg (1931)
more than f i f t y years aqo.
EXPERIMENTAL
Rock samples were ground t o (100 mesh w i t h subsequent H C l d i s s o l u t i o n
and o r g a n i c carbon combustion u s i n g a Lec0 Carbon Analyzer i n order t o d e t e r m i n e
I
f
'
#
approximate percent carbonate and t o t a l organic carbon.
Powdered samples were
s o x h l e t extracted w i t h chlorofarm/methanol (90fl0, V:V)
t o remove extractable
organic material
f o l l o w e d by deasphal t i n g i n pentane a f t e r
s o l v e n t removal.
The pentane sol ubie materi al was then separated i n t o al i p h a t i c hydrocarbon,
aromatic hydrocarbon, and NSO Inonhydrocarbon) fractions on alumina and s i l i c a
gel l i q u i d c h r o m a t o g r a p h i c
determined gravimetrically.
-
columns,
and the quantity
o f each fraction was
The stable carbon isotopic compositions of both
the aliphatic and a r o m a t i c hydrocarbon f r a c t i o n s were determined u s i n g t h e
.
combustion method o f S o f e r (1980) with subsequent analysis on a V.G.
602 mass spectrometer.
Micromass
Capill ary gas chromatographic separation of the a7 ipha-
t i c f r a c t i o n was accomplished on a Hewlett Packard 5880 gas chromatograph
f i t m i w i t h a SP-2100 fused s i l i c a coiurnn (12.5 m X 0.02 m i-d.1.
Combined
gas chromatography/mass s p e c t r o m e t r y was performed on a Finnagi n 4000 GC/MS/DS
system by Global Geochemical Corporation, Canoga P a r k , California, to determine
cterane and terpane di s t r j b u t i o n s
M i c r o s c o p i al
and elemental analyses o f
kerogen concentrates ( H C l and HF d i s s o l u t i o n of i n o r g a n i c matter followed by
-
f l o a t a t i o n i n Z n B r Z ) were made using a Z e i s s U n i v e r s a l Microscope for
vitrinite
reflectance measurements and C a r l a Erba CHNO analyzers (Williams Brothers Co. ,
.
Tulsa, Oklahoma).
RESULTS AND üISCUSSION
T o t a l organic carbon val uec and approximate carbonate percentages for
the three members o f
the la Luna Formation are presented i n T a b l e 1.
Galemba (youngest) member samples ( L L l - L L 6 )
contain 7 i t t l e carbonate minerals
(avg. = 2.4%) and average less than 0.9% organic carbon.
.,
.
The
The Pujamana and
____
TABLE 1
Organic Geochemical Data
Sample No.,
Mernher
Carbon
La Luna Source Rocks
Extractable C15+ Organic Material
(PPml
tiy drocarbons
Nanhy drocarbons
Total
Sat
Aro
N so
ASPh
( ppm 1
1039
1986
336 1
935
523
2605
676
1452
261 6
294
377
542
189
249
580
385
1508
1245
1252
2680
1777
6954
54
25
94
129
302
LL1 Gaiembo
0.7
1.97
459
lL2
1.9
605
tL4
"
LL5
"
1.3
1.5
8.3
LL6
"
0.6
0.57
1 .o3
0.79
0.77
O. 16
13,6
2.90
394
45
656
577
1472
1.2
o. 40
17
430
294
127
1204
2473
7 58
4163
1320
485
3900
7643
5626
4975
2807 5
'I
LL3
-
%
Carbonates
x
Organic
-
LL7 Pujamana
299
17.5
4.82
44.2
45 .O
3.40
3.37
17
359
1938
1000
51.9
4.41
303
1145
8 34
3302
3967 7
5 584
47 .O
53.5
4.78
455
1166
663
3105
5389
3.99
438
1224
7 29
3670
6070
t L 1 5 Salada
46.5
3.77
627
1180
1499
3170
6476
LL16
I'
38.2
4.52
1223
2806
1749
4134
9912
Li17
"
37 .a
1579
2543
7006
1979
2111
4725
9896
37 -8
4.94
918
1081
1253
1966
41.5
4-60
4.70
3033
1651
4722
10659
1.5
71.52
6372
64521
97366
366282
534541
LL8
I'
LL9
I'
LtlO
I'
*LL11
"
-_
Lua
Ll19
"
*LL20 Puj amana
*
A s p h a l t i t e material ( s o l i d bitumen) present, o c c u r r i n g as fracture flllings
up t o 1 m thick*
..
.
i
"
I
Salada member rocks, however, contain an the average 42.8% and 40.4% carbonate,
respectively (excluding samples LL7 and LL8 which a r e from t h i n interbedded
chert l a y e r s ) .
These two carbonate-rich lower members a l s o contain almost f i v e
times more organic carbon (Pujamana average = T S % a n d Salada averaye = 4 . 5 X 1
than t h e carbonate-poor Galembo member.
Sample LLll (Pujamana member) i s a
fractured carbonate-rich sample which is in-filled w i t h a solid bitumen, soluble
i n organic s o ? v e n t s , known as asphalite (Hunt, 1979), and sample U 2 0 i s a "pure"
-
sample o f an asphalite v e i n which occurs t y p i c a l l y up t o 1 rn i n thickness.
-
T h i s fracture-filling organic m a t e r i a l is similar to the Gilsonite common in
t h e U i n t a Basin, Utah, and may represent an early, preserved stage of m i g r a t i o n
ín which o i l generated from La Luna kerogen has migrated short distances Snto
a s a i . z k d fractures w i t h i n the La
Luna carbonate-rich
rocks.
Microscopial examination o f la Luna kerogen revealed predominantly f i n e grai ned amorphous mater1 a l w i t h few we1 1 -defi ned vi tri n i t e particles or spores.
F1uorescence was often observed under both transmitted and reflected modes,
i n d i c a t i n g marine amorphous kerogen,
-
v i trinite reflectance measurements
average value o f i.DfO.2%
.
prone t o o i l generation.
Although few
were p o s s i b l e for rnaturi-ty estimate-s, m
R, for all samples was obtained which I s well w i t h i n
the main phase of petroleum generation { T i s s r i t and Welte, 1978).
Table 2 lists the results o f elemental analyses o f f i v e l a Luna samples
f r o m the PuJarnVa and Salada members; the atomic ratios of hydrogen t o carbon
and oxygen t o carbon are also given.
kerogen samples are 0.85 and 0.05,
as Type i i marine
The H/C
a n d O/C averages f o r
the f i v e
respectively, which classifies these samples
kerogen and places them w i t h i n the principle zone o f o i l
g e n e r a t i o n on t h e van Krevelen diagram as defined by Tissot and Welte ( 1 9 7 8 ) .
These results are consistant w i t h the v i s u a l analysis o f the La Luna kerogen.
f
1
as evldenced by the l a r g e , unresolved "hump" under the n-alkane peaks.
%
This
chromatogram i s consistent w i t h organic matter: d e r i v e d from marine organisms
deposited in a reduci ng environment.
The s t a b l e carbon isotopic composition o f the a l i p h a t i c and aromatic
CIS+ e x t r a c t a b l e f r a c t i o n s average -27.5
hydrocarbon
0.4'/00,
respectively
Salada samples.
-c
( r e l a t i v e t o the PDB
f 0.4*/0~
+-
and -27.1
standard) f o r t h e Pujamana and
These v a l u e s are t y p i c a l f o r o i l s of marine o r i g i n as reported
ilaervofi-ed o i ? s prcrduced frm the Payoa*_ La S a l i n a ,
by Safer ii9Sii.
and
Cararon F i e l d s i n the Middle Magdalena V a l l e y ( - 3 0 krn Nbí o f La Luna o u t c r o p
locations) average
-27.6
2 0,2'/00
and -27.2
2
O.l0/oo
for the aliphatic
and aromatic hydrocarbon fractions, r e s p e c t i v e l y , and is an important parameter
when c o r r e l a t i n g the o i l s t o La Luna saurce rocks; the s t a b l e carbon Isotope
r a t i o s o f the reservoired oils are e s s e n t l a l l y identical t o the La tuna extracta b l e hydrocarbons, f.e.,
the proposed source rock.
A l so i m p o r t a n t i n e v a l u a t i n g geochemical correlations are the d i s t r i b u -
tions o f the biochemical fossils (biomarkers) known as steranes (tetracyclic
-
alkanes) and
d i terpanes
terpanes
(tricyclic and pentacyclic
alkanes).
The tricyclic
are especially u s e f u l in c o r r e l a t i n g nandegraded t o biodegraded
crude oils (such as commonly found
in the Middle Magdalena Valley) because
t h e y appear t o be r e i a t i v e l y uneffected by even severe microbial a t t a c k (e.9.
Reed, 1977).
A l s o , sterane and terpane biomarkers a r e o f t e n useful in determin-
i n g source rock d e p o s i t i o n a l environments.
distributions of
The sterane, diterpane, and terpane
a r e p r e s e n t a t i v e La Luna extract (LL15) are illustrated i n
Figure 2 , and i d e n t i ' f i e d components are listed i n Table 3.
The C27
sterane
stereoisomers (peaks 6 - 9 , F i g u r e 2a) are more abundant than the C2g steranes
[peaks 14-17), indfcatíng a predominance of aquatic microorganisms ( r e l a t i v e
TABLE 2
i
Elemental Camposition of La Luna Kerogen
Sampi e
LL12
%C
%H
%O
%N
H/C
O K
69.4
4.8
5.3
5.2
4.9
5.2
3.5
2.1
0.83
O .O4
O .87
0.79
0.87
0.05
0.07
O . 04
73.6
72.1
LL13
LL16
LL17
74.4
LL19
71.5
0.86
2.2
2.4
2.5
2.2
3.3
4.7
6.6
4.0
0.03
Quantit i c s of the various C15+ e x t r a c t a b l e f r a c t i o n s are presented i n
-
As i n the case o f t o t a l organic carbon, t h e carbonate-rich samples
Table 1.
-
of the
Pujamana and Salada members average more extractable indigenous organic
m a t t e r than the shaley Gatembo member.
Typically, t h e aromatic hydrocarbons
a r e more abundant then t h e a l i p h a t i c hydrocarbon f r a c t i o n ( a v e r a g i n g 1638 ppm
and 860 pprn, respectively}
in
the
asphal tite-containing L L i l sample).
carbonate-rich
samples
The nonhydrocarbon extractable f r a c t i o n s
are y e t more abundant than the hydrocarbon f r a c t i o n s .
( L L Z D } contains
primarily
(excluding the
pentane-insoluble
The a s p h a l t i t e sarnpl e
asphal tenes and NSO ( n i t r o g e n -
sulphur-oxygen) organic compounds; aromatic hydrocarbons are an order o f magni
-
tude greater than aliphatic hydrocarbons.
-
Almost 6% o f t h e tata1 organic car-
bon c o n s i s t s o f extractable C15+ hydrocarbons in the carbonate-rich La Luna
samples which is cornpatiable w i t h maturities estimated from v i t r i n i t e reflec-
tance v a l u e s and H/C atomic ratios o f La Luna kerogen and i s consistent w i t h
very good possible o i l source rocks.
In F i g u r e 1, a r e p r e s e n t a t f v e capillary gas chromatogram (sample LL15)
o f a L a Luna C15+ a l i p h a t i c f r a c t i o n is displayed.
typicaily
more
The i s o p r e n o i d phytane is
abundant than pristane, and the n-alkane d i s t r i b u t i o n i n d i c a t e s
o n l y a s l i g h t preference in odd- o v e r even-numbered alkanes i n t h e Cz8+ region,
An even carbon
p r e f e r e n c e i s noticeable i n t h e n - C i q t o n-C28
m a j o r i t y of the aliphatic fraction consists of
range.
The
branched and cyclic alkanes
i
-
TABLE 3
8
identi f l ed Sterane and
Peak
( F i g u r e 2al
1
2
3
4
5
-
6
- 7
8
STE RAN E
Tri terpane Components
Peak
(Figure 2 c )
TRITERPANE
18aI H)-22, 24, 30-trl snarhopane
170(H)-22, 2 9 , 30-trisnorhopane
17dH) 18a(H), 21B(H)-28, 30bisnorhopane
17a(H), 2lg(H)-30-norhopane
17@(HI, ZlaI HI-norrnoretane
1 7 d H) , 2lfi(H)-hopane
1 7 ~ ( H ) ,21a( HI-rnoretane
9
17a(H), Zlg(H)-30-homohopane (22s)
10
i7a(ti), 2lg(Hl-30-homohopane (22R)
gammacerane
11
17p(H), 21a( H)-homomoretane
17a(H), 218(H)-30, 31-bi ShomO-
12
hopane (22s)
17a(H), 21p(H)-30, 31-bIShom0-
13
-
!-c
15
16
17
hopane (22R)
i1
f
'
1
Tissot and Llelte, 1978) whích c o n t r i b u t e d
t o higher land-dertved p l a n t s , e.g.,
t o t h e La Luna sediments,
2a)
are p r e s e n t , perhaps
menL
Few rearranged C27 steranes (peaks 1-5, Figure 2 a )
indi cat1 ng a nonaci d i e
carbonate deposi t i onal envi ron-
The roughly equal abundance o f t h e 20s and 20R component pairs o f the
5a(H), 1 4 a ( H ) ,
17a(H) steroisomers (peak p a i r s 6 and 9 , 10 and 1 3 , and 14 and
7
17; Figure 2 a } ' i s characteristic of m a t u r i t i e s s u f f i c i e n t t o generate s i g n i f i -
cant q u a n t i t i e s of hydrocarbons (Seif e r t and Moldowan, 1981 and Mackenxie e t
-
a l . , 1980).
The most abundant tricyclic diterpane compouna' (-i-.E.,
4
F i g u r e 2);
in the
La Luna samples is the same component
in the o i l s f r o m the Payoa,
Cn,:W-3-18;
which i s
La S a l i n a , and Coraron F i e l d s .
most abundant
The r e l a t i v e lack
of C1g and C20 diterpanes [compounds generally b e l i e v e d t o be derived from
terrestrial p l a n t s ) i n b o t h La Luna rocks and Middle Magdalena o i l s i s again
s u g g e s t i v e of a marine source.
The range o f tricyclic diterpanes extends o u t
1
t o the C30 molecular w e i g h t range (MW 416; F i g u r e 2b and 20.
The pentacyclic
-
t r i t e r p a n e components
in the
La Luna source rocks
( F i g u r e 2 c ) consist primarily o f the ubiquitous hopane series w i t h t h e C29
norhopane
(peak O; Figure 2c) and C30 hopane (peak F predominating.
The thermo-
dynamically less s t a b l e moretane series ( i . e . , t h e 1 7 6 ( H ) , 2 1 d H ) hopane stereo-
isomers, peaks €, G , and K ) are present i n minor amounts which i s consistent
w i t h the other m a t u r i t y indicators.
The C 3 p hopanes are believed to be d e r i v e d
from b a c t e r i a [ e . g . , Yan Dorsselaer e t a l . , 1977). Not shown i n Figure 2c are
traces of C 3 p hopane 225 and 22R pairs.
.
CONCLUSIONS
The following listing is a summary o f t h e significant results and i n f e r -
ences o f the organic geochemistry analyses of the Upper Cretaceous La Luna
Formati on f r o m the M i ddl e Magdalena Val 1ey , Col ombia.
rabonate minerals) o f the Pujamana
(1) CzrSoni&e-+-ich l a Luna samples
1
and Salada members average 4.3% t o t a l organic carbon.
The carbonate-poor
1'
/L
Galembo samples average l e s s than 0.9% organic carbon.
(2) Microscopial and elemental analyses of La Luna kerogen suggest a marine
origin with a
13)
C 1 5 + extractable hydrocarbons o f Carbonate-rich
almost 2500 ppm which
+'--
(4)
\ \
present maturity well w i t h i n the main phase of oil
generation.
La Luna samples a v e r a g e
indicate very goad possible o i l
source rocks.
Gas chromatographic results of the aliphatic f r a c t i o n s , i n c l u d i n g pristane/
phytane v a l u e s l e s s than 1, abundant C 1 5 t o C1g n-alkanes w i t h respect
to C20+ alkanes, and a predominance of cycloalkanes, i n d i c a t e t h a t L a Luna
o r g a n i c matter i s d e r i v e d f r o m aquatqc microorganisms, i n agreement w i t h
-
-
._
_
I
the kerogen analyses.
(5)
S t a b l e carbon i s o t o p e ratios o f
t o t t i o s e of crude o i l - s prü&&
La Luna hydrocarbon e x t r a c t s are identical
i-n- TertS-ayy- r e s e ~ v o i r swj?M!l the M4-ddl-e
Magdalena Valley which suggests a genetic reiationship.
u
i
"
I
,
(6) Biochemical
fossil
distributions
al so i n d i c a t e a marine depositional
environment (due t o abundant C27 steranes ' r e l a t i v e t o C 2 9 steranes; reiati v e l y 1 ow quanti ti es o f C 1 g and C20 d i terpanes ; and b a c t e r i a l ly-deri ved
hopanes) w i t h molecular maturation' parameters consistent w i t h t h e generation of oil.
ACKNOWLEDGMENTS
-/
I would like t o thank
and
T. Murray,
P. Hoffman f o r technical analyses
J + Heard, S. Sellers, C. S c h i e f e l b e i n ,
and M. Draughon f o r typing the manuscript.
I a l s o thank L. B a i e , M. Leenheer, S. Palmer, and C. Sutton f o r r e v i e w f n g t h e
manuscript and providing helpful comments and suggestions.
Special thanks go
t o R. S. Williams ( C i t i e s Service, Houston International) and R. M e j i a , A .
Erazo, and G . Velasco (Colcltco, Colombia) f o r sample collection and geological
i n f o r m a t i o n and advice.
.
REFERENCES
Backmeulen, H.,
Barker, C.,
and Dickey, P. A. (1981) Geology and Geochemistry
of Crude O i l s in the Bolivar Coastal Fields, Venezuela.
Bull. AAPG,
in p r e s s .
Hedberg, It. D.
( 1 9 3 1 ) Cretaceous Limestone as Petroleum Source
western Venezuela.
Rock
in North-
Bull. AAPG, 15, 229-246.
Hunt, J. M. (1979) Petroleum Geochemistry and Geology. Freeman, San Francisco.
Durand, B.
(1980) Molecular Parameters o f Matlirtion in the Toarcian
Shales, Paris B a s i n ,
-
France
acyci ic isoprenoid- &Wanes,
I. Changes
Steranes,
in the
Configuration of
and- Tri-terpanes. Geochim. e t
Cosmochim. Acta, 44, 1709-1721.
, Reed, W. E. (19791 Moiecular Compositions o f Weathered Petroleurn and Comparison
w i t h i t s P o s s i b l e Source.
‘Seifert,
d
W,
41, 237-247.
K, and Moldowan, 3. M. (1981) Paleoreconstruction by B i o l o g i c a l
Markers. Geochim. e t Cosmochim. Acta, 45, 783-794,
*
Sofer, Z. (1980) Preparation o f
Carbon D i o x i d e f o r Stable Carbon Isotope Analy-
s i s of Petroleum Fractiuns.
Soh-,
Anal
. Chern, , 5 2 ,
1389-1391.
i. i i 3 8 i i isütq~ic C m p o s i t i o n o f Heavy i C 1 5 t j Saturate ana A r o m a t i c
Fractions of Crude Oils,
-
Geochim. e t Casmachim. Acta,
T i s s o t , B.
P.
and tlelte,
O,
H.
Ann. AAPG Convention, San Francisco.
Abst.
(1978) Petroleum Formation and Occurrence.
Springer-Ver1 ag, New York
van Dorsselaer, A . ,
Albrecht,
Novel (17&)-Hopanes
leum.
Zumberge ,
P., and Ourisson,
G.
(1977) Identification
of
i n Shales, Coals, L i g n i t e s , Sediments, and Petro-
B u l l . Soc. C h i m . Fr., 5 8 , 1243-1252
J. E. t 1980) O i 1 -Di 1 and Oi 1 -Source Rock Corre1 a t i ons
Degraded O i l s and Cretaceous Outcrops from Colombia,
26th int. Geological Congress, P a r i s , A b s t r a c t p s 806.
of Bac t e r i a7 1y
South America,
FIGURE CAPTIONS
I
F i g u r e 1.
Gas Chromatagram of t h e aliphatic hydrocarbon fraction of a Salada
member s a p r e iLL15) from the La t u n a Formation.
represent n-alkanes;
Pr
and Ph
represent
Numbered peaks
pristane and phytane,
respect ively
-
Figure 2.
--
Biochemical fossil composition o f a La Luna hydrocarbon extract
(LL15).
a)
b)
Sterane d i s t r i b u t i o n as determined by the m/z
=
217
fragmentograrn.
Numbered peaks are i d e n t i f i e d in Tab1 e 3 ;
RA = rearranged
steranes.
mass
Tricyclic diterpane distribution (m/z = 191)- Molecular weights
were determined by monitoring m/z = 262 ( C 1 9 ) , 276 I C 2 0 1 , 290
(C211, 304 ( C 2 2 1 , 318 (C231, etc,
c)
Pentacyclic
trlterpane distribution (m/r = 191).
Lettered
peaks are i d e n t i f i e d in T a b l e 3.
,-
.
..
.
,,
... .
.I
SAMPLEi LALUNA 15
ENLARGE= 2324
KAWi S A 4 4 1 2
m
a +FRJXZ
TIMEi 0 TO 35 M I N (2.5 MIN/INCH)
__
i
'
N
+
N'
UI
Iu
m-
nl
nl-
Ln
N
vu1
M-
; I
-
I.'
-
--
/
.
ci+
