Organically bound metals and biomarkers in the Monterey Formation of the Santa Maria Basin, California

Chemical Geology, 91 ( 1991 ) 99-113 Elsevier Science Publishers B.V., Amsterdam

99

Organically bound metals and biomarkers in the Monterey Formation of the Santa Maria Basin, California John R. Odermatt and Joseph A. Curiale UNOCAL Science and Technology Division, P.O. Box 76, Brea, CA 92621, USA (Accepted for publication November 13, 1990)

ABSTRACT Odermatt, J.R. and Curiale, J.A., 199 I. Organically bound metals and biomarkers in the Monterey Formation of the Santa Maria Basin, California. In: J.F. Branthaver and R.H. Filby (Guest-Editors), Trace Metals in Petroleum Geochemistry. Chem. Geol., 91:99-113. Systematic variations in metal concentration ratios and biomarker ratios are observed with depth in cores of the Monterey Formation of the Union Leroy 51-18 well in the Santa Maria Basin, California. Specific metal ratios--V/(V + Ni ) and M o / ( M o + C r ) - - c o r r e l a t e between kerogen and extractable organic matter. Further, the organic matter in the two predominant lithofacies (siliceous shales vs. phosphatic shales) can be distinguished based upon metal concentration ratios (e.g., V / ( V + Ni ) ) and certain biomarker characteristics (e.g., sterane/terpane, mono/triaromatic steroid hydrocarbon ratios). Maximum 28,30-bisnorhopane/hopane ratios occur over a narrow range of V / ( V + N i ) ratios in kerogen concentrates and extractable organic matter. This suggests that metal ratios (in kerogen concentrates and EOM) may be useful for oil-source rock correlation studies in the Monterey. Further, while kerogen parameters (metals) are discontinuous at the lithofacies boundary, extract parameters (biomarkers) are gradational at this boundary, suggesting about 30 ft. (9 m ) of vertical hydrocarbon migration across the lithofacies contact.

1. Introduction

Trace elements have been used to characterize crude oils (Hodgson, 1954; Bonham, 1956; Abu-Elgheit et al., 1979; Saban et al., 1984; Hitchon and Filby, 1984; Curiale, 1987a, b) and soluble organic matter in sedimentary rocks (Lewan, 1980; Jacobs, 1982; Jacobs et al., 1984). These elements have recently been used to characterize the insoluble organic matter (kerogen) of petroleum source rocks (Van Berkel, 1987; Hirner, 1987) and oil shales (Dabard and Paris, 1986; Patterson et al., 1986). Although these studies established the organic affinities of certain trace metals in kerogen, they did not address the question of variability of kerogen-associated metal distribution through a single sedimentary section. This paper reports the results of a geochemical in-

vestigation of a suite of four transition elements: chromium (Cr), molybdenum (Mo), nickel (Ni) and vanadium (V); and selected biomarker parameters (mono/(mono+ tri)aromatic steroid hydrocarbons, sterane/ terpane and bisnorhopane/hopane ratios ). The metals were determined in kerogen concentrates and extractable organic matter (EOM), while the biomarkers were determined only in the EOM. The samples were collected over closely spaced core intervals from the Monterey Formation in the Union Leroy 51-18 well, Santa Maria Valley Field, California (Fig. 1 ). The purpose of this investigation is to study small-scale variations in the metal (i.e., Cr, Mo, Ni and V) composition of kerogen concentrates and extractable organic matter (EOM), and compare these variations to those of selected biomarker parameters. Considera-

0009-2541 / 9 1 / $ 0 3 . 5 0 © 1991 Elsevier Science Publishers B.V. All rights reserved.

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O

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Fig. 1. Regional location map of the Union Leroy 51-18 well in the western extension of the Santa Maria Valley Field, California. Shaded areas denote the location of major oil fields in the Santa Maria Basin region. tion of both types of data provides a unique perspective on (a) the utility of trace elements in the characterization of organic matter, and (b) the detection of zones of hydrocarbon migration within the Monterey Formation of the Santa Maria Basin. Forty-eight samples spaced fairly evenly over 338 ft. (103 m ) of core were examined. The samples include siliceous shales, phosphatic shales, dolomitic shales and dolomites (Fig. 2 ). The sedimentary sequence in the Monterey of the Santa Maria Basin generally grades from a clastic-carbonate assemblage (base of section) to predominantly biogenic siliceous lithologies (top of section) (Woodring and Bramlette, 1950 ). The Leroy 51-18 section has been divided into two lithofacies (nomenclature after Pisciotto, 1978, and Pisciotto and Garrison, 1981): (a) phosphatic-carbonate lithofacies (4645-4871 ft.; 1 4 1 6 - 1 4 8 4 m ) a n d (b) siliceous lithofacies (4484-4645 ft.; 13661416m). The phosphatic-carbonate lithofacies is confined to the lower 226 ft. (69 m ) of the core,

and includes phosphatic shales, and interbedded carbonates. Ten carbonate samples (from massive and laminated sequences) and twenty shale samples were studied. The thickness and frequency of both the massive and laminated carbonate beds increase noticeably toward the base of the cored interval (especially in the interval from 4774 to 4871 ft.; 1455-1485 m). The clastic lithologies in this lithofacies are primarily phosphatic shales and mudstones; the phosphatic component occurs as irregularly shaped white to grey blebs, and thin discontinuous laminae. Fractures are generally limited to intervals surrounding the more brittle carbonate beds, and generally exhibit little or no offset. The siliceous lithofacies is confined to the upper 161 ft. (49 m) of the core, and includes siliceous shales, thin carbonates and minor phosphatic shales. Phosphate blebs and carbonate beds increase in frequency and abundance down section (within the lithofacies). Twenty samples from this interval were examined; all but one are siliceous shales. The

O R G A N I C A L L Y B O U N D MET*~LS A N D B I O M A R K E R S IN T H E M O N T E R E Y F O R M A T I O N O F T H E SANTA MAR[A BASIN

UNION LEROY 51-18 SAMPLE LOCATIONS/LITHOLOGY SANTA MARIAVALLEYFIELD LITHOFACIES (After PISCIOTTO,

LITHOLOGY

(Generalization) •

1978)

4484.00 4494.00

101

single exception is a sample from a white dolomite bed at 4589.3 ft. (1398.8 m). The thickness and frequency of the siliceous shales decrease down section to 4645 ft. (1416 m), where the last occurrence of siliceous shale in this core is noted.

~4504.00 ~4514.00

2. Results

4524.00 4534.00

--4644,oo

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~ 48841oo

SHALE

~4684oo

LITHOFACIES

14574100

~

--4584.00 4587.00 4589,3o 4594.00 4594.75 460400 4614.00 4624.00 4634.00

~4645.00-

Siliceous/Phosphatic

Shale Boundry

4654.00

~

4664.00

1"

4674.00

I SILICEOUS SHALE

~4684.00

I

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48doo

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~4700.30 ~4704.00 ~=4713.50 4714,00

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4725, 30

CORE UNAVAILABLE

4774.00 4784.00

4793.50

4804.00

PHOSPHATICCARBONATE LITHOFACIES

The elements Cr, Mo, Ni and V were chosen for examination because of: ( 1 ) the probable organic nature of their chemical environment as reported from studies of crude oils (Filby, 1973, 1975), EOM (Jacobs et al., 1984) and oil shales (Patterson et al., 1986, 1988); and (2) the observed correlation between the concentration of these elements in whole bitumen (EOM) and kerogen concentrates (Odermatt, 1986). The correlation of metals in common between kerogen concentrates and EOM is considered from three perspectives: (1) element to element relationships between kerogen concentrates and EOM; (2) correlation of concentration ratios ( V / ( V + N i ) and M o / (Mo + Cr) ) between kerogen concentrates and EOM; and ( 3 ) classification of the samples examined during this study into meaningful lithostratigraphic groups on the basis of these ratios. Methods used in this study are detailed in Appendix I. Biomarker ratio definitions are also given in Appendix I. The data for metals in kerogen concentrates (corrected and raw concentrations) and EOM (raw concentrations) are listed in Appendix II. Biomarker data are found in Curiale and Odermatt (1989). Correlations between concentrations of metals (Cr, Mo, V and to a much lesser extent

4814.00 4825.80 4828.80 4834.00 444.0 a=4|45.~0 4847.50 4854.00

~4864.00 4871.00

Fig. 2. Generalized stratigraphic column of the Monterey Formation of the Leroy 51-18 well (Santa Maria Valley Field). Lithofacies break occurs at 4645 ft. ( 1416 m ): siliceous shales above and phosphatic shale/carbonate below (nomenclature after Pisciotto, 1978; Pisciotto and Garrison, 1981 ). Sample locations are denoted by arrows along the right-hand margin of the stratigraphic column.

102

J.R. ODERMATT

Ni) in kerogen concentrates and EOM suggest that a significant proportion of these metals occurs as organically bound species (Fig. 3). The lower correlation of Ni in kerogen concentrates and EOM may be an indication that the effects of inorganic Ni have not been removed totally from the kerogen concentrates (Appendix I ). Correlation coefficients were calculated for the ratios of V / ( V + N i ) and M o / ( M o + C r ) in the kerogens and extracts. A correlation coefficient of 0.80 was calculated for V / (V + Ni) ratios in kerogen concentrates and EOM from 49 samples. The correlation coefficient calculated for M o / ( M o + C r ) in kerogen concentrates and EOM from 46 samples was 0.84. The probability of obtaining either

1000

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of these coefficients by chance alone is less than 0.01. Statistically significant correlations also occur between biomarker ratios and metal ratios ( V / ( V + N i ) and M o / ( M o + C r ) ) in EOM and kerogen concentrates. Correlation coefficients for metal ratios and biomarker ratios are listed in Table 1. Positive correlation coefficients were observed between metal ratios and the sterane/terpane ratio, while negative correlations characterize the relationship between m o n o / ( m o n o + t r i ) aromatic steroid hydrocarbons and metal ratios. The V / ( V + N i ) and M o / ( M o + C r ) ratios for the kerogen concentrates vs. EOM are illustrated in Figs. 4 and 5, respectively. In each figure, the metal ratios in bitumen (EOM) are on

•

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Fig. 3. Cross-plots of metal'concentrations in kerogen concentrates and EOM (bitumen). The r-variable is the PearsonProduct-Moment correlation coefficient for each pair. All concentrations are in ppm.

103

O R G A N I C A L L Y B O U N D M E T A L S A N D B I O M A R K E R S IN T H E M O N T E R E Y F O R M A T I O N O F T H E SA N T A M A RI A BASIN

TABLE I Correlation coefficients M o n o / ( m o n o + tri ) aromatic steroid hydrocarbons

Sterane/terpane

Bisnorhopane/ hopane

V / ( V + N i ) kerogen

-0.69(48)

0.44(49)

-

M o / ( M o + C r ) kerogen

-0.72(46)

0.67(47)

-

V / ( V + N i ) bitumen (EOM)

- 0 . 5 3 (49)

0.44(50)

-

M o / ( M o + C r ) bitumen ( EOM )

-0.72(48)

0.57(48)

-

M o n o / ( m o n o + tri) aromatic steroid hydrocarbons

-

Sterane/terpane

-

- 0.62 (48) -

0.58 (48) - 0.76 (49)

Correlation coefficients for metal ratios and biomarkers (at 0.05 significance level), Monterey Formation, California. See Appendix I for compound ratio definitions. Values shown are Pearson-Product-Moment coefficients. The number in parentheses is equal to the number of samples analyzed. 10

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Fig. 4. Cross-plot of E O M V / ( V + N i ) ratio vs. kerogen concentrate V / ( V + N i ) ratio. Metal ratios for kerogen concentrates are f o u n d on the x-axis, ratios for b i t u m e n ( E O M ) are f o u n d on the y-axis. Plot symbol indicates lithofacies of sample. C i r c l e = p h o s p h a t i c s h a l e - c a r b o n ate, and s q u a r e = s i l i c e o u s . Correlation coefficient ( r ) is 0.80.

Fig. 5. Cross-plot of EOM M o / ( M o + C r ) ratio vs. kerogen concentrate M o / ( M o + C r ) ratio. Metal ratios for kerogen concentrates are f o u n d on the x-axis, ratios for b i t u m e n ( E O M ) are f o u n d on the y-axis. Plot symbol indicates lithofacies o f sample. Circle = p h o s p h a t i c s h a l e carbonate, a n d s q u a r e = siliceous. Correlation coefficient ( r ) is 0.84.

the y-axis and metal ratios in the kerogen concentrates are on the x-axis. Both of these plots exhibit generally linear trends between the metal ratios in kerogen concentrates and EOM from the same samples. These data suggest that there is a genetic relationship between kerogen

concentrates and EOM in the Monterey from this well. Another pattern is evident when the samples are classified according to their lithofacies. In Figs. 4 and 5, the lithofacies have been assigned as siliceous (above 4645 ft.; 1416 m)

104

J.R. ODERM,XTT ,AN[) J.A. CURIALE BITUMEN IDashedl

DEPTH IFeetl

KEROGEN [Solidi 0.0 0.3 0.6 0.9

KEROGEN V/(V +Ni) 0.0 0.3 0.6 0.9

BITUMEN

SOURCE OF V/(V + Nil RATIOS

V/(V÷Ni) 0.0 0.3 0.6 0.9

I

,, KEROGEN

rl

0.42 - 0 , 8 3

7

BITUMEN 0.57 - 0.85

I

- -

4845

FT.

KEROGEN 0.13 - 0.55

BITUMEN 0.32 - 0 . 7 0

Fig. 6. Stratigraphic distribution of kerogen V / ( V + Ni) and EOM V / ( V + Ni ) ratios. Metal ratio is plotted separately for kerogen (center) and bitumen (fight) vs. depth. The vertical dashed lines in these figures show the mean value of the V / ( V + Ni ) ratio for kerogen concentrates and bitumen above and below the lithofacies break at 4645 ft. (1416 m). These values are: kerogen=0.66 (SILICEOUS) and 0.40 (PHOS/CARBONATE); bitumen=0.75 ( S I L I C E O U S ) a n d 0.57 (PHOS/CARBONATE). Metal ratios for kerogen (solid line) and bitumen (dashed line) are plotted together in the left hand column. The range of V / ( V + Ni) ratios in each lithofacies is given at the right of the figure.

and phosphatic shale-carbonate (below 4645 ft.; 1416 m ) . The distribution of the data in Figs. 4 and 5 indicates that the values of metal ratios for kerogen concentrates and EOM differ between the two lithofacies. The distinction between the two lithofacies is seen most clearly in Fig. 5 for the M o / ( M o + C r ) ratios. Samples from the siliceous interval are generally higher in V / ( V + N i ) and M o / ( M o + C r ) ratios, while the samples from the carbonate interval are characterized by lower metal ra-

tios and are more dispersed across the plot. In Fig. 5, the major lithologic zones are less clearly defined and a zone of overlap is observed between 0.64 and 0.72 on the V / ( V + N i ) ratio for EOM (y-axis). The distinction between organic matter derived from the two lithofacies in this section may also be accomplished using other geochemical parameters. A similar distinction has been reported for these samples using RockEval pyrolysis (Hydrogen Index vs. Oxygen Index ) and the distribution of biomarker compound classes (figs. 2 and 6 of Curiale and Odermatt, 1989 ). Fig. 6 is a plot of the V / ( V + N i ) ratio vs. depth, with the ratios for kerogen concentrates and EOM superimposed. Examination of this plot illustrates the disparity between the V/ ( V + N i ) ratio for kerogen concentrates and that of EOM within the lithostratigraphic framework. Generally, the V / ( V + N i ) ratios for EOM are higher than those observed for kerogen concentrates. Nevertheless, the distribution of V / ( V + Ni) ratios in EOM appears to follow that of the kerogen concentrates over much of the section (i.e., stratigraphic patterns are very similar in both sets of ratios, except over the interval from 4534 to 4594 ft.; 1383-1401 m ) . The vertical dashed lines in Fig. 6 indicate the value of mean V / ( V + N i ) ratios in kerogen concentrates and EOM in the siliceous (kerogen=0.66; E O M = 0 . 7 5 ) and phosphatic shale-carbonate (kerogen=0.40; EOM = 0.57 ) lithofacies. The comparison between the lithostratigraphic distribution of V / ( V + Ni ) in kerogen concentrates and the distribution of several biomarker parameters (sterane/terpane, m o n o / ( m o n o + t r i ) a r o m a t i c steroid hydrocarbons and bisnorhopane/hopane ratios) are illustrated in Fig. 7. A discontinuity in the trend of kerogen V / ( V + N i ) ratios coincides with the change in lithofacies at 4645 ft. ( 1416 m ). Examination of the stratigraphic trends of the biomarker indices show a much less distinct break, beginning about 31 ft. (9 m) shallower

ORGANICALLY BOUND METALS AND BIOMARKERS IN THE MONTEREY FORMATION OF THE SANTA MARl& BASIN

DEPTH KEROGEN IFeetl V/IV ÷ Ni) 0.0 0.3 0.6 0.9

STERANE/ TERPANE 0.0 0.3 0.6 0.9

[ 05

MONO/ BISNORHOPANE/ (MONO + T R I ) HOPANE 0.0 0.3 0.6 0.9 0 25 50 75100

4500 4520 4540 4560 4580 4600 4620 4640

4614

FT.

4645

FT.

4660 4680 B 4700 4720 4740 4760 4780 4800 4820 4840

/.

4860

Fig. 7. Stratigraphic distribution of kerogen V/(V + N i) and biomarker parameters (sterane/terpane, mono/(mono + tri ) aromatic steroid hydrocarbons, bisnorhopane/hopane ratios). See Appendix I for biomarker ratio definitions. Lithofacies and kerogen V/(V + Ni ) breaks are at 4645 ft. ( 1416 m). Biomarker parameters show gradational trends across the lithofacies boundary beginning at 4614 ft. ( 1406 m). This gradational region is shaded across the three biomarker columns. The average values for these ratios in the siliceous lithofacies (exclusive of the interval 4614 to 4645 ft.; 1406 to 1416 m) are: sterane/terpane=0.27, mono/(mono+tri)=0.77, bisnorhopane/hopane=3.6 and kerogen V/ ( V + Ni ) = 0.66. The averages for samples from the phosphatic shales-carbonate lithofacies (below 4645 ft.; 1416'm ) are: sterane/terpane = 0.15, mono/(mono + tri ) = 0.96, bisnorhopane/hopane = 22.0 and kerogen V/( V + Ni ) = 0.40. in the section, at 4 6 1 4 ft. ( 1406 m ) . U s i n g the V / ( V + N i ) ratio o f k e r o g e n c o n c e n t r a t e s as a reference, the o b s e r v e d b i o m a r k e r distribution in Fig. 7 m a y suggest t h a t vertical h y d r o c a r b o n m i g r a t i o n has t a k e n place in this M o n t e r e y section ( C u r i a l e a n d O d e r m a t t , 1 9 8 9 ) . Also n o t e t h a t the c o r r e l a t i o n b e t w e e n V / ( V + N i ) in k e r o g e n c o n c e n t r a t e s a n d E O M across this b o u n d a r y (Fig. 6) suggests t h a t the m e t a l ratios in E O M h a v e n o t b e e n significantly a l t e r e d b y m i g r a t i o n o v e r the s a m e strat i g r a p h i c interval.

T h e plot o f b i s n o r h o p a n e / h o p a n e vs. V / ( V + N i ) shows a m o r e c o m p l e x d i s t r i b u t i o n t h a n t h o s e o f the p r e v i o u s l y c o n s i d e r e d biom a r k e r s . In Fig. 8, it can be seen t h a t samples w h i c h are relatively e n r i c h e d in b i s n o r h o p a n e (bisnorhopane/hopane>10) also exhibit a relatively n a r r o w range in V / ( V + N i ) ratios in k e r o g e n ( V / ( V + N i ) - 0 . 2 8 to 0.58; left plot) and EOM (V/(V+Ni)=0.44 to 0.70; right p l o t ) . T h e s o u r c e o f b i s n o r h o p a n e has b e e n the subject o f several r e c e n t investigat i o n s (Seifert a n d M o l d o w a n , 1978; K a t z a n d

106

J.R. O D E R M A T T A N D J.A. C U R I A L E

?

POSSIBLE

MIGRATED

EOMI

+

PHOSPHATIC SHALECARBONATE LITHOFACIES

X

SILICEOUS LITHOFACIES

I I I

I

'90

90 80

BITUMEN

KEROGEN CONCENTRATE

00

ooo 70

70

,-no ~ 00 g ~ 5o "rill rrZ O< ZO,. t/~O

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•

~xj x~ x xx + I + ~* x• + 0 I I II I I xl ]1 I I I " 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

+s x +x ~jjFx ~ xx x [ I I I I I I ] I 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

V V + Ni

V V + Ni

Fig. 8. Cross-plot of V/(V + Ni ) Aratios (for kerogen concentrates and EOM ) vs. bisnorhopane/hopane ratios. Samples which are characterized by high bisnorhopane/hopane ratios ( > 10) exhibit relatively narrow ranges in the metal ratio. This relationship may be useful in locating specific source intervals in the Monterey. Lithofacies of the samples are indicated in the figure by + (phosphatic shale-carbonate) and × (siliceous).

Elrod, 1983 ). It is characteristic of many Monterey crude oils and rock extracts (King and Claypool, 1983; Curiale et al., 1985 ), and may be a product of anaerobic bacteria occurring in highly anoxic localized depocenters offshore California during Miocene time (Katz and Elrod, 1983; Curiale and Odermatt, 1989). 3. Discussion

Concentration ratios for metals have often been used to demonstrate a genetic relationship between two geochemical substances (e.g., V / N i used in oil to oil correlation; Hodgson, 1954; AI-Shahristani and A1-Atiya, 1972; Saban et al., 1984; Curiale, 1987b). V / ( V + N i ) correlations between kerogen concentrates and EOM are of interest because such correlations would imply a genetic relationship for these two substances. Such information would be of use in establishing the presence of indigenous vs. non-indigenous bitumen (EOM) in fractured reservoirs. Furthermore, such a relationship has potential use as a correlation parameter between a source rock (kerogen) and its

thermally generated soluble organic matter (including crude oils and solid bitumens). However, the use of metal data to characterize kerogens has been hampered by the presence of inorganic occurrences of metals (i.e., sulfides) in kerogen concentrates. From the data presented here, the problem appears to affect Ni to a greater extent than V, Mo or Cr. This suggests that the effects of inorganic Ni concentrations in the kerogen concentrates have not been completely negated by the correction method employed here (see Appendix I ). The non-linearity of the cross-plot of Ni in kerogen concentrates vs. Ni in bitumen (EOM) (Fig. 3) also suggests that there are lingering effects of inorganic Ni concentrations in the kerogen concentrates. The stratigraphic signature of V / ( V + Ni ) ratios in kerogen and EOM are often subparallel (Fig. 6 ), yet the kerogen concentrate V / ( V + Ni) ratio exhibits a consistently lower value than that of associated EOM (except for samples from 4534 to 4594 ft; 1383-1401 m ) . This pattern is consistent with the presence of lingering effects from inorganic occurrences of Ni (e.g.,

ORGANICALLY BOUND METALS AND BIOMARKERS IN THE MONTEREY FORMATION OF THE SANTA MARIA BASIN

pyrite) in kerogen concentrates. Alternatively, this consistent ratio difference between kerogen concentrates and EOM may indicate the occurrence of a fractionation mechanism through which the EOM becomes preferentially enriched in V during the thermal generation of organometallics from the kerogen structure. Good correlations between the V / ( V + Ni) and M o / ( M o + C r ) ratios in EOM and kerogen concentrates imply that these metals have a strong organic association in kerogen concentrates from the Monterey. Further, the metal ratios from kerogen concentrates and EOM are useful in classifying these samples according to their lithofacies (Figs. 4 and 5). Although a lithofacies distinction can be made using metal ratios, it should also be noted that there is an area of overlap (Fig. 4) which would partially restrict the application of V / ( V + Ni ) ratios for this purpose. Changing Eh-pH conditions and the availability of sulfur in the depositional environment have been invoked to account for the variations in the metal composition of sedimentary organic matter (Lewan and Maynard, 1982; Lewan, 1984; Dabard and Paris, 1986). Variations in E h - p H and sulfur availability are thought to limit the concentration of chalcophile and siderophile elements (e.g., Fe, Mn, Cu(?), Ni(?) ) by incorporating these into inorganic phases (e.g., pyrite) during deposition and early diagenesis (Lewan, 1980; Lewan and Maynard, 1982). Eh in the depositional environment may be affected by a number of factors, including restriction of bottom-water circulation under a source of abundant organic matter (i.e., upwelling conditions), movement of the oxygen minimum zone (OMZ) within the water column, and the activity of sulfate reducing bacteria (Didyk et al., 1978; Summerhayes, 1981). The pH of pore waters near the Miocene seawater-sediment interface may have been affected by inorganic and organic reactions associated with early diagenesis (Taguchi et al., 1988). It has

107

been suggested previously that changes in chemical conditions of the depositional environment (especially available sulfur) resulted in variability of the m o n o / ( m o n o + tri) aromatic steroid ratio in rock extracts (Curiale et al., 1985; Curiale and Odermatt, 1989). Relative enrichment of triaromatic steroids could result from sulfur-mediated dehydrogenation of sterenes during very early diagenesis (Douglas and Mair, 1965; Curiale et al., 1985 ). It is interesting to note that the trend toward relative enrichment of triaromatic steroid hydrocarbons (generally mono / ( mono + tri ) aromatic steroid ratio <0.90) correlates with higher V / ( V + Ni) ratios in the kerogen concentrates and EOM (Fig. 6) of the siliceous lithofacies (4484-4645 ft.; 1367-1416 m). Higher V / ( V + Ni ) ratios ( > 0.5 ) in metalloporphyrins of crude oils may indicate a move toward lower pH and possibly sulfur-rich depositional conditions ( Lewan, 1984 ). Conditions which lead to the availability of sulfur in the depositional environment (e.g., low sedimentation rate and abundant organic matter), are also used to account for high concentrations of organic sulfur in kerogens (Orr, 1986; Lewan, 1986) and crude oils (Gransch and Posthuma, 1973; Magoon and lsaacs, 1983; lsaacs and Petersen, 1987 ) from the Monterey Formation. Concentrations of organic sulfur in kerogens examined here were calculated by subtracting molar amounts of pyrite (FeS~) from the total sulfur (after Orr, 1986). The median values for kerogen concentrates from each lithofacies were essentially equal ( 11% ). Our data compare favorably with other reports of organic sulfur concentrations in kerogen concentrates from the Monterey (Lewan, 1986). Correlations between the distribution of lithofacies, metal ratios in kerogen concentrates and biomarker parameters (e.g., mono/ (mono + tri ) aromatic steroid hydrocarbons) are useful in detecting hydrocarbon migration in this Monterey section (Curiale and Odermatt, 1989). In Fig. 7, the stratigraphic trend

108

of V / ( V + Ni ) ratios in kerogen concentrates is broken at the depth which corresponds to a change oflithofacies (4645 ft.; 1416 m). However, the nature of the biomarker trends across this boundary indicates the presence of gradients in these molecular parameters. The gradients are particularly prominent in the mono/ ( m o n o + t r i ) aromatic steroid hydrocarbon ratio and bisnorhopane/hopane ratio over the interval immediately above the lithofacies break (4614-4645 ft.; 1406-1416 m). It is also interesting to note that the stratigraphic distribution of V / ( V + N i ) ratios in EOM is discontinuous precisely at the lithofacies boundary (4645 ft.; 1416 m in Fig. 6). This suggests that the metal ratio in whole rock EOM is not as sensitive to modifications caused by hydrocarbon migration as are the associated biomarker ratios. Finally, it is noted that samples which exhibit high relative concentrations of bisnorhopane (bisnorhopane/hopane> 10) also have relatively similar V / ( V + N i ) ratios in kerogen concentrate and EOM (Fig. 8). Further, whereas the bisnorhopane/hopane ratios may be diminished in crude oils relative to sourcerock extracts (Curiale et al., 1985), the metal ratios may serve as intact oil-source correlation parameters throughout the generational history of the Monterey.

4. Conclusions Our examination of selected metals and biomarkers from organic matter in the Monterey Formation supports the following conclusions. ( 1 ) The transition elements examined (V, Ni, Mo and Cr) have significant organic association in kerogen concentrates from cores of the Monterey Formation of the Union Leroy 51-18 well. This conclusion is supported by good correlations between metal concentrations in kerogen concentrates and EOM (except for Ni), and good correlations between concentration ratios (e.g., V / ( V + N i ) and

J.R. ODERMATT AN[) J.A. ([JR[ALE

M o / ( M o + C r ) ) in kerogen concentrates and EOM. (2) Using concentration ratios of metals-V / ( V + N i ) and M o / ( M o + C r ) - - o r g a n i c matter from the two lithofacies in the Monterey Formation from this well can be distinguished. This distinction is also supported by analyses of source rock potential (Rock-Eval) and biomarkers as reported previously (Curiale and Odermatt, 1989). ( 3 ) The comparison of kerogen metal ratios (e.g., V / ( V + N i ) ) and biomarker indices (e.g., m o n o / ( m o n o + tri ) aromatic steroids, bisnorhopane/hopane ratios ) are useful in the assessment of vertical hydrocarbon migration within the Monterey Formation. (4) The correspondence of concentration ratios with lithofacies suggests that factors in the depositional environment (e.g., redox potential (Eh), pH and concentration of sulfur species) are important in fixing metals in geochemical organic matter (Lewan, 1980; Lewan, 1984; Sundararaman, 1986; Patterson et al., 1986; Dabard and Paris, 1986 ).

Acknowledgements The authors gratefully acknowledge helpful discussions and comments from Drs. John Dunham, Robert Sweeney, Bruce Bromley (UNOCAL) and Steve Larter (University of Newcastle, Newcastle-upon-Tyne). This work grew out of a Master's thesis (JRO) at California State University Los Angeles. The thesis study benefited from discussions with each of the committee members, Drs. Richard Hurst (CSULA), Joe Curiale (UNOCAL), Alan Coleville (CSULA) and Terry Davis (CSULA). We thank Terry Budden and John Shastid (UNOCAL Western Region, Ventura) for allowing us to sample the Union Leroy 51-18 core. Greg Ouellette and Gary Roquet helped with the preparation of wholerock extracts and kerogen concentrates used in this study. David Ahlborn provided expertise in the final design and preparation of the illus-

ORGANICALLYBOUND METALSAND BIOMARKERSIN THE MONTEREYFORMATIONOF THE SANTAMARIABASIN

trations. The manuscript was improved by comments of two anonymous reviewers. Finally, we acknowledge support from the management of U N O C A L Corporation, and their approval of publication.

Appendix I

TABLE A- 1 Analytical precision Sample (ft.)

Organic matter

Percent difference in metal concentrations of duplicates Cr

Fe

Mo

Ni

V

4524.5

Kerogen Bitumen (EOM)

6 28

2 3

13 7

4 2

5 1

4804.0

Kerogen Bitumen ( EOM )

7 l0

8 14

6 7

5 6

7 I1

Methods Each rock sample was crushed to approximately 0.25 inch (0.64 cm) using a Braun " C h i p m u n k " crusher. The crushed material was then passed under a magnet to remove any metallic contaminants which may have been introduced by this procedure. This material was then pulverized to pass through a 30 mesh (0.024 inch; 0.06 cm) screen and again treated with a magnet before being passed to the bitumen extraction siep. The soluble organic matter ( E O M ) was removed using a ternary solvent mixture: 70% toluene, 15% methanol and 15% acetone (by volume ). Samples were placed in 600 ml of solvent for 24 hr. (at ambient temperature ). Boiling solvents were avoided so as not to destroy labile organometallic complexes that might exist in the EOM. The soluble organic matter solution was then filtered through a 5-/lm teflon filter (after Curiale, 1987a). The solution was then centrifuged for 30 rain at 4000 R.P.M. The solvent was removed under flowing nitrogen. Kerogen concentration methods are similar to those reported for palynological preparations (Pocock, 1982) and organic petrographic and chemical analysis purposes ( Durand, 1980: Durand and Nicaise, 1980). Concentration of kerogen from the extracted rock involved non-oxidizing acids (37% HC1 and 70% H F ) for removal of carbonates and silicates. The acid treatments were carried out in a fume hood, at ambient temperatures, and followed by treatment with a deflocculant (Darvan ~4 ). A density separation step using an aqueous zinc bromide solution at a specific gravity of 1.85 removed most of the sulfides. The tloat material was then collected and extracted a second time in the ternary solvent under the same conditions previously described. This material was then washed exhaustively using acetone and centrifuged to remove any remaining solvent and EOM. This step was repeated until the supernatant was clear after the centrifuging step. The material collected at the end of this procedure contained both organic matter and inorganic matter, and is hereafter referred to as "kerogen concentrate". Inductively coupled plasma (1CP) emission spectroscopy ( A R L 340000 ) was used to analyze the ash of EOM and kerogen concentrates for the transition elements Cr, Mo. Ni and V. Summaries of the ICP analytical technique can be found elsewhere (Bauch and Lomb, 1982; Walsh and Howie, 1986). Variations in sample sizes resulted in

109

Precision checks on Cr, Fe, Mo, Ni and in kerogen concentrates and bitumen (EOM) using the ICP method. variations in detection limits. Correction factors were applied to the concentrations of metals determined in kerogen concentrates. The derivation and application of these correction factors are described later in this appendix. Samples at 4524.5 and 4804 ft. ( 1379 and 1465 m ) were selected as precision checks for kerogen concentrates and EOM. The results of these analyses are shown in Table A-I and suggest that V and Ni concentrations are more reliable (precision in EOM and kerogen concentrates less than or equal to 11%) than those for Mo and Cr. In addition, V / ( V + Ni ) ratios in kerogen concentrates and EOM from these samples were reproduced to within < 1%. Extracts were prepared for biomarker analysis by separation of hydrocarbons and removal of n-alkanes according to Curiale et al. (1985) and O ' C o n n o r et al. ( 1962 t. These branched and cyclic hydrocarbon fractions (including aliphatic and aromatic compounds) were analyzed using selected ion monitoring with a Finnigan TSQ 4500 instrument outfitted for conventional G C M S analysis, according to methods described in Curiale et al. ( 1985 ) and Curiale and Odermatt ( 1989 ). All biomarker ratios are calculated from peak areas using appropriate mass chromatograms. Compound type designations are as follows: Sterane/Terpane = ( 5a + 5fl), 14ol, 17ol, 20R •C27_29steranes ( 17 ol,21 fl+ 17fl,21 ot ) =vC27_32pentacyclic triterpanes M o n o / ( M o n o + Tri) aromatic steroid hydrocarbons = (5ol + 5 f l ) , 2 0 ( R + S ) ~ C 2 7 _ > (5Ot+5fl), 20(R"I-S)ZC27 29+20 (R-t-S)SC26 28 Bisnorhopane/Hopane = ( 17ot,21 fl+ 17fl,21 ol) - 28,30 bisnorhopane ( 1701,21 fl+ 17fl, 21 c~) ~C27 32pentacyclic triterpanes

110

J.R. ODERMATT AND J.A. CURIALE

Correction of kerogen concentrates for inorganic metals Transition element composition of kerogen concentrates is thought to be affected by the presence of inorganic (e.g., sulfide) contaminants (Lewan, 1980; Jacobs, 1982; Van Berkel, 1987 ). A correction factor was devised, using density separation methods, to account for the influence of inorganic metals on the total metal content. A density separation was made on kerogen concentrates of three samples (at 4494, 4645 and 4793.2 ft.; 1370, 1416 and 1461 m) using aqueous zinc bromide at a specific gravity of 2.85. The sample which appeared to contain the least organic matter, on the basis of visual examination, in the > 2.85 density fraction was selected (i.e., at 4494 It.; 1370 m) for metal analysis, on the presumption that metal/Fe ratios of this fraction would be indicative of corresponding inorganic metal contamination in the whole kerogen. The results of X-ray diffraction analysis of the > 2.85 specific gravity fraction from this sample suggest that the inorganic phases are predominantly pyrite (FeS2) and ralstonite (CaA/MgF6) (Odermatt, 1986). These same inorganic phases have also been reported previously from X-ray diffraction analyses of kerogen concentrates from the Green River Formation (Van Berkel, 1987). This comparison suggests that the inorganic components of kerogen concentrates are pyrite from the original sample and neoformed fluorides (such as ralstonite) derived during laboratory preparation of kerogen concentrates. The concentrations ofCr, Fe, Mo, Ni and V were determined for the material collected from the > 2.85 density fraction of the sample at 4494 ft. (1370 m). Concentration ratios o f C r / ( F e + C r ) , M o / ( F e + M o ) , N i / ( F e + N i ) and V / ( F e + V ) were calculated to estimate the percentage of each element which may be expected to behave

similar to Fe (in the inorganic phase ). The ratios thus calculated follow a logical progression based upon similarities in ionic properties (i.e., charge and ionic radius) of the elements to Fe. These ratios are: V (0.0002), Mo (0.0007), Cr (0.0011 ) and Ni (0.0022). These ratios are applied as correction factors in the determination of metal concentrations in each kerogen concentrate. The correction factor is multiplied by the iron (Fe) concentration of each individual sample, and the product is subtracted from the total concentration of that metal in the kerogen concentrate. All data presented here are corrected for mineralic metal contamination using this method. See Appendix It for a tabulation of raw and corrected metal concentrations in kerogen concentrates. The derivation and utility of this correction method necessarily depends on the validity of several assumptions. First, the mineral matter present in the organic residue is pyrite (FeS2), or may be assumed to be attributed to pyrite for the purposes of correction. Second, the Fe content of the kerogen concentrate is presumed to be present totally as sulfide. This is not certain. However, under this assumption, organically bound Fe is presumed to be a minor constituent relative to the Fe of inorganic and framboidal pyrite. This assumption seems justified on the basis of the range of concentrations for Fe observed for kerogen concentrates in this study (0.6 to 8.2% ), visual identification of pyrite from kerogen strewn mounts of these samples (Odermatt, 1986), and the few literature reports of minor concentrations of Fe metallo-organics in heavy crude oil (Franceskin et al., 1986). Further, elements which have an affinity for Fe will substitute for Fe in the sulfide phase. If these assumptions are valid then the method is useful in correcting total metal concentrations to arrive at concentrations of organically bound metals in kerogen concentrates.

Appendix II Raw and corrected metal concentrations for kerogen concentrates, and raw metal concentrations for bitumen (EOM) (all data in ppm ) Depth (It)

4484.00 4494.00 4504.00 4514.00 4524.50 4524.50 4534.00 4544.30

Depth (m)

1367.1 1370.1 1373.2 1376.2 1379.4 1379.4 1382.3 1385.5

Kerogen

EOM

Cr/Cr *l

Mo/Mo .1

Ni/Ni *1

113.8/204 66.48/103 142.9/173 91.40/131 39.65/71 47.53/78 46.69/71 97.60/135

258.6/316 205.8/229 236.8/256 306.8/332 262/282 320.6/340 504.5/520 376.2/400

419.6/600 159/232 279.7/340 243.8/323 265.3/328 250.1/311 174.4/223 133.2/208

V/V *l 345.4/370 182/192 491.8/500 299.2/310 411.4/420 381.7/390 683.4/690 639.8/650

Cr

Mo

Ni

V

0.60 1.20 0.90 1.40 2.10 1.40 1.30 0.20

2.50 5.40 4.70 8.60 11.00 10.00 6.90 1.90

25.00 47.00 42.00 52.00 99.00 102 54.00 5.10

68.00 106 175 112 270 273 146 36.00

111

ORGANICALLY BOUND METALS AND BIOMARKERS IN THE MONTEREY FORMATION OF THE SANTA MARIA BASIN

Appendix II (continued) Depth (It)

4554.00 4564.00 4574.00 4584.00 4587.00 4589.30 4594.00 4594.75 4604.00 4614.00 4624.00 4634.00 4645.00 4654.00 4664.00 4674.00 4684.00 4692.40 4693.00 4700.30 4704.00 4713.50 4714.00 4725.30 4774.00 4784.00 4793.20 4793.30 4793.50 4794.00 4804.00 4804.00 4814.00 4825.80 4828.80 4834.0(I 4844.00 4845.4(I 4847.50 4854.00 4871.00

-

Depth (m)

1388.4 1391.5 1394.5 1397.6 1398.5 1399.2 1400.6 1400.8 1403.7 1406.7 1409.8 1412.8 1416.2 1418.9 1422.0 1425.0 1428.0 1430.6 1430.8 1433.0 1434.1 1437.0 1437.2 1440.6 1455.5 1458.5 1461.3 1461.4 1461.4 1461.6 1464.6 1464.6 1467.7 1471.3 1472.2 1473.8 1476.8 1477.3 1477.9 1479.9 1485.1

Kerogen

EOM

Cr/Cr *l

Mo/Mo .1

Ni/Ni *~

V/V *l

Cr

Mo

Ni

V

121.6/156 132.3/195 45.5/177 72.79/96 122.6/171 nd/nd 127.4/167 30.93/46 99.30/140 154/184 179.1/222 147.1/178 253.2/295 117.5/156 159.2/201 134.8/158 151.4/191 99.67/111 155/210 180/235 228.1/262 108/129 210.8/257 97.26/123 164.6/202 154.3/162 203.3/244 96.70/155 93.90/139 133.5/172 226.8/261 196.5/235 -/80 130.7/152 187.9/233 67.84/96 221.2/296 89.60/127 104.5/143 44.60/104 114.1/128

448.1/470 700.1/740 450/470 575.2/590 629.21660 100.81105 434.81460 171.4~181 354.1t380 730.91750 962.7/990 670.3%90 238.4/265 285.5/310 180.4/207 100.2t115 141.8 167 265.8¢273 120/155 42.00/77 112.4/134 191.6/205 112.6/142 139.6/156 191.2/215 219.1/224 78.10/104 94.90/132 92.30/111 79.50/104 154.2/176 166.5/191 606.1/660 105.4/119 82.30/111 172.1/190 117.4/165 45.20/69 66.50/91 170.2/208 92.18/101

311.1/380 159.6/285 297.1/360 232.6/279 236.2/333 74.80/88 173.8/253 144.9/175 488.6/570 399.9/460 554.2/640 448.2/510 486.4/570 683/760 396.4/480 323.6/370 430.8/510 268.3/291 440/550 290/400 552.2/620 418/460 517.6/610 338.5/390 595.2/670 301.6/317 368.6/450 653.4/770 509.8/600 363/440 561.6/630 603/680 180.6/350 417.3/460 489.8/580 433.7/490 570.4/720 265.2/340 333/410 561.2/680 362.3/390

780.6/790 782.9/800 541.4/550 823.7/830 726.8/740 113.2/115 619.2/630 240.9/245 548.9/560 1032/1040 1288/1300 621.6/630 428.6/440 499.5/510 398.6/410 373.7/380 302.2/313 249.9/253 253/268 275/290 490.8/500 504.3/510 487,4/500 137/144 369.8/380 308,9/311 319.9/33l 267.1/283 243.7/256 275.5/286 530.7/540 479.5/490 102.9/126 364.2/370 276.7/289 65.32/73 202.6/223 187.8/198 108.5/119 220.8/237 89.22/93

2.30 4.20 1.30 1.50 2.10 nd 1.80 0.10 1.00 1.90 4.30 1.50 6.10 3.90 3.80 1.70 2.20 0.50 3.30 2.50 2.90 2.30 7.90 0.30 1.40 1.70 5.10 4.20 2.10 4.20 3.90 3.40 0.60 3.20 5.70 0.50 5.00 4.60 1.50 3.30 0.60

15.00 24.00 9.50 ll.00 9.20 nd 12.00 0.90 5.70 11.00 10.00 8.90 8.90 9.50 4.70 2.20 2.80 0.80 3.00 0.90 0.90 5.60 3.10 0.20 2.90 2.00 3.20 1.00 1.40 1.20 3.00 3.30 0.40 2.30 4.70 0.20 4.50 2.70 nd 5.30 0.20

62.00 62.00 49.00 68.00 47.00 6.60 56.00 16.00 60.00 81.00 40.00 34.00 109 125 101 54.00 67.00 24.00 65.00 65.00 65.00 80.00 94.00 15.00 49.00 80.00 100 29.00 53.00 42.00 79.00 73.00 35.00 118 105 23.00 119 132 90.00 121 30.00

340 230 139 173 120 8.70 202 30.00 175 400 217 175 172 229 198 72.00 85.00 31.00 67.00 106 106 183 185 10.00 90.00 187 132 32.00 58.00 54.00 166 143 70.00 145 137 36.00 99.00 138 42.00 95.00 7.60

*~ Kerogen metals reported as "corrected/raw concentrations"; bitumens reported as raw concentrations only. See Appendix 1 for correction method. nd = not detected in this sample. = sample contained measurable concentrations of metal, but correction method subtracted the metal from the sample.

1 12

References Abu-Elgheit, M., Khalil, S.O. and Barakat, A.O., 1979. Characterization of crude oils by new trace element indices. American Chemical Society Symposium on the Chemistry of Asphaltenes, ACS Meeting September 814, 1979, pp. 793-797. AI-Shahristani, H. and AI-Atiya, M.J., 1972. Vertical migration ofoil in Iraqi oil fields: Evidence based on vanadium and nickel concentrations. Geochim. Cosmochim. Acta, 36: 929-938. Bauch and Lomb, 1982. ICP Spectrometry: Instrumentation and Operating Parameters. Bauch and Lomb Inc., New York, N.Y., 76 pp. Bonham, L.C., 1956. Geochemical investigation of crude oils. AAPG Bull., 40: 897-908. Curiale, J.A., 1987a. Distribution and occurrence of metals in heavy crude oils and solid bitumens--implications for petroleum exploration. In: R.F. Meyer (Editor), Exploration for Heavy Crude Oil and Natural Bitumen. AAPG Stud. Geol. Ser., 25:207-219. Curiale, J.A., 1987b. Distribution of transition metals in north Alaskan crude oils. In: R.H. Filby and J.F. Branthaver (Editors), Metal Complexes in Fossil Fuels: Geochemistry, Characterization and Processing. American Chemical Society, Washington, D.C., Syrup. Set., 344: 124-145. Curiale, J.A. and Odermatt, J.R., 1989. Short Term Biomarker Variability in the Monterey Formation, Santa Maria Basin. Org. Geochem., 14: 1-13. Curiale, J.A., Cameron, D. and Davis, D.V., 1985. Biological marker distribution and significance in oils and rocks of the Monterey Formation, California. Geochim. Cosmochim. Acta, 49:271-288. Dabard, M.P. and Paris, F., 1986. Palaeontological and geochemical characteristics of Silurian black shale formations from the central Brittany domain of the Armorican Massif (Northwest France). Chem. Geol., 55: 17--29. Didyk, B.M., Simoneit, B.R.T., Brassell, S.C. and EglinIon, G., 1978. Organic geochemical indicators of palaeoenvironmental conditions of sedimentation. Nature (London), 272:216-222. Douglas, A.G. and Mair, B.J., 1965. Sulfur: role in genesis of petroleum. Science, 147: 499-501. Durand, B., 1980. Sedimentary organic matter and kerogen definition and quantitative importance of kerogen. In: B. Durand (Editor), Kerogen: Insoluble Organic Matter from Sedimentary Rocks. Imprimerie Bayeusaine, Paris, pp. 17-26. Durand, B. and G. Nicaise, 1980. Procedures for kerogen isolation, In: B. Durand (Editor), Kerogen: Insoluble Organic Matter from Sedimentary Rocks, Imprimerie Bayeusaine, Paris, pp. 35-52. Filby, R.H., 1973. Trace element distribution in petro-

J.R. ODERMATT AND J.A. CIJRIALE

leum components. Symposium on the Role of Trace Metals in Petroleum, ACS Meeting Chicago, August 26-31, 1973. Am. Chem. Soc., Div. Pet. Chem., Prepr., pp. 630-643. Filby, R.H., 1975. The nature of metals in petroleum. In: T.F. Yen (Editor), The Role of Trace Metals in Petroleum. Ann Arbor Science Publishers, Ann Arbor, Mich., pp. 31-58. Franceskin, P,J., Gonzalez-Jimenez, F., La Rosa, M.G., Abrams, O. and Katan, L., 1986. First observation of an iron porphyrin in heavy crude oil. Hyperiine Interactions, 28: 825-828. Gransch, J.A. and Posthuma, J., 1973. On the origin of sulphur in crudes. In: B. Tissol and F. Bienner (Editors), Advances in Organic Geochemistry, 1973. Editions Technip, Paris, pp. 727-739. Hirner, A.V., 1987. Metals in crude oils, asphaltenes, bitumens and kerogen--Molasse Basin, southern Germany. In: R.H. Filby and J.F. Branthaver (Editors), Metal Complexes in Fossil Fuels: Geochemistry, Characterization and Processing. American Chemical Society, Washington, D.C., Syrup. Ser., 344:146-153. Hitchon, B. and Filby, R.H., 1984. Use of trace elements for classification of crude oils into families--example from Alberta, Canada. AAPG Bull., 68: 838-850. Hodgson, G.W., 1954. Vanadium, nickel and iron trace metals in crude oils of western Canada. AAPG Bull., 38: 2537-2554. lsaacs, C.M. and Petersen, N.F., 1987. Petroleum in the Miocene Monterey Formation, California. In: J.R. Hein (Editor), Siliceous Sedimentary, Rock-Hosted Ores and Petroleum. Van Nostrand Reinhold, New York, N.Y., pp. 83-116. Jacobs, F.S.U., 1982. The Nature and Significance of Trace Metals in Oil Sands and Heavy Oils. Ph.D. Dissertation, Washington State University, Pullman, Wash., 212 pp. Jacobs, F.S.U., Bachelor, F.W. and Filby, R.H., 1984. Trace metals in Alberta oil sand bitumen components. In: Characterization of Heavy Crude Oils and Petroleum Residues, International Symposium, Lyon, June 25-27, 1984, pp. 173-178. Katz, G.J. and Elrod, L.W., 1983. Organic geochemistry of DSDP Site 467, offshore California, Middle Miocene to Lower Pliocene strata. Geochim. Cosmochim. Acta, 47: 389-386. King, J.D. and Claypool, G.E., 1983. Biological marker compounds and implications for generation and migration of petroleum in rocks of the Point Conception deep-stratigraphic test well, OCS-CAL 78-164 No. 1, offshore California. In: C.M. Isaacs and R.E. Garrison (Editors), Petroleum Generation and Occurrence in the Miocene Monterey Formation, California. Soc. Econ. Paleontol. Mineral.. Pac. Secl., pp. 39-51,

ORGANICALLY BOUND METALS AND BIOMARKERS IN THE MONTEREY FORMATION OF THE SANTA MARIA BASIN

Lewan, M.D., 1980. Geochemistry of Vanadium and Nickel in Organic Matter of Sedimentary Rocks. Ph.D. Dissertation, University of Cincinnati, Cincinnati, Ohio, 353 pp. Lcwan, M.D., 1984. Factors controlling the proportionality of vanadium to nickel in crude oils. Geochim. Cosmochim. Acta, 48: 2231-2238. Lewan, M.D., 1986. Organic sulfur in kerogens from different lithofacies of the Monterey Formation (Abstr.). American Chemical Society Symposium on Geochemistry in Petroleum ExplorationIThe Monterey Formation, California and Related Environments, ACS Meeting Anaheim, Calif., Sept. 7-12, 1986. Lewan, M.D. and Maynard, J.B., 1982. Factors controlling the enrichment of vanadium and nickel in bitumen of organic sedimentary rocks, Geochim. Cosmochim. Acta, 46: 2547-2560. Magoon, L.B. and lsaacs, C.M., 1983. Chemical characteristics of some crude oils from the Santa Maria Basin, California. In: C.M. lsaacs and R.E. Garrison (Editors), Petroleum Formation and Occurrence in the Miocene Monterey Formation, California. Am. Assoc. Pet. Geol., Pac. Sect., Los Angeles, Calif., pp. 201-211. O'Connor, J.G., Burow, F.H. and Norris, M.S., 1962. Determination of normal paraffins in C20 to C32 paraffin waxes by molecular sieve adsorption. Anal. Chem.. 34: 82-85. Odermatt, J.R., 1986. Transition Element Geochemistry of Organic Matter from the Monterey Formation, Union Leroy 51-18 well, Santa Maria Valley Field, Santa Barbara County, California. M.S. Thesis, California State University, Los Angeles, Calif., 213 pp. Orr, W.L., 1986. Kerogen/asphaltene/sulfur relationships in sulfur rich Monterey oils. In: D. Leythaeuser and J. Rullkotter (Editors), Advances in Organic Geochemistry 1985: Part I, Petroleum Geochemistry, Pergamon, London, pp. 499-516. P a t t e r s o n , J . H . , Ramsden, A.R., Dale, L.S. and Fardy, J.J., 1986. Geochemistry and mineralogical residences of trace elements in oil shales from Julia Creek, Queensland, Australia. Chem. Geol., 55: 1-16. Patterson, J.H., Dale, L.S. and Chapman, J.F., 1988. Trace clement partitioning during the retorting of Condor and Rundle oil shales. Environ. Sci. Technol., 22: 532-537. Pisciotto, K.A., 1978. Basinal Sedimentary Facies and Diagenetic Aspects of the Monterey Shale. California, Ph.D. Dissertation, University of California, Santa Cruz, Calif., 450 pp. Pisciotto, K.A. and Garrison, R.E., 1981. Lithofacies and depositional environments of the Monterey Forma-

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tion. California. In: R.E. Garrison and R.G. Douglas (Editors), The Monterey Formation and Related Siliceous Rocks of California. Soc. Econ. Paleontol. Mineral., Pac. Sect., Los Angeles, Calif., pp. 97-122. Pocock, S.A.J., 1982. Identification and recording of particulate matter. In: F.L. Staplin (Editor), How to Assess Maturation and Paleotemperatures. SEPM, Tulsa, Okla., Short Course, 7:13-132. Saban, M., Vitrrovic, O. and Votorovic, D., 1984. Correlation of crude oils from Vojvodina (Yugoslavia) based on trace elements. In: Characterization of Heavy Crude Oils and Petroleum Residues, International Symposium, Lyon, June 25-27, 1984, pp. 122-127. Seifert, W.K. and Moldowan, J.M.. 1978. Application of steranes, terpanes and monoaromatics to the maturation, migration and source of crude oils. Geochim. Cosmochim. Acta, 42: 77-95. Summerhayes, C.P,, 1981. Oceanographic controls on organic matter in the Miocene Monterey Formation, Offshore California. In: R.E. Garrison and R.G. Douglas (Editors), The Monterey Formation and Related Siliceous Rocks of California. SEPM, Tulsa, Okla., pp. 213-219. Sundararaman, P., 1986. Porphyrins in geochemical correlation: depositional environment (Abstr.). Symposium on Metalloporphyrins and Metal Complexes in Petroleum and Source Rocks: Aspects of their Geochemistry and Behavior in Processing, ACS Meeting New York City, April 13-18, 1986. Am. Chem. Soc., Div. Pet. Chem., Prepr., p. 633. Taguchi, K., Hasegawa, K. and Suzuki, T., 1988. The relationship between silica minerals and organic matter diagenesis: its implication for the origin of oil. In: L. Mattavelli and L. Novelli (Editors), Advances in Organic Geochemistry 1987. Pergamon Press, London, 13: 97-108. Tissot, B.P. and Welte, D.H., 1984. Petroleum Formation and Occurrence. Springer-Verlag, New York, N.Y., 2nd ed., 699 pp. Van Berkel, G.J., 1987. The Role of Kerogen in the Origin and Evolution of Nickel and Vanadyl Geoporphyrins. Ph.D. Dissertation, Washington State University, Pullman, Wash., 246 pp. Walsh, J.N. and Howie, R.A., 1986. Recent developments in analytical methods: uses of inductively coupled plasma source spectrometry in applied geology and geochemistry. Appl. Geochem., 1: 161-171. Woodring, W.P. and Bramlette, M.N., 1950. Geology and Paleontology of the Santa Maria District, California. US Geol. Surv., Prof. Pap., 222, 182 pp.