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1 Department of Geological and Geophysical Sciences, University of Wisconsin, 1215 W. Dayton St., Madison, Wisconsin, 53706; carroll{at}geology.wisc.edu
2 ExxonMobil Upstream Research Co., 2189 Buffalo Speedway, Houston, Texas, 77252; kmbohac{at}upstream.xomcorp.com
Alan R. Carroll has been an assistant professor at the University of Wisconsin, Madison, since 1996, specializing in sedimentary basins in western China and the western United States. He received geology degrees from Carleton College (B.A. degree, 1980), the University of Michigan, Ann Arbor (M.Sc. degree, 1983), and Stanford University (Ph.D., 1991). He worked as an exploration geologist for Sohio (1983-1986) and a research geologist for Exxon Production Research Company (1991-1995). He is an associate editor of the AAPG Bulletin.Kevin M. Bohacs is a sedimentologist and stratigrapher with the Petroleum Geochemistry section of ExxonMobil Upstream Research Company (URC) in Houston, Texas. He received his B.Sc. (honors) degree in geology from the University of Connecticut in 1976 and his Sc.D. degree in experimental sedimentology from M.I.T. in 1981. At URC, he leads the application of sequence stratigraphy and sedimentology to organic-rich rocks from deep sea to swamps and lakes in basins around the world. As a research associate, his primary focus is to keep the geo- in geochemistry, integrating field work, subsurface investigation, and laboratory analyses. He has written numerous articles on the stratigraphy and sedimentology of mudrocks, hydrocarbon source rocks, and lake systems. He was co-recipient of the AAPG Jules Braunstein Memorial Award for best poster session paper in 1995 for work on coal sequence stratigraphy and the AAPG International Paper Award in 1998 and was an AAPG Distinguished Lecturer for 1999-2000.
Based on numerous empirical observations of lacustrine basin strata, we propose a three-fold classification of lacustrine facies associations that accounts for the most important features of lacustrine petroleum source rocks and provides a predictive framework for exploration in nonmarine basins where lacustrine facies are incompletely delineated.
1. The fluvial-lacustrine facies association is characterized by freshwater lacustrine mudstones interbedded with fluvial-deltaic deposits, commonly including coal. Shoreline progradation dominates basin fill, resulting in the stacking of indistinctly expressed cycles up to 10 m thick. In map view, the deposits may be regionally widespread but laterally discontinuous and contain strong facies contrasts. Transported terrestrial organic matter contributes to mixed type I-III kerogens that generate waxy oil (type I kerogen is hydrogen rich and oil prone; type III kerogen is hydrogen poor and mainly gas prone). The Luman Tongue of the Green River Formation (Wyoming) and the Honyanchi Formation (Junggar basin, China) provide examples of this facies association, which is also present in the Songliao basin of northeastern China, the Central Sumatra basin, and the Cretaceous Doba/Doseo basins in west-central Africa.
2. The fluctuating profundal facies association represents a combination of progradational and aggradational basin fill and includes some of the world's richest source rocks. Deposits are regionally extensive in map view, having relatively homogenous source facies containing oil-prone, type I kerogen. Examples include the Laney Member of the Green River Formation (Wyoming), the Lucaogou Formation (Junggar basin, China), the Bucomazi Formation (offshore west Africa), and the Lagoa Feia Formation (Campos basin, Brazil).
3. The evaporative facies association represents dominantly aggradational fill related to desiccation cycles in saline to hypersaline lakes and may include evaporite and eolianite deposits. Sublittoral organic-rich mudstone facies are relatively thin but may be quite rich and widespread. The highest organic enrichment coincides with the deepest lake stages. Low input of land plant organic matter results in minimal lateral contrasts in organic content. In some cases a distinctive type I-S (sulfur-rich) kerogen may generate oil at thermal maturities as low as 0.45% vitrinite reflectance equivalent. Examples include the Wilkins Peak Member of the Green River Formation (Wyoming), the Jingjingzigou Formation (Junggar basin, China), the Jianghan and Qaidam basins (China), and the Blanca Lila Formation (Argentina).
This article has been cited by other articles:
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  F. Hao, X. Zhou, Y. Zhu, X. Bao, and Y. Yang Charging of the Neogene Penglai 19-3 field, Bohai Bay Basin, China: Oil accumulation in a young trap in an active fault zone AAPG Bulletin, February 1, 2009; 93(2): 155 - 179. [Abstract] [Full Text] [PDF]
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 M. E. Smith, A. R. Carroll, and B. S. Singer Synoptic reconstruction of a major ancient lake system: Eocene Green River Formation, western United States Geological Society of America Bulletin, January 1, 2008; 120(1-2): 54 - 84. [Abstract] [Full Text] [PDF]
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Y. Chen, L. Liu, X. Cai, J. Ma, and S. Huang Characteristics of petroleum geology of the Baise Basin in Guangxi, China AAPG Bulletin, October 1, 2007; 91(10): 1449 - 1466. [Abstract] [Full Text] [PDF]
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 L. H. Nielsen, H. I. Petersen, N. D. Thai, N. A. Duc, M. B. W. Fyhn, L. O. Boldreel, H. A. Tuan, S. Lindstrom, and L. V. Hien A Middle-Upper Miocene fluvial-lacustrine rift sequence in theSong Ba Rift, Vietnam: an analogue to oil-prone, small-scale continental rift basins Petroleum Geoscience, May 1, 2007; 13(2): 145 - 168. [Abstract] [Full Text] [PDF]
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P.G. DeCelles, P. Kapp, L. Ding, and G.E. Gehrels Late Cretaceous to middle Tertiary basin evolution in the central Tibetan Plateau: Changing environments in response to tectonic partitioning, aridification, and regional elevation gain Geological Society of America Bulletin, May 1, 2007; 119(5-6): 654 - 680. [Abstract] [Full Text] [PDF]
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 J. T. Pietras and A. R. Carroll High-Resolution Stratigraphy of an Underfilled Lake Basin: Wilkins Peak Member, Eocene Green River Formation, Wyoming, U.S.A. Journal of Sedimentary Research, November 1, 2006; 76(11): 1197 - 1214. [Abstract] [Full Text] [PDF]
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 Paleolimnology: The History and Evolution of Lake Systems Palaios, April 1, 2004; 19(2): 184 - 186.
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M. E. Smith, B. Singer, and A. Carroll 40Ar/39Ar geochronology of the Eocene Green River Formation, Wyoming Geological Society of America Bulletin, May 1, 2003; 115(5): 549 - 565. [Abstract] [Full Text] [PDF]
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