1Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; 2Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China; 3University of Chinese Academy of Sciences, Beijing 100049, China; 4Hebei GEO University, Shijiazhuang 050031, Hebei Province, China; 5Research Institute of Petroleum Exploration and Development, Tarim Oilfield Company, PetroChina, Korla 841000, Xinjiang Uygur Autonomous Region, China
Abstract The fabrics of microbialites preserved in limestones are generally better than in dolostones. What are the fabrics of the microbialites preserved in heavily dolomitized dolostones? This paper presents an example of a strongly dolomitized Cambrian microbialite profile. The Xiaoerblak Formation (Cambrian Series 2 Stage 3 and lower Stage 4) of the Sugaitblak section in Aksu, Xinjiang Uygur Autonomous Region, China is mainly composed of microbial dolostones. Due to strong alteration by diagenesis, their features, formation and environments have not been fully understood. Here, based on detailed observation on outcrops and thin sections, we show that this formation comprises four kinds of microbialites: laminite, thrombolite, thrombolitic laminite, and Renalcis framestone, in five intervals (Interval I to Interval V). We identified three main types of microbialite fabrics, i.e., clotted fabric, laminated fabric and skeletal fabric, and established a high-resolution vertical evolution sequence of the microbialites. The clotted fabric and the laminated fabric were further divided into subtypes. We found that the original fabrics were mainly affected by dolomitization, recrystallization and dissolution, and the alteration degree of the microbialite fabric is stronger in the lower part of this formation. The laminated fabric has the strongest resistance to diagenesis, followed by the clotted fabric. Based on studies of different rock types and sedimentary structures, we concluded that the sedimentary environment of Xiaoerblak Formation consists of three settings: a) Intervals I to III formed in restricted tidal flat environments, b) Interval IV and the lower part of Interval V in restricted deep subtidal environments, and c) upper part of Interval V in shallowing-up open subtidal environments.
[1] Adachi N.,Y. Ezaki, and J.B. Liu.2011. Early Ordovician shift in reef construction from microbial to metazoan reefs.Palaios 26(2): 106-114. [2] Aitken J.D.1967. Classification and environmental significance of cryptalgal limestones and dolomites, with illustrations from the Cambrian and Ordovician of southwestern Alberta.Journal of Sedimentary Petrology 37(4): 1163-1178. [3] Bai Y.,P. Luo,W. Liu,X.F. Zhai, and C.M. Zhou.2018. Characteristics and main controlling factors of microbial carbonate reservoir: A case study of upper member of Lower Cambrian Xiaoerbulake Formation in Akesu area, Tarim Basin.China Petroleum Exploration 23(4): 95-106 (in Chinese with English abstract). [4] Braga J.C.,J.M. Martin, and R. Riding.1995. Controls on microbial dome fabric development along a carbonate-siliciclastic shelf-basin transect, Miocene, SE Spain.Palaios 10(4): 347-361. [5] Bullen S.B.,D.F. Sibley.1984. Dolomite selectivity and mimic replacement.Geology 12(11): 655-658. [6] Burne R.V.,L.S. Moore.1987. Microbialites: Organosedimentary deposits of benthic microbial communities.Palaios 2(3): 241-254. [7] Chen J.T.,J.H. Lee, and J. Woo.2014. Formative mechanisms, depositional processes, and geological implications of Furongian (Late Cambrian) reefs in the North China Platform.Palaeogeography, Palaeoclimatology, Palaeoecology 414: 246-259. [8] Du R.L.1992. The Paleobiology and Historical Geology of the Precambrian. Beijing: Geological Publishing House, pp. 1-193 (in Chinese). [9] Feng Z.Z.,Y.M. Peng,Z.K. Jin, and Z.D. Bao.2002. Lithofacies palaeogeography of the Early Cambrian in China.Journal of Palaeogeography (Chinese Edition) 4(1): 1-12 (in Chinese with English abstract). [10] Feng Z.Z.,Z.D. Bao,M.B. Wu,Z.K. Jin, and X.Z. Shi.2006. Lithofacies palaeogeography of the Cambrian in Tarim area.Journal of Palaeogeography (Chinese Edition) 8(4): 427-439 (in Chinese with English abstract). [11] Friedman G.M.,A.J. Amiel,M. Braun, and D.S. Miller.1973. Generation of carbonate particles and laminites in algal mats — Example from sea-marginal hypersaline pool, Gulf of Aqaba, Red Sea.AAPG Bulletin 57(3): 541-557. [12] Glumac B.,K.R. Walker.1997. Selective dolomitization of Cambrian microbial carbonate deposits: A key to mechanisms and environments of origin.Palaios 12(2): 98-110. [13] Golubic S.1973. The relationship between blue-green algae and carbonate deposits. In: The Biology of Blue-Green Algae, eds. N.G. Carr, and B.A. Whitton, pp. 434-472. Blackwell: Oxford. [14] Han Z.Z.,J.T. Chen,N.J. Chi,Z.P. Wang,R.C. Yang, and A.P. Fan.2009. Microbial carbonates: A review and perspectives.Marine Geology and Quaternary Geology 29(4): 29-38 (in Chinese with English abstract). [15] Harwood Theisen, C.,D.Y. Sumner.2016. Thrombolite fabrics and origins: Influences of diverse microbial and metazoan processes on Cambrian thrombolite variability in the Great Basin, California and Nevada.Sedimentology 63(7): 2217-2252. [16] Hofmann H.J.1975. Stratiform Precambrian stromatolites, Belcher Islands, Canada: Relations between silicified microfossils and microstructure.American Journal of Science 275(10): 1121-1132. [17] Huang Q.Y.,S.Y. Hu,W.Q. Pan,W. Liu,Y.L. Chi,K. Wang,S.Y. Shi, and Q. Liu.2016. Sedimentary characteristics of intra-platform microbial mounds and their controlling effects on the development of reservoirs: A case study of the Lower Cambrian Xiaoerbulake Formation in the Keping-Bachu area, Tarim Basin.Natural Gas Industry 36(6): 21-29 (in Chinese with English abstract). [18] Huang Z.B.,L.J. Liu,H.J. Yang,Y.S. Wu,Z.L. Yang,R. Zhao,Z.Y. Xiao, and W.Q. Pan.2017. The spatial-temporal distribution of paleocommunities on the Cambrian Platform of the Tarim Block and its stratigraphic significances.Journal of Stratigraphy 41(1): 1-16 (in Chinese with English abstract). [19] Jahnert R.J.,L.B. Collins.2012. Characteristics, distribution and morphogenesis of subtidal microbial systems in Shark Bay, Australia. Marine Geology 303-306: 115-136. [20] James N.P.,D.I. Gravestock.1990. Lower Cambrian shelf and shelf margin buildups, Flinders Ranges, South Australia.Sedimentology 37(3): 455-480. [21] Kiessling W.2009. Geologic and biologic controls on the evolution of reefs.Annual Review of Ecology, Evolution, and Systematics 40(1): 173-192. [22] Lee J.H.,J.T. Chen, and S.K. Chough.2010. Paleoenvironmental implications of an extensive maceriate microbialite bed in the Furongian Chaomidian Formation, Shandong Province, China.Palaeogeography, Palaeoclimatology, Palaeoecology 297(3-4): 621-632. [23] Lee J.H.,J.T. Chen,S.J. Choh,D.J. Lee,Z.Z. Han, and S.K. Chough.2014. Furongian (Late Cambrian) sponge-microbial maze-like reefs in the North China Platform.Palaios 29(1): 27-37. [24] Li P.W.,P. Luo,J.M. Song,T.F. Jin, and G.Q. Wang.2015. Characteristics and main controlling factors of microbial carbonate reservoirs: A case study of Upper Sinian-Lower Cambrian in the northwestern margin of Tarim Basin.Acta Petrolei Sinica 36(9): 1074-1089 (in Chinese with English abstract). [25] Machel H.G.2004. Concepts and models of dolomitization: A critical reappraisal. In: The Geometry and Petrogenesis of Dolomite Hydrocarbon Reservoirs, eds. C.J.R. Braithwaite, G. Rizzi, and G. Darke. Geological Society, London, Special Publications, 235: 7-63. [26] Mettraux M.,P. Homewood, C. Dos Anjos, M. Erthal, R. Lima, N. Matsuda, A. Souza, and S. Al Balushi. 2015. Microbial communities and their primary to early diagenetic mineral phases: The record from Neoproterozoic microbialites of Qarn Alam, Oman. In: Conference on Microbial Carbonates in Space and Time: Implications for Global Exploration and Production. Geological Society, London, Special Publications, 418: 123-154. [27] Monty C.L.V. 1976. The origin and development of cryptalgal fabrics. In: Developments in Sedimentology, Volume 20, ed. M.R. Walter, pp. 193-249. New York: Elsevier. [28] Murray R.C.,F.J. Lucia.1967. Cause and control of dolomite distribution by rock selectivity.GSA Bulletin 78(1): 21-35. [29] Pratt B.R.1984. Epiphyton and Renalcis - diagenetic microfossils from calcification of coccoid blue-green algae. Journal of Sedimentary Petrology 54(3): 948-971. [30] Riding R.1991. Calcareous Algae and Stromatolites, ed. R. Riding, pp. 21-51. Heidelberg: Springer. [31] Riding R.2000. Microbial carbonates: The geological record of calcified bacterial-algal mats and biofilms.Sedimentology 47(s1): 179-214. [32] Riding R.2006. Cyanobacterial calcification, carbon dioxide concentrating mechanisms, and Proterozoic-Cambrian changes in atmospheric composition.Geobiology 4(4): 299-316. [33] Riding R.2011. Microbialites, stromatolites, and thrombolites. In: Encyclopedia of Geobiology, Encyclopedia of Earth Science Series, eds. J. Reitner, and V. Thiel, pp. 635-654. Heidelberg: Springer. [34] Riding R.2012. A hard life for cyanobacteria.Science 336: 427-428. [35] Rowland S.M.,R.A. Gangloff.1988. Structure and paleoecology of Lower Cambrian reefs.Palaios 3(2): 111-135. [36] Shapiro R.S.2000. A comment on the systematic confusion of thrombolites.Palaios 15(2): 166-169. [37] Shapiro R.S.2004. Neoproterozoic-Cambrian microbialite record.The Paleontological Society Papers 10: 5-16. [38] Shen A.J.,J.F. Zheng,Y.Q. Chen,X.F. Ni, and L.L. Huang.2016. Characteristics, origin and distribution of dolomite reservoirs in Lower-Middle Cambrian, Tarim Basin, NW China.Petroleum Exploration and Development 43(3): 340-349 (in Chinese with English abstract). [39] Sibley D.F.1980. Climatic control of dolomitization, Seroe Domi Formation (Pliocene), Bonaire, N.A. In: Concepts and Models of Dolomitization. SEPM Special Publications 28: 247-258. [40] Sibley D.F.1982. The origin of common dolomite fabrics: Clues from the Pliocene.Journal of Sedimentary Petrology 52(4): 1087-1100. [41] Sibley D.F.2003. Dolomite textures. In: Encyclopedia of Sediments and Sedimentary Rocks, pp. 231-234. Dordrecht: Springer. [42] Song J.M.,P. Luo,S.S. Yang,D. Yang,C.M. Zhou,P.W. Li, and X.F. Zhai.2014. Reservoirs of Lower Cambrian microbial carbonates, Tarim Basin, NW China.Petroleum Exploration and Development 41(4): 404-413 (in Chinese with English abstract). [43] Song J.M.,P. Luo,S.S. Yang,X.F. Zhai,G. Zhou, and P.P. Lu.2012. Carbonate rock microbial construction of the Lower Cambrian Xiaoerblak Formation in Sugaitblak area, Tarim Basin.Journal of Palaeogeography (Chinese Edition) 14(3): 341-354 (in Chinese with English abstract). [44] Stephens N.P.,D.Y. Sumner.2002. Renalcids as fossilized biofilm clusters.Palaios 17(3): 225-236. [45] Turner E.C.,N.P. James, and G.M. Narbonne.1997. Growth dynamics of Neoproterozoic calcimicrobial reefs, Mackenzie Mountains, Northwest Canada.Journal of Sedimentary Research 67(3): 437-450. [46] Wang J.,R.L. Zhuang,K.T. Lao, and G.H. Long.1990. Division and geological implications of calcareous algal morphological groups and environmental zones in the Lower Cambrian Qingxudong Formation, Huayuan District, western Hunan.Sedimentary Facies and Palaeogeography 10(3): 9-19 (in Chinese with English abstract). [47] Wang J.P.,Y. Li,L. Cheng,X.W. Zeng, and G. Wang.2014. Paleozoic reefs and their paleogeological controls in South China Block.Acta Palaeontologica Sinica 53(1): 121-131 (in Chinese with English abstract). [48] Wood R.1998. The ecological evolution of reefs.Annual Review of Ecology and Systematics 29(1): 179-206. [49] Wood R.1999. Reef Evolution, pp. 33-59. Oxford: Oxford University Press. [50] Wu Y.S.,H.X. Jiang,G.L. Yu, and L.J. Liu.2018. Conceptions of microbialites and origin of the Permian-Triassic boundary microbialites from Laolongdong, Chongqing, China.Journal of Palaeogeography (Chinese Edition) 20(5): 737-775 (in Chinese with English abstract). [51] Xiong Y.X.,Y.Q. Chen,B.Z. Guan,L.P. Deng,X.F. Ni, and R. Xiong.2015. Distribution of Northern Platform margin and implications to favorable exploration regions on Lower Cambrian Xiaoerbulake Formation, Tarim Basin.Acta Sedimentologica Sinica 33(2): 408-415 (in Chinese with English abstract). [52] Zhao Z.J.,J.H. Luo,Y.B. Zhang,X.N. Wu, and W.Q. Pan.2011. Lithofacies paleogeography of Cambrian sequences in the Tarim Basin.Acta Petrolei Sinica 32(6): 937-948 (in Chinese with English abstract). [53] Zheng J.F.,Y.Q. Chen,L.L. Huang,W. Yan,X.F. Ni,B.H. Li, and X.Y. Guo.2019. Reservoir modeling of the Lower Cambrian Xiaoerblak Formation in the Sugaitblak Section and its significance for exploring regions in the Tarim Basin, NW China.Acta Sedimentologica Sinica 37(3): 601-609 (in Chinese with English abstract). [54] Zhu M.Y.,A.H. Yang,J.L. Yuan,G.X. Li,J.M. Zhang,F.C. Zhao,S.Y. Ahn, and L.Y. Miao.2019. Cambrian integrative stratigraphy and timescale of China.Science China Earth Sciences 62(1): 25-60.
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