Sedimentary environment and major controlling factors of organic matter-rich shale from the Wufeng-Longmaxi formation in eastern Sichuan Basin, China

Abstract

The major controlling factors of organic matter and its enrichment model of the black shale from the Wufeng-Longmaxi Formation were explored by investigating the vertical variation characteristics, as well as major element and trace element abundances in the Wuxi Bailu section. The results show that the sedimentary tectonic setting of the Wufeng-Longmaxi Formation in the north-east margin of the upper Yangtze platform is located on the active continental margin, which is a passive continental margin and continental island arc. The parent rock in the source area is mainly felsic volcanic rocks mixed with small amounts of sedimentary recycling materials. Due to increased plate activity and a drop in sea levels, terrigenous pyroclastic input increased. The palaeoclimate was semi-humid, and a robust dysoxic-reduction environment and a high level of palaeoproductivity, causing the formation of the organic-rich shale in the Wufeng Formation. At the base of the Longmaxi Formation, the sedimentary water body was affected by global transgression, showing a strong anoxic-reductive environment, and the paleoclimate was a warm and humid condition. The palaeoproductivity level was high, resulting in the formation of organic shale. Due to the sea level drop at the top of the Longmaxi Formation, the sedimentary water was in an oxic-reduced environment, but the input of terrigenous pyroclastic matter increased. Because the paleoclimate was warm and humid and the palaeoproductivity level was high, organic-rich shale was formed. The findings demonstrate that terrigenous clastic input circumstances, palaeoproductivity conditions, and paleo-redox conditions had the greatest influence on the enrichment of organic matter in the Wufeng-Longmaxi Formation. Thus, organic matter enrichment was controlled by multiple paleoenvironmental factors.

Graphical abstract

Keywords

Wufeng-Longmaxi Formation / organic-rich shale / organic matter enrichment / depositional palaeoenvironment / eastern Sichuan Basin

References

[1] Adegoke A K, Abdullah W H, Hakimi M H, Yandoka B M S (2015). Geochemical characterisation and organic matter enrichment of Upper Cretaceous Gongila shales from Chad (Bornu) Basin, northeastern Nigeria: bioproductivity versus anoxia conditions.J Petrol Sci Eng, 135: 73–87

[2] Algeo T J, Li C (2020). Redox classification and calibration of redox thresholds in sedimentary systems.Geochim Cosmochim Acta, 287: 8–26

[3] Algeo T J, Liu J S (2020). A re–assessment of elemental proxies for paleoredox analysis.Chem Geol, 540: 119549

[4] Algeo T J, Maynard J B (2004). Trace–element behavior and redox facies in core shales of Upper Pennsylvanian Kansas–type cyclothems.Chem Geol, 206(3–4): 289–318

[5] Allègre C J, Minster J F (1978). Quantitative models of trace element behavior in magmatic process.Earth Planet Sci Lett, 38(1): 1–25

[6] Arthur M A, Dean W E, Laarkamp K (1998). Organic carbon accumulation and preservation in surface sediments on the Peru margin.Chem Geol, 152(3–4): 273–286

[7] Bai J K, Zhang S H, Liu C Y, Jia L B, Luo K Y, Jiang T, Peng H (2022). Mineralogy and geochemistry of the Middle Permian Pingdiquan Formation black shales on the eastern margin of the Junggar Basin, north–west China: implications for palaeoenvironmental and organic matter accumulation analyses.Geol J, 57(5): 1989–2006

[8] Bai Y Y, Liu Z J, Sun P C, Liu R, Hu X F, Zhao H Q, Xu Y B (2015). Rare earth and major element geochemistry of Eocene fine–grained sediments in oil shale– and coal–bearing layers of the Meihe Basin, northeast China.J Asian Earth Sci, 97: 89–101

[9] Berry W B N, Wilde P (1978). Progressive ventilation of the oceans: an explanation for the distribution of the Lower Paleozoic black shales.Am J Sci, 278(3): 257–275

[10] Bhatia M R (1985). Rare earth element geochemistry of Australian Paleozoic graywackes and mudrocks: provenance and tectonic control.Sediment Geol, 45(1–2): 97–113

[11] Bhatia M R, Crook K A W (1986). Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins.Contrib Mineral Petrol, 92(2): 181–193

[12] Borjigin T, Shen B J, Yu L J, Yang Y F, Zhang W T, Tao C, Xi B B, Zhang Q Z, Bao F, Qin J Z (2017). Mechanisms of shale gas generation and accumulation in the ordovician Wufeng–Longmaxi Formation, sichuan basin, SW China.Pet Explor Dev, 44(1): 69–78

[13] Calvert S E, Pedersen T F (1993). Geochemistry of recent oxic and anoxic marine sediments: implications for the geological record.Mar Geol, 113(1–2): 67–88

[14] Cao J, Wu M, Chen Y, Hu K, Bian L Z, Wang L G, Zhang Y (2012). Trace and rare earth element geochemistry of Jurassic mudstones in the northern Qaidam Basin, northwest China.Geochemistry, 72(3): 245–252

[15] Carroll A R, Bohacs K M (1999). Stratigraphic classification of ancient lakes: balancing tectonic and climatic controls.Geology, 27(2): 99–102

[16] Casacci M, Bertinelli A, Algeo T J, Rigo M (2016). Carbonate–to–biosilica transition at the Norian–Rhaetian boundary controlled by rift–related subsidence in the western Tethyan Lagonegro Basin (southern Italy).Palaeogeogr Palaeoclimatol Palaeoecol, 456: 21–36

[17] Chen L, Jiang S, Chen P, Chen X H, Zhang B M, Zhang G T, Lin W B, Lu Y C (2021). Relative sea–level changes and organic matter enrichment in the Upper Ordovician–Lower Silurian Wufeng–Longmaxi Formations in the Central Yangtze area, China.Mar Pet Geol, 124: 104809

[18] Chen Y H, Wang Y B, Guo M Q, Wu H Y, Li J, Wu W T, Zhao J Z (2020). Differential enrichment mechanism of organic matters in the marine–continental transitional shale in northeastern Ordos Basin, China: control of sedimentary environments.J Nat Gas Sci Eng, 83: 103625

[19] Cullers R L (2000). The geochemistry of shales, siltstones and sandstones of Pennsylvanian–Permian age, Colorado, USA: implications for provenance and metamorphic studies.Lithos, 51(3): 181–203

[20] Ding J H, Sun J S, Zhang J C, Yang X T, Shi G, Wang R Y, Huang B, Li H L (2022). Elemental geochemical evidence for controlling factors and mechanisms of transitional organic matter accumulation: the upper Permian Longtan Formation black shale in the Lower Yangtze region, south China.J Nat Gas Sci Eng, 98: 104385

[21] Ding J H, Zhang J C, Tang X, Huo Z P, Han S B, Lang Y, Liu T (2018). Elemental geochemical evidence for depositional conditions and organic matter enrichment of black rock series strata in an inter-platform basin: the Lower Carboniferous Datang Formation, Southern Guizhou, southwest China.Minerals, 8(11): 509

[22] Floyd P A, Leveridge B E (1987). Tectonic environment of the Devonian Gramscatho basin, south Cornwall: framework mode and geochemical evidence from turbiditic sandstones.J Geol Soc London, 144(4): 531–542

[23] Hatch J R, Leventhal J S (1992). Relationship between inferred redox potential of the depositional environment and geochemistry of the Upper Pennsylvanian (Missourian) Stark Shale Member of the Dennis Limestone, Wabaunsee County, Kansas, U. S. A.Chem Geol, 99(1–3): 65–82

[24] Ji R S, Qin D Y, Gao C L (1990). Closing of eastern Qinling palaeoocean and collaging between the North China and Yangtze Blocks.Petroleum Geo Experiment, 12(4): 353–365

[25] Lan Z K, Shen J J (2022). Depositional paleo–environments of Lower Cambrian Qiongzhusi Formation in the Western Middle Yangtze Block and its controlling effect on the organic matter enrichment.Energies, 15(10): 3761

[26] Lewan M D, Maynard J B (1982). Factors controlling enrichment of vanadium and nickel in the bitumen of organic sedimentary rocks.Geochim Cosmochim Acta, 46(12): 2547–2560

[27] Liang C, Jiang Z X, Yang Y T, Wei X J (2012). Shale lithofacies and reservoir space of the Wufeng–Longmaxi Formation, Sichuan Basin, China.Pet Explor Dev, 39(6): 736–743

[28] Liao Z W, Hu W X, Cao J, Wang X L, Hu Z Y (2019). Petrologic and geochemical evidence for the formation of organic–rich siliceous rocks of the Late Permian Dalong Formation, Lower Yangtze region, southern China.Mar Pet Geol, 103: 41–54

[29] Liu S X, Wu C F, Li T, Wang H C (2018). Multiple geochemical proxies controlling the organic matter accumulation of the marine–continental transitional shale: a case study of the Upper Permian Longtan Formation, western Guizhou, China.J Nat Gas Sci Eng, 56: 152–165

[30] Liu Y, Wu B, Gong Q S, Cao H Y (2019). Geochemical characteristics of the lower Silurian Longmaxi Formation on the Yangtze Platform, South China: implications for depositional environment and accumulation of organic matters.J Asian Earth Sci, 184: 104003

[31] McLennan S M (1989). Rare earth elements in sedimentary rocks: influence of provenance and sedimentary processes.Rev Mineral Geochem, 21(1): 169–200

[32] Murphy A E, Sageman B B, Hollander D J, Lyons T W, Brett C E (2000). Black shale deposition and faunal overturn in the Devonian Appalachian Basin: clastic starvation, seasonal water–column mixing, and efficient biolimiting nutrient recycling.Paleoceanography, 15(3): 280–291

[33] Roser B P, Korsch R J (1988). Provenance signatures of sandstone–mudstone suites determined using discriminant function analysis of major–element data.Chem Geol, 67(1–2): 119–139

[34] Ross D J, Bustin R M (2009). Investigating the use of sedimentary geochemical proxies for paleoenvironment interpretation of thermally mature organic–rich strata: examples from the Devonian–Mississippian shales, Western Canadian Sedimentary Basin.Chem Geol, 260(1–2): 1–19

[35] Sugisaki R, Yamamoto K, Adachi M (1982). Triassic bedded cherts in central Japan are not pelagic.Nature, 298(5875): 644–647

[36] Shang F H, Zhu Y M, Hu Q H, Wang Y, Li Y, Li W, Liu R Y, Gao H T (2020). Factors controlling organic–matter accumulation in the Upper Ordovician–Lower Silurian organic–rich shale on the northeast margin of the Upper Yangtze platform: evidence from petrographic and geochemical proxies.Mar Pet Geol, 121: 104597

[37] Shen J, Schoepfer S D, Feng Q L, Zhou L, Yu J X, Song H Y, Wei H Y, Algeo T J (2015). Marine productivity changes during the end–Permian crisis and Early Triassic recovery.Earth Sci Rev, 149: 136–162

[38] Sweere T, van den Boorn S, Dickson A J, Reichart G J (2016). Definition of new trace–metal proxies for the controls on organic matter enrichment in marine sediments based on Mn, Co, Mo and Cd concentrations.Chem Geol, 441: 235–245

[39] Talbot M R (1988). The origins of lacustrine oil source rocks: evidence from the lakes of tropical Africa.Geological Society, 40: 29–43

[40] Taylor S R, McLennan S M (1985). The Continental Crust: Its Composition and Evolution. Oxford: Blackwell Scientific Publications, 1–328

[41] Tribovillard N, Algeo T J, Lyons T, Riboulleau A (2006). Trace metals as paleoredox and paleoproductivity proxies: an update.Chem Geol, 232(1–2): 12–32

[42] Wang Y M, Li X J, Dong D Z, Zhang C C, Wang S F (2017). Major controlling factors for the high–quality shale of Wufeng–Longmaxi Formation, Sichuan Basin.Energ Explor Exploit, 35(4): 444–462

[43] Wang Y Y, Chen J F, Shen W B, Li M (2022). Mechanism of organic matter accumulation in black shales of the Yuertusi Formation in the Tarim Basin: insights from paleoenvironmental variation during the Early Cambrian.Front Earth Sci (Lausanne), 10: 879658

[44] Wignall P B, Newton R (2001). Black shales on the basin margin: a model based on examples from the Upper Jurassic of the Boulonnais, northern France.Sediment Geol, 144(3–4): 335–356

[45] Wu B (2022). The sedimentary geochemical characteristics and geological significance of the Wufeng–Longmaxi Formation accumulation of organic matter black shale on the southeastern Sichuan Basin, China.Geofluids, 2022: 1900158

[46] Wu Z R, He S, He Z L, Li X C, Zhai G Y, Huang Z Q (2022). Petrographical and geochemical characterization of the Upper Permian Longtan Formation and Dalong Formation in the Lower Yangtze region, South China: implications for provenance, paleoclimate, paleoenvironment and organic matter accumulation mechanisms.Mar Pet Geol, 139: 105580

[47] Xu L F, Cheng Y S, Zhang J C, Liu Y, Yang Y Y (2022). Controls on the organic matter accumulation of the marine–continental transitional Shanxi Formation shale in the southeastern Ordos Basin.ACS Omega, 7(5): 4317–4332

[48] Yan D T, Chen D Z, Wang Z Z, Li J, Yang X R, Zhang B (2019). Climatic and oceanic controlled deposition of Late Ordovician–Early Silurian black shales on the North Yangtze platform, south China.Mar Pet Geol, 110: 112–121

[49] Yin K, Xu J, Li X M (2019). A new grey comprehensive relational model based on weighted mean distance and induced intensity and its application.Grey Systems-Theory and Application, 9(3): 374–384

[50] Yuan W, Liu G D, Zhou X X, Xu L M, Li C Z (2020). Palaeoproductivity and organic matter accumulation during the deposition of the Chang 7 organic–rich shale of the Upper Triassic Yanchang Formation, Ordos Basin, China.Geol J, 55(4): 3139–3156

[51] Zeng S Q, Wang J, Fu X G, Chen W B, Feng X L, Wang D, Song C Y, Wang Z W (2015). Geochemical characteristics, redox conditions, and organic matter accumulation of marine oil shale from the Changliang Mountain area, northern Tibet, China.Mar Pet Geol, 64: 203–221

[52] Zhang L C, Xiao D S, Lu S F, Jiang S, Lu S D (2019). Effect of sedimentary environment on the formation of organic–rich marine shale: insights from major/trace elements and shale composition.Int J Coal Geol, 204: 34–50

[53] Zou C N, Dong D Z, Wang S J, Li J Z, Li X J, Wang Y M, Li D H, Cheng K M (2010). Geological characteristics and resource potential of shale gas in China.Pet Explor Dev, 37(6): 641–653

Acknowledgments

The authors would like to acknowledge the financial support of the National Natural Science Foundation of China (Grant Nos. 42172156 and 41802183), the Fundamental Research Funds for the Central Universities (No. 2022YCPY0201) and the National Key R&D Program of China (No. 2020YFA0711800).

Competing interests

The authors declare that they have no competing interests.

RIGHTS & PERMISSIONS

2024 Higher Education Press