Aliphatic biomarker signatures of early Oligocene−early Miocene source rocks in the central Qiongdongnan Basin: Source analyses of organic matter
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Abstract: The geochemical signatures of fifty-four rock samples and three supplementary drill stem test (DST) oils from the Yacheng-Sanya formations in the central Qiongdongnan Basin (CQB) were analysed. Reconstruction of the early Oligocene−early Miocene (36–16 Ma) palaeovegetation and source analyses of organic matter (OM) were conducted using aliphatic biomarkers in ancient sediments and DST oils. Both the interpreted aquatic and terrigenous OM contributed to the CQB source rocks (SRs) but had varying relative proportions. The four distribution patterns derived from n-alkanes, terpanes, and steranes are representative of four OM composition models of the Yacheng-Sanya SRs, including model A, model B, model C, and model D, which were classified based on the increasing contribution from terrigenous OM relative to aquatic OM. Some terrigenous higher plant-derived biomarkers, including oleanane, des-A-oleanane, C29 ααα 20R sterane, bicadinanes, the C19/(C19 + C23) tricyclic terpane ratio, and other n-alkane-derived ratios suggest that angiosperms had increased proportions in the palaeoflora from early Oligocene to early Miocene, and the bloom of terrigenous higher plants was observed during deposition of upper Lingshui Formation to lower Sanya Formation. These findings are consistent with the incremental total organic carbon and free hydrocarbons + potential hydrocarbons (S1 + S2) in the lower Lingshui-lower Sanya strata with a significant enrichment of OM in the E3l1-N1s2 shales. The maturity- and environment-sensitive aliphatic parameters of the CQB SRs and DST oils suggest that all the samples have predominantly reached their early oil-generation windows but have not exceeded the peak oil windows, except for some immature Sanya Formation shales. In addition, most of the OM in the analysed samples was characterised by mixed OM contributions under anoxic to sub-anoxic conditions. Furthermore, terrestrial-dominant SRs were interpreted to have developed mainly in the Lingshui-Sanya formations and were deposited in sub-oxic to oxic environments, compared to the anoxic to sub-anoxic conditions of the Yacheng Formation.
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Figure 1. Map showing the regional geological outline of the Qiongdongnan Basin (QDNB). a. Geographic location of the QDNB in the South China Sea. b. Schematic structure of the QDNB and location of associated wells, well names in black include cutting samples, names in red contain core/sidecore samples, and letters in blue indicate drill stem test oils involved. c. The stratigraphic column of QDNB. Dep. env. : depositional environment.
Figure 2. Normalized n-alkane profiles of four distribution patterns for the early Oligocene to early Miocene source rocks from the Qiongdongnan Basin and partial m/z 85 mass chromatograms of the aliphatic hydrocarbon fractions showing the distributions of n-alkanes and isoprenoids in the representative samples for each pattern. Numbers in each figure represent carbon numbers of n-alkanes; Pr: Pristane; Ph: Phytane.
Figure 4. Partial m/z 191 (left) and 412 (right) mass chromatograms of the aliphatic fractions illustrating four different distribution patterns of terpanes and bicadinanes in the rock extracts from the Qiongdongnan Basin. In m/z 191, TT: tricyclic teranes; TeT: tetracyclic teranes; peak distributions assign hopane stereochemistry at C-22 (S and R); Ts: 18α(H),22,29,30-trisnorneohopane; Tm: 17α(H),22,29,30-trisnorhopane; C29Ts: 18α(H)-30-norneohopane; Cx, x: carbon number; H: 17α(H)-hopane; M: 17β(H) moretane. In m/z 412, W: cis-cis-trans-bicadinane; T: trans-trans-trans-bicadinane; R: bicadinane.
Figure 5. Partial m/z 217 mass chromatograms showing the sterane and diasterane distributions in the rock extracts from the Qiongdongnan Basin. C20: norpregnane; C21: pregnane; C22: homopregnane; D-C27 S: 13β(H), 17α(H)-C27 diasterane 20S; D-C27 R: 13β(H), 17α(H)-C27 diasterane 20R; C27: C27 ααα 20R sterane; C28: C28 ααα 20R sterane; C29: C29 ααα 20R sterane.
Figure 11. Cross-plot of terrestrial-derived indicators versus depths from middle lingshui Formation to lower Sanya Formation in Well BD-1. For abbreviations, see Table 1.
Table 1. Abbreviations and definitions for some geochemical parameters mentioned in the text
Abbreviation Definition CPI22-32 carbon preference index=2(C23+C25+C27+C29+C31)/(C22+2C24+2C26+2C28+2C30+C32) alkanes OEP odd-to-even predominance=[(Cmax−2+6×Cmax+Cmax+2)/$(4{\rm{C}}_{\max-1}+4{\rm{C}}_{\max+1})]^{(-1)^{\max-1}} $ alkanes Wax index (C21+C22)/(C28+C29) alkanes TAR terrigenous/aquatic ratio=(C27+C29+C31)/(C15+C17+C19) alkanes ACL15-33 average chain length=∑(n×Cn)/ ∑Cn, n is among 15−33 Pr pristane Ph phytane C19/(C19+C23) TT C19/(C19+C23) tricyclic terpanes C23/C21 TT C23/C21 tricyclic terpanes C24 TeT/C23TT C24 tetracyclic terpane/C23 tricyclic terpane Ts/(Ts+Tm) C27 18$\alpha $(H)-22,29,30-trisnorneohopane/(C27 17$\alpha $(H)-22,29,30-trisnorhopane + C27 18$\alpha $(H)-22,29,30-trisnorneohopane) C29 Ts/C29 H 18$\alpha $-30-neohopane/C29 $\alpha\beta $ norhopane C29 H/(H+M) C29 $\alpha \beta /(\alpha\beta+\beta \alpha )$ norhopanes C30 H/(H+M) C30 $\alpha \beta/(\alpha \beta+\beta\alpha $) hopanes C31/C30 H C31 $\alpha \beta$ homohopane/ C30 $\alpha \beta$ hopanes C31 22S/(22S+22R) H C31 $\alpha \beta$ 22S/(22S+22R) homohopanes O/C30 H oleanane/C30 $\alpha \beta$ hopane GA/C30 H gammacerane/C30 $\alpha \beta$ hopane DAO/C30 H des-A-oleanane/C30 $\alpha \beta$ hopane Ta/C30 H taraxerane/C30 $\alpha \beta$ hopane (O+DAO+Ta)/C30 H (oleanane+des-A-oleanane+taraxerane)/C30 $\alpha \beta$ hopane (W+T)/C30 H (cis-cis-cis-bicadinane+trans-trans-trans-bicadinane)/C30 $\alpha \beta$ hopane T/∑C29 steranes trans-trans-trans-bicadinane/C29 ($\alpha\alpha\alpha $ 20S+$\alpha \beta\beta$ 20R+$\alpha\beta\beta $ 20S+$\alpha\alpha\alpha $ 20R) steranes C27/C29 $\alpha\alpha\alpha $ 20R steranes C27 $\alpha\alpha\alpha $ 20R sterane/C29 $\alpha\alpha\alpha $ 20R sterane C29 20S/(20R+20S) steranes C29 $\alpha\alpha\alpha $ 20S/(20R+20S) steranes C29 $\beta\beta $/($\alpha\alpha $+$\beta\beta $) steranes C29 $\alpha \beta\beta$/($\alpha\alpha\alpha $+$\alpha \beta\beta$) 20R steranes Table 2. Detailed information and bulk geochemical parameters of representative rock samples from nine wells in the Qiongdongnan Basin
Sample ID Well Formation Depth/m Type Lithology TOC/% (S1+S2)/(mg·g −1) Ro/% Tmax/°C R1 BD-1 N1s1 2 537 cutting shale 0.44 0.65 0.61 434 R2 BD-1 N1s2 2 669 cutting shale 0.72 1.03 0.63 437 R3 BD-1 E3l1 3 249 cutting silty muds. 0.82 2.28 0.71 443 R4 BD-1 E3l2 4 183–4 221 cutting shale 0.93 1.58 0.84 447 R5 BD-1 E3l3 4 599–4 601 cutting silty muds. 0.58 1.02 0.84 451 R6 BD-2 E3l1 2 888.2–2 896.2 cutting shale 0.50 0.52 0.71 435 R7 BD-2 E3l3 3 326.2–3 330.2 cutting shale 0.52 0.5 0.76 437 R8 BD-2 E3y1 3 998.2–4 004.2 cutting shale 0.98 0.67 1.03 451 R9 BD-3 E3l3 2 615.7 sidecore shale 0.201 0.51 n.d. 440 R10 BD-3 E3y1 3 076.7 sidecore shale 0.317 0.61 n.d. 445 R11 BD-3 E3y3 3 498.7 sidecore shale 0.529 0.51 n.d. 446 R12 LS-1 E3l 2 357.2 sidecore shale 0.9 2.74 0.42 431 R13 ST-1 N1s 2 719.2 sidecore siltstone n.d. 0.87 n.d. n.d. R14 YL-1 N1s2 1 255 sidecore shale n.d. 1.43 n.d. 423 R15 YL-1 E3l2 2 051–2 053 cutting shale n.d. n.d. n.d. n.d. R16 YL-1 E3l3 2 133.5 sidecore siltstone n.d. 0.69 n.d. n.d. R17 YL-2 N1s 1 105.5 sidecore shale n.d. 2.54 n.d. n.d. R18 YL-2 E3y 1 125.5 sidecore siltstone n.d. 1.28 n.d. n.d. R19 YL-3 N1s 992–996 cutting shale n.d. n.d. n.d. n.d. R20 YL-3 E3y 1 024.5 sidecore shale n.d. 12.78 n.d. 406 R21 YL-4 E3y1 680.8 sidecore siltstone n.d. 0.91 n.d. n.d. O1 BD-3 E3l3 2 618.1–2 680.5 oil DST n.d. n.d. n.d. n.d. O2 BD-3 E3l3 2 618.1–2 680.5 oil DST n.d. n.d. n.d. n.d. O3 BD-3 E3l3 2 618.1–2 680.5 oil DST n.d. n.d. n.d. n.d. Note: Rx and Ox point to rock samples and drill stem test oils, respectively. “x” is the number of each representative sample; “Depth” points to buried depth of each sample with deduction of water-depth; TOC: total organic carbon; S1+S2: free hydrocarbons+potential hydrocarbons; Ro: vitrinite reflectance; Tmax: temperature of maximum hydrocarbon generation rate; muds.: mudstone; n.d.: no data. Table 3. Biomarker parameters of the early Oligocene-early Miocene source rocks for representative rock samples from the Qiongdongnan Basin
Sample ID and parameters R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 O1 O2 O3 Cmax 21&29 29 27 20&26 19 17&27 14 17&20 22 21 20 24 29 21 25 18 20 20 27 20 18&24 20 19 20 OEP 1.38 1.32 1.03 1.12 0.99 1.00 0.80 1.12 1.00 1.02 1.10 0.98 1.22 1.21 1.26 0.76 0.96 1.03 1.18 1.05 0.90 1.08 1.01 1.08 CPI22–32 1.30 1.26 1.08 1.06 1.03 1.08 1.07 1.03 1.04 1.04 1.04 1.04 1.19 1.23 1.16 0.99 0.94 1.00 1.26 1.08 1.01 1.00 1.00 1.02 Pr/Ph 2.23 3.72 3.12 1.21 1.38 1.70 1.03 1.58 1.07 2.37 1.21 1.05 0.96 0.45 0.64 0.45 0.45 0.39 0.27 0.23 0.54 1.85 1.39 1.68 Pr/nC17 2.89 4.82 3.30 1.07 1.41 1.28 0.67 0.38 0.78 0.79 0.22 1.33 1.91 0.68 1.73 0.50 0.69 0.68 0.64 0.43 0.69 0.87 0.63 0.96 Ph/nC18 0.95 1.02 0.71 0.57 0.82 0.79 0.68 0.28 0.71 0.30 0.15 1.27 0.87 0.97 2.17 0.60 0.93 0.79 0.80 0.57 1.07 0.33 0.34 0.35 Wax index 0.80 0.43 0.62 1.20 2.13 0.81 1.49 2.84 1.49 1.55 1.76 1.29 1.02 2.86 1.54 5.43 3.05 4.72 0.97 5.87 1.44 3.19 3.94 2.28 ACL15-33 25.18 26.53 25.61 23.70 22.05 22.77 21.75 21.44 23.16 23.02 22.92 22.98 25.21 22.82 23.36 20.69 22.33 21.78 25.47 22.09 23.22 22.27 22.27 22.27 TAR 2.57 6.34 4.46 1.38 0.54 0.83 0.46 0.37 0.85 0.86 0.82 0.85 3.34 0.91 1.16 0.16 0.57 0.36 6.33 0.38 0.92 0.51 0.35 0.78 ACL15-33 0.34 0.57 0.57 0.14 0.19 0.11 0.07 0.09 0.12 0.30 0.04 0.10 0.21 0.05 0.19 0.11 0.06 0.05 0.04 0.05 0.06 0.34 0.29 0.32 Pr 0.95 1.05 1.44 1.80 1.70 1.65 2.40 1.44 1.29 1.33 2.61 1.97 1.13 1.57 1.82 1.46 1.62 1.69 2.22 2.11 1.81 0.73 1.03 0.82 Ph 1.03 2.40 1.59 0.55 0.35 0.29 0.42 0.27 0.41 0.40 0.33 0.75 1.12 0.35 0.63 0.32 0.34 0.29 0.63 0.42 0.39 0.28 0.18 0.28 C19/(C19+C23) TT 0.45 0.35 0.46 0.35 0.38 0.38 0.52 0.49 0.63 0.43 0.55 0.48 0.54 0.35 0.30 0.42 0.45 0.42 0.19 0.20 0.55 0.68 0.69 0.68 C23/C21 TT 0.31 0.35 0.41 0.26 0.25 0.31 0.46 0.42 0.81 0.26 0.26 0.32 0.55 0.23 0.30 0.33 0.21 0.23 0.11 0.11 0.31 0.36 0.37 0.29 C24 TeT/C23TT 0.80 0.82 0.90 0.86 0.83 0.88 0.91 0.88 0.92 0.88 0.85 0.90 0.80 0.69 0.66 0.77 0.78 0.74 0.68 0.56 0.83 0.91 0.90 0.93 Ts/(Ts+Tm) 0.81 0.81 0.86 0.84 0.84 0.84 0.88 0.89 0.86 0.86 0.85 0.86 0.86 0.68 0.80 0.82 0.77 0.75 0.57 0.51 0.86 0.83 0.84 0.85 C29Ts/C29 H 0.59 0.58 0.59 0.56 0.57 0.57 0.56 0.42 0.45 0.44 0.52 0.58 0.59 0.34 0.43 0.47 0.48 0.54 0.31 0.44 0.55 0.43 0.45 0.46 C29 H/(H+M) 0.81 0.45 0.45 0.08 0.09 0.16 0.10 0.09 0.60 1.40 0.08 0.59 1.07 0.08 0.21 0.19 0.07 0.09 0.03 0.04 0.08 1.36 1.20 1.16 C30 H/(H+M) 0.06 0.05 0.06 0.23 0.23 0.15 0.21 0.20 0.29 0.15 0.22 0.04 0.07 0.23 0.10 0.18 0.17 0.17 0.13 0.11 0.17 0.21 0.21 0.16 C31/C30 H 0.52 0.60 0.53 0.34 0.37 0.51 0.40 0.59 0.78 0.25 0.47 0.49 0.49 0.57 0.38 0.58 0.55 0.49 0.51 0.60 0.47 0.47 0.48 0.47 C31 H 20S/(20S+20R) 0.10 0.07 0.17 0.01 0.01 0.09 0.02 0.03 0.04 0.13 0.02 0.06 0.14 0.03 0.05 0.04 0.03 0.04 0.01 0.01 0.02 0.66 0.58 0.54 O/C30 H 0.15 0.12 0.13 0.03 0.04 0.08 0.03 0.02 0.12 0.09 0.02 0.06 0.10 0.06 0.05 0.07 0.02 0.02 0.02 0.01 0.03 0.16 0.15 0.15 GA/C30 H 1.06 0.63 0.76 0.12 0.13 0.32 0.15 0.14 0.76 1.62 0.12 0.70 1.32 0.22 0.31 0.37 0.13 0.15 0.06 0.07 0.13 2.17 1.93 1.85 DAO/C30 H 0.022 0.008 0.137 0.006 0.008 0.181 0.017 0.020 0.014 0.167 0.004 0.007 0.117 n.d. n.d. n.d. n.d. n.d. 0.004 n.d. n.d. 0.382 0.337 0.336 Ta/C30 H 0.042 0.027 0.300 0.006 0.008 0.505 0.061 0.062 0.037 0.965 0.008 0.018 0.016 n.d. n.d. n.d. n.d. n.d. 0.055 n.d. n.d. 0.991 0.917 0.946 (O+DAO+Ta)/C30 H 0.67 0.31 0.69 0.81 0.85 0.88 0.65 1.02 1.17 1.23 1.18 1.62 1.36 0.97 1.32 0.68 1.39 1.23 0.56 0.49 1.41 1.16 1.49 1.85 (W+T)/C30 H 0.40 0.47 0.42 0.38 0.38 0.53 0.44 0.45 0.47 0.47 0.39 0.43 0.44 0.05 0.12 0.18 0.40 0.35 0.24 0.24 0.43 0.45 0.47 0.51 T/∑C29 steranes 0.34 0.35 0.48 0.39 0.40 0.47 0.43 0.51 0.58 0.53 0.40 0.35 0.53 0.28 0.31 0.32 0.49 0.48 0.14 0.46 0.53 0.54 0.57 0.57 Notes: Rx and Ox are sample IDs consistent with that in Table 2. For definition of each parameter see Table 1. Cmax: maximum n-alkanes; n.d.: no data. -
Ahmed M, Volk H, Allan T, et al. 2012. Origin of oils in the eastern Papuan Basin, Papua New Guinea. Organic Geochemistry, 53: 137–152. doi: 10.1016/j.orggeochem.2012.06.002 Albrecht P, Vandenbroucke M, Mandengué M. 1976. Geochemical studies on the organic matter from the Douala Basin (Cameroon)—I. Evolution of the extractable organic matter and the formation of petroleum. Geochimica et Cosmochimica Acta, 40(7): 791–799. doi: 10.1016/0016-7037(76)90031-4 Alexander R, Larcher A V, Kagi R I, et al. 1988. The use of plant derived biomarkers for correlation of oils with source rocks in the Cooper/Eromanga Basin system, Australia. The APPEA Journal, 28(1): 310–324. doi: 10.1071/AJ87024 Alkhafaji M W. 2021. Biomarker assessment of oil biodegradation, water washing, and source rock characteristics of oil seeps from the Foothill Zone along the Tigris River, Northern Iraq. Journal of Petroleum Science and Engineering, 197: 107946. doi: 10.1016/j.petrol.2020.107946 Andrusevich V E, Engel M H, Zumberge J E, et al. 1998. Secular, episodic changes in stable carbon isotope composition of crude oils. Chemical Geology, 152(1–2): 59–72 Blocho R M, Smith R W, Noll M R. 2021. Analyses of depositional environments of the Marcellus formation in New York using biomarker and trace metal proxies. Journal of Petroleum Exploration and Production Technology, 11(8): 3163–3175. doi: 10.1007/s13202-021-01237-8 Bourbonniere R A, Meyers P A. 1996. Sedimentary geolipid records of historical changes in the watersheds and productivities of Lakes Ontario and Erie. Limnology and Oceanography, 41(2): 352–359. doi: 10.4319/lo.1996.41.2.0352 Cao Ying, Li Chunfeng, Yao Yongjian. 2017. Thermal subsidence and sedimentary processes in the South China Sea Basin. Marine Geology, 394: 30–38. doi: 10.1016/j.margeo.2017.07.022 Chattopadhyay A, Dutta S. 2014. Higher plant biomarker signatures of early Eocene sediments of North Eastern India. Marine and Petroleum Geology, 57: 51–67. doi: 10.1016/j.marpetgeo.2014.04.004 Didyk B M, Simoneit B R T, Brassell S C, et al. 1978. Organic geochemical indicators of palaeoenvironmental conditions of sedimentation. Nature, 272(5650): 216–222. doi: 10.1038/272216a0 Ding Wenjing, Hou Dujie, Gan Jun, et al. 2021. Palaeovegetation variation in response to the late Oligocene–early Miocene East Asian summer monsoon in the Ying-Qiong Basin, South China Sea. Palaeogeography, Palaeoclimatology, Palaeoecology, 567: 110205 Ding Wenjing, Hou Dujie, Gan Jun, et al. 2022. Sedimentary geochemical records of late Miocene-early Pliocene palaeovegetation and palaeoclimate evolution in the Ying-Qiong Basin, South China Sea. Marine Geology, 445: 106750. doi: 10.1016/j.margeo.2022.106750 Ding Wenjing, Hou Dujie, Zhang Weiwei, et al. 2018. A new genetic type of natural gases and origin analysis in northern Songnan-Baodao Sag, Qiongdongnan Basin, South China Sea. Journal of Natural Gas Science and Engineering, 50: 384–398. doi: 10.1016/j.jngse.2017.12.003 Eglinton G, Hamilton R J. 1967. Leaf Epicuticular Waxes: The waxy outer surfaces of most plants display a wide diversity of fine structure and chemical constituents. Science, 156(3780): 1322–1335. doi: 10.1126/science.156.3780.1322 Fan Caiwei, Xu Changgui, Xu Jie. 2021. Genesis and characteristics of miocene deep-water clastic rocks in Yinggehai and Qiongdongnan Basins, northern South China Sea. Acta Geologica Sinica (English Edition), 95(1): 153–166. doi: 10.1111/1755-6724.14637 Fazeelat T, Asif M, Jalees M I, et al. 2011. Source correlation between biodegraded oil seeps and a commercial crude oil from the Punjab Basin, Pakistan. Journal of Petroleum Science and Engineering, 77(1): 1–9. doi: 10.1016/j.petrol.2011.01.003 Fyhn M B W, Thomsen T B, Keulen N, et al. 2019. Detrital zircon ages and heavy mineral composition along the Gulf of Tonkin—Implication for sand provenance in the Yinggehai-Song Hong and Qiongdongnan basins. Marine and Petroleum Geology, 101: 162–179. doi: 10.1016/j.marpetgeo.2018.11.051 Galarraga F, Urbani F, Escobar M, et al. 2010. Main factors controlling the compositional variability of seepage oils from Trujillo state, western Venezuela. Journal of Petroleum Geology, 33(3): 255–267. doi: 10.1111/j.1747-5457.2010.00477.x Gao Gang, Zhang Gongcheng, Chen Guo, et al. 2018. Geochemistry of borehole cutting shale and natural gas accumulation in the deepwater area of the Zhujiang River Mouth-Qiongdongnan Basin in the northern South China Sea. Acta Oceanologica Sinica, 37(2): 44–53. doi: 10.1007/s13131-018-1151-2 Grantham P J, Posthuma J, Baak A. 1983. Triterpanes in a number of Far-Eastern crude oils. In: Bjory M, Albrecht C, eds. Advances in Organic Geochemistry 1981: International Conference Proceedings. Chichester: Blackwell, 710–724 Guo Shusheng, Liao Gaolong, Liang Hao, et al. 2021. Major breakthrough and significance of deep-water gas exploration in Well BD21 in Qiongdongnan Basin. China Petroleum Exploration, 26(5): 49–59 Haberer R M, Mangelsdorf K, Wilkes H, et al. 2006. Occurrence and palaeoenvironmental significance of aromatic hydrocarbon biomarkers in Oligocene sediments from the Mallik 5L-38 Gas Hydrate Production Research Well (Canada). Organic Geochemistry, 37(5): 519–538. doi: 10.1016/j.orggeochem.2006.01.004 Hakimi M H, Abdullah E S, Ebiad M A, et al. 2021. Early mature sulfur-rich oils from the central gulf of Suez province: bulk property and geochemical investigations of maltene and asphaltene show source related-type. Arabian Journal of Geosciences, 14(12): 1119. doi: 10.1007/s12517-021-07280-3 Hakimi M H, Mohialdeen I M J, Al Ahmed A A, et al. 2018. Thermal modeling and hydrocarbon generation of the late Jurassic–early Cretaceous Chia Gara Formation in Iraqi Kurdistan region, northern Zagros Fold Belt. Egyptian Journal of Petroleum, 27(4): 701–713. doi: 10.1016/j.ejpe.2017.10.007 Hautevelle Y, Michels R, Malartre F, et al. 2006. Vascular plant biomarkers as proxies for palaeoflora and palaeoclimatic changes at the Dogger/Malm transition of the Paris Basin (France). Organic Geochemistry, 37(5): 610–625. doi: 10.1016/j.orggeochem.2005.12.010 Hoş-Çebi F. 2017. Organic geochemical characteristics and paleoclimate conditions of the Miocene coals at the Çan-Durali (Çanakkale). Journal of African Earth Sciences, 129: 117–135. doi: 10.1016/j.jafrearsci.2016.12.003 Huang Heting, Huang Baojia, Huang Yiwen, et al. 2017. Condensate origin and hydrocarbon accumulation mechanism of the deepwater giant gas field in western South China Sea: A case study of Lingshui 17–2 gas field in Qiongdongnan Basin. Petroleum Exploration and Development, 44(3): 409–417. doi: 10.1016/S1876-3804(17)30047-2 Huang Baojia, Li Li, Huang Heting. 2012. Origin and accumulation mechanism of shallow gases in the North Baodao Slope, Qiongdongnan Basin, South China Sea. Petroleum Exploration and Development, 39(5): 567–573. doi: 10.1016/S1876-3804(12)60077-9 Huang Wen-Yen, Meinschein W G. 1979. Sterols as ecological indicators. Geochimica et Cosmochimica Acta, 43(5): 739–745. doi: 10.1016/0016-7037(79)90257-6 Huang Baojia, Tian Hui, Li Xushen, et al. 2016. Geochemistry, origin and accumulation of natural gases in the deepwater area of the Qiongdongnan Basin, South China Sea. Marine and Petroleum Geology, 72: 254–267. doi: 10.1016/j.marpetgeo.2016.02.007 Huang Baojia, Xiao Xianming, Li Xuxuan. 2003. Geochemistry and origins of natural gases in the Yinggehai and Qiongdongnan basins, offshore South China Sea. Organic Geochemistry, 34(7): 1009–1025. doi: 10.1016/S0146-6380(03)00036-6 Izart A, Suarez-Ruiz I, Bailey J. 2015. Paleoclimate reconstruction from petrography and biomarker geochemistry from Permian humic coals in Sydney Coal Basin (Australia). International Journal of Coal Geology, 138: 145–157. doi: 10.1016/j.coal.2014.12.009 Jeng W L. 2006. Higher plant n-alkane average chain length as an indicator of petrogenic hydrocarbon contamination in marine sediments. Marine Chemistry, 102(3–4): 242–251 Jiang Lian, Ding Wenjing, George S C. 2020. Late Cretaceous–Paleogene palaeoclimate reconstruction of the Gippsland Basin, SE Australia. Palaeogeography, Palaeoclimatology, Palaeoecology, 556: 109885 Jiang Lian, George S C. 2018. Biomarker signatures of Upper Cretaceous Latrobe Group hydrocarbon source rocks, Gippsland Basin, Australia: Distribution and palaeoenvironment significance of aliphatic hydrocarbons. International Journal of Coal Geology, 196: 29–42. doi: 10.1016/j.coal.2018.06.025 Jiang Lian, George S C. 2019. Biomarker signatures of Upper Cretaceous Latrobe Group petroleum source rocks, Gippsland Basin, Australia: Distribution and geological significance of aromatic hydrocarbons. Organic Geochemistry, 138: 103905. doi: 10.1016/j.orggeochem.2019.103905 Kennicutt M C, Barker C, Brooks J M, et al. 1987. Selected organic-matter source indicators in the orinoco, Nile and Changjiang deltas. Organic Geochemistry, 11(1): 41–51. doi: 10.1016/0146-6380(87)90050-7 La Croix A D, He Jianhua, Bianchi V, et al. 2020. Early Jurassic palaeoenvironments in the Surat Basin, Australia—marine incursion into eastern Gondwana. Sedimentology, 67(1): 457–485. doi: 10.1111/sed.12649 Lai Hongfei, Fang Yunxin, Kuang Zenggui, et al. 2021. Geochemistry, origin and accumulation of natural gas hydrates in the Qiongdongnan Basin, South China Sea: implications from site GMGS5-W08. Marine and Petroleum Geology, 123: 104774. doi: 10.1016/j.marpetgeo.2020.104774 Large D J, Gize A P. 1996. Pristane/phytane ratios in the mineralized Kupferschiefer of the Fore-Sudetic Monocline, southwest Poland. Ore Geology Reviews, 11(1–3): 89–103 Lei Chao, Clift P D, Ren Jianye, et al. 2019. A rapid shift in the sediment routing system of lower-upper Oligocene strata in the Qiongdongnnan Basin (Xisha Trough), Northwest South China Sea. Marine and Petroleum Geology, 104: 249–258. doi: 10.1016/j.marpetgeo.2019.03.012 Li Chao, Lyu Chengfu, Chen Guojun, et al. 2019. Zircon U-Pb ages and REE composition constraints on the provenance of the continental slope-parallel submarine fan, western Qiongdongnan Basin, northern margin of the South China Sea. Marine and Petroleum Geology, 102: 350–362. doi: 10.1016/j.marpetgeo.2018.12.046 Li Wenhao, Zhang Zhihuan. 2017. Paleoenvironment and its control of the formation of oligocene marine source rocks in the deep-water area of the northern South China Sea. Energy & Fuels, 31(10): 10598–10611 Li Hangyu, Zhang Ming, Lau H C, et al. 2020. China’s deepwater development: subsurface challenges and opportunities. Journal of Petroleum Science and Engineering, 195: 107761. doi: 10.1016/j.petrol.2020.107761 Li Wenhao, Zhang Zhihuan, Li Youchuan, et al. 2012. New perspective of Miocene marine hydrocarbon source rocks in deep-water area in Qiongdongnan Basin of northern South China Sea. Acta Oceanologica Sinica, 31(5): 107–114. doi: 10.1007/s13131-012-0241-9 Li Wenhao, Zhang Zhihuan, Li Youchuan, et al. 2013. The main controlling factors and developmental models of Oligocene source rocks in the Qiongdongnan Basin, northern South China Sea. Petroleum Science, 10(2): 161–170. doi: 10.1007/s12182-013-0263-8 Liu Zhen, Sun Zhipeng, Wang Zisong, et al. 2016a. Evaluation of abundant hydrocarbon-generation depressions in the deepwater area of Qiongdongnan Basin, South China Sea. Acta Oceanologica Sinica, 35(2): 137–144. doi: 10.1007/s13131-015-0784-7 Liu Zhifei, Zhao Yulong, Colin C, et al. 2016b. Source-to-sink transport processes of fluvial sediments in the South China Sea. Earth-Science Reviews, 153: 238–273. doi: 10.1016/j.earscirev.2015.08.005 Mathur N. 2014. Tertiary oils from Upper Assam Basin, India: a geochemical study using terrigenous biomarkers. Organic Geochemistry, 76: 9–25. doi: 10.1016/j.orggeochem.2014.07.007 Miao Yufa, Warny S, Clift P D, et al. 2018. Climatic or tectonic control on organic matter deposition in the South China Sea? A lesson learned from a comprehensive Neogene palynological study of IODP Site U1433. International Journal of Coal Geology, 190: 166–177. doi: 10.1016/j.coal.2017.10.003 Mohamed N S, El Nady M M, Sharaf L M. 2018. Evaluation of possible source rocks and extracts characteristics from Safir-1x well, North Western Desert, Egypt. Petroleum Science and Technology, 36(16): 1235–1241. doi: 10.1080/10916466.2018.1465974 Moldowan J M, Dahl J, Huizinga B J, et al. 1994. The molecular fossil record of oleanane and its relation to angiosperms. Science, 265(5173): 768–771. doi: 10.1126/science.265.5173.768 Murray A P, Sosrowidjojo I B, Alexander R, et al. 1997. Oleananes in oils and sediments: Evidence of marine influence during early diagenesis?. Geochimica et Cosmochimica Acta, 61(6): 1261–1276 Nytoft H P, Kildahl-Andersen G, Samuel O J. 2010. Rearranged oleananes: Structural identification and distribution in a worldwide set of late Cretaceous/Tertiary oils. Organic Geochemistry, 41(10): 1104–1118. doi: 10.1016/j.orggeochem.2010.06.008 Otto A, Simoneit B R T, Rember W C. 2005. Conifer and angiosperm biomarkers in clay sediments and fossil plants from the Miocene Clarkia Formation, Idaho, USA. Organic Geochemistry, 36(6): 907–922. doi: 10.1016/j.orggeochem.2004.12.004 Ourisson G, Albrecht P, Rohmer M. 1979. The hopanoids: palaeochemistry and biochemistry of a group of natural products. Pure and Applied Chemistry, 51(4): 709–729. doi: 10.1351/pac197951040709 Ourisson G, Albrecht P, Rohmer M. 1982. Predictive microbial biochemistry—from molecular fossils to procaryotic membranes. Trends in Biochemical Sciences, 7(7): 236–239. doi: 10.1016/0968-0004(82)90028-7 Paul S, Sharma J, Singh B D, et al. 2015. Early Eocene equatorial vegetation and depositional environment: Biomarker and palynological evidences from a lignite-bearing sequence of Cambay Basin, western India. International Journal of Coal Geology, 149: 77–92. doi: 10.1016/j.coal.2015.06.017 Peters K E, Fraser T H, Amris W, et al. 1999. Geochemistry of crude oils from eastern Indonesia. AAPG Bulletin, 83(12): 1927–1942 Peters K E, Walters C C, Moldowan J M. 2005. The Biomarker Guide. Cambridge: Cambridge University Press Philp R P, Gilbert T D. 1986. Biomarker distributions in australian oils predominantly derived from terrigenous source material. Organic Geochemistry, 10(1–3): 73–84 Preston J C, Edwards D. 2000. The petroleum geochemistry of oils and source rocks from the northern Bonaparte Basin, offshore northern Australia. The APPEA Journal, 40(1): 257–282. doi: 10.1071/AJ99014 Ren Jianye, Lei Chao, Wang Shan, et al. 2011. Tectonic stratigraphic framework of Yinggehai-Qiongdongnan Basins and its implication for tectonic province division in South China Sea. Chinese Journal of Geophysics, 54(12): 3303–3314 Ren Jinfeng, Wang Hua, Sun Ming, et al. 2014. Sequence stratigraphy and sedimentary facies of lower Oligocene Yacheng Formation in deepwater area of Qiongdongnan Basin, northern South China Sea: implications for coal-bearing source rocks. Journal of Earth Science, 25(5): 871–883. doi: 10.1007/s12583-014-0479-6 Ren Jinfeng, Zhang Yingzhao, Wang Hua, et al. 2015. Identification methods of coal-bearing source rocks for Yacheng Formation in the western deepwater area of South China Sea. Acta Oceanologica Sinica, 34(4): 19–31. doi: 10.1007/s13131-015-0647-2 Rudra A, Dutta S, Raju S V. 2017. The Paleogene vegetation and petroleum system in the tropics: A biomarker approach. Marine and Petroleum Geology, 86: 38–51. doi: 10.1016/j.marpetgeo.2017.05.008 Samad S K, Mishra D K, Mathews R P, et al. 2020. Geochemical attributes for source rock and palaeoclimatic reconstruction of the Auranga Basin, India. Journal of Petroleum Science and Engineering, 185: 106665. doi: 10.1016/j.petrol.2019.106665 Seifert W K, Moldowan M J. 1978. Applications of steranes, terpanes and monoaromatics to the maturation, migration and source of crude oils. Geochimica et Cosmochimica Acta, 42(1): 77–95. doi: 10.1016/0016-7037(78)90219-3 Seifert W K, Moldowan J M. 1986. Use of biological markers in petroleum exploration. In: Johns R B, ed. Methods in Geochemistry and Geophysics. Msterdam: Elsevier, 261–290 Simoneit B R T, Oros D R, Karwowski Ł, et al. 2020. Terpenoid biomarkers of ambers from Miocene tropical paleoenvironments in Borneo and of their potential extant plant sources. International Journal of Coal Geology, 221: 103430. doi: 10.1016/j.coal.2020.103430 Su Ao, Chen Honghan, Chen Xu, et al. 2018. New insight into origin, accumulation and escape of natural gas in the Songdong and Baodao regions in the eastern Qiongdongnan Basin, South China Sea. Journal of Natural Gas Science and Engineering, 52: 467–483. doi: 10.1016/j.jngse.2018.01.026 Su Ao, Chen Honghan, He Cong, et al. 2017. Complex accumulation and leakage of YC21–1 gas bearing structure in Yanan Sag, Qiongdongnan Basin, South China Sea. Marine and Petroleum Geology, 88: 798–813. doi: 10.1016/j.marpetgeo.2017.09.020 Su Long, Zheng Jianjing, Chen Guojun, et al. 2012. The upper limit of maturity of natural gas generation and its implication for the Yacheng Formation in the Qiongdongnan Basin, China. Journal of Asian Earth Sciences, 54–55: 203–213 Tamburini F, Adatte T, Föllmi K, et al. 2003. Investigating the history of East Asian monsoon and climate during the last glacial-interglacial period (0–140 000 years): Mineralogy and geochemistry of ODP Sites 1143 and 1144, South China Sea. Marine Geology, 201(1–3): 147–168 Ten Haven H L, De Leeuw J W, Schenck P A. 1985. Organic geochemical studies of a Messinian evaporitic basin, northern Apennines (Italy) I: Hydrocarbon biological markers for a hypersaline environment. Geochimica et Cosmochimica Acta, 49(10): 2181–2191. doi: 10.1016/0016-7037(85)90075-4 Ten Haven H L, Rullkötter J. 1988. The diagenetic fate of taraxer-14-ene and oleanene isomers. Geochimica et Cosmochimica Acta, 52(10): 2543–2548. doi: 10.1016/0016-7037(88)90312-2 Ten Haven H L, Rullkötter J, De Leeuw J W, et al. 1988. Pristane/phytane ratio as environmental indicator. Nature, 333(6174): 604–604 Van Aarssen B G K, Alexander R, Kagi R I. 2000. Higher plant biomarkers reflect palaeovegetation changes during Jurassic times. Geochimica et Cosmochimica Acta, 64(8): 1417–1424. doi: 10.1016/S0016-7037(99)00432-9 Van Aarssen B G K, Hessels J K C, Abbink O A, et al. 1992. The occurrence of polycyclic sesqui-, tri-, and oligoterpenoids derived from a resinous polymeric cadinene in crude oils from Southeast Asia. Geochimica et Cosmochimica Acta, 56(3): 1231–1246. doi: 10.1016/0016-7037(92)90059-R Volkman J K. 2005. Sterols and other triterpenoids: Source specificity and evolution of biosynthetic pathways. Organic Geochemistry, 36(2): 139–159. doi: 10.1016/j.orggeochem.2004.06.013 Vuković N, Životić D, Filho J G M, et al. 2016. The assessment of maturation changes of humic coal organic matter—Insights from closed-system pyrolysis experiments. International Journal of Coal Geology, 154–155: 213–239 Wang Dongdong, Dong Guoqi, Zhang Gongcheng, et al. 2020. Coal seam development characteristics and distribution predictions in marginal sea basins: Oligocene Yacheng Formation coal measures, Qiongdongnan Basin, northern region of the South China Sea. Australian Journal of Earth Sciences, 67(3): 393–409. doi: 10.1080/08120099.2019.1661286 Wang Zhengfeng, Jiang Tao, Zhang Daojun, et al. 2015a. Evolution of deepwater sedimentary environments and its implication for hydrocarbon exploration in Qiongdongnan Basin, northwestern South China Sea. Acta Oceanologica Sinica, 34(4): 1–10. doi: 10.1007/s13131-015-0645-4 Wang Ce, Liang Xinquan, Foster D A, et al. 2016. Zircon U-Pb geochronology and heavy mineral composition constraints on the provenance of the middle Miocene deep-water reservoir sedimentary rocks in the Yinggehai-Song Hong Basin, South China Sea. Marine and Petroleum Geology, 77: 819–834. doi: 10.1016/j.marpetgeo.2016.05.009 Wang Zhengfeng, Liu Zhen, Cao Shang, et al. 2014a. Vertical migration through faults and hydrocarbon accumulation patterns in deepwater areas of the Qiongdongnan Basin. Acta Oceanologica Sinica, 33(12): 96–106. doi: 10.1007/s13131-014-0579-2 Wang Zhengfeng, Shi Xiaobin, Yang Jun, et al. 2014b. Analyses on the tectonic thermal evolution and influence factors in the deep-water Qiongdongnan Basin. Acta Oceanologica Sinica, 33(12): 107–117. doi: 10.1007/s13131-014-0580-9 Wang Zhengfeng, Sun Zhipeng, Zhang Daojun, et al. 2015b. Geology and hydrocarbon accumulations in the deepwater of the northwestern South China Sea—with focus on natural gas. Acta Oceanologica Sinica, 34(10): 57–70. doi: 10.1007/s13131-015-0715-7 Wang Zhenfeng, Sun Zhipeng, Zhu Jitian, et al. 2015c. Natural gas geological characteristics and great discovery of large gas fields in deep-water area of the western South China Sea. Natural Gas Industry B, 2(6): 489–498. doi: 10.1016/j.ngib.2016.03.001 Wang Dongdong, Zhang Gongcheng, Li Zengxue, et al. 2021. The development characteristics and distribution predictions of the Paleogene coal-measure source rock in the Qiongdongnan Basin, northern South China Sea. Acta Geologica Sinica (English Edition), 95(1): 105–120. doi: 10.1111/1755-6724.14625 Webster P J. 1994. The role of hydrological processes in ocean-atmosphere interactions. Reviews of Geophysics, 32(4): 427–476. doi: 10.1029/94RG01873 Wingert W S, Pomerantz M. 1986. Structure and significance of some twenty-one and twenty-two carbon petroleum steranes. Geochimica et Cosmochimica Acta, 50(12): 2763–2769. doi: 10.1016/0016-7037(86)90225-5 Wu Piao, Hou Dujie, Gan Jun, et al. 2018a. Paleoenvironment and controlling factors of Oligocene source rock in the eastern deep-water area of the Qiongdongnan Basin: evidences from organic geochemistry and palynology. Energy & Fuels, 32(7): 7423–7437 Wu Xiaochuan, Pu Renhai, Chen Ying, et al. 2018b. Seismic analysis of early-mid Miocene carbonate platform in the southern Qiongdongnan Basin, South China Sea. Acta Oceanologica Sinica, 37(2): 54–65. doi: 10.1007/s13131-017-1128-6 Wu Guoxuan, Qin Jungan, Mao Caizhi. 2003. Deep-water Oligocene pollen record from South China Sea. Chinese Science Bulletin, 48(22): 2511–2515 Xiao Xianming, Xiong M, Tian Hui, et al. 2006. Determination of the source area of the Ya13–1 gas pool in the Qiongdongnan Basin, South China Sea. Organic Geochemistry, 37(9): 990–1002. doi: 10.1016/j.orggeochem.2006.06.001 Xu Min, Hou Dujie, Lin Xiaoyun, et al. 2022. Organic geochemical signatures of source rocks and oil-source correlation in the Papuan Basin, Papua New Guinea. Journal of Petroleum Science and Engineering, 210: 109972. doi: 10.1016/j.petrol.2021.109972 Yang Gengxiong, Yin Hongwei, Gan Jun, et al. 2022. Explaining structural difference between the eastern and western zones of the Qiongdongnan Basin, northern South China Sea: insights from scaled physical models. Tectonics, 41(2): e2021TC006899 Zhang Gongcheng, Wang Dongdong, Zeng Qingbo, et al. 2019. Characteristics of coal-measure source rock and gas accumulation belts in marine-continental transitional facies fault basins: A case study of the Oligocene deposits in the Qiongdongnan Basin located in the northern region of the South China Sea. Energy Exploration & Exploitation, 37(6): 1752–1778 Zhang Gongcheng, Zeng Qingbo, Su Long, et al. 2016. Accumulation mechanism of LS 17–2 deep water giant gas field in Qiongdongnan Basin. Acta Petrolei Sinica, 37(S1): 34–46 Zhao Rui, Chen Si, Olariu C, et al. 2019. A model for oblique accretion on the South China Sea margin; Red River (Song Hong) sediment transport into Qiongdongnan Basin since upper Miocene. Marine Geology, 416: 106001. doi: 10.1016/j.margeo.2019.106001 Zhao Meng, Shao Lei, Liang Jianshe, et al. 2015. No Red River capture since the late Oligocene: Geochemical evidence from the northwestern South China Sea. Deep-Sea Research Part II: Topical Studies in Oceanography, 122: 185–194. doi: 10.1016/j.dsr2.2015.02.029 Zhou Yi, Sheng Guoying, Fu Jiamo, et al. 2003. Triterpane and sterane biomarkers in the YA13–1 condensates from Qiongdongnan Basin, South China Sea. Chemical Geology, 199(3–4): 343–359 Zhu Weilin, Shi Hesheng, Huang Baojia, et al. 2021. Geology and geochemistry of large gas fields in the deepwater areas, continental margin basins of northern South China Sea. Marine and Petroleum Geology, 126: 104901. doi: 10.1016/j.marpetgeo.2021.104901 Zhu Yangming, Sun Linting, Hao Fang, et al. 2018. Geochemical composition and origin of Tertiary oils in the Yinggehai and Qiongdongnan Basins, offshore South China Sea. Marine and Petroleum Geology, 96: 139–153. doi: 10.1016/j.marpetgeo.2018.05.029