Late Cretaceous marine fossils and seawater incursion events in the Songliao Basin, NE China
Introduction
The Cretaceous represents the warmest periods in the Mesozoic, with high sea level and oceanic anoxic events (Schlanger and Jenkyns, 1976, Haq et al., 1987; Skelton, 2003, Jenkyns, 2010, Hu et al., 2012). However, our knowledge of Cretaceous terrestrial climatic change remains weak, which is largely because of the fragmentary nature of the continental stratigraphic record (Wu et al., 2009, Wu et al., 2014). The Songliao Basin in northeast China is one of the largest Cretaceous continental rift basins in the world. The palaeo Songliao Lake was at its greatest extent in the Late Cretaceous, depositing continuous lacustrine sediments, which provide a unique opportunity to study the Cretaceous terrestrial biota, palaeoenvironment, and palaeoclimate. Two large transgressions occurred during the late Turonian (lower Qingshankou Formation) and late Santonian–early Campanian (lower Nenjiang Formation), depositing suites of dark mudstone, black shale, and oil shale (Huang et al., 1998, Feng et al., 2011). During the Late Cretaceous, the palaeo Songliao Lake was a large lake, which was not far from the western Pacific Ocean (Gao et al., 1992, Wang et al., 2013). Thus, it is possible that the Songliao Basin experienced seawater incursion events during these periods (Wang et al., 2001, Xi et al., 2011a, Xi et al., 2011b, Wang et al., 2013, Hu et al., 2015).
Since the 1950s, researchers have proposed that seawater incursion events occurred frequently in the palaeo Songliao Lake and that such events were closely related to the development of the oil-source rocks found within the basin (Hu et al., 2015). Evidence of seawater incursion events includes marine and brackish-water fish, bivalves, dinoflagellates, shark teeth, calcareous nannofossils, foraminifera (Gu, 1976, Zhang et al., 1977, Gao et al., 1992, Ye and Wei, 1996, Xi et al., 2011a), biological marker dinoflagellate steranes, 24-n-propyl and 24-isopropyl cholestanes (Hou et al., 2000, Feng et al., 2011, Hu et al., 2015), and stable sulphur isotopes and elements (Wang et al., 2001, Huang et al., 2013). However, fossil evidence supporting the hypothesis of seawater incursions remains poorly studied, and it is difficult to use geochemical parameters to distinguish non-marine and marine environments directly. Consequently, any suggestion regarding the occurrence of marine water incursions is doubted (Huang et al., 1999, Li et al., 2000, Zhang et al., 2014).
The Cretaceous Continental Scientific Drilling project in the Songliao Basin (CCSD-SKI) offers a unique opportunity to investigate the nature of the non-marine Upper Cretaceous palaeoenvironment (Gao et al., 2008, Gao et al., 2009a, Gao et al., 2009b, Wang, 2013). The sedimentary sequence has been studied in two boreholes (SKI south and north): the lower 959.55 m from the south core (SKI(s)), and the upper 1636.72 m from the north core (SKI(n)) (Fig. 1). The south core comprises the upper Quantou (K2q), Qingshankou (K2qn), Yaojia (K2y), and lower Nenjiang formations (K2n), while the north core comprises the middle to upper Nenjiang (K2n), Sifangtai (K2s), and Mingshui formations (K2m). Since the first discovery of foraminifera in the Lower K2n SKI(s) (Xi et al., 2011a, Xi et al., 2011b), relatively abundant foraminifera, calcareous nannofossils, and brackish-water dinoflagellates have been found more recently in the SKI(s) and SKI(n).
In this study, based on the first report of foraminifera in the Lower K2n of SKI(s) (Xi et al., 2011a, Xi et al., 2011b), we report new discoveries of foraminifera, calcareous nannofossils, brackish-water dinoflagellates, and other brackish-water fossils, together with previously discovered marine and brackish-water fossils, to discuss the likelihood of seawater incursion events of the Songliao Basin. This will help us better understand the seawater incursion events, palaeoenvironment, and formation of the hydrocarbon source rocks within this basin.
Section snippets
Geological setting
The Songliao Basin is a Mesozoic–Cenozoic intracratonic basin in northeastern China. The modern fault-bounded Songliao Basin is about 750-km long and 300–370-km wide, with a total area of 26 × 104 km2. It is one of China's most prolific oil- and gas-producing sedimentary basins and it contains a complete Cretaceous sequence of terrestrial sediments (Gao et al., 1994, Huang et al., 1998, Wan et al., 2013). The Sk1 boreholes are situated in the Qijia-Gulong Depression, which is one of the major
Studied material
Samples for the study of the foraminifera and ostracods were collected on average at 1-m intervals. Samples of 100 g dry weight were dissolved in deionised water for several weeks prior to sieving through a 200-μm sieve. Foraminifera were picked from the samples under a low-power binocular microscope and stored on micropalaeontological specimen slides. Scanning electron microscope images of the foraminifera were taken at the China University of Geosciences (Beijing).
Samples from the lower K2n
Foraminifera
Relatively abundant foraminiferal tests were identified from Member 1 (K2n1) and lower Member 2 (K2n2) of the Nenjiang Fm. About nine species of eight genera were identified from K2n1 and lower K2n2 of SKI(s), including benthic calcareous foraminifera: Gavelinella sp., Anomalinoides sp., Haplophragmoides sp., and Pullenia sp., benthic agglutinated foraminifera: Karrerulina hokkaidoana, Clavulinoides sp., and planktonic foraminifera: Archaeoglobigerina blowi, Archaeoglobigerina cretacea, and
Distribution and ages of the brackish-water fossils in the Songliao Basin
Brackish-water and sea-related fossils have been discovered in the K2qn1 and lower K2qn2, uppermost K2qn2+3, and K2n1+2 (Fig. 5). Most of the brackish-water fossils were found in the K2n1+2; a few brackish-water fossils were found in the K2qn1 and lowermost K2qn2, and just a few possibly brackish-water fossils were discovered in the uppermost K2qn2+3, e.g., bivalves, ostracods, and the biomarker 24-isopropyl cholestane (1320 m of SKI(s)). The distribution of 24-isopropyl cholestane has good
Conclusion
Discovery of relatively abundant benthic and planktonic foraminifera, nanofossils, brackish-water algae, fish, and bivalves in the K2qn1, lowermost K2qn2, uppermost K2qn3, and K2n1+2 provide evidence supporting the hypothesis of periodic seawater incursions into the Songliao Basin. These seawater incursion events into the Songliao Basin were controlled by regional tectonic activity, evolution of the palaeo Songliao Lake, and global sea level change. Furthermore, because of these periodic
Acknowledgements
This study was financially supported in part by the fund of the National Basic Research Program of China (973 Program, No. 2012CB822002), National Natural Science Foundation of China (41302008, 41172037, 41372110, 41172015), State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS) (123111), State Key Laboratory of Biogeology and Environmental Geology (GBL21314) and Beijing Higher Education Young Elite Teacher Project (YETP0665). Thanks to
References (74)
- et al.
Paleoecology of liminic ostracodes: A review of some major topics
Palaeogeography, Palaeoclimatology, Palaeoecology
(1988) - et al.
Nonmarine Cretaceous stratigraphy of eastern China
Cretaceous Research
(1994) - et al.
Description of Cretaceous sedimentary sequence of the Yaojia Formation recovered by SK-I(s) borehole in Songliao Basin: lithostratigraphy, sedimentary facies and cyclic stratigraphy
Earth Science Frontiers
(2009) - et al.
Chronology of the terrestrial Upper Cretaceous in the Songliao Basin, northeast Asia
Palaeogeography, Palaeoclimatology, Palaeoecology
(2013) - et al.
Description of Cretaceous sedimentary sequence of the first member of the Qingshankou Formation recovered by SK-I(s) borehole in Songliao Basin: lithostratigraphy, sedimentary facies and cyclic stratigraphy
Earth Science Frontiers
(2009) Cretaceous eustasy revisited
Global and Planetary Change
(2014)- et al.
Marine transgressional events in the gigantic freshwater lake Songliao: paleontological and geochemical evidence
Organic Geochemistry
(2000) - et al.
Marine rapid environmental/climatic change in the Cretaceous greenhouse world
Cretaceous Research
(2012) - et al.
Marine incursion events in the Late Cretaceous Songliao Basin: Constraints from sulfur geochemistry records
Palaeogeography, Palaeoclimatology, Palaeoecology
(2013) - et al.
Mid-Cretaceous faunal turnover of intermediate-water benthic foraminifera in the northwestern Pacific Ocean
Marine Micropaleontology
(1993)
Cretaceous stratigraphy of northeast China: non-marine and marine correlation
Cretaceous Research
The Upper Jurassic-Lower Cretaceous of eastern Heilongjiang, Northeast China: stratigraphy and regional basin history
Cretaceous Research
Post-rift geodynamics of the Songliao Basin, NE China: Origin and significance of T11 (Coniacian) unconformity
Tectonophysics
The Cretaceous climax of compression in Eastern Asia: Age 87–89 Ma(late Turonian/Coniacian), Pacific cause, continental consequences
Cretaceous Research
Late Cretaceous stratigraphy, Songliao Basin, NE China: Sk1 cores
Palaeogeography, Palaeoclimatology, Palaeoecology
Cretaceous paleogeography and paleoclimate and the setting of SKI borehole sites in Songliao Basin, northeast China
Palaeogeography, Palaeoclimatology, Palaeoecology
Description of Cretaceous sedimentary sequence of the Quantou Formation recovered by SK-Is borehole in Songliao Basin: lithostratigraphy, sedimentary facies and cyclic stratigraphy
Earth Science Frontiers
Paleosalinity significance of occurrence and distribution of methyltrimethyltridecyl chromans in the Upper Cretaceous Nenjiang Formation, Songliao Basin, China
Organic Geochemistry
Cretaceous climate changes recorded in Eastern Asian lacustrine deposits and North American Epieric sea strata
Earth-Science Reviews
The floating astronomical time scale for the terrestrial Late Cretaceous Qingshankou Formation from the Songliao Basin of Northeast China and its stratigraphic and paleoclimate impli-cations
Earth and Planetary Science Letters
Astrochronology of the Early Turonian–Early Campanian terrestrial succession in the Songliao Basin, northeastern China and its implication for long-period behavior of the Solar System
Palaeogeography, Palaeoclimatology, Palaeoecology
Cyclostratigraphy and orbital tuning of the terrestrial upper Santonian–Lower Danian in Songliao Basin, northeastern China
Earth and Planetary Science Letters
An unrecognized major collision of the Okhotomorsk Block with East Asia during the Late Cretaceous, constraints on the plate reorganization of the Northwest Pacific
Earth Science Review
Fossil Quaternary and living foraminifera from athalassic (non-marine) saline lakes, southern Australia
Journal of Paleontology
Cretaceous planktic foraminifera
Centimeter-scale sedimentary sequence description of Upper Cretaceous–Lower Paleocene Mingshui Formation: lithostratigraphy, facies and cyclostratigraphy, based on the scientific drilling (Sk1) borehole in the Songliao Basin
Earth Science Frontiers
Tectonostratigraphic units and stratigraphic sequences of the nonmarine Songliao basin, northeast China
Basin Research
Depositional environment of terrestrial petroleum source rocks and geochemical indicators in the Songliao Basin
Science in China Series D: Earth Sciences
A new genus and species of cretaceous dinoflagellates from two transgressive beds in the Songliao Basin, northeast China (in Chinese with English abstract)
Acta Palaeontologica Sinica
Cretaceous Oil and Gas Strata of Songliao Basin
Cretaceous Oil Strata Palynology from Songliao Basin
Well site selecting, core profile characteristics and distribution of the special lithology in CCSD—Sk-1s
Acta Geologica Sinica
Well site selecting, core profile characteristics and distribution of the special lithology in CCSD—Sk-1n
Earth Science Frontiers
Centimeter-scale sedimentary sequence description of Upper Cretaceous Nenjiang Formation (lower members 1&2): lithostratigraphy, facies and cyclostratigraphy, based on the scientific drilling (Sk1) borehole in the Songliao Basin
Earth Science Frontiers
Fossil Lamellibranchiata of China
Cretaceous bivalves of the region of Songhuajiang and Liaohe rivers in northeast China
Palaeontologia Sinica, 188, New Series B
Chronology of fluctuating sea levels since the Triassic
Science
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