The floating astronomical time scale for the terrestrial Late Cretaceous Qingshankou Formation from the Songliao Basin of Northeast China and its stratigraphic and paleoclimate implications

doi:10.1016/j.epsl.2008.12.016

Earth and Planetary Science Letters

Volume 278, Issues 3–4, 25 February 2009, Pages 308-323

https://doi.org/10.1016/j.epsl.2008.12.016 Get rights and content

Abstract

The Upper Cretaceous Qingshankou Formation (K₂qn) in the Songliao Basin (SLB) of Northeast China consists of up to 550 m thick, lacustrine mudstone and shale that constitute one of the most important source rocks of the Daqing oil field. A high-resolution cyclostratigraphic analysis of the natural gamma-ray logging from 10 wells of the Qingshankou Formation (K₂qn) reveals orbital cycles of precession (20 ka), obliquity (40 ka) and eccentricity (100 ka and 405 ka), providing strong evidence for astronomically driven climate changes in the Late Cretaceous terrestrial environments. Floating astronomical time scales (ATS) are established for all sections, which demonstrate variable durations of K₂qn across the basin (1.09 Ma–5.20 Ma) and strong diachroneity of the lacustrine strata. Four periods of high depositional rates can be identified in the central parts of the basin, possibly recording deposition during times of sustained wet climate and high chemical weathering. An ATS established from well M206 in the central depression zone of the basin, where the most complete and stable Milankovitch cycles are present, suggests that the maximum duration of the K₂qn is 5.20 Ma (from 94.27 Ma to 89.07 Ma; Late Cenomanian to Early Coniacian). The lacustrine anoxic event 1 (LAE1) at the Cenomanian–Turonian boundary lasted ~ 210–310 ka, during which the most prolific petroleum source rocks in SLB were deposited. The onset (~ 94.21–94.18 Ma) and duration (~ 210–310 Ka) of LAE1 in SLB are comparable to those of the oceanic anoxic event 2 (OAE2; onset at 94.21 Ma and duration of ~ 320–900 ka), suggesting that the same trigger mechanism, such as increased atmospheric CO₂ from large-scale igneous activity, may have initiated high primary productivity and organic carbon burial in both marine and terrestrial systems.

Introduction

The Cretaceous represents one of the warmest periods of the Phanerozoic eon and a time with significant ocean anoxic events (OAEs). Establishing a high-precision chronostratigraphic framework is fundamental for a better understanding of the global climate change under the Cretaceous supergreenhouse conditions. Owing to the limitations of radiometric ages and paleontological data in general, the astronomical time scale (ATS), established by tuning astronomical forcing signals recorded in sedimentary strata, plays critical roles for defining and correlating the Cretaceous paleoclimatic/paleoceanographic events including OAEs (e.g. Fiet et al., 2006, Li et al., 2008, Locklair and Sageman, 2008, Mitchell et al., 2008). With the progresses made in the last decade, it is anticipated that an ATS covering the entire Cretaceous Period will be completed in a few years (Hinnov and Ogg, 2007). The existing ATS, however, is restricted to marine strata. There is an immediate need to establish the Cretaceous ATS from terrestrial sedimentary basins so that the marine and terrestrial records can be compared and a better understanding of thex Cretaceous Earth system change can be achieved.

Continental rift basins are unique repositories for long-term palaeoclimate records (Olsen and Kent, 1999). Lacustrine mudstone and shales deposited in continental rift basins, due to their sensitivity to changes in precipitation–evaporation ratios and/or water-level changes, are particularly suitable for high-resolution cyclostratigraphic studies (e.g., Olsen and Kent, 1999, Prokoph and Agterberg, 2000) and for establishing astronomical time scales with resolution potentially down to 0.02 to 0.40 Ma (e.g., Hinnov, 2004, Hinnov and Ogg, 2007).

The Songliao Basin in northeastern China is one of the largest Cretaceous continental rift basins in the world (Fig. 1). Well-preserved Cretaceous lacustrine deposits in this basin provide a unique opportunity for the construction of terrestrial Cretaceous ATS. Particularly, the Upper Cretaceous Qingshankou Formation (K₂qn) consists of up to 550 m thick, black mudstone, shale and oil shale that have attracted considerable attention regarding their potential linkage with Milankovitch climate forcing (e.g., Wu et al., 2007, Cheng et al., 2008). The basal interval of this unit is enriched in oil shale and was considered as deposits during a lacustrine anoxic event (Huang et al., 1998, Huang et al., 2007). This event, referred to as lacustrine anoxic event 1 (LAE1), has been suspected to be time equivalent to the oceanic anoxic event 2 (OAE2), but the lack of age controls prevents a chronostratigraphic correlation with the marine record.

In this paper, we present a cyclostratigraphic study based on the high-resolution natural gamma-ray logging of the Qingshankou Formation from 10 wells in an east–west transect across the Songliao Basin (Fig. 2). The major objective of this study is to establish an astronomically calibrated time scale (ATS) for the Late Cretaceous lacustrine strata. With the new floating ATS, we discuss (1) the stratigraphic correlation across the basin and temporal variations in sedimentary rates, (2) the duration of the ostracod biozones constrained by the ATS that may be useful for stratigraphic correlation between terrestrial and marine successions, and (3) the duration of the lacustrine anoxic event 1 (LAE1) and its correlation with the oceanic anoxic event 2 (OAE2).

Section snippets

Tectonics and stratigraphy

Geographically, the Songliao Basin (SLB) in northeastern China is surrounded by the Great Xing'an Mountains in the west, the Lessar Xing'an Mountains in the north and the Zhangguangcai Mountains in the east (Fig. 1a–c). The southern margin of the basin is separated from the North China plate by the Late Paleozoic Chifeng–Kaiyuan fault zone (Sun et al., 2007). The tectonic evolution of the SLB can be divided into (1) a pre-rift phase, (2) a syn-rift phase, (3) a post-rift phase, and (4) a

Data processing

Natural gamma-ray logging records the intensity of the gamma ray emitted during the decay of atomic nuclei of radioactive elements contained in sedimentary rocks. The intensity of gamma ray relates to the amount of ⁴⁰K, ²³²Th and ²³⁸U in rocks. Clay and organic particles have strong capacity of absorbing radioactive elements. The gamma-ray logging curves can therefore reflect changes in the amount of clay and organic materials in sediments, both of which are sensitive to controlling factors

Orbital parameters in Late Cretaceous

According to geological and paleomagnetic evidence (Zhao et al., 1990, Chi et al., 2000), the Songliao Basin has been adjacent to the present position in early Late Cretaceous. We used the June 21 insolation curve at 45°N from 94 to 90 Ma as a reference (Fig. 3a-1), which is calculated using Analyseries 2.0 (Paillard et al., 1996) and the improved La2004 solution (Laskar et al., 2004). Four distinct frequency bands can be observed from the continuous wavelet analysis scalogram (Fig. 3a-2),

Astrochronology of the Qingshankou Formation (K₂qn)

The records from the K₂qn in the SLB display excellent precession, obliquity, short and long eccentricity signals (Fig. 3, Fig. 4, Fig. 5, Fig. 6), and theoretically, every band of signals can be used for tuning to the orbital solutions. However, because the precision of the orbital solution for Mesozoic is limited (Laskar et al., 2004), the high frequency cycles may not be suitable for constructing the ATS. Changes in resonance between the orbits of Earth and Mars may have altered the 95 to

Conclusions

Wavelet and spectral analyses on the natural gamma-ray logging of 10 wells of the Late Cretaceous lacustrine Qingshankou Formation (K₂qn) in the Songliao Basin reveal Milankovitch cycles of precession (20 ka), obliquity (40 ka) and eccentricity (100 ka and 405 ka). The sedimentary cyclicity may have been formed by cyclic changes from wet to dry climate in response to astronomical forcing. The number of cycles decreases from the central depression zone to the margin of the basin, possibly

Acknowledgements

The authors are grateful for the help from Chengshan Wang, Xiaoqiao Wan, Pujun Wang, Yanguang Ren and Yimin Dang. We express our sincere appreciation to the journal editor (Prof. Peter B. deMenocal) and four anonymous reviewers for their careful review and constructive suggestions that significantly improved the paper. This study was jointly supported by the National Key Basic Research Development Program of China (Grant 2006CB701400), the National Science Foundation of China (Grant 40802012),

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The floating astronomical time scale for the terrestrial Late Cretaceous Qingshankou Formation from the Songliao Basin of Northeast China and its stratigraphic and paleoclimate implications

Abstract

Introduction

Section snippets

Tectonics and stratigraphy

Data processing

Orbital parameters in Late Cretaceous

Astrochronology of the Qingshankou Formation (K2qn)

Conclusions

Acknowledgements

J. Geochem. Explor.

Earth Planet. Sci. Lett.

Org. Geochem.

Earth Planet. Sci. Lett.

Sediment. geol.

Comput. Geosci.

Cretac. Res.

Mar. Pet. Geol.

Geochemical and climatic effects of increased marine organic carbon burial at the Cenomanian/Turonian boundary

Nature

Estimation de la durée de lévénement anoxique global au passage Cénomanien/Turonian: Approche cyclostratigraphique dans la formation Bahloul en Tunisie central

Bull. Soc. Géol. Fr.

Comments on the classification and correlation of non-marine Jurassic and Cretaceous of China

J. Stratigr.

Sedimentary cycles of Quantou–Nenjiang, Cretaceous and Milankovitch cycles from the south hole of CCSD–SK in Songliao basin

Acta Geol. Sin.

New perspectives on orbitally forced stratigraphy

Annu. Rev. Earth Planet. Sci.

Earth's orbital parameters and cycle stratigraphy

Cyclostratigraphy and the astronomical time scale

Stratigraphy

Geological and geochemical evidences of anoxic event in the Songliao Basin

Geoscience

The late Cretaceous bio-evolution and anoxic events in the ancient lake in the Songliao Basin

Acta Micropalaeontol. Sin.

The characteristics of Cretaceous microbiotas and formation of hydrocarbon-rich source rocks in Songliao Basin

Acta Palaeontol. Sin.

Oceanic plateau formation: a cause of mass extinction and black shale deposition around the Cenomanian–Turonian boundary

J. Geol. Soc. Lond.

Orbital-scale record of the late Cenomanian–Turonian oceanic anoxic event (OAE-2) in the Tarfaya Basin (Morocco)

Int. J. Earth Sci. (Geol. Rundsch.)

A long-term numerical solution for the insolation quantities of the Earth

Astron. Astrophys.

Hydrocarbon habitat in the Songliao Rift Basin, China

Palynoflora from the Quantou Formation of Songliao Basin, NE China and its bearing on the Upper–Lower Cretaceous boundary

Acta Palaeontol. Sin.

Albian palynological assemblage from the borehole Yu2302 in Yushu—with focus on the age of the Denglouku Formation in Songliao Basin

Acta Palaeontol. Sin.

Astrochronology of the Qingshankou Formation (K₂qn)