A Floating Astronomical Time Scale for the Early Late Cretaceous Continental Strata in the Songliao Basin, Northeastern China

Abstract

A continuous terrestrial succession was recovered from the Songke‐2 (SK‐2) borehole in the Songliao Basin, Northeastern China. This borehole provides a unique material for further research on the continental paleoclimate during Cretaceous greenhouse period, following a series of achievements of the Songke‐1 (SK‐1) core. In this study, thorium (Th) logging data were chosen as a paleoclimate proxy to conduct a detailed cyclostratigraphic analysis. The Th series varies quasi‐periodically; power spectra and evolutionary fast Fourier transformation (FFT) analysis reveal significant cycles in the Quantou (K2q), Qingshankou (K2qn), Yaojia (Ky and Nenjiang (K2n) formations. The ratio of cycle wavelengths in these stratigraphic units is approximately 20:5:2:1, corresponding to long orbital eccentricity (405 kyr), short orbital eccentricity (100 kyr), obliquity (37 kyr), and precession cycles (22.5 kyr and 18.4 kyr). The durations of the K2n, K2y, K2qn and K2q are estimated as 6.97, 1.83, 5.30 and 4.52 Myr, respectively, based on the constructed ∼18.62 Myr “floating” astronomical time scale (ATS). Comparison of the durations between the SK‐1 s and SK‐2 boreholes exhibits a slight difference of 0.06 Myr and 0.459 Myr for K2qn and K2y. Nevertheless, our ATS of K2n supports the chronostratigraphic frame constructed by the CA‐ID‐TIMS data of the SK‐1s borehole. This new “floating” ATS provides precise numerical ages for stratigraphic boundaries, biozones and geological events in the Songliao Basin, and can serve as a basis for correlation of strata and events between marine and terrestrial systems.

Geo‐thermochronological analysis reveals transition from transverse to axial detrital inputs during Cretaceous rifting in the Songliao Basin, NE China

“…(a) The depositional age constraints of the Shahezi, Yingcheng, Denglouku and Quantou Fms. References: a–An (2018); b–Yu et al (2020); c–Liu et al (2021); d–Wang, Wang, et al (2022); e–Ma et al (2020). (b) Accumulation rate estimated by the depositional age constrains and thickness from the SK2E well.…”

Characteristics of Hydrogen and Oxygen Isotopes and Noble Gas Isotopes in the Groundwater of Weishan, Wudalianchi, Northeast China

“…The Wudalianchi Volcano Field (WFD) is located in the central part of Heilongjiang Province, China, on the northeastern margin of the Songnen Basin (Late Mesozoic sedimentary basin, see Ma et al, 2020) and the southern edge of the Xing'an Mountains uplift. The southern boundary of the WFD is the east-west direction Namor River fault zone, and the east boundary is the Sunwu graben.…”