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The Jiaolai Basin, to the east of the Tan-Lu Fault Zone (TLFZ), is a Cretaceous NE-trending basin in eastern North China and has a multi-episodic evolution. Different from other contemporary NW-trending en-echelon graben systems west to the TLFZ, the origin of the Jiaolai Basin (three episodes: K 1 l , 135–120 Ma; K 2 q , 120–105 Ma; K 2 w , 88–65 Ma) cannot be simply explained by the sinistral displacement of the TLFZ at the beginning of the Early Cretaceous (around ca. 135 Ma). The purpose of this paper is to investigate the critical factors (e.g., bounding faults, tectonic setting, stress field) driving the development of the Jiaolai Basin and constraint its evolution. Three episodes of two-dimensional finite element models were generated in order to determine the roles of the boundary conditions and to reveal the tectonic development of the basin. When compared to the calculated maximum horizontal compressive stress (σ Hmax ) trajectories and the observed data, along with a comparison between the Von Mises Stress ( u Von ) and the depocenters of the basin, the calculated results can be well proved by the geological evidence both in stress field evolution and in the basin patterns. Our analysis show that the three episodes of the maximum principle stress trajectories changed from NE-SW (earlier Early Cretaceous, K 1 l ) NNE-SSW (later Early Cretaceous, K 1 q ) then E-W (Late Cretaceous, K 2 w ). Moreover, the results show a good consistency between the u Von and the depocenters in the basin through geological cross-sections. Via models we suggest that the origin and evolution of the Jiaolai Basin were controlled by three episodes of tectonic events, (i) the reactivated bounding faults and the post-orogenic extension of the Sulu Orogen during the earlier Early Cretaceous, (ii) the lithospheric delamination of the thickened lithosphere during the later Early Cretaceous, and (iii) the likely far-field effects produced by the collision between the Kohistan-Drags arc complex and Asia during the Late Cretaceous. The Jiaolai Basin evolved from extension to pull-apart experiencing volcanic activity during the three episodes of the Cretaceous. [ABSTRACT FROM AUTHOR]

Abstract: Songliao Basin in NE China developed the most productive oilfield in the world sourced from terrestrial rocks. The main source rock of the basin includes member 1 of the Qingshankou (K2qn1) and members 1 and 2 of the Nenjiang Formation (K2nj1–2). However the exact reasons for the formation of the source rock, especially the K2qn1 are still controversial. Former paleontological and organic geochemical research suggested that organic matter was deposited during marine incursion events of K2qn1 but further geochemical evidence is needed. This paper explores the distinct sulfate levels that distinguish marine from fresh waters of the Songliao paleo-lake. We undertook a systematic investigation the sulfur geochemistry of the sediments from top of member 4 of the Quantou Formation (K1q4) to top of member 1 of the Qingshankou (K2qn1). The ratio of organic carbon to the pyrite sulfur (TOC/PYS) proved the previously suggested saline conditions during the deposition of K2qn1; and the pyrite sulfur isotope indicated that marine incursion may not only have occurred for K2qn1, but also for top of K1q4. The exact time for the beginning of marine incursion is to be determined. The marine incursion within K2qn1 is not strong and partially controlled by the fluctuation of paleo-lake level. The present study will be helpful for understanding the contribution of marine incursion events to the burial of organic carbon in the Songliao paleo-lake, although further studies are still needed. [Copyright &y& Elsevier]

Abstract: As a paradigm of greenhouse climate in Earth's history, the Cretaceous provides significant rock records of global climate changes under conditions of greenhouse climate. The Songliao Basin, among the longest duration (85–90m.y.) of continental sedimentary basins, provides an excellent opportunity to recover a nearly complete Cretaceous terrestrial sedimentary record. Extensive lake deposits, ten-kilometers deep and covering an area of 260,000km2 of the Songliao Basin, provide unique, detailed records that can be tied to the global stratigraphic time scale, thereby improving our understanding of the continental paleoclimate and ecological system. The two coreholes at SKIs and SKIn sites were drilled into this basin and completed with a total length of 2485.89m of recovered core that spanned the complete middle-to-Upper Cretaceous strata in the basin. The unique geological setting of long-term continuous subsidence within the largest Cretaceous landmass in the world — makes the Cretaceous Songliao Basin of northeastern China an ideal place to study Cretaceous climate change on the continent. This paper reviews the literature on the paleogeography and paleoclimate of the northern East Asia and the Songliao Basin during the Cretaceous. Based on the climatologically sensitive deposits, oxygen isotope studies, and paleontology, the climate during the Cretaceous in the Songliao Basin was temperate and humid with relatively abundant rainfall. During the period, significant changes – four cooling, three warming, and three semiarid events – are generally consistent with the oxygen isotope data from East Asia, and the four cooling events, in Berriasian–Valanginian, Aptian–Albian, early Santonian, and Campanian–Maastrichtian, may be related to potential glaciations in Cretaceous. [Copyright &y& Elsevier]

Abstract: The Continental Scientific Drilling Project at the Cretaceous-age Songliao Basin is a drilling initiative under the framework of the International Continental Scientific Drilling Program, to recover a nearly complete Cretaceous terrestrial sedimentary record in the Songliao Basin, northeastern China. The recovered cores will provide unique opportunities for the geosciences community to advance the understanding of climate change in the Cretaceous greenhouse world, and provide a documentation of geological events relevant to the carbon cycle during this time period. This drilling project will address significant geological questions, such as the identification of important stratigraphic boundaries and the marine-terrestrial correlations of stratigraphy, the reasons for the biotic response to the terrestrial environmental changes, the terrestrial response to the Cretaceous oceanic anoxic events, the formation of terrestrial petroleum source rocks, and the mechanisms for the Cretaceous magnetic Normal Superchron (CNS). In the first stage of this drilling project, the SKI drilling, rock cores of 2485.89m in total length were recovered and the recovery ratio reached 96.46%. A series of drilling and coring technologies including regular, confined, directional, and sealed coring, were utilized to ensure a higher recovery ratio for the core, and will be described at the end of this paper. Well loggings were conducted right after coring. Core handling and storage were arranged in such a way that the scientific research was conducted on half of each core, whereas the other half of each core was preserved for long-term storage. The upcoming second stage, the SKII drilling, will combine with data from the existing SKI to provide complete high-resolution climate records of the terrestrial environment for the whole Cretaceous time period. [Copyright &y& Elsevier]