Scientific Drilling of the Terrestrial Cretaceous Songliao Basin

Abstract

Investigations of critical climate changes during the Cretaceous have the potential to enhance our understanding of modern global warming because the extreme variances are the best-known and most recent example of a greenhouse Earth (Bice et al., 2006). Marine Cretaceous climate archives are relatively well explored by scientific ocean drilling programs such as the Integrated Ocean Drilling Program (IODP) and its predecessors. However, Cretaceous terrestrial climate records are at best fragmentary (Heimhofer et al., 2005). The long-lived Cretaceous Songliao Basin of NE China is an excellent candidate to fill this gap and provide important ocean-continent linkages in relation to environmental change (Fig. 1). This basin, located within one of the largest Cretaceous landmasses (Scotese, 1988), acted for about 100 million years as an intra-continental sediment trap; the present-day area of the basin is about 260,000 km2. It provides an almost complete terrestrial sedimentary recordfrom the Upper Jurassic to the Paleocene (Chen and Chang, 1994). Large-scale geological and geophysical investigations of lacustrine sediments and basin structures demonstrate that a rich archive of Cretaceous paleoclimate proxies exists. For example, the basin includes the Jehol Biota, a terrestrial response to the Cretaceous oceanic anoxic events (OAEs), and a potential K/T boundary (Qiang et al., 1998). An ongoing drilling program is supported by the Ministry of Science and Technology of China and by the Daqing Oilfield. It allowed for recovering of nearly complete cores from Upper Albian to the Uppermost Cretaceous in two boreholes (SK-I, SK II; commenced in 2006, Fig. 1). However, the older Cretaceous sedimentary record of Songliao Basin has not yet been cored. For that reason, a scientific drilling program has been proposed to the International Continental Scientific Drilling Program (ICDP) to sample the deeper sedimentaryrecord of the Songliao Basin through a new drill hole (Figs. 1 and 2).

Keywords

• Songliao Basin