LATE CRETACEOUS TERRESTRIAL CLIMATE RECORDED IN THE SONGLIAO BASIN, CHINA

Because of the need to understand the links and feedbacks of the carbon cycle during times of global greenhouse conditions numerous studies have focused on the Cretaceous climate. Much of what we know about this warm period in Earth’s history comes from the study of ocean sediments recovered from both ocean drill cores and marine sediments exposed at the Earth’s surface. In contrast, there are few studies of Cretaceous terrestrial sediments. The Songliao basin located in northeast China offers a unique opportunity to understand Cretaceous paleoclimate of terrestrial settings because it contains a nearly complete record of lacustrine sediments deposited throughout the Cretaceous and there is an active drilling program to recover core from this paleolake. Over the past several years we, and others, have undertaken an ambitious effort to extract quantitative climate records from lake sediments and paleosols preserved in sediment cores taken from the Songliao Basin. Our stable isotopic research on ostracods from the interval from Turonian through the Maastrichtian demonstrates that a high-resolution climate record can be extracted from these sediments. We show that oxygen and carbon isotopes of ostracods in these lacustrine sediments record global climate events such as major ocean anoxic events (OAE2 and OAE3). Moreover, using a new quantitative lake model that solves a series of total differential equations coupled with robust statistical techniques we are able to assess the role of temperature, runoff, and evaporative effects on these isotopic records. Here, we review the findings of our climate research and outline future research directions and opportunities in the Songliao basin that will allow for a deeper understanding of the terrestrial response to changing climate.