Late Neogene environmental changes in the central Himalaya related to tectonic uplift and orbital forcing Yang Wang a,⇑ , Tao Deng b , Lawrence Flynn c , Xiaoming Wang d , An Yin e , Yingfeng Xu a , William Parker a , Eric Lochner f , Chunfu Zhang a , Dana Biasatti a,g a Department of Earth, Ocean and Atmospheric Science, Florida State University and National High Magnetic Field Laboratory, Tallahassee, FL 32306-4100, USA b Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China c Peabody Museum, Harvard University, Cambridge, MA 02138, USA d Department of Vertebrate Paleontology, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 9007, USA e Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, USA f Analytical Facilities, MARTECH, Tallahassee, FL 32306-4351, USA g Two Medicine Dino Center, Bynum, MT 59419, USA article info Article history: Available online 17 June 2011 Keywords: Paleo-lake basin Mammalian fossils Stable isotopes Neogene environmental change Himalaya Tibetan Plateau abstract The linkage between tectonic forces and climate evolution remains a matter of much debate and specu- lation. Here we present high-resolution oxygen and carbon isotope data from an ancient lake basin in the central Himalaya. These data, together with sedimentologic evidence, reveal major changes in drainage systems and depositional settings at 7.2, 5.5 and 3.2 Ma. These environmental changes appear to be driven by regional-scale tectonics. The oxygen isotope record also reveals alternating wet and dry cli- mates with periodicities of 24 and 100 kyr that were likely controlled by orbital forcing. Paleo-tempera- tures, estimated using a fossil-based oxygen isotope ‘‘paleo-thermometer’’, are 21 ± 6 °C at 7 Ma, which is 19 ± 6 °C higher than the present-day mean annual temperature in the same area. The much warmer environment inferred here is consistent with fossil mammalian and pollen assemblages and sediment clay mineralogy as well as carbon isotope data from fossil tooth enamels and paleosol carbonates. The estimated temperature difference would require the study area to have been raised by 2–2.5 km since 7 Ma to its current elevation of 4100–4500 m above sea level. This result can be interpreted as either indicating the presence of a low-altitude intermountain basin in the hanging wall of the already formed Main Central Thrust or a protracted development of a north-trending rift basin that has experienced changes in drainage system and depositional environment through time. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Cenozoic paleoclimatic records within the Himalaya and Tibe- tan Plateau are sparse, but are needed to compare with the marine record of global climate changes for elucidating the role of Tibetan uplift in controlling regional and global climate (e.g., Kutzbach et al., 1989, 1993; Quade et al., 1989; Manabe and Broccoli, 1990; Harrison et al., 1992; Molnar et al., 1993; An et al., 2001; Molnar, 2005; Wang and Deng, 2005; Dupont-Nivet et al., 2007; Wang et al., 2008a). Intermontane basins in the Himalayan–Tibe- tan orogen often contain thick sequences of lacustrine and fluvial deposits with diverse fossils (Ji et al., 1980; CAS, 1989; Wang et al., 1996, 2006, 2008a; Yue et al., 2004; Horton et al., 2004). These sediments and fossils preserve a record of environmental changes in the region. In this study, we determined the d 13 C and d 18 O values of lacus- trine marls, carbonate cement and mammalian fossil material from late Miocene–Pliocene lacustrine and fluvial sediments in the Gyir- ong Basin on the north slope of the central Himalaya in southern Tibet (Fig. 1). We also performed X-ray diffraction analysis on se- lected sediment samples to determine their mineralogical compo- nents. The d 18 O values of lacustrine carbonates record past changes in the d 18 O of lake water and water temperature (e.g., Talbot, 1990; Dettman et al., 2003), which are controlled by regional climate and hydrology. Fluvial carbonates are generally believed to have formed by cementation of sediments due to percolation of shallow groundwater, and their oxygen isotopic compositions reflect the oxygen isotopic composition of shallow groundwater derived from local meteoric water (e.g., Dettman et al., 2003). Sediment clay mineralogy, on the other hand, helps to understand weathering conditions in the paleo-lake catchment that contributed sediment and water to the lake. Wang et al. (1996) reported limited carbon- ate d 18 O data from about 40 lacustrine sediment samples from the 1367-9120/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jseaes.2011.05.020 ⇑ Corresponding author. Tel.: +1 850 644 1121; fax: +1 850 644 0827. E-mail address: ywang@magnet.fsu.edu (Y. Wang). Journal of Asian Earth Sciences 44 (2012) 62–76 Contents lists available at ScienceDirect Journal of Asian Earth Sciences journal homepage: www.elsevier.com/locate/jseaes