Timing and nature of Holocene glacier advances at the northwestern end of the Himalayan-Tibetan orogen Sourav Saha a, * , Lewis A. Owen a , Elizabeth N. Orr a , Marc W. Caffee b a Department of Geology, University of Cincinnati, Cincinnati, OH 45221, USA b Department of Physics, Department of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA article info Article history: Received 6 September 2017 Received in revised form 20 February 2018 Accepted 5 March 2018 Keywords: Holocene Glaciation Glacial geology Cosmogenic surface exposure dating Himalaya Intertropical convergence zone Paleoclimate abstract Holocene glacial chronostratigraphies are developed for four glaciated valleys at the northwestern end of the Himalayan-Tibetan orogen using geomorphic mapping and cosmogenic 10 Be surface exposure dating. The study areas include the Hamtah valley in the Lahul Himalaya, and the Karzok, Lato and upper Stok valleys in Zanskar. Five local glacial stages are dated to ~10.4, ~6.1e3.3, ~2.1e0.9, ~0.7e0.4, and ~0.3e0.2 ka based on 49 new moraine boulder ages. Large age dispersions are evident for each of the local glacial stages. This is especially the case for ~6.1e3.3 and ~2.1e0.9 ka, which is likely a result of prior and/or incomplete exposures in very young moraine boulders. An additional compilation of 187 published 10 Be moraine boulder ages help define seven Himalayan Holocene regional glacial stages (HHs) for the northwestern end of the Himalayan-Tibetan orogen. These HHs date to ~10.9e9.3, ~8.2e7.4, ~6.9e4.3, ~4.5e2.8, ~2.7e1.8, ~1.8e0.9, and <1 ka. Early Holocene glacier advances were generally more extensive and had larger equilibrium-line altitude depressions (DELA ¼ ~425 ± 229 m) than glacier advances during the mid-Holocene (DELA ¼ ~141 ± 106) and late Holocene (DELA ¼ ~124 ± 121 m). The early Holocene glacier advances likely correspond to orbitally-forced northerly migration of the Intertropical Conver- gence Zone and enhanced summer monsoon. The timing of the majority of HHs during mid- and late Holocene corresponds well with the North Atlantic cooling that is likely teleconnected via mid-latitude westerlies, particularly during ~8 ka and after ~5 ka. These chronostratigraphies suggest that Holocene glaciation in the northwestern part of the Himalayan-Tibetan orogen is largely influenced by long-term orbital forcing amplified by large-scale migration of the Earth's thermal equator and the associated hemispheric oceanic-atmospheric systems. © 2018 Elsevier Ltd. All rights reserved. 1. Introduction Over the past decade, several compilations of young glacial chronologies have been used to help reconstruct and understand the nature of Holocene glaciation on a global scale (Grove, 2008; Davis et al., 2009; Solomina et al., 2015, 2016). Most of these studies conclude that glacier advances during the Holocene in extratropical regions are broadly the consequence of climatic change driven by long-term orbital forcing, with occasional forcing by explosive volcanic eruptions and El Ni ~ no-Southern Oscillations (Solomina et al., 2015). Changes in oceanic-atmospheric circulations in the North Atlantic (Denton and Broecker, 2008; Chiang and Friedman, 2012, 2014; Wanner et al., 2015) represent another possible amplification mechanism. By way of contrast, long-term forcing behind Holocene glacier variability in the Himalaya has been attributed to distinct regional teleconnections, and do not correlate directly with orbital forcing (Solomina et al., 2015, 2016). Despite the impressive preservation of glacial landform assemblages throughout the Himalaya, this view has not been adequately tested due to the lack of well-defined Holocene glacial chronostratig- raphies (Fig. 1A). To examine the nature of Holocene glaciations and possible forcing factors behind glacier advances in the Himalaya, we developed Holocene glacial chronostratigraphies for four glaciated valleys at the northwestern end of the Himalayan-Tibetan orogen using remote sensing and field mapping, geomorphic techniques, and cosmic-ray-produced (cosmogenic) 10 Be surface exposure age dating. We also compare these new studies with existing glacial chronostratigraphies developed using 10 Be dating in adjacent * Corresponding author. 500, Geology-Physics, University of Cincinnati, Cincin- nati, Oh 45221, USA. E-mail address: sahasv@mail.uc.edu (S. Saha). Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev https://doi.org/10.1016/j.quascirev.2018.03.009 0277-3791/© 2018 Elsevier Ltd. All rights reserved. Quaternary Science Reviews 187 (2018) 177e202