Early Holocene monsoonal fluctuations in the Garhwal higher Himalaya as inferred from multi-proxy data from the Malari paleolake Pradeep Srivastava a, ⁎, Anil Kumar a , Akanksha Mishra b , Narendra K. Meena a , Jayant K. Tripathi b , Y.P. Sundriyal c , Rajesh Agnihotri d , Anil K. Gupta a a Wadia Institute of Himalayan Geology, 33 GMS Road, Dehradun 248001, India b School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India c Department of Geology, H.N.B. Garhwal University, Srinagar 246174, India d National Physical Laboratory, New Delhi 110012, India abstract article info Article history: Received 3 August 2012 Available online 27 August 2013 Keywords: Paleolake profile Semiarid Himalaya Organic phosphorus Mineral susceptibility Indian Summer Monsoon Solar forcing A 4.9-m-thick lake sequence, formed due to the landslide damming of a stream in the semiarid Garhwal Himalaya, was studied to understand past monsoonal variations in the region. The Optically Stimulated Lumines- cence (OSL) chronology indicates that the lake existed between ~12 and ~7 ka ago. Chronologically constrained trends of sand percent, organic phosphorus (OP), apatite inorganic phosphorus (AIP) and parameters of environ- mental magnetism were measured in the paleolake profile. Measured proxies indicate that the Indian summer monsoon ameliorated in the early Holocene after 12 ka cooling, and it appears that all the proxies from the lake have captured this globally recognized early Holocene warming. Four phases of wet conditions (intensified monsoon) are recognized at ~11.5 ka, ~11–10.5 ka, ~10–9 ka and ~8–7 ka with maximum uncertainties of ~1000 years. The wet phases are characterized by high magnetic susceptibility, increased OP and reduced AIP. In an attempt to understand the primary forcing of the sharp fluctuations in monsoonal activity in the region, we show that changes in magnetic susceptibility match variations of residual atmospheric δ 14 C, suggesting a role for solar variability as an explanation of climatic variability. © 2013 University of Washington. Published by Elsevier Inc. All rights reserved. Introduction The landscape of the Himalaya is a result of precipitation and tecton- ic processes occurring on a variety of time scales. During long cold and dry spells, the vegetation cover on steep slopes is depleted leading to the production of loose soil and debris. During wetter phases the loose debris and soil are mobilized down the slope, particularly as landslides that block streams, creating landslide dammed lakes. These events are often found in sedimentary archives flanking the rivers and represent phases of intense Southwest (SW) Indian Monsoon (Bookhagen et al., 2005; Sundriyal et al., 2007; Juyal et al., 2009; Phartiyal et al., 2009). The sedimentation in the Himalayan lakes is often continuous and their study thus offers an opportunity to understand the sharp climatic variations in the past. The dated profiles of these lakes help to under- stand not only the climatic variability through time but also the climate forcing factors and their global linkages. Paleolakes have been studied from the Lesser Himalayas of Kumaun (Kotlia et al., 1997a) and in the upper Indus Valley (Skardu in Ladakh) to understand past climatic variations (Burgisser et al., 1982; Cronin, 1989; Fort et al., 1989; Shroder et al., 1989; Bagati et al., 1996; Kotlia et al., 1997b; Shukla et al., 2002). However, most of these studies focused largely on landscape evolution and the causes of formation of paleolakes. Studies also indicated that 14 C dating is not suitable for paleolake se- quences located in carbonate-dominated country rocks. Recent investi- gations using luminescence ages in the Goting Lake sequence suggest that the lacustrine environment spanned a range of 20–11 ka (Juyal et al., 2004, 2009) instead of 40–30 ka based on 14 C ages, demonstrating that radiocarbon dates are overestimated due to old carbon contamina- tion. Lately, Tso Kar lake, located in the Zanskar ranges of the arid Himalaya, was studied to decipher the latest Pleistocene–Holocene cli- matic conditions during the last 15 ka (Wünnemann et al., 2010). Since the Higher Himalaya is a seismically active zone that is impacted by intense rainfall during intensification of the monsoon, few lakes exist. Nonetheless there are some lakes that contain important climatic archives because of their sensitivity to minor changes in temperature and precipitation. Also, reconstructions of monsoon history from this re- gion are important to provide better understanding of the spatial and temporal changes and forcing factors responsible for monsoon dynamics at time scales beyond the instrumental era. The studies undertaken so far utilized sedimentology, pollen taxono- my, environmental magnetism and chemical indices involving major, trace and rare earth elements. The present study, however, focuses on (a) the variability in organic/inorganic phosphorus and (b) environmen- tal magnetism in response to prevailing paleoclimate/monsoonal Quaternary Research 80 (2013) 447–458 ⁎ Corresponding author. E-mail address: Pradeep@wihg.res.in (P. Srivastava). 0033-5894/$ – see front matter © 2013 University of Washington. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.yqres.2013.07.006 Contents lists available at ScienceDirect Quaternary Research journal homepage: www.elsevier.com/locate/yqres