Late Quaternary glacial and climate history of the Pamir Mountains derived from cosmogenic ¹⁰Be exposure ages

Abstract

Moraines southwest of Lake Yashilkul, Pamir, Tajikistan, were dated using 10Be exposure ages of boulder surfaces. We found evidence for (1) an extensive glaciation ∼60,000 yr ago; (2) a less extensive glacial advance, which deposited a characteristic hummocky moraine lobe with exposure ages ranging from ∼11,000 to 47,000 yr, probably deposited at or before 47,000 yr ago; and (3) lateral moraines with exposure ages of ∼40,000 yr, 27,000 yr and 19,000 yr, respectively. Increasing aridity in the Pamir is most likely responsible for the progressively limited extent of the glaciers during the Late Pleistocene.

Quaternary glaciation of the Himalayan–Tibetan orogen

“…Defining the ages of landforms and sediments throughout much of the HimalayanTibetan orogen has been particularly difficult because of the Shiraiwa, 1993;Sharma and Owen, 1996;Phillips et al, 2000;Richards et al, 2000a,b;Owen et al, 2001Owen et al, , 2002aOwen et al, ,b, 2003aOwen et al, ,b,c, 2005Owen et al, , 2006aSchäfer et al, 2002;Tsukamoto et al, 2002;Yi et al, 2002;Finkel et al, 2003;Zech et al, 2003Zech et al, , 2005Barnard et al, 2004aBarnard et al, ,b, 2006aMeriaux et al, 2004;Spencer and Owen, 2004;Chevalier et al, 2005;Abramowski et al, 2006;Colgan et al, 2006;Seong et al, 2007Seong et al, , 2008a. The red dots in part (A) highlight regions where TCN surface exposure dating has been undertaken.…”

“…60 and 30 ka, and that glaciers advanced during the early to middle Holocene. A plethora of papers following this work emerged and they included distant regions throughout the HimalayanTibetan orogen (Owen et al, , 2002a(Owen et al, ,b, 2003a(Owen et al, ,b,c, 2005Schäfer et al, 2002;Finkel et al, 2003;Zech et al, 2003Zech et al, , 2005Barnard et al, 2004aBarnard et al, ,b, 2006aMeriaux et al, 2004;Chevalier et al, 2005;Abramowski et al, 2006;Seong et al, 2007Seong et al, , 2008a. summarised the TCN studies and suggested that the regional patterns and timing of glaciation reflect temporal and spatial variability in the South Asian monsoon and, in particular, in regional precipitation gradients.…”

“…The possibility of numerous glacier advances also complicates correlations between regions based on TCN dating, especially because the TCN dating method is relatively imprecise ($8% systematic error; Balco et al, 2008). A detailed interpretation of the interregional variability therefore requires more comprehensive Owen et al, 2001Owen et al, , 2002aOwen et al, ,c, 2003aOwen et al, ,b,c, 2005Owen et al, , 2006aSchäfer et al, 2002;Finkel et al, 2003;Zech et al, 2003Zech et al, , 2005Barnard et al, 2004aBarnard et al, ,b, 2006aMeriaux et al, 2004;Chevalier et al, 2005;Abramowski et al, 2006;Colgan et al, 2006;Seong et al, 2007Seong et al, , 2008a. The number of samples used to produce each probability plot is indicated by 'n' All data 20 30 40 50 60 70 80 90 100 110 120 20 30 40 50 60 70 80 90 100 110 120 20 30 40 50 60 70 80 90 100 110 120 20 30 40 50 60 70 80 90 100 110 Figure 9 Probability density functions of TCN 10 Be ages for all published data from the Himalayan-Tibetan orogen plotted for each major climatic region.…”

“…The number of samples used to produce each probability plot is indicated by 'n' All data 20 30 40 50 60 70 80 90 100 110 120 20 30 40 50 60 70 80 90 100 110 120 20 30 40 50 60 70 80 90 100 110 120 20 30 40 50 60 70 80 90 100 110 Figure 9 Probability density functions of TCN 10 Be ages for all published data from the Himalayan-Tibetan orogen plotted for each major climatic region. (A) All published data; (B) MIS 1 and MIS 2; and (C) MIS 3 to MIS 5e (data from Phillips et al, 2000;Owen et al, 2001Owen et al, , 2002aOwen et al, ,b, 2003aOwen et al, ,b,c, 2005Owen et al, , 2006aSchäfer et al, 2002;Finkel et al, 2003;Zech et al, 2003Zech et al, , 2005Barnard et al, 2004aBarnard et al, ,b, 2006aMeriaux et al, 2004;Chevalier et al, 2005;Abramowski et al, 2006;Colgan et al, 2006;Seong et al, 2007Seong et al, , 2008a. The number of samples used to produce each probability plot is indicated by 'n' in the order of the regions shown in the legend of part (A).…”

Rates of river incision across the main tectonic units of the Pamir identified using optically stimulated luminescence dating of fluvial terraces

“…Feedbacks with topography result in climatic gradients between the margins and the plateau of the Pamir. Glacial moraines on the Pamir Plateau provide evidence for multiple glacial advances during the Late Quaternary (Zech et al, 2005a;Abramowski et al, 2006;Röhringer et al, 2012).…”