Quaternary glaciation of the Tashkurgan Valley, Southeast Pamir

Owen, Lewis A.; Chen, Jie; Hedrick, Kathryn A.; Caffee, Marc W.; Robinson, Alexander C.; Schoenbohm, Lindsay M.; Yuan, Zhaode; Li, Wenqiao; Imrecke, Daniel B.; Liu, Jinfeng

doi:10.1016/j.quascirev.2012.04.027

Cited by 72 publications

(55 citation statements)

References 75 publications

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“…4,7,8). The tightest pre-LGM age clustering occurs in the westernmost regions of the study area with eleven deglaciation ages between 61 ka and 84 ka, in line with previous suggestions of glacial advance in these regions during marine isotope stage 4 (Owen et al, 2008(Owen et al, , 2012Zech et al, 2013).…”

Section: Discussionsupporting

confidence: 90%

Paleoglaciation of the Tibetan Plateau and surrounding mountains based on exposure ages and ELA depression estimates

Heyman

2014

Quaternary Science Reviews

177

154

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The Tibetan Plateau holds an ample record of past glaciations, and there is an extensive set of glacial deposits dated by exposure dating. Here a compilation is presented of 10 Be exposure ages from 485 glacial deposits with 1855 individual samples on the Tibetan Plateau, and ELA depression estimates for the glacial deposits based on a simple toe to headwall ratio approach. To recalculate the Tibetan Plateau exposure ages, 10Be production rates from 24 calibration sites across the world are compiled and recalibrated yielding an updated global reference 10 Be production rate. The recalculated exposure ages from the Tibetan Plateau glacial deposits are then divided into three groups based on exposure age clustering, to discriminate good (well-clustered) from poor (scattered) deglaciation ages. A major part of the glacial deposits have exposure ages affected by prior or incomplete exposure, complicating exposure age interpretations. The well-clustered deglaciation ages are primarily from mountain ranges along the margins of the Tibetan Plateau with a main peak between 10 and 30 ka, indicating glacial advances during the global LGM. A large number of deglaciation ages older than 30 ka indicates maximum glaciation predating the LGM, but the exposure age scatter generally prohibits accurate definition of the glacial chronology. The ELA depression estimates scatter significantly, but the main part is remarkably low. Average ELA depressions of 337 ± 197 m for the LGM and 494 ± 280 m for the pre-LGM indicate restricted glacier expansion.

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Section: Discussionsupporting

confidence: 90%

Paleoglaciation of the Tibetan Plateau and surrounding mountains based on exposure ages and ELA depression estimates

Heyman

2014

Quaternary Science Reviews

177

154

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“…Cosmogenic nuclide dating of the moraine yielded two age clusters of 136 -93 kyr and 86 -60 kyr (Zech et al, 2005a;Abramowski et al, 2006;Röhringer et al, 2012). The oldest glacial moraine from the Lake Yashilkul, the Southern Alichur Range and the Ailuitek Pass indicates the presence of paleo-glaciers down to the intra-plateau valley floors at ∼3600 m a.s.l.. Hummocky moraines accompanied by two lateral moraine ridges indicate a glacial advance during MIS 3, which is synchronous with an increased influence of the ISM (Zech et al, 2005a;Röhringer et al, 2012) as reported from the Hindu Kush, Karakoram Range and Tibet (e.g., Owen et al, 2002bOwen et al, ,a, 2008Owen et al, , 2012. Additional scattered younger ages are interpreted as prolonged ice degradation and/or glacial recession (Zech et al, 2005b).…”

Section: Present and Past Climatic Conditionsmentioning

confidence: 71%

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

et al. 2014

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Calculated incision rates along the Panj, the main river of the Pamir, are used to investigate any influence by tectonics or climate on the architecture of the river. The depositional ages of Panj river terraces were calculated using optically stimulated luminescence (OSL) dating of terrace sand. Fluvial incision rates were generated by integrating the terrace depositional ages with accurate kinematic GPS measurements of terrace heights above the modern Panj. We investigated 16 terraces along the Panj at the western Pamir margin and one terrace from the Vakhsh River to the north of the Pamir. The results reveal brief periods of fluvial deposition over the past 26 kyr. The oldest Panj terrace depositional ages coincide with early MIS 2 and MIS 2/1 glaciations on the Pamir Plateau. Younger terrace ages have no apparent link with glacial cycles. Terraces with varying heights above the modern Panj at different localities yielded similar depositional ages. This suggests that local conditions have determined fluvial incision rates. Combining all of the terrace measurements, the average incision rate of the Panj over the last 26 kyr has been ∼5.6 mm/yr. A high mean incision rate of ∼7.3 mm/yr was calculated from terraces where the Panj has cut a steep-sided valley through the Shakhdara Dome. Significantly lower incision rates (∼2 -3 mm/yr) were calculated from terraces where the Panj flows along the southern boundaries of the Shakhdara and Yazgulom domes. At those localities, graded segments of the Panj river profile and increased valley widths are indicative of local base levels. Downstream of the Yazgulom Dome, river incision rates are generally lower (∼4 -5 mm/yr) than the Panj average. However, there is one exception where higher incision rates (∼6 mm/yr) were calculated upstream of the Darvaz Fault Zone, a major tectonic feature that forms the western boundary of the Pamir. The Vakhsh river terrace to the north of the Pamir yielded a lower incision rate (∼3 mm/yr) compared to the Panj average. Variation in incision rates along the Panj does not correspond to changes in rock type or river catchment area. Instead, incision rates appear to have been primarily influenced by river capture across the southern and central metamorphic domes of the Pamir. Wherever the Panj cuts these domes it displays a convex river profile. The combination of localized river profile convexity and changes in incision rates across the Pamir domes indicates that the dome boundaries have been active recently.

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“…Possible re-advances or recessional stages are indicated at ∼16 kyr and 13-12 kyr (Seong et al, 2009a). No evidence for glacial advances at MIS 3, but for MIS 4 and MIS 2 is found to the south in the Tashkurgan valley (Owen et al, 2012).…”

Section: The Last Glacial Cycle (Mis 4 and 2)mentioning

confidence: 88%

Tectonic and climatic forcing on the Panj river system during the Quaternary

Fuchs

Gloaguen

Pohl

2013

Int J Earth Sci (Geol Rundsch)

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Surface processes involve complex feedback effects between tectonic and climatic influences in the high mountains of Pamir. The ongoing India-Asia collision provokes the development of east-west-trending mountain ranges that impose structural control on flow directions of the Pamir rivers. The evolving relief is further controlled by strong moisture gradients. The decreasing precipitations from the southern and western margins of the Pamir Plateau to its center, in their turn, control the emplacement of glaciers. Chronologies of glacial records from the Pamir Plateau attest for strong climatic variability during the Quaternary. Corresponding remnants of glacial advances suggest glacial morphodynamic restricted to >4,000 m a.s.l. since marine isotope stage (MIS) 4. The Panj, the trunk river of Pamir, deflects from the predominant westward drainage, connecting its main tributaries at the western margin of the drainage basin. The geometry of the river network and the pattern of incision characterize the Panj as a composite river. River reaches of indicated low incision coincide with west-trending valleys, parallel to domes and their bounding faults. Valley shape ratios reflect increased incision in north-trending sections, but do not match with changes in the catchment geometry or erodibility of rock types. Modelled riverbed profiles distinguish three Panj reaches. The upstream increase in convexity suggests successive river captures in response to local base-level changes. The northward-deflected river reaches link the local base levels, which coincide with the southern boundaries of the Shakhdara and Yazgulom Dome and Darvaz Range. We argue that tectonics plays a large role controlling the drainage system of the Panj and hence surface processes in the Pamir mountains.

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Quaternary glaciation of the Tashkurgan Valley, Southeast Pamir

Cited by 72 publications

References 75 publications

Paleoglaciation of the Tibetan Plateau and surrounding mountains based on exposure ages and ELA depression estimates

Paleoglaciation of the Tibetan Plateau and surrounding mountains based on exposure ages and ELA depression estimates

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

Tectonic and climatic forcing on the Panj river system during the Quaternary

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