scholarly journals Post-LGM glacial retreat and Early Holocene monsoon intensification drives aggradation in the interiors of the Kashmir Himalaya

2021 ◽  
Author(s):  
Saptarshi Dey ◽  
Naveen Chauhan ◽  
Pritha Chakravarti ◽  
Anushka Vashistha ◽  
Vikrant Jain
Keyword(s):  
High Elevation ◽  
Sediment Supply ◽  
Early Holocene ◽  
Kashmir Himalaya ◽  
Glacial Retreat ◽  
Valley Fill ◽  
Initial Stage ◽  
Exposure Ages ◽  
The Himalaya ◽  
Semi Arid

Understanding the response of glaciated catchments to climate change is crucial for assessing sediment transport from the high-elevation, semi-arid sectors in the Himalaya. The fluvioglacial sediments stored in the semi-arid Padder valley in the Kashmir Himalaya record valley aggradation during ~20 -10 ka. We relate the initial stage of valley aggradation to increased sediment supply from the deglaciated catchment during the glacial-to-interglacial phase transition. Previously-published bedrock-exposure ages in the upper Chenab River valley suggest ~180 km retreat of the valley glacier during ~20 - 15 ka. Increasing roundness of sand-grains and reducing mean grain-size from the bottom to the top of the valley-fill sequence hint about increasing fluvial transport with time and corroborate with the glacial retreat history. The later stages of aggradation can be attributed to strong monsoon during the early Holocene. Especially, the hillslope debris that drapes the fluvioglacial sediment archive may have resulted from the early Holocene monsoon maximum. We observe a net degradation of the valley-fill in the Holocene reflecting the weakening of summer monsoon or reduced input from the glaciers. Our study highlights the coupled effect of deglaciation and monsoon intensification in sediment transfer from the high-elevation sectors of the Himalaya.

scholarly journals Post-LGM glacial retreat drives aggradation in the interiors of the Kashmir Himalaya

2021 ◽  
Author(s):  
Saptarshi Dey ◽  
Naveen Chauhan ◽  
Anushka Vashistha ◽  
Vikrant Jain
Keyword(s):  
Climate Change ◽  
Foreland Basin ◽  
High Elevation ◽  
Sediment Supply ◽  
Kashmir Himalaya ◽  
Glacial Retreat ◽  
Valley Fill ◽  
Mean Grain Size ◽  
Exposure Ages ◽  
Semi Arid

Understanding the response of glaciated catchments to climate change is fundamental for assessing sediment transport from the high-elevation, semi-arid to arid sectors in the Himalaya to the foreland basin. The fluvioglacial sediments stored in the semi-arid Padder valley in the Kashmir Himalaya record valley aggradation during ~19-11 ka. We relate the valley aggradation to increased sediment supply from the deglaciated catchment during the glacial-to-interglacial phase transition. Previously-published bedrock-exposure ages in the upper Chenab valley suggest ~180 km retreat of the valley glacier during ~20-15 ka. Increasing roundness of sand-grains and reducing mean grain-size from the bottom to the top of the valley-fill sequence hint about increasing fluvial transport with time and corroborate with the glacial retreat history. Our result also correlates well with late Pleistocene-early Holocene sediment aggradation observed across most Western Himalayan valleys. It highlights the spatiotemporal synchronicity of sediment transfer from the Himalayas triggered by climate change.

Late Pleistocene and Early Holocene aeolian deposits of Tasmania and their climatic implications

2020 ◽  
pp. 1-24
Author(s):  
Peter D. McIntosh ◽  
Christina Neudorf ◽  
Olav B. Lian ◽  
Adrian J. Slee ◽  
Brianna Walker ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Cold Climate ◽  
Sediment Supply ◽  
Early Holocene ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Aeolian Deposits ◽  
Semi Arid ◽  
The Last Glacial

Abstract Late Pleistocene and Early Holocene aeolian deposits in Tasmania are extensive in the present subhumid climate zone but also occur in areas receiving >1000 mm of rain annually. Thermoluminescence, optically stimulated luminescence, and radiocarbon ages indicate that most of the deposits formed during periods of cold climate. Some dunes are remnants of longitudinal desert dunes sourced from now-inundated continental shelves which were previously semi-arid. Others formed near source, often in the form of lunettes east of seasonally-dry lagoons in the previously semi-arid Midlands and southeast of Tasmania, or as accumulations close to floodplains of major rivers, or as sandsheets in exposed areas. Burning of vegetation by the Aboriginal population after 40 ka is likely to have influenced sediment supply. A key site for determining climate variability in southern Tasmania is Maynes Junction which records three periods of aeolian deposition (at ca. 90, 32 and 20 ka), interspersed with periods of hillslope instability. Whether wind speeds were higher than at present during the last glacial period is uncertain, but shells in the Mary Ann Bay sandsheet near Hobart and particle size analysis of the Ainslie dunes in northeast Tasmania suggest stronger winds during the last glacial period than at present.

Tracing erosion patterns in South Tibet: balancing sediment supply to the Yarlung Tsangpo from the Himalaya versus Lhasa Block

2021 ◽  
Author(s):  
Wendong Liang ◽  
Eduardo Garzanti ◽  
Xiumian Hu ◽  
Alberto Resentini ◽  
Giovanni Vezzoli ◽  
...  
Keyword(s):  
Sediment Supply ◽  
Yarlung Tsangpo ◽  
The Himalaya ◽  
South Tibet

scholarly journals Constant wind regimes during the Last Glacial Maximum and early Holocene: evidence from Little Llangothlin Lagoon, New England Tablelands, eastern Australia

2016 ◽  
Vol 12 (7) ◽  
pp. 1435-1444 ◽  
Author(s):  
James Shulmeister ◽  
Justine Kemp ◽  
Kathryn E. Fitzsimmons ◽  
Allen Gontz
Keyword(s):  
Last Glacial Maximum ◽  
High Elevation ◽  
Glacial Maximum ◽  
Early Holocene ◽  
Luminescence Dating ◽  
Ice Age ◽  
Last Glacial ◽  
Eastern Australia ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Here we present the results of a multi-proxy investigation – integrating geomorphology, ground-penetrating radar, and luminescence dating – of a high-elevation lunette and beach berm in northern New South Wales, eastern Australia. The lunette occurs on the eastern shore of Little Llangothlin Lagoon and provides evidence for a lake high stand combined with persistent westerly winds at the Last Glacial Maximum (LGM – centring on 21.5 ka) and during the early Holocene (ca. 9 and 6 ka). The reconstructed atmospheric circulation is similar to the present-day conditions, and we infer no significant changes in circulation at those times, as compared to the present day. Our results suggest that the Southern Hemisphere westerlies were minimally displaced in this sector of Australasia during the latter part of the last ice age. Our observations also support evidence for a more positive water balance at the LGM and early Holocene in this part of the Australian sub-tropics.

Climate forcing of volcano lateral collapse: evidence from Mount Etna, Sicily

2010 ◽  
Vol 368 (1919) ◽  
pp. 2559-2577 ◽  
Author(s):  
K. R. Deeming ◽  
B. McGuire ◽  
P. Harrop
Keyword(s):  
Slope Failure ◽  
Climatic Conditions ◽  
Early Holocene ◽  
Mount Etna ◽  
Watershed Development ◽  
Eastern Flank ◽  
Consequent Reduction ◽  
Water Saturated ◽  
Excess Pore Pressures ◽  
Exposure Ages

In this study, we present evidence for early Holocene climatic conditions providing circumstances favourable to major lateral collapse at Mount Etna, Sicily. The volcano’s most notable topographic feature is the Valle del Bove, a 5×8 km cliff-bounded amphitheatre excavated from the eastern flank of the volcano. Its origin due to prehistoric lateral collapse is corroborated by stürtzstrom deposits adjacent to the amphitheatre’s downslope outlet, but the age, nature and cause of amphitheatre excavation remain matters for debate. Cosmogenic 3 He exposure ages determined for eroded surfaces within an abandoned watershed flanking the Valle del Bove support channel abandonment ca 7.5 ka BP, as a consequence of its excavation in a catastrophic collapse event. Watershed development was largely dictated by pluvial conditions during the early Holocene, which are also implicated in slope failure. A viable trigger is magma emplacement into rift zones in the eastern flank of a water-saturated edifice, leading to the development of excess pore pressures, consequent reduction in sliding resistance, detachment and collapse. Such a mechanism is presented as one potential driver of future lateral collapse in volcanic landscapes forecast to experience increased precipitation or melting of ice cover as a consequence of anthropogenic warming.

scholarly journals A taxonomic revision of Gaultheria series Trichophyllae (Ericaceae)

2020 ◽  
Vol 14 (2) ◽  
pp. 289-341
Author(s):  
Peter W. Fritsch ◽  
Lu Lu
Keyword(s):  
New Species ◽  
Central Asia ◽  
Taxonomic Revision ◽  
High Elevation ◽  
Key To Species ◽  
East Central ◽  
Present Treatment ◽  
Taxonomic Changes ◽  
Species Descriptions ◽  
The Himalaya

The last taxonomic revision of Gaultheria series Trichophyllae (Ericaceae), a clade of high-elevation species endemic to the Himalaya-Hengduan Shan region of east-central Asia, was published in 1941. Since then, a number of new species have been described and other taxonomic changes have occurred in the group, prompting the need for a comprehensive revision. The present treatment of the series comprises 21 species, including Gaultheria x biluoensis, a newly described hybrid between G. crassifolia and G. major. A key to species and species descriptions is provided, and lectotypes are newly designated for G. cardiosepala, G. gonggashanensis, G. marronina, and G. stenophylla.

Late Quaternary sedimentation on the southwestern Scotian Slope, eastern Canada: relationship to glaciationGeological Survey of Canada Contribution 20070176.

2008 ◽  
Vol 45 (3) ◽  
pp. 267-285 ◽  
Author(s):  
Thian Hundert ◽  
David J.W. Piper
Keyword(s):  
Late Quaternary ◽  
Sediment Cores ◽  
Sediment Supply ◽  
Scotian Shelf ◽  
Eastern Canada ◽  
Glacial Retreat ◽  
Air Gun ◽  
Continental Slopes ◽  
History Of ◽  
Seismic Reflection Profiles

The sedimentary record on continental slopes has the potential to preserve a record of glacial retreat on the adjacent continental shelf. The glacial history of the southwestern part of the Scotian Shelf is poorly known. Air-gun and high-resolution sparker profiles and numerous sediment cores up to 10 m long have been used to determine the character of sedimentation on the southwestern Scotian Slope since the last glacial maximum (LGM). Seismic-reflection profiles show that glacial till was deposited at shallow depths on the upper continental slope, and correlation to dated piston cores farther downslope show that this till dates from the LGM. Slope sedimentation at this time was dominated by local ice and deposited as plume fallout and turbidites. Progressively increasing importance of red-brown sediment derived from glacial supply to Laurentian Channel indicates retreat of ice from the shelf edge and diminishing supply of proglacial sediment from the calving embayment in the mid-Scotian Shelf. With the termination of distal proglacial sediment supply, the sedimentation rate diminished rapidly and hemipelagic sedimentation prevailed through the Holocene.

scholarly journals Armor breakup and reformation in a degradational laboratory experiment: detailed measurements of spatial and temporal changes of the bed surface texture

2016 ◽  
Author(s):  
C. Orru ◽  
A. Blom ◽  
W.S.J. Uijttewaal
Keyword(s):  
Laboratory Experiment ◽  
Sediment Supply ◽  
Sudden Increase ◽  
Normal Flow ◽  
Flow Conditions ◽  
Initial Stage ◽  
The Reformation ◽  
Spatial And Temporal Changes ◽  
Sand And Gravel ◽  
Slope Adjustment

Abstract. Armor breakup and reformation was studied in a laboratory experiment using a trimodal mixture composed of sand and gravel. The armor was formed in the initial stage of the experiment under conditions without sediment supply. Higher flow conditions led to the breakup of the mobile armor and the reformation of a new coarser armor. The breakup initially induced a fining due to the exposure of the finer substrate, which was accompanied by a sudden increase of the local sediment transport rate, followed by the formation of an armor that was coarser than the initial one. The reformation of the armor was due to the supply of coarse material from the upstream degrading reach and the presence of gravel in the original substrate sediment. Provided that the gravel supply from upstream suffices for armor reformation, armor breakup enables slope adjustment such that the new steady state is closer to normal flow conditions.

Progressive glacial retreat in the Southern Altiplano (Uturuncu volcano, 22°S) between 65 and 14 ka constrained by cosmogenic 3He dating

2014 ◽  
Vol 82 (1) ◽  
pp. 209-221 ◽  
Author(s):  
Pierre-Henri Blard ◽  
Jérôme Lave ◽  
Kenneth A. Farley ◽  
Victor Ramirez ◽  
Nestor Jimenez ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Late Glacial ◽  
Glacial Period ◽  
Tropical Andes ◽  
Equilibrium Line Altitude ◽  
Glacial Retreat ◽  
Late Glacial Period ◽  
Cold Episode ◽  
Glacial Landforms ◽  
Exposure Ages

AbstractThis work presents the first reconstruction of late Pleistocene glacier fluctuations on Uturuncu volcano, in the Southern Tropical Andes. Cosmogenic 3He dating of glacial landforms provides constraints on ancient glacier position between 65 and 14 ka. Despite important scatter in the exposure ages on the oldest moraines, probably resulting from pre-exposure, these 3He data constrain the timing of the moraine deposits and subsequent glacier recessions: the Uturuncu glacier may have reached its maximum extent much before the global LGM, maybe as early as 65 ka, with an equilibrium line altitude (ELA) at 5280 m. Then, the glacier remained close to its maximum position, with a main stillstand identified around 40 ka, and another one between 35 and 17 ka, followed by a limited recession at 17 ka. Then, another glacial stillstand is identified upstream during the late glacial period, probably between 16 and 14 ka, with an ELA standing at 5350 m. This stillstand is synchronous with the paleolake Tauca highstand. This result indicates that this regionally wet and cold episode, during the Heinrich 1 event, also impacted the Southern Altiplano. The ELA rose above 5450 m after 14 ka, synchronously with the Bolling–Allerod.

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