Pb isotopic variability in the modern-Pleistocene Indus River system measured by ion microprobe in detrital K-feldspar grains

Fluvial–Eolian Interactions In Sediment Routing and Sedimentary Signal Buffering: An Example From the Indus Basin and Thar Desert

“…An approximately 200-kyr record from the east-central Thar Desert of sediment composition, mineralogy, and optically stimulated luminescence (OSL) and thermoluminescence (TL) ages showed at least 12 cycles of eolian sedimentation, alternating with geomorphic stability accompanied by soil formation (Singhvi et al 2010). Several sedimentary profiles with relevance for dating desert evolution and determining provenance are reproduced in Figure 2 (Singhvi and Kar 2004;Clift et al 2008;Alizai et al 2011a;, demonstrating the westward expansion of the desert during Holocene time. Singhvi and Kar (2004) inferred rapid sediment accumulation in the central part of the desert through the Holocenefor example, 7 m of accretion since the LGM at Chamu (Fig.…”

“…Image courtesy of Google Earth. The site at Tatapani included both a pre-existing zircon U-Pb analysis (Alizai et al 2011a) and newly analyzed Nd isotope data for the Sutlej River (this study). B) False-color image of a portion of the northwestern downwind end of the Thar Desert and Sutlej River course, in Cholistan.…”

Comment on “Geochemistry of buried river sediments from Ghaggar Plains, NW India: Multi-proxy records of variations in provenance, paleoclimate, and paleovegetation patterns in the late quaternary” by Ajit Singh, Debajyoti Paul, Rajiv Sinha, Kristina J. Thomsen, Sanjeev Gupta

“…The trend to more positive ε Nd values in the Ghaggur through the Holocene does not reflect change in erosion patterns in the mountains themselves,which the delta records show to be the opposite of what is proposed in this study. Alizai et al (2011) interpreted single grain Pb isotope data from the Hakkra that parallels the Nd isotopes published by East et al (2015) to reflect evolution of a Himalayan fed stream being clogged by Thar Desert sand as the stream dried up . Such a change does not imply a major change of erosion in the source, as proposed by Singh et al (2016).…”

“…If we accept that the sediments are really deposited by the Sutlej, as suggested by Sinha et al (2013), then it is possible that the relatively negative ε Nd values prior to 17 ka could be Himalayan (Sutlej) derived, but such flow is known to be finished by 5.2-5.7 ka at the latest . The fact that the ε Nd values of the sands considered by Singh et al (2016) have been consistently more positive than known modern Sutlej compositions since ~17 ka (-17 to -19) (Alizai et al, 2011;Tripathi et al, 2004) also indicates that the drift to more positive ε Nd values was not caused by changes in the Sutlej basin, which is now more negative, but to mixing with another sediment source. The trend in Ghaggar-Hakkra ε Nd values is not directed towards a known modern river that could actually have received material from the Lesser and Higher Himalaya.…”

“…The Ghaggar, on whose floodplains the drill sites of Singh et al (2016) sit, together with the Hakkra drill sites at Marot, Alkasur and Tilwalla (Alizai et al, 2011;East et al, 2015) (Fig. 2), is only draining the Sub-Himalayas, not the Lesser or the Higher Himalaya, so its not clear how changes in the relative flux from these ranges would have actually impacted the drilled location.…”