Holocene Dune Activity in the Thar Desert, India

Abstract

The Thar Desert dune system in north‐west India and eastern Pakistan provides a rich archive of past environmental, geomorphological and climatic change. Much of the knowledge about the timing of dune accumulation in the Thar stems from scattered and sporadic records, based on older luminescence dating protocols. If the Thar dune record is to be incorporated within a growing multiproxy framework of past climate and environmental dynamics, it is necessary to generate a systematic record of the timing of dunefield accumulation. From this, relationships to climate and other drivers of dune activity may then be better established. To this end, an intensive programme of field sampling and optically stimulated luminescence (OSL) dating was carried out from a dunefield in the east‐central Thar Desert. This study presents the first detailed Holocene dune accumulation history from the region, and sheds light on the development of the multi‐generational parabolic dune systems. In contrast to previously published work, we identify the importance of the Holocene and the last millennium as periods with a number of preserved accumulation phases. OSL ages suggest that accumulation was persistent during the early and mid‐Holocene (within 11.7‐5.5 ka), late Holocene (2‐1 ka), as well as two major phases in the last millennium (600 – 200 a and within the last 70 a). Potential drivers of dune mobility in the last century include a strong anthropogenic dimension. Rapid net accumulation is recorded in the last 70 years, with rates varying between 2 and 5 m/year, in an environment where agricultural pressures have increased dramatically with the advent of irrigation schemes expanding into dunefield areas. © 2019 John Wiley & Sons, Ltd.

Analysis of late Quaternary linear dune development in the Thar Desert, India

“…The organic content by weight is less than 2 %, while carbonate content by weight increases with depth in a section, varying between ~1 and ~5 %. These organic and carbonate values are consistent with other recently reported values from Thar parabolic dune sands (Srivastava et al, 2019). distributions for the majority samples in this study ranges between 20 % and 45 % (Table 2), with slightly higher values (~45%) observed for two of the younger samples.…”

“…As a result, almost a third of the luminescence ages from drylands listed in the INQUA dune database are from linear dunes (Lancaster et al, 2016). In contrast, there are no ages in the database from linear dunes in the Thar Desert because the majority of chronometric studies to date have focussed on parabolic dunes (Thomas et al, 1999; 4 Kar et al, 2001;Singhvi and Kar, 2004;Dhir et al, 2010;Srivastava et al, 2019). The aim of this work therefore, is to apply a spatially intensive sampling strategy and modern luminescence dating techniques to develop a linear dunefield chronology from the Thar and integrate it into existing knowledge of the geomorphic evolution of the Thar dunes and regional palaeoenvironmental interpretations arising from such results.…”

“…Equivalent dose (De) measurements were made using Risø DA-15 TL/OSL readers (for full reader specification see Srivastava et al, 2019) and a post-infrared blue single aliquot regenerative (SAR) dose protocol (Banerjee et al, 2001). Following pre-heat plateau and dose recovery tests, a pre-heat of 240°C for 10 s and a cut-heat of 160°C for 0 s were selected for use.…”

“…The organisation and orientation of these dunes reflects the role of dominant south-west monsoon winds, which have governed aeolian dynamics regionally during the late Quaternary. The presence of superimposed forms, for example young meso-scale dunes on older, bigger parabolic dunes (Srivastava et al, 2019) attests to a more complex history of dune dynamics in the Thar.…”

Quaternary Aeolian Landscape Development in Thar Desert and its drivers

“…In this context, a recent paper (Srivastava et al, 2019a), based on few OSL dates on five parabolic sand dunes in the Jodhpur-Shergarh-Dechu tract, claimed to have identified several Holocene dunebuilding phases which they alleged our OSL-based data could not. To clarify the issue we provide here a summary of the major Holocene aeolian sand accumulation phases identified by them vis-a-vis our data (Table 1).…”