Continental record of the southwest monsoon during the last 130ka: evidence from the southern margin of the Thar Desert, India

Juyal, Navin; Chamyal, L. S.; Bhandari, Subhash; Bhushan, Ravi; Singhvi, A. K.

doi:10.1016/j.quascirev.2005.07.020

Cited by 165 publications

(112 citation statements)

References 44 publications

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“…Possibly, it records some tectonic disturbance in this region during this period which could have triggered mass flow of lateritic cover over the Mio-Pliocene sediments. It is known that rivers in the arid and semi-arid environments are capable of carrying large volume of sediments during episodic storms when the area is devoid of vegetation (Juyal et al, 2006). Another possible implication of the layer of lateritic soil (~40 m) is that it was deposited during seasonal storms or continuous water discharge during heavy rain.…”

Section: Discussionmentioning

confidence: 99%

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Chronology of Cauvery Delta Sediments from Shallow Subsurface Cores Using Elevated-Temperature Post-IR IRSL Dating of Feldspar

et al. 2010

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Abstract:We present the results of luminescence dating of sediments from two cores from the Cauvery Delta in south-east India. Since all natural quartz OSL signals except one sample were in saturation, the elevated temperature post-IR IRSL protocol for K-feldspar was applied to establish a chronology. Internal dose rates of K-feldspar grains were calculated from the measured internal content of potassium, uranium, thorium and rubidium in the bulk of K-feldspar grains using solution ICP-OES and ICP-MS analysis. A substantial scatter in single-aliquot D e values was observed which is most probably due to the effect of incomplete bleaching of fluvial sediments before burial. A minimum age model was applied to extract possible depositional ages. The study revealed that except an upper layer of Holocene sediments (< 5m), the majority of the upper ~50m of Cauvery delta sediments were deposited between marine isotope stage MIS-5 and MIS-10 or older. The feldspar luminescence ages also indicate the existence of a period of non deposition or erosion in the upper part of the cores.

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Section: Discussionmentioning

confidence: 99%

“…Ganges) and fluvial systems (e.g. Luni River) in India have been studied in the past using luminescence dating method (Kale et al, 2000;Srivastava et al, 2003a, b;Juyal et al, 2000Juyal et al, , 2006Jain et al, 2005;Thomas et al, 2005;Chandra et al, 2007;Sinha et al, 2007;Gibling et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Chronology of Cauvery Delta Sediments from Shallow Subsurface Cores Using Elevated-Temperature Post-IR IRSL Dating of Feldspar

et al. 2010

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“…The choice of the analysis protocol is dictated by the nature of spread in palaeodoses (e.g. Galbraith, 1990;Juyal et al, 2006). Mayya et al, (2006) quantified the dose distribution in individual quartz grains due to spatial fluctuation of 40 K beta emitters (K-feldspar) in sediment matrix by developing a statistical basis to compute the spread in palaeodose derived using single grains of quartz.…”

Section: Introductionmentioning

confidence: 99%

Distribution in SAR palaeodoses due to spatial heterogeniety of natural beta dose

Chauhan

Singhvi

2011

Geochronometria

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Abstract:In luminescence dating of sediments, Mayya et al. (2006) pointed out that at single grain level, the beta dose for quartz grains is heterogeneous. This heterogeneity arises due the fact that the total potassium in sediment is contributed by few feldspar grains with up to 11-14% stoichiometric potassium (Huntley and Baril, 1997). Beta particles have a range of ~2 mm, which is comparable to grain sizes and inter-grain distances. This fact implies that the spatial fluctuation of beta emitters (Kfeldspars) around individual quartz grains results in heterogeneous dose deposition. These fluctuations therefore, lead to an inherent spread in palaeodoses received by individual quartz grains. In this study, we compute the spread in single aliquot palaeodoses that arises exclusively due to heterogeneity in beta radiation dose received by individual grains. We thus postulate that 'single aliquots' (comprising several -typically 100 -heterogeneously irradiated single grains) would have an inherent spread in the palaeodose. In this work, we used Monte Carlo simulations to quantify the extent of spread in palaeodoses arising due to heterogeneity of beta dose and hence put a limit on the precision of age estimation. Simulations results indicated, that, 1) the average of the single aliquot palaeodoses provides the closest approximation to the true palaeodose, 2) the minimum number of aliquots that are needed to obtain a robust estimate of average palaeodose value depend upon desired precision and the concentration of K, and 3) the ratio of maximum to minimum single aliquot palaeodose values for a given K concentration provides a measure of inherent spread arising due to beta dose heterogeneity. Any spread over and above this range, can be ascribed to other sources such as heterogeneous bleaching and sensitivity changes. Radiation dose from other uniformly distributed sources of beta particles (U, Th and Rb) however would reduce this spread.

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“…was its location on the fringe of the Thar Desert with the highest population density in any desert region of the globe, and where expansion and contraction of the desert has been linked to the change in past atmospheric circulation and associated arid phase in climate history (Bryson and Swain, 1981;Chawla et al, 1992;Enzel et al, 1999;Juyal et al, 2003;Juyal et al, 2006). Although aeolian activity presently occurs in regions with annual rainfall <250 mm (Goudie et al, 1973), the presence of fossil dunes in areas with present day annual rainfall exceeding 1000 mm indicates a spatial shift in the overall monsoon gradient during the past.…”

Section: Introductionmentioning

confidence: 99%

“…Although aeolian activity presently occurs in regions with annual rainfall <250 mm (Goudie et al, 1973), the presence of fossil dunes in areas with present day annual rainfall exceeding 1000 mm indicates a spatial shift in the overall monsoon gradient during the past. These changes in atmospheric circulation and the resultant variation in rainfall, aridity regime and the aeolian activity have not only shaped the landforms in this region but also influenced the settlement of ancient civilizations (Singh, 1971;Bryson and Swain, 1981;Possehl, 2002;Chamyal et al, 2003;Juyal et al, 2003Juyal et al, , 2006. Even in the present day scenario, inter-annual variation in rainfall is an important factor influencing agricultural productivity in this region because there is no perennial river to supplement any rainfall shortage.…”

Section: Introductionmentioning

confidence: 99%

Water vapour source identification for daily rain events at Ahmedabad in semi‐arid western India: wind trajectory analyses

Deshpande

Dave

Padhya

et al. 2015

Meteorological Applications

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ABSTRACT:The Arabian Sea (AS), the Bay of Bengal (BOB) and continental recycling are three principal vapour sources identified for the rain events at Ahmedabad located in semi-arid western India. In the present study, the 48 h backward wind trajectories, at 6 h intervals, converging at an altitude of 1.5 km above the ground, for 120 daily rain events during the monsoon seasons of 2005-2008, have been examined using HYsplit Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Temperature, relative humidity, altitude and rainfall along each trajectory were studied at hourly intervals. The temperature and relative humidity data were used to compute the absolute humidity (g m −3 ) of the air parcel at its location at hourly intervals. The relationship between the height of the air parcel, its relative humidity and rainfall along each trajectory was used to identify the vapour pick-up region. The region around the maximum value of absolute humidity for each trajectory was designated as the dominant vapour pick-up region for each rain event at Ahmedabad. In this manner, principal vapour source identification was unambiguously possible for 93.3% of all the 120 rain events. The fraction of total events and the fractions of total rainfall attributable to the three principal vapour sources, respectively, are: AS, 68.3 and 62.1%; BOB, 2.5 and 1.5%; recycled, 22.5 and 24.5%; mixed, 6.7 and 11.8%. Most of the rain events with recycled vapour contribution occur during the latter part of the monsoon season, namely during September.

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Continental record of the southwest monsoon during the last 130ka: evidence from the southern margin of the Thar Desert, India

Cited by 165 publications

References 44 publications

Chronology of Cauvery Delta Sediments from Shallow Subsurface Cores Using Elevated-Temperature Post-IR IRSL Dating of Feldspar

Chronology of Cauvery Delta Sediments from Shallow Subsurface Cores Using Elevated-Temperature Post-IR IRSL Dating of Feldspar

Distribution in SAR palaeodoses due to spatial heterogeniety of natural beta dose

Water vapour source identification for daily rain events at Ahmedabad in semi‐arid western India: wind trajectory analyses

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