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Sequence stratigraphy of the Oxfordian to Tithonian sediments (Baisakhi Formation) in the Jaisalmer Basin

Pandey D. K., Pooniya D.

Volumina Jurassica

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2015

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Vol. 13, no. 1

65--76

EN

The Oxfordian to Tithonian sediments deposited along the southern Tethyan margin exhibit very diverse sedimentary facies. The Jaisalmer Basin, situated along the northwestern margin of the Indian peninsula, is a good example of those preserving these sediments (Baisakhi Formation). The scattered nature of the outcrops, due to peneplanation and desert sand cover, and the diversity in sedimentary facies, have led earlier workers to employ a confusing lithostratigraphy and lithostratigraphic correlations. New records of ammonites, more detailed facies description and the application of the sequence stratigraphic method helped to sort out the stratigraphical problems of these isolated outcrops. The complexity of the Oxfordian-Kimmeridgian-Tithonian sediments present in the Jaisalmer Basin, as evidenced by ammonite finds can be traced along an onshore – offshore transect. Within the Oxfordian-Tithonian strata of the Baisakhi Formation, Jaisalmer Basin, 35 parasequences grouped into three depositional sequences (TST-HST/FSST) have been recognized. In at least two cases, the maximum flooding surfaces (MFS) are superimposed on the transgressive surfaces within very condensed sections. The parasequences belong to a continuous succession representing shoreface (deepest part of the basin) to foreshore (shallowest part of the basin). During deposition of the Tithonian succession the southern part of the basin witnessed shallow, nearshore, or foreshore to fluvial depositional environments and, consequently, contains several depositional gaps and less distinct parasequences. The chronological order of the parasequences has been established on the basis of ammonites: Oxfordian – Perisphinctes (Dichotomosphinctes) sp. and P. (Dichotomoceras) sp.; Kimmeridgian – Torquatisphinctes alterniplicatus (Waagen) and Pachysphinctes aff. major Spath; Tithonian – Aulacosphinctoides sp., Virgatosphinctinae and other zonal ammonites recorded by earlier workers. The most logical facies correlation in conformity with Walther’s law was also used. Unfortunately, no marker beds have been recognized; however, the record of at least two brackish-water phases helped in the understanding of depositional settings along the onshore-offshore transects during these time intervals. In general, the Kimmeridgian-Tithonian part of Baisakhi Formation exhibits a general coarsening-upward trend and a change from lower shoreface zone to fluvial environments. The three sequence cycles interpreted within the Oxfordian-Tithonian sediments in the Jaisalmer Basin correspond to second-order sequence cycles.

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Dinosaur footprints from the Thaiat ridge and their palaeoenvironmental background, Jaisalmer Basin, Rajastan, India

Pieńkowski G., Brański P., Pandey D. K., Schlögl J., Alberti M., Fürsich F. T.

Volumina Jurassica

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2015

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Vol. 13, no. 1

17--26

EN

Two dinosaur footprints: Eubrontes cf. giganteus and Grallator tenuis, both attributed to theropods, have been found in the Lower Jurassic Thaiat Member of the Lathi Formation at the Thaiat ridge, near Jaisalmer in western Rajasthan, India. The footprints were left in sediments of a tidal origin, located in profile a few meters above a marked transgressive/flooding surface. They show different states of preservation – the smaller Grallator tenuis represents a well-preserved concave epirelief footprint on the upper surface of a sandstone containing nerineid gastropod shells, while the bigger Eubrontes cf. giganteus footprint shows a rare state of preservation as a positive epirelief on the top of a calcareous sandstone bed, where recent erosion exposed the footprint cast by removing the mud above and around the footprint. The Thaiat ridge section has been amended in its lower part, to indicate the marked transgressive surface. Geochemical analyses and calculated weathering indices (such as CIA) show that the hinterland climate was seasonal to semi-arid during deposition of that part of the succession.

3

An overview of Yellow Limestone deposits of the Jaisalmer Basin, Rajasthan, India

Srivastave N., Ranawat T. S.

Volumina Jurassica

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2015

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Vol. 13, no. 1

107--112

4

Development of Index to Assess Drought Conditions Using Geospatial Data a Case Study Of Jaisalmer District, Rajasthan, India

Chhajer V., Prabhaka S., Prasad P. R. C.

Geoinformatica Polonica

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2015

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T. 14

29--39

EN

The Jaisalmer district of Rajasthan province of India was known to suffer with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. However flood-like situation prevails in the drought prone Jaisalmer district of Rajasthan as torrential rains are seen to affect the region in the recent years. In the present study, detailed analysis of meteorological, hydrological and satellite data of the Jaisalmer district has been carried out for the years 2006−2008. Standardized Precipitation Index (SPI), Consecutive Dry Days (CDD) and Effective Drought Index (EDI) have been used to quantify the precipitation deficit. Standardized Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI), Temperature Condition Index (TCI), Vegetation Health Index (VHI), Normalized Difference Vegetation Index (NDVI) and Modified Soil-Adjusted Vegetation Index 2 have been calculated. We also introduce two new indices Soil based Vegetation Condition Index (SVCI) and Composite Drought Index (CDI) specifically for regions like Jaisalmer where aridity in soil and affects vegetation and water-level.

PL

Okręg Jaisalmer w indyjskiej prowincji Radżasthan znany był z częstych susz, spowodowanych słabymi i pojawiającymi się zbyt późno opadami monsunowymi, wyjątkowo wysokimi temperaturami w lecie i niewystarczającą ilością zasobów wodnych. Jednakże ostatnio, w podatnym na suszę okręgu Jaisalmer w Radżasthanie, częstsze jest zagrożenie ze strony powodzi, spowodowanych ulewnymi deszczami. W niniejszej pracy przedstawiono szczegółową analizę danych meteorologicznych, hydrologicznych i satelitarnych z okręgu Jaisalmer, zgromadzonych w latach 2006−2008. Aby ilościowo opisać deficyt opadów, użyto następujących wskaźników: standaryzowany wskaźnik opadów (Standardized Precipitation Index – SPI), ciągły wskaźnik dni suchych (Consecutive Dry Days – CDD) oraz efektywny wskaźnik suszy (Effective Drought Index – EDI). Aby ocenić deficyt wód grunto wych, opracowano standaryzowany wskaźnik poziomu wód (Standardized Water-Level Index – SWI). Obliczono wskaźniki suszy wegetacyjnej takie jak: wskaźnik stanu wegetacji (Vegetation Condition Index – VCI), wskaźnik stanu temperatury (Temperature Condition Index – TCI), wskaźnik zdrowia wegetacji (Vegetation Health Index – VHI), znormalizowany różnicowy wskaźnik wegetacji (Normalized Difference Vegetation Index – NDVI) oraz zmodyfikowany wskaźnik wegetacji z uwzględnieniem poprawki na glebę – wskaźnik wegetacji 2 (Vegetation Index 2). Wprowadzono również dwa nowe wskaźniki: oparty na glebie wskaźnik stanu wegetacji (Soil based Vegetation Condition Index – SVCI) i złożony wskaźnik suszy (Composite Drought Index – CDI), uwzględniając specyfikę dla regionów takich jak Jaisalmer, gdzie suchość w glebie ma wpływ na wegetację i poziom wód.