干旱区生态环境知识资源中心

Pedogenic carbonates, widespread in paleosols throughout the geological ages, have been widely used to infer climatic conditions and vegetation type during their formation. They are ubiquitous and widespread in the Late Quaternary loess-paleosol sequence of the Kashmir Valley, mostly in the form of carbonate nodules. In the present study, pedogenic carbonates are studied to analyze trends in the stable isotopic composition of carbonate nodules across three well-developed loess-paleosol sections in the Kashmir Valley. The stable carbon isotopic (delta C-13) analysis reveals a gradual increase of the C-4 vegetation towards the top of the sections. The development of C-4 plant biomass towards the top of sections possibly reflects water stress and/or reduced atmospheric pCO(2) and increasing aridity. The oxygen (delta O-18) isotopic analysis reveals little variation with the values ranging from -6.37 parts per thousand to -7.75 parts per thousand, reflecting stable climatic conditions during the development of pedogenic carbonate nodules. The use of geospatial data including digital elevation model (DEM) and Landsat TM remote sensing imagery have added morphological characterization of the topographic and landform features observed in the area. The tectonic uplift of the Pir Panjal Range, variation in the geometry of Karewa Basin and the slope gradient have played a key role in the spatial variation of loess-paleosol sequences in the valley. The Late Quaternary climate changes, deposition of loessic sediments, formation of the interbedded paleosol profiles and the subsequent denudation processes have resulted in the present day typical geomorphic landscape of the Kashmir Valley. The micromorphological analysis of loess-paleosol horizons reveals cold arid to semi-arid climatic conditions prevailed during the Late Quaternary in the valley. (C) 2014 Elsevier Ltd and INQUA. All rights reserved.