Proterozoic intracontinental basin: The Vindhyan example

Journal of Earth system science

Chandan Chakraborty1¹ 

[1] Geological Studies Unit, Indian Statistical Institute, 203 B.T. Road, Kolkata 700 108, India.$$

关键词: Intracratonic basin;    Proterozoic;    depositional environments;    sedimentation;    sequence stratigraphy.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

The Vindhyan basin is a classic example of Proterozoic intracontinental basin that developed in the central part of the Indian shield along with several other basins such as Cuddapah,Chattisgarh,etc.The strata are exposed in three major sectors:Son valley,Bundelkhand and Rajasthan. Substantially thick Vindhyan rocks have also been recognized under the Gangetic alluvium.The constituent stratigraphic units of the Vindhyan Supergroup are laterally correlatable and vertically stacked in similar fashion in individual sectors,but their stratigraphic and sedimentologic attributes vary from one sector to the other.The basin fill in the Son valley (around 3 km thick) exhibits an asymmetric cross-sectional geometry normal to the regional strike (ENE –WSW),with the thickest part occurring to the south,and is divisible into four groups:Semri,Kaimur,Rewa and Bhander,from bottom to top.The boundary between the Semri and Kaimur Groups is marked by a pronounced unconformity.The dominant lithologies include conglomerate,sandstone,shale, limestone as well as volcaniclastics.The Vindhyan strata de fine a broad,regional syncline trending ENE –WSW.The axis of the syncline is slightly curved (convex towards north)and plunges gently towards west.The average dip of the southern limb is greater than that of the northern limb rendering the axial plane to dip southerly.The Vindhyan succession can be divided into five major sequences separated by unconformities. The unconformities are manifested in the field by angular discordances and/or long-term subaerial exposure features.Unconformity surfaces are disposed in the succession de fining what is known as progressive unconformity,indicating contemporaneous tectonic activity during sedimentation. Individual sequences comprise of a spectrum of depositional systems that include alluvial fan, fan delta,braidplain,braidplain delta,eolian sandsheet,siliciclastic/carbonate tidal flat,siliciclas- tic/carbonate shoreface,siliciclastic/carbonate shelf.The paleocurrents revealed by the Vindhyan strata are typically northerly suggesting that the evolving Satpura orogen served as the source for the Vindhyan sediments.However,the source for the clastics occurring within the Semri and the lower parts of the Kaimur and Rewa Groups in the Bundelkhand sector was perhaps the Bundelkhand Granite Gneiss,Bijawar and Gwalior Group of rocks as manifested by the southerly paleocurrent.The sequences of the Vindhyan succession are composed of several systems tracts.The different paleogeographic settings characterizing the systems tracts within individual sequences are as follows:Sequence 1:TST – alluvial fan–fan delta–shelf (Deoland and Arangi Formations)

【 授权许可】

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