Rajeev Upadhyay

Tectonic and magmatic evolution of the eastern Karakoram, India

AbstractThe Shyok suture zone separates the Ladakh terrane to the SW from the Karakoram terrane to the NE. Six tectonic units have been distinguished. From south to north these are; 1. Saltoro formation; 2. Shyok volcanites; 3. Saltoro molasse; 4. Ophiolitic melange; 5. Tirit granitoids; 6. Karakoram terrane including the Karakoram batholith. Albian—Aptian Orbitolina-bearing lime-stones and turbidites of the Saltoro formation tectonically overlie high-Mg-tholeiites similar to the tectonically overlying Shyok volcanites. The high-Mg tholeiitic basalts and calcalkaline andesites of the Shyok volcanites show an active margin signature. The Saltoro molasse is an apron-like, moderately folded association of redgreen shales and sandstones that are interbedded with ~ 50 m porphyritic andesite. Desiccation cracks and rain-drop imprints indicate deposition in a subaerial fluvial environment. Rudist fragments from a polygenic conglomerate of the Saltoro molasse document a post-Middle Cretaceous age. The calcalkalin...

Tectonics and sedimentation in the passive margin, trench, fore-arc and backarc areas of the Indus Suture Zone in Ladakh and Karakorum: a review

AbstractThree distinct turbidite basins are recognised in the Indus-Tsangpo Suture Zone of NW Indian Himalayan region. The broad facies organisation of these turbidite basins suggests that they are attributable to passive and active margins of the Neo-Tethyan oceanic realm. The syn-post-rift deep marine, fine-grained Lamayuru Formation, dated from Triassic to Eocene, represents an accreted oceanic basin of the Indian passive margin. The syn-tectogenic trench and trench-slope volcanogenic turbidites of the Nindam Formation represent an accretionary fore-arc basin of Late Cretaceous-Eocene age. The Nindam Formation is correlated with the Congdu trench sediments of southern Tibet. The syn-orogenic composite turbidites of the Indus Formation represent a residual fore-arc basin that lately evolved towards composite type as a result of the changing geometry of provenance terrains. The Middle-Late Cretaceous to Eocene Indus Formation is correlated with the Xigaze forearc basin of southern Tibet.Adjacent to the I...