Geology, Structural and Exhumation History of the Higher Himalayan Crystallines in Kumaon Himalaya, India

Abstract

The crystallines in the Kumaon Himalaya, India are studied along Goriganga, Darma and Kaliganga valleys and found to be composed of two high-grade metamorphic gneiss sheets i.e. the Higher Himalayan Crystalline (HHC) and Lesser Himalayan Crystalline (LHC) zones. These were tectonically extruded as a consequence of the southward directed propagation of crustal deformation in the Indian plate margin. The HHC and its cover rocks i.e. the Tethyan Sedimentary Zone (TSZ) are exposed through tectonic zones within the hinterland of Kumaon Himalaya. The HHC records history of at least one episode of pre-Himalayan deformation (D 1 ), three episodes of Himalayan deformation (D 2 , D 3 , D 4 ). The rocks of the HHC in Kumaon Himalaya are thoroughly transposed by D 2 deformation into NW-SE trending S m (S 1 +S 2 ). The extent of transposition and a well-developed NE-plunging L 2 lineation indicate intense strain during D 2 throughout the studied portion of the HHC. Ductile flow continued, resulting in rotation of F 1 and F 2 folds due NE-direction and NW-SE plunging F 3 folds within the HHC. The over thickened crystalline was finally, superimposed by late-to-post collisional brittle-ductile deformation (D 4 ) and exposed the rocks to rapid erosion.Apatite Fission Track (AFT) and Zircon Fission Track (ZFT) studies from the Kumaon Himalaya suggest reactivation of the Main Central/Munsiari Thrust (MCT/MT) and Vaikrita Thrust (VT), rapid exhumation and a system that has been in topographic and exhumation steady-state since at least 4 Ma.

Geometric and strain analyses in folds of the area around Gankot, district Pithoragarh, Uttarakhand, India

“…Many workers have discussed about the Kumaon Himalaya pertaining to different aspects of structure and tectonics in this region (Bhattacharya, 2008;Valdiya and Pande, 2009;Joshi and Tiwari, 2009;Agarwal et al 2010Agarwal et al , 2016Agarwal and Sharma, 2011;Bhargava, 2011;Patel et al, 2007Patel et al, , 2011Srivastava et al 2011;Verma and Bhattacharya, 2011;Jain et al 2012Jain et al , 2016Shah et al, 2012;Singh et al, 2012;Jade et al 2014;Dubey 2014;Banerjee et al 2015;Bhattacharya and Ahmed 2016)and their works have thrown much light on the tectonic evolution of the rocks of the region which are highly folded and tectonically much complex. The mesoscopic folds have been used by many workers for the analysis of the folding and the strain conditions (Dieterich and Carter, 1969;Roberts and Strömgard, 1972;Hudleston, 1973;Sanderson, 1976;Bhattacharya, 1978;Hudleston, and Holst, 1984;Lisle, 1992;Bastida, 1993;Bastida et al, 2003;Srivastava, 1995Srivastava, , 2003Srivastava and Gairola, 2003).…”

“…The folding in these Neoproterozoic rocks must have been developed in multiple phases during the Himalayan Orogeny in Tertiary. Patel et al (2011) recognized four phases of deformation (D 1 to D 4 ) in the Higher Himalayan Crystallines of Kumaun Himalaya, which are responsible for complex geometries of the folds in the region. Analysis of fold geometry and strain in this region however, is very much lacking.…”

“…There has been significant contributions on the geology of Kumaon Himalaya by workers like Rupke (1974), Valdiya (1980) , Chamyal (1991), Azmi and Paul (2004), Tiwari (2008), Sharma (2009, 2011), Patel et al (2011) and Chakrabarti (2016). The study area around Gankot lies in the Kumaon Himalaya in Pithoragarh district of Uttarakhand between latitudes 29°°3°°r ocks of the study area belong to the Inner Sedimentary Belt of Lesser Himalaya and form a part of the Mandhali Formation (Sor + Thalkedar Formation) of Lesser Kumaon Himalayan region (Valdiya, 1980: Fig.…”

Examining the tectono-stratigraphic architecture, structural geometry, and kinematic evolution of the Himalayan fold-thrust belt, Kumaun, northwest India

“…In India, the Lesser Himalayan sequence is composed of Paleoproterozoic to Cambrian igneous and metasedimentary rocks and is divided into two parts, Paleoproterozoic-Mesoproterozoic Lesser Himalayan rocks (1900-1600 Ma) and Neoproterozoic Lesser Himalayan rocks (1100-500 Ma), commonly referred as lower Lesser Himalaya and upper Lesser Himalaya, respectively (McKenzie et al, 2011;Mandal et al, 2016). Detailed descriptions of Lesser Himalayan rocks have been presented elsewhere (Valdiya, 1980;Srivastava and Mitra, 1994;Célérier et al, 2009;Patel et al, 2007Patel et al, , 2011Mandal et al, 2015) and are summarized in Table 1. Paleoproterozoic-Mesoproterozoic Lesser Himalayan rocks include the Berinag-Munsiari and Rautgara Formations (Figs.…”

Zircon U‐Pb ages and Hf isotopes of the Askot klippe, Kumaun, northwest India: Implications for Paleoproterozoic tectonics, basin evolution and associated metallogeny of the northern Indian cratonic margin

“…Two geochemically distinct tectonostratigraphic units—the Neoproterozoic‐Ordovician Greater Himalaya and lowermost part of the Paleoproterozoic lower Lesser Himalaya—form the high‐grade metamorphic core of the Himalayan orogen in the Kumaun‐Garhwal region (Uttarakhand) of northwestern India (Figure ) [ Valdiya , ; Srivastava and Mitra , ; Célérier et al ., ; Spencer et al ., ; Kohn , ]. However, similar lithologies, metamorphism, and ductile deformation make it difficult to differentiate these two similar looking rock units [ Valdiya , ; Célérier et al ., ; Rawat and Sharma , ; Patel et al ., , , ] and to interpret the structural significance of klippen that carries these rocks, including the Almora, Bajnath, Askot, Chiplakot, and Lansdowne klippen (Figure ). These klippen occur as metamorphic rock outliers within the Lesser Himalayan tectonostratigraphic zone, and identifying their proper tectonostratigraphic affinity is crucial to structural reconstructions of the orogen in this region [ Valdiya , ; Célérier et al ., ; Rawat and Sharma , ; Patel et al ., , ].…”