Provenance of the Late Neogene Siwalik sandstone, Kumaun Himalayan Foreland Basin: Constraints from the metamorphic rank and index of detrital rock fragments

Abstract

An understanding about lithology, tectonics and unroofing history of provenance is mostly drawn from the compositional and textural parameters of the detrital fragments. We here use different metamorphic ranks (Rm) and metamorphic index (MI) values of rock fragments present in Late Neogene Siwalik sandstone of the Ramganga sub-basin to infer the provenance history. The study indicates maximum contribution from metamorphic ranks 1 and 2 (Rm1 and Rm2; meta-sedimentary and very low grade metamorphic rocks) and minimum from metamorphic rank 4 (Rm4; high metamorphic grade rocks). The metamorphic index (MI) values range from 118 to 224, with an average of 186. The meta-sedimentary and very low-grade metamorphic rock fragments are derived from the Lesser Himalayan domain. The medium-to-high grade metamorphic fragments are derived from the Lesser Himalayan Crystalline bodies. The abundance of Rm2 and Rm3 detrital modes suggest the exhumation of crystalline bodies of the Ramgarh and Almora most likely occurred prior to 7 Ma and subsequently the source area shifted and resulted abundant supply of Rm1 fragments due to the upliftment along Main Boundary Thrust around 5.55 Ma.

Provenance of the Middle Siwalik sandstones of the Himalayan foreland basin (south central Kumaun, India): Implications for tectonics and paleoclimate of the source area

“…Figure shows QtFL petrofacies compositional fields of the Middle Siwalik sandstones of Potwar Plateau, Pakistan (Critelli & Ingersoll, ); Ramnagar, Kumaun (Tandon, ); Ranibag‐Jeolikot, Kumaun (this study); Baliya River section, Kumaun (Jalal & Ghosh, ); Western Nepal (four section between west of Karnali River and Surai Khola; DeCelles et al, ); Karnali River section, Nepal (Sigdel & Sakai, ); Surai Khola section, Nepal (Critelli & Ingersoll, ); Bakiya Khola section, Nepal (Critelli & Ingersoll, ); Muksar Khola section, Nepal (Chirouze et al, ); Koshi River Section, Nepal (Baral et al, ), Tista valley, eastern India (Kundu et al, ); and Lish River section, eastern India (Kundu et al, ). The sandstones of the Potwar Plateau, representing the western part of the foreland basin, are slightly depleted in quartz and enriched in feldspar as compared with sandstones from the rest of the central and eastern parts of the basin.…”

“…Given the absence of any evidences of deposition from a contemporaneously existing large axial river systems, like Indus, Ganga or Brahmaputra (Taral & Chakraborty, ), it is likely that the exposed Middle Siwalik sequences were deposited only to the orogen‐ward side of the axial river systems and thus did not receive sediments from the peninsular India. Conforming to this presumption, the previous studies have determined that the Middle Siwalik sediments in different parts of the foreland basin were supplied exclusively from the Himalayan hinterlands (Baral et al, , ; Critelli & Ingersoll, ; Chirouze et al, ; Jalal & Ghosh, ; Kundu et al, ; 2016; Sigdel & Sakai, ).…”

“…The present study pertains to the Middle Siwalik Subgroup of the south central Kumaun Himalaya, the sedimentology of which has so far been determined only along a few sectors in north‐western Pakistan, northern and north‐eastern India, and Nepal (Agrawal & Singh, ; Baral, Lin, & Chamlagain, ; Chirouze et al, ; Jalal & Ghosh, ; Khan, Bridge, Kappelman, & Wilson, ; Khan & Tewari, ; Kumar & Nanda, ; Kundu et al, ; 2016; More, Paruya, Taral, Chakraborty, & Bera, ; Nakayama & Ulak, ; Sigdel & Sakai, ; Tandon, ; Taral & Chakraborty, ; Thomas, Parkash, & Mohindra, ; Zaleha, ; and references therein). Specifically, the present study pertains to detailed petrography and petrofacies of the Middle Siwalik sandstones exposed between Ranibag and Jeolikot, along the Nainital‐Kathgodam motor road (Figure b).…”

“…Specifically, the present study pertains to detailed petrography and petrofacies of the Middle Siwalik sandstones exposed between Ranibag and Jeolikot, along the Nainital‐Kathgodam motor road (Figure b). Petrofacies and/or petrography of the Middle Siwalik sandstones has so far been determined only along the Potwar plateau in Pakistan (Critelli & Ingersoll, ); Jwalamukhi, Ramnagar, and Baliya river sections in north‐western India (Jalal & Ghosh, ; Najman et al, , ; Tandon, ); Karnali River and Surai Khola in western Nepal (four sections between west of Karnali River and Surai Khola) Bakiya Khola, Muksar Khola, and Koshi River sections in eastern Nepal (Baral et al, ; Baral, Lin, & Chamlagain, ; Chirouze et al, ; Critelli & Ingersoll, ; DeCelles et al, ; Sigdel & Sakai, ); and Tista valley and Lish River sections in eastern India (Kundu et al, , 2016; Figure a). These studies have established that the Middle Siwalik sandstones are mainly quartzolithic (lithic and sublithic) arenites, with spatially varying population of lithic fragments; the lithic fragments in Middle Siwalik sandstones of Potwar Plateau are dominantly of metamorphic, ophiolitic, and sedimentary affinity, whereas those in the Middle Siwalik sandstones of the north‐western and north‐eastern India, and Nepal are of sedimentary and metamorphic affinity.…”

Detrital zircon U–Pb geochronology of the Siwalik Group of the Nepal Himalaya: implications for provenance analysis

“…Similar result was obtained by White et al (2002) from the study of early Middle Miocene Molasse deposit in northern India. In Kumaun Himalaya, Jalal and Ghosh (2012) found that at ~7.7-4.5 Ma, metamorphic rocks of LH acted as a dominant source of the Siwalik Group that gradually changes to low-grade metamorphic rocks of LH (Janusar Group) after the reactivation of MBT at ~5.5 Ma. In the eastern Himalaya, Higher Himalaya acted as a prominent source of sediment between 13-7 and <2.6 Ma, while in between ca.…”