| Autor: |
Yogesh Ray, Subhajit Sinha, Sumit K Ghosh |
| Jazyk: |
angličtina |
| Rok vydání: |
2022 |
| Předmět: |
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| Zdroj: |
Geosystems and Geoenvironment, Vol 1, Iss 2, Pp 100016- (2022) |
| Druh dokumentu: |
article |
| ISSN: |
2772-8838 |
| DOI: |
10.1016/j.geogeo.2021.100016 |
| Popis: |
We present petrographical and geochemical data for the Lesser Himalayan sedimentary succession from the Tons Valley section of the Garhwal Lesser Himalaya. The succession consists of the least metamorphosed shale-dominant Chandpur Formation overlain by coarser-grained sandstones of Nagthat Formation. Petrographic studies of the Jaunsar Group siliciclastics reveal that apart from quartz 84 ± 9%, feldspar forms 5 ± 4% (with PF > KF) and rock fragments (micro- to mega-crystalline chert, orthoquartzite, gneisses, phyllites, and schists) constitute the remaining 11 ± 8%. The occurrence and existence of the labile components like feldspars, and rock fragments such as phyllites and schists, indicate less weathering and a relatively short distance of transport and provenance from a clastic wedge with a recycled nature of sediments. The major element discriminant function analysis indicates that the Nagthat Formation samples plot in the quartzose sedimentary-felsic igneous field and the Lower Chandpur Formation plots in the intermediate igneous provenance, supporting derivation from an Upper Continental Crust-like source. The TiO2 vs Ni diagram indicates acidic source rocks. Trace and REE combined discriminant diagrams support significant mafic input and confirm mafic and ultramafic rocks in the source area. In the Eu/Eu* vs GdN/YbN plot, lower values of Eu/Eu* suggest that the igneous/metamorphic provenance was affected by intra-crustal differentiation. The GdN/YbN > 2 value indicates a contribution from older sources like the Archean, whereas Phanerozoic granites have a ratio |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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