Tansen Gr
Period:
Permian, Jurassic, Paleogene, Neogene
Age Interval:
earliest Permian, late Jurassic-early Cretaceous, Paleogene, early Miocene
Province:
Nepal Lesser Himalaya
Type Locality and Naming
Tansen and lower Kali Gandaki region. Incorporates upward succession of Sisne Fm (partly glacial), Taitung Fm, Amile Fm, Bhainskati Fm, and Dumri Fm. [NOTE: Martin (2017) recommends abandoning this Tansen Gr term, because it artificially merges a span of nearly 250 Myr that is mainly non-deposition.]
Lithology and Thickness
Sakai (1983) investigated the Tansen Group of predominantly clastic sedimentary rocks from the Lesser Himalaya of west Nepal. The Tansen Group attains a maximum thickness of 2,400 m.
Lithology Pattern:
Clayey sandstone
Relationships and Distribution
Lower contact
Major unconformity (ca. 1 billion years) at the top of the underlying Kerabari Fm (early-middle Proterozoic)
Upper contact
Disconformably overlain by the Siwalik Gr (Lower Siwalik Fm) foreland basin fill
Regional extent
GeoJSON
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Fossils
Age
Earliest Permian, late Jurassic-early Cretaceous, Paleogene, early Miocene => spans some major hiatuses. Age spans of component formations partly based on correlation to Pakistan units by K.S. Valdiya (2016; The Making of India; Springer Publ.)
Age Span:
Beginning stage:
Asselian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
298.89
Ending stage:
Burdigalian
Fraction up in the ending stage:
0.5
Ending date (Ma):
18.22
Depositional setting
Depositional pattern:
Additional Information
Compiler:
Descriptions from Megh Raj Dhital (2015, Geology of Nepal: Regional Perspective of the Classic Collided Orogen, Springer Publ., 499 pp.). Age spans estimated from correlation diagrams in Martin, A.J. (2017, "A review of Himalayan stratigraphy, magmatism, and structure", Gondwana Research, 49: 42-80; http://dx.doi.org/10.1016/j.gr.2017.04.031), but these are often controversial.