Shyok Volcanic Fm
Period:
Cretaceous
Age Interval:
Early Aptian?
Province:
NW Himalaya Karakoram-east
Type Locality and Naming
Lower Shyok Valley
Lithology and Thickness
Basalt. " The high-Mg tholeiitic basalts and calcalkaline andesites of the Shyok volcanites show an active margin signature." (from Upadhyay et al., 1999. Tectonic and magmatic evolution of the eastern Karakoram, India. Geodinamica Acta, 12: 341-358; https://doi.org/10.1016/S0985-3111(99)00101-1)
Lithology Pattern:
Lava
Relationships and Distribution
Lower contact
Not defined
Upper contact
Overlying units are Hundiri Fm and Saltoro Flysch Fm that are unevenly distributed at various locations.
Regional extent
Lower Shyok Valley.
GeoJSON
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Fossils
Age
Coeval (?) Deosai volcanics in northern Pakistan: " The volcanics comprise basalt, andesite, dacite, and rhyolite and are part of the Kohistan–Ladakh arc, exposed east of the Nanga Parbat–Haramosh Massif. Based on the U–Pb ages, this volcanic suite is classified into three chronostratigraphic units: (a) Chota Pani volcanics, (b) Shatung Nala volcanics, and (c) Bara Pani volcanics, with ages ranging between 123–115, 86–63, and 48–46 Ma, respectively. This study suggests that the Chota Pani volcanics are arc-related, as their ages coincide well with the timing of initiation of the Kohistan–Ladakh arc." (Jadoon et al., 2020, Early Cretaceous to Eocene magmatic records in Ladakh arc: Constraints from U–Pb ages of Deosai volcanics, northern Pakistan. Geological Journal, 55: 5384-5397.). Therefore, assumed as ca. 123-120 Ma here, due to constraints of overlying units as earliest Aptian.
Age Span:
Beginning stage:
Barremian
Fraction up in beginning stage:
0.6
Beginning date (Ma):
123.44
Ending stage:
Aptian
Fraction up in the ending stage:
0.3
Ending date (Ma):
118.94
Depositional setting
Part of an active "Ladakh volcanic arc"
Depositional pattern:
Additional Information
This is a "holding" entry; pending more details from the regional specialists or publications.
Compiler:
:J.Ogg (temporary)