Fossil Microbiota from the Vaishnodevi Limestone, Himalayan Foothills, Jammu: Age and Palaeoenvironmental Implications

Vaishnodevi Limestone is a distinctive landmark succession in the Jammu Himalaya. Significant biotas have been identified from a well exposed chert outcrop near Bidda and shale near Muttal. The chert biota is dominated by mat forming crustose, coccoid, chroococcacean cyanobacteria that include Eoentophysalis belcherensisand Palaeopleurocapsa wopfnerii. The other coccoid taxa are Myxococcoides grandis, Gloeodiniopsis lamillosa, Eogloeocapsa avzyanica, Sphaerophycus cf., S. medium, Eosynechococccus moorei, E. grantiis, Siphonophycus kestron, S. robustum, Oscillatoriopsis sp., Circumvaginalis elongatus, Archaeoellipsoides major, and A. minor. Stratigraphically this is the oldest biota thus far known from the Vaishnodevi Limestone and is assigned a palaeoproterozoic-Mesoproterozoic age.

The Muttal biota is composed of Siphonophycus kestron, S. robustum, Oscillatoriopsis sp., Calyptothrix spp., Eosynechococcus medius, Archaeotrichion contortum, Archaeollipsoides bactriformis, A. grandis, A. obesus, Arctacellularia ellipsoidea, Nostochomorpha prisca, Paleonostocalia irregularia, Leiosphaeridia laminariala, Leiosphaeridia sp., Lophosphaeridum spp., Micrhystridium spp., Sphaerocongregus sp., Obruchevella sp., Chuaria sp., Kildinosphaera sp., Spiromorpha indet. and vase shaped microfossils (VSMs). The Muttal biota is from the topmost shale unit of Vaishnodevi Limestone and is assigned a Neoproterozoic age.

It is concluded that the age of the Vaishnodevi Limestone spans the entire Proterozoic and deposited in a supratidal to intertidal and subtidal environment within a shallow shelf regime.