Potential for oil and gas in the Proterozoic carbonates (Sirban Limestone) of Jammu, northern India

The Proterozoic Sirban Limestone of Jammu in northern India contains an assemblage of Neoproterozoic microflora comparable to other such assemblages from different Proterozoic oil- and gas-bearing carbonate successions in India, Morocco and Siberia. The stromatolitic Sirban Limestone succession is composed of lamina-scale organic-rich source rocks, limestone units with good-quality reservoir characteristics and seal horizons that together constitute the basic physical elements of a petroleum system. A reworked microfloral assemblage of Neoproterozoic age is also recovered from the unconformably overlying Subathu Formation (Eocene) from the area. Some in situ elements of this assemblage, including a few genera, were also recovered from the Sirban Limestone. This reworked assemblage may be related either to upwards migration of hydrocarbons from deeper sediments or, more likely, to the existence of the Sirban Limestone and younger Neoproterozoic formations as a positive area that sourced the microflora to the Eocene Subathu Basin.