NOTE ON THE C AND O STRATIGRAPHY OF THE GARBYANG FORMATION (MALLA JOHAR AREA), TETHYAN HIMALAYA, INDIA

The carbonate rich deposits of the Garbyang Formation, Tethys Himalaya in Malla Johar area, Uttarakhand, India possibly hosts the latest Precambrianearly Cambrian sediments based on earlier studies of trace fossils. To further investigate this issue, fifty-four samples of carbonate were collected and analysed for delta C-13-carb and delta O-18-carb. The results are significant in absence of any chemostratigraphic dataset of the Garbyang Formation till date. The delta C-13-carb varies from -5.8 parts per thousand to 1.0 parts per thousand. But, delta O-18-carb show anomalously low values between -10 parts per thousand and -33 parts per thousand that reflects significant meteoric water diagenesis. The influence of meteoric water diagenesis on the carbon isotopic ratios is apparently minimal as delta C-13-carb stratigraphy of the Garbyang Formation closely follows the established global PC-carb curve for near Precambrian-Cambrian time frame. Signature of the probable Precambrian-Cambrian (Pc-C) boundary has been identified in the lower part of the formation (Garbyang B). Various types of burrows and trace fossils of the Cambrian affinity have been reported from succession overlying the probable Pc-C boundary.