Discovery of Precambrian-Cambrian boundary protoconodonts from the Gangolihat Dolomite of Inner Kumaun Lesser Himalaya: Implication on age and correlation

摘要

The Gangolihat Dolomite (Deoban Formation) of the Calc Zone of Pithoragarh in the Inner Kumaun Lesser Himalaya, hitherto regarded of Mesoproterozoic age (similar to1600-1000 Ma) on the basis of the so-called Riphean stromatolites, has yielded numerous earliest Cambrian protoconodont sclerites characterizing the Precambrian-Cambrian boundary (similar to544 Ma). This fossil discovery fosters a firm chronostratigraphic correlation between the Inner Carbonate Belt and the Krol Belt (Outer Carbonate Belt), now both of Vendian-Early Cambrian age. The present contribution thus resolves an important stratigraphic correlation problem of the Lesser Himalayan geology. And it has a major implication on the tectonic interpretation of the Lesser Himalaya, which is crucial for its palinspastic reconstruction.