Abstract
The Vindhyan Basin of north-central India represents one of the world’s largest and most extensively preserved Proterozoic sedimentary successions. It is also among the most debated in terms of its depositional history and chronostratigraphic framework. Auden (1933) first subdivided the sequence into four major groups—Semri, Kaimur, Rewa, and Bhander—in ascending order. An angular unconformity separates the lowermost Semri Group from the overlying Kaimur. Owing to its remarkably undeformed and unmetamorphosed character, the Vindhyan succession was long presumed to be of Neoproterozoic to early Paleozoic age. The first radiometric constraints, provided by Crawford and Compston (1969), placed the onset of sedimentation between 1200 and 1400 Ma. Over the ensuing five decades, the chronology of the lower Vindhyan has become progressively better constrained, whereas the age of the upper Vindhyan remains one of the most persistent and contentious problems in Indian Proterozoic stratigraphy. In this talk, I will explore the intertwined (and oft-convoluted) stories of paleontology, geochronology, and paleomagnetism—and examine why, despite decades of study, the age of the Vindhyan Basin remains a matter of debate.