CORRELATION OF FOUR MAGNETOSTRATIGRAPHICALLY CONSTRAINED SECTIONS OF MIOCENE BHUBAN FORMATION OF SURMA BASIN IN MIZORAM, INDIA

Abstract

In the present study, four magnetostratigraphically constrained isolated sections in the Mizoram part of the Surma basin, namely, Kolasib-Rengtekawn (KR) section in Kolasib district; and Bawngkawn–Durtlang (BD); Tuirial and Sairang sections in Aizawl district of Mizoram have been successfully correlated. The youngest magnetozone of BD section i. e. C5Cn magnetozone (16.726-16.014 Ma) has also been recorded in the KR section and both the sections expose Middle Bhuban Unit of Bhuban Formation, Surma Group. Thus KR section is correlated with the upper part of BD section. Three younger magnetozones, viz., C4 An (9.025 - 8.699 Ma), C4Ar.1n (9.308 - 9.230 Ma) and C4Ar.2n (9.642 - 9.580 Ma) of Tuirial section have been delineated in the Sairang section and both the sections belong to Upper Bhuban Unit. Thus Sairang section is correlatable with the upper part of Tuirial section. Stratigraphically also, KR and BD sections are older than the Tuirial and Sairang sections. Similar pattern in rate of deposition has been noticed in the KR and BD sections and Turial and Sairang sections. The study thus demonstrates that magnetostratigraphy may emerge as the reliable tool for regional correlation of isolated successions of varied litho-stratigraphic units in the Surma basin. An integrated study on litho-, bio- and magnetostratigraphy along with sedimentology is needed to reconstruct the tectono-depositional history of the basin and biotic evolution in it.