Magnetostratigraphic study of Cretaceous depositional succession in the northern Kuqa Depression, Northwest China

Stratigraphic studies on the depositional succession in the Kuqa Depression can be traced back to as early as 1950s1], however, there are still some disputes about chronostratigraphic division of the Bashenjiqike For- mation because of the paucity of fos…

Magnetostratigraphic study of Cretaceous depositional succession in the northern Kuqa Depression, Northwest China

There are some quite different disputes about chronostratigraphic division of the Cretaceous in the Kuqa Depression, northern margin of the Tarim Basin. We then carried on a magnetostratigraphic study on Cretaceous succession in the Kuqa River and Kezilenuer Channel profiles. Detailed paleomagnetic analyses on 446 specimens from 265 sites permit a construction of a preliminary magnetic polarity sequence for the Cretaceous strata. Together with paleobiologic constraints from calcareous nannofossils, magnetostratigraphic results show that the Bashenjiqike Formation was probably deposited during the late Campanian to Maastrichtian stages of the Late Cretaceous, ranging from about 79.1 to 65.6 Ma. On the other hand, magnetozones identified from the Yageliemu, Shushanhe, and Baxigai formations may principally correlate with chrons M18r to M3 of the Geomagnetic Polarity Time Scale (GPTS). This correlation suggests that these three formations were very likely to be formed during the early-middle stage of the Early Cretaceous between the Berriasian to the early Berremian stages (141.9–124.1Ma). Therefore it is possible that the Bashenjiqike Formation contacts the underlying strata with an unconformity and there is a giant sedimentary hiatus during the period of the late Barremian to early Maastrichtian stages in the Kuqa Depression.