Cretaceous stratigraphy of northeast China: non-marine and marine correlation

Cretaceous rocks yielding coal, oil and gas are widely distributed in several basins, separated by faults, in northeast China and eastern Inner Mongolia. Marine rocks containing the bivalve Buchia, encompassing the Jurassic/Cretaceous boundary, are limited to the northeast corner of eastern Heilongjiang Province. Lower Cretaceous (Hauterivian) to Upper Cretaceous strata commonly include volcanic intercalations of lavas and tuffs and are generally non-marine, but most contain some marine and/or brackish-water intercalations. The typical Jehol Biota occurs in the Jehol Group of western Liaoning Province and some non-marine bivalve taxa of the Jehol Biota also occur in the Jixi Group, which in addition contains marine intercalations with the Barremian–Albian bivalve Aucellina in eastern Heilongjiang. Using the stratigraphic occurrences of non-marine and marine strata, together with radiometric ages, the Cretaceous strata of northeast China and Inner Mongolia are correlated. The Jehol Group is dated as Hauterivian/Barremian–Early Albian, potential Tethyan and Boreal Jurassic/Cretaceous boundaries are examined, and preliminary ideas on the palaeogeography of the area are summarized.