Middle Jurassic to Early Cretaceous dinoflagellate assemblage zones in eastern Heilongjiang Province, northeast China

Abstract

A Jurassic–Cretaceous marine dinoflagellate cyst biostratigraphic sequence is established for the first time in eastern Heilongjiang Province, northeast China, based on 20 years of data accumulation. This consists of eight assemblage zones (AZs, including three peak zones), of which four are of Callovian–Valanginian age in the Suibin area and four are of early Cretaceous age in the Jixi Basin (including one that is also present in, and coeval with, deposits of Berriasian–Valanginian age in the Suibin area). They are, in ascending order: 1, the Pareodinia ceratophora-Nannoceratopsis pellucida AZ, Suibin Formation; 2, the Gonyaulacysta jurassica AZ (peak zone) in the lower part of the Dongrong Formation; 3, the Amphorula delicata AZ in the upper part of the Dongrong Formation; 4, the marine Oligosphaeridium pulcherrimum AZ (peak zone) in the uppermost Dongrong Formation, Suibin area; 5, the coeval slightly brackish Vesperopsis didaoensis– Lagenorhytis granorugosa AZ in the Didao Formation, Jixi Basin; 6, the marine Odontochitina operculata– Muderongia tetracantha AZ in the lower part of the Chengzihe Formation; 7, the marine Canningia reticulata AZ in the upper part of the Chengzihe Formation; and 8, the Cribroperidinium? parorthoceras AZ (peak zone) in the lower part of the Muling Formation.