Shandong Early Cambrian Sequence Lithofacies Palaeogeography

Shandong zone is more than 400km at its length from south to north, about 700km at its width from east to west, and total area is about 1,500,000km~2, including east-south in the north-China and part of Bohai space. The region extensively develop early Cambrian series stratum whose accumulative thickness has about 100-300m. It has multiplicity sediment types and fruitful biological fossils. This region is ideal region and stratum study, in which has good base of the rock stratum, biology stratum, time stratum and sediment facies. This paper mainly gains following conclusions by this research.1. On the basis of the early study result as well as new rock stratum cleaning up mind, early Cambrian stratums in the Shandong region are studied completely. It is divided 2 stages: Changlangpu stage, Longwangmiao stage; 3 formations: Liguang formation, Zhushatong formation, Mantou formation. Lithostratigraphy, biostratum, and depositional sequence are consolidated by the whole region stratum contrast in research field.2. According to characters of the rock types, sediment structure, palaeocommunite, section structure, etc. early Cambrian sediment system is divided shore sediment system and tidal flat sediment system in the Shandong region. We traverse character of each sediment system, facies, sub-facies, tiny facies and erect sediment model.3. Four types of the sequence boundary wre recognized: unconformable surface, litholgy- lithofacies diversion surface, overlapping surface and maximum flooding surface, etc. Based on this, early Cambrian in the Shandong region is divided 4 sequences. This paper discuss each sequence character as well as change from different facies, contrast in the region, and erect sequence trellis. In short, each third sequence may contrast in the region. But sequences develop differently, it reflect that sequences upgrowth are controlled together by palaeoclimate, sea level change and regional tectonic activity.4. Lithofacies paleogeography characters were posted by upbuiding isochronous sequences frame and sequence-based lithofacies-paleogeography map working out. On the production of researching tectonic evolve, the author discussed the reason of transgression directional change.