Tectonic and high-latitude climate controls on Quaternary sedimentary processes on the northern coast of Bohai Bay

Abstract

Separating the relative roles of tectonics and climate change in geological evolution is complicated. The northern coast of Bohai Bay (NCBB), with a thick accumulation of Quaternary lacustrine sediments, is a subsiding area and is well suited to studying tectonic versus climatic controls on sedimentary processes. We used magnetostratigraphy and sedimentological analyses of borehole core JL01 from the NCBB to provide new insights into the effects of tectonic processes and climate changes in this region. The results show the following: (1) A shallow lacustrine delta, a deep-water lacustrine sedimentary system and a subaqueous fan-delta sedimentary system developed during 2.1–1.4 Ma, 1.4–0.78 Ma, and from 0.78 Ma to the present, respectively, corresponding to the rift-initiation, rift-climax, and late-rift tectonic stages of the evolution of an extensional basin, respectively. These stages constitute a low-order tectono-sedimentary cycle. (2) Tectonic and orbital-scale climate changes can be distinguished, particularly the 2.5 Ma climatic transition and a significant shift from 41- to 100-kyr cyclicity across the Mid-Pleistocene climatic transition. These changes indicate that the sedimentary processes of the NCBB were influenced by high-latitude climate forcing since the Late Pliocene. Our results demonstrate that detailed sedimentary facies analyses can provide valuable information about the effects of tectonics and climate changes on basin sedimentary evolution. This approach can be applied to other regional basins worldwide.