报告题目：Proxy-Based Palaeoclimatology and Holocene Climate Changes from a Saudi Arabia Record
报告人：杨晚
报告人单位：密苏里科技大学
报告时间：5月16日（星期二）上午9：30
报告地点：图书馆三楼报告厅
主办：国家重点实验室、科技处、青促会、人教处
报告人简介：
杨晚，男，密苏里科技大学地质科学与工程学院教授，博士生导师，主要从事沉积学、旋回地层学、层序地层学和古气候学和石油地质学等方面的研究，曾担任菲利普斯石油公司的勘探地质工程师，德克萨斯大学经济地质局研究员，威奇塔州立大学地质系副教授和主任。主持包括美国自然科学基金在内的科研项目20余项，发表学术论文160余篇。
报告简介：
The stratigraphic architecture of Upper Holocene sediments along the coast of Al Qahmah in southern Red Sea, Saudi Arabia, provides a high-resolution analog of marginal marine carbonate and siliciclastic sedimentation under variable climatic, tectonic, and sea-level conditions. The sediments include a basal shallow marine limestone and overlying beach, deltaic, fluvial, eolian, and sabkha siliciclastic deposits, comprising four stratigraphic units ranging from 10s to 100 s cm thick. A lithostratigraphy is established using subsurface stratigraphic and petrographic data from 64 trenches and three shallow refraction seismic sections. A chronostratigraphy is established using four age points and sedimentation rates. The entire interval has been deposited in the last ~4000 years. Significant stratigraphic variability is reflected by vertical and lateral changes in the thickness, type, and stratal geometry of the four units. Five major geological events are interpreted: Initial shallow marine carbonate deposition during a relative sea-level highstand was terminated by seaward progradation of deltaic-beach sediments during a slow shoreline regression. This is followed by a major stream channel incision during the maximum regression and a relative sea-level fall. The ensuing fluvial channel filling, transgressive ravinement, and deposition of beach sediments signify a relative sea-level rise. Finally, eolian, sabkha, and beach sediments have been deposited in a stabilized and diversified environmental setting under an arid climate. The lacuna associated with stream erosion and transgressive ravinement is up to ~400 years long, resulting in a stratigraphic completeness of ~88%. The sedimentation rate of the siliciclastic sediments is ~0.1 cm/year estimated at a scale of 1000s of years. Episodic syn-depositional faulting in the source area and depositional site, relative seal-level change, autogenic environmental shift, and/or climatic changes between humid and arid conditions have collectively played variable roles in the formation of the stratigraphic variability. The interpreted tectonic, relative sea-level, and climatic trends offer an important data point for future studies in the Red Sea region and beyond for the Late Holocene.
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