名家论坛（2015-8）：Chris Hawkesworth教授学术报告会

应地质过程与矿产资源国家重点实验室刘勇胜教授邀请，英国皇家学会院士、苏格兰皇家学会院士、中国科学院“国际杰出学者”、英国圣安德鲁斯大学Chris Hawkesworth教授来我校进行学术交流与访问。

报告题目：Geological Cycles and the Evolution of the Continental Crust

报告专家：Chris Hawkesworth教授

报告时间：7月13日（周一）上午 9:00

报告地点：八角楼学术报告厅

Chris Hawkesworth教授简介：

Hawkesworth教授是国际著名地球化学家和岩石学家。他的研究领域和兴趣非常广泛，主要包括同位素地球化学、大陆地壳形成与演化、沉积和构造过程的地质记录、大火成岩省和地幔柱、造山带热演化以及气候变化的地球化学记录等等，并在这些领域均做出了具有重要国际影响力的杰出成果。他已经出版学术专著6本，发表论文315篇，且主要发表在国际重要刊物上，其中在《Nature》和《Science》上就发表论文37篇(第一作者11篇)，论文引用逾16000次。他先后荣获英国皇家学会院士和苏格兰皇家学会院士、美国地球物理联合会和欧洲地球化学协会Fellow、伦敦地质学会Wollaston和Major John Coke奖、英国皇家学会Wolfson Merit奖、欧洲地质协会Robert Wilhelm Bunsen奖、英国矿物学会Schlumberger奖以及丹麦哥本哈根大学荣誉博士学位等。Hawkesworth教授也曾任《Science》、《EPSL》和《Geology》等刊物编委和英国圣安德鲁斯大学副校长。

报告摘要：

Geological Cycles and the Evolution of the Continental Crust

The continental crust is the archive of Earth history, and the apparently cyclical nature of geological evolution is a feature of the geological record. The advent of radiometric ages has highlighted that the continental crust is characterised by distinctive peaks and troughs in the distribution of ages of igneous crystallization, metamorphism, continental margins and mineralization. It is argued that the temporal distribution largely reflects the different preservation potential of rocks generated in different tectonic settings, rather than fundamental pulses of activity, and the peaks of ages are linked to the timing of supercontinent assembly.

Less than 5% of the geological record consists of rocks older than 3 Ga, and there no known rocks older than 4 Ga. The sedimentary record is biased by preferential sampling of relatively young material in their source terrains. The implication is that there were greater volumes of continental crust in the Archaean than might be inferred from the compositions of detrital zircons and sediments. Recent studies based on the U-Pb, Hf and O isotope ratios of detrital zircons suggest that at least ~60-70% of the present volume of the continental crust had been generated by 3 Ga. The growth of continental crust was a continuous process, but there was a decrease in the rate of crustal growth at ~3 Ga. Before 3 Ga the rates of continental growth were high (~3.0 km3.yr-1), broadly similar to the rates at which new crust is generated and destroyed at the present time. Since 3 Ga the net growth rate was much lower (~0.8 km3.yr-1), perhaps because of higher rates of destruction of crustal materials. It is inferred that subduction-driven plate tectonics and discrete subduction zones have been dominant since ~3 Ga.

地质过程与矿产资源国家重点实验室

地球科学学院

2015-7-7