地球的起源与演化研究进展

地球科学在研究远古地球的形成与演化方面积累了越来越多的证据 ,人类对于太空的观测程度也不断提高 ,加深了对类地行星的认识 ,取得了重要的成果。太阳系中的火星和金星可能存在已经绝灭了的生命。慧星和小行星对地球的多次撞击有能力导致严重的环境效应及生命大灭绝。行星的演化可能有两种模式 :冷的星团加热及热的星云冷却。火星上存在与地球壳体非常相似的沉积岩 ,说明有流动水存在的可能。较高地热的太古代地壳热流输出被认为是认识地壳构造特性的关键。晚太古代会聚与离散大陆边缘的对比研究表明太古代板块运动与年轻的板块构造旋回在样式及幕次方面都没有根本的区别。元古代大陆的增生是由于元古代源于地幔的板块构造及产生于地幔的热柱构造导致新生成分的加入而造成的。裂谷、盆地、推覆及伸展、火山侵入作用是显生宙大陆增生的主要因素。

ADVANCES IN EARTH ORIGIN AND EVOLUTION

More and more geological evidences have been accumulated in the study of earth formation and evolution. Mankind improves the observation level to the outer space, and deepens the recognition to terrestrial planet, and gains important achievements. Mars and Venus in solar system are candidates for possible extinct life. Geologic data on mass extinctions of life and evidence of large impacts on the Earth are thus far consistent with a quasi-periodic modulation of the flux of Oort cloud comets. There are two end-member models for the evolution of planets: cool clusters warming and hot nebulae cooling. There exist sedimentary rocks similar to earth crust on the Mars. These results are consistent with the hypothesis that a large standing body of water may have occupied the northern lowlands in the past history of Mars. The higher heat output of crust during the Archean is key to understand tectonic features. Comparison of coeval divergent and convergent continental margins indicates that Archaean and younger tectonic cycles do not differ significantly in either style or duration. Throughout the Proterozoic mantle-driven plate tectonics and mantle-generated plume tectonics led to major juvenile additions and volumetric growth of continents. Subduction-generated arcs and plume-generated oceanic plateaus are the principal mechanisms. The growth of the continental crust in the Phanerozoic was commonly thought to be related to rifting, depression, thrusting, extension and magmatism.