Department of Geophysics, Stanford University, Stanford, CA 94305, USA.
Cold Spring Harb Perspect Biol. 2010 Jun;2(6):a002527. doi: 10.1101/cshperspect.a002527. Epub 2010 May 5.
A sparse geological record combined with physics and molecular phylogeny constrains the environmental conditions on the early Earth. The Earth began hot after the moon-forming impact and cooled to the point where liquid water was present in approximately 10 million years. Subsequently, a few asteroid impacts may have briefly heated surface environments, leaving only thermophile survivors in kilometer-deep rocks. A warm 500 K, 100 bar CO(2) greenhouse persisted until subducted oceanic crust sequestered CO(2) into the mantle. It is not known whether the Earth's surface lingered in a approximately 70 degrees C thermophile environment well into the Archaean or cooled to clement or freezing conditions in the Hadean. Recently discovered approximately 4.3 Ga rocks near Hudson Bay may have formed during the warm greenhouse. Alkalic rocks in India indicate carbonate subduction by 4.26 Ga. The presence of 3.8 Ga black shales in Greenland indicates that S-based photosynthesis had evolved in the oceans and likely Fe-based photosynthesis and efficient chemical weathering on land. Overall, mantle derived rocks, especially kimberlites and similar CO(2)-rich magmas, preserve evidence of subducted upper oceanic crust, ancient surface environments, and biosignatures of photosynthesis.
一个稀疏的地质记录，加上物理和分子系统发育学，限制了早期地球上的环境条件。月球形成的撞击使地球开始变得炽热，然后冷却，大约在 1000 万年内出现了液态水。随后，一些小行星撞击可能短暂地加热了地表环境，只留下在数公里深的岩石中生存的嗜热生物。一个温暖的 500K、100 巴 CO2 温室持续存在，直到俯冲的海洋地壳将 CO2 隔离到地幔中。目前尚不清楚地球表面是否在古生代时期长期处于约 70°C 的嗜热环境中，或者在冥古宙时期冷却到宜人或冰冻的条件。最近在哈德逊湾附近发现的大约 43 亿年前的岩石可能是在温暖的温室环境中形成的。印度的碱性岩石表明碳酸盐俯冲发生在 42.6 亿年前。格陵兰岛的 38 亿年前的黑色页岩的存在表明，S 基光合作用已经在海洋中进化，并且可能在陆地上发生了 Fe 基光合作用和有效的化学风化作用。总的来说，地幔来源的岩石，特别是金伯利岩和类似的富含 CO2 的岩浆，保存了俯冲的上层海洋地壳、古代地表环境和光合作用生物特征的证据。
