Weathering, the carbon cycle, and the differentiation of the continental crust and mantle
Weathering, the carbon cycle, and the differentiation of the continental crust and mantle
复制标题
风化、碳循环以及大陆地壳和地幔的分异
DOI：
10.1029/jb093ib08p08952
复制
发表时间：
1988
影响因子：
--
通讯作者：
A. F. K. Groos
中科院分区：
文献类型：
--
作者：
A. F. K. Groos
在地球历史上，风化作用产生了大约2-4 × 1025克的碳酸盐、粘土矿物和SiO2（燧石和石英）。这大约相当于地幔质量的1%。第三个是在Hadean期间产生的，在3900 Ma之前。碳的消耗量大大超过地壳碳库，相当于上地幔碳的总量。它的结论是，大部分的物质产生的俯冲，只有一小部分保存在沉积岩。俯冲沉积物的化学成分因气候和沉积环境的变化而高度多样化。这导致了不同尺度上的地幔不均一性。冥古宙沉积岩的缺失可以通过假设这一时期产生的所有沉积物质在与大量来自强烈陨石流的玄武质和科马提质撞击碎片混合后被俯冲来解释。在Hadean-Archean边界，陨石流量减少到0.2-0.4 km 3/yr，这导致撞击碎片数量大幅减少，沉积物开始在地球表面积累。与此同时，大量的长英质侵入岩，来自富含二氧化硅的俯冲物质，产生了大陆地壳开始迅速增长。该模型表明，最古老的沉积岩含有相当大比例的撞击衍生材料，对这些岩石的仔细调查可能会为该模型提供支持。
Weathering produced a total of 2–4 × 1025 g of carbonates, clay minerals and SiO2 (chert and quartz) in approximately equal proportions during the history of the Earth. This amounts to approximately 1% of the mass of the mantle. A third was produced during the Hadean, before 3900 Ma. The amount of carbon consumed is greatly in excess of the crustal carbon reservoir and is equivalent to the total amount of carbon in the upper mantle. It is concluded that most of the material produced was subducted and that only a small fraction is preserved in sedimentary rocks. The chemistry of the subducted sediments was highly diverse in response to the variability of the climatological and depositional environment. This resulted in significant mantle heterogeneities on different scales. The absence of Hadean sedimentary rocks is explained by postulating that all the sedimentary material produced in this period was subducted after being mixed with a large amount of basaltic and komatiitic impact debris derived from the intense meteorite flux. The meteorite flux diminished to 0.2–0.4 km3/yr at the Hadean-Archean boundary, which resulted in a large reduction of the amount of impact debris, and sediments began to accumulate at the earth's surface. At the same time copious amounts of felsic intrusive rocks, derived from silica-enriched subducted material, were produced and a continental crust began to grow rapidly. The model indicates that the oldest sedimentary rocks contain a substantial proportion of impact-derived material and that careful investigation of these rocks may provide support for the model.