Emergence of continents above sea‐level influences sediment melt composition
Emergence of continents above sea‐level influences sediment melt composition
复制标题
大陆出现在海平面以上影响沉积物熔体组成
DOI：
10.1111/ter.12531
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发表时间：
2021-04
期刊：
影响因子：
2.4
通讯作者：
J. Liebmann;C. J. Spencer;C. Kirkland;C. Bucholz;X. He;M. Santosh;X. Xia;Martín L.;N. Evans
中科院分区：
文献类型：
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作者：
J. Liebmann;C. J. Spencer;C. Kirkland;C. Bucholz;X. He;M. Santosh;X. Xia;Martín L.;N. Evans
太古宙-元古代的过渡预示着地球上许多基本的变化，包括大气的氧化作用，海平面以上大陆的显著出现，以及长英岩浆δ18O的增加。后者的潜在驱动因素是表壳物质组成的变化或地壳改造的增加。虽然俯冲引起的大陆碰撞的开始和相关的地壳再循环增强可能产生高δ18O的长英质岩浆，但时间限制的锆石δ18O显示，δ18O的增加在~2.35 Ga，早于最古老的公认的超大陆。本文利用华北克拉通太古宙和元古代沉积花岗岩中岩浆锆石晶体的O和Hf同位素比值，追踪了地壳上物质进入岩浆的过程。结果与古元古代陆相干舷沉积储层的增加相一致，δ18O相对较高，随后部分熔融形成花岗岩类。
The Archean‐Proterozoic transition heralded a number of fundamental changes on Earth, including the oxygenation of the atmosphere, a marked emergence of continents above sea‐level, and an increase in δ18O of felsic magmas. The potential drivers for the latter are changes in the composition of supracrustal material or increased crustal reworking. Although the onset of subduction‐induced continental collision and associated enhanced crustal recycling could produce high‐δ18O felsic magmas, temporally constrained zircon δ18O reveals an increase in δ18O at ~2.35 Ga that predates the oldest widely recognized supercontinent. In this work, we use the O and Hf isotope ratios of magmatic zircon crystals in Archean and Proterozoic sediment‐derived granitoids of the North China Craton to track the incorporation of supracrustal material into magmas. The results are consistent with a Paleoproterozoic increase of continental freeboard producing sedimentary reservoirs with comparatively elevated δ18O that subsequently partially melted to generate the granitoids.