Sedimentary Geochemical Evolution from the Upper Proterozoic to the Triassic in the Southwest Yangtze Massif
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摘要: 本文通过对扬子地块西南部自上元古界板溪群到三叠系发育在盆地和下斜坡背景中的泥质岩的系统的无素地球化学研究，首次发现了下寒武统、上泥盆统和上二叠统这三个在元素地球化学性质上明显不同于其它层位的地球化学异常层，从而构成了本区地质历史中三个明显的地球化学旋回。通过地球化学旋回与本区地壳演化和一系列沉积事件之间关系的研究，发现它们之间存在着内在的必然联系，说明沉积地层的地球化学演化是地球发展演化的必然结果和物质表现形式。因此，可通过这些地层的元素地球化学体系来恢复地壳发育和演化历史，这为我们正确认识本区的地壳演化和成矿作用的时控性提供了强有力的地球化学证据.Abstract: Through the systematic study of trace elements and REE geochemistry of mudstones deposited inthe basin and lower slope environments from the Upper Proterozoic to the Triassic in the SouthwestYangtze Massif, three geochemical abnormal horizons, Lower Cambrian, Upper Devonian and Upper Per-mian, were discovered.Because of the alternate occurrence of three geochemical abnormal horizons, threegeochemical cycles in geological history were distinguished.The geochemical cycles are corresponding tothe geotectonic ones in this area.The geochemical abnormal horizons are corresponding to the pull-apartstages of geotectonic cycles and to a series of geological events, such as hydrothermal sedimentaryevents, anoxic events, extinct events of living things and so on.That so many events occur red in the geo-chemical abnormal horizons at the same time indicated these geochemical anomalies are the result ofearth evolution.They are the products originating in the particular stages of earth evolution.So thesegeochemical anomalies, conversely, are the effective geochemical tracer to understand the earth, especiallythe crustal evolution.
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Key words:
- sedimentary geochemical /
- evolution /
- sedimentary event /
- crustal evolution
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