摘要
作者在胡乐寒武—奥陶系界线剖面上作了多种地球化学测试。依据测试结果，分析了地球化学特征。碳、氧同位素、微量元素和稀土元素组成的变化主要位于西阳山组与谭家桥组之间，它可能与海平面变化有关。在寒武－奥陶系界线上仅见有小的碳同位素负偏移。
The Cambrian-Ordovician booundary section in Hule is one of the well-established section of this stratigraphic sequence. Fossils from bed 5 to bed 12 are dominated by the grapto-lites. Two graptolite zones were recognized. They are the Staurograptus zone in the lower and the An;fsograptus-Clonograptrs zone in t he uppe r. No fossi graptolites have been found from bed l to bed 4 except of trilobite Charchaqia ? sp. Accordingly, the Cambrian-Ordovician boundary is placed on the base of Bed 5. However, only minor negative excursion of 813C displays across the Cambrian-Ordovician boundary though the trilobites dominated shelly fauna was replaced by the graptolites dominated pelagic fauna around this level. Dramatic changes in value of δ13C, δ18 O and REE appear across the boundary between two lithostratigraphic units, i. e. the Tangjiaqiao and the Xiyangshan Formations. These conspicuous geochemical changes are likely coincident with shifting from anoxic to oxide environments following rapid falling of sea-level.
出处
《高校地质学报》
CAS
CSCD
1995年第2期107-113,共7页
Geological Journal of China Universities
基金
国家自然科学基金
关键词
地球化学特征
安徽
寒武系
地层界线
奥陶系
Cambrian-Ordovician boundary, geochemical variation, δ￣(13)C value
