关键词: 志留系&mdash, 三叠系沉积地层l层序地层l微量元素地球化学l沉积环境l安徽铜陵

Abstract:

The Silurian to Triassic strata of clastic sedimentary rocks and carbonates are widely distributed in the Tongling area, Anhui Province, East China, and closely associated with stratabound skarn deposits. This paper presents sequence stratigraphy and trace element geochemistry of the strata, and provides some constraints on their sedimentary environment. Sequence stratigraphical investigation shows occurrence of three events of sea level varying responsible for the formation of three sedimentary successions of regression through transgression to regression during the Paleozoic to Mesozoic period. These sedimentary successions include: (1) Early Silurian to Late Devonian regressive sequence, (2) Late Devonian to Early Permian transgressive sequence, and (3) Late Permian to Early Triassic regressive sequence. Trace element geochemistry analyses indicates existence of three evident variations in physicochemical conditions (especially oxidation-reduction conduction) of the sea bottom water during the Paleozoic to Mesozoic sedimentary period in the Tongling area. These variations are corresponded to the three events of sea level varying. It is significant that most of stratabound skarn deposits occur in the strata formed during the last two events of sea level varying.