Isotope stratigraphy of the Neoproterozoic Togari Group, Tasmania
Isotope stratigraphy of the Neoproterozoic Togari Group, Tasmania
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DOI：
10.1080/08120099808728441
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发表时间：
1998-12-01
影响因子：
1.2
通讯作者：
Calver, CR
中科院分区：
文献类型：
--
作者：
Calver, CR
A carbon and strontium isotope study of the Togari Group, northwest Tasmania, provides significant new age constraints based on chemostratigraphic correlation with key Neoproterozoic sections on other continents. The Black River Dolomite is late Riphean (middle Cryogenian: ca 750-650 Ma) on delta(13)C, Sr-87/Sr-86 and stromatollte-biostratigraphic evidence. In the upper part of the Black River Dolomite, a diamictite unit (the Julius River Member) is associated with a negative delta(13)C excursion and may correlate with the Sturtian glaciation. The succeeding rift volcanics and clastics of the Kanunnah Subgroup, and the probably correlative Crimson Creek Formation of western Tasmania, are inferred to be late Cryogenian to early Neoproterozoic III in age (ca 650-580 Ma). The Smithton Dolomite is middle to late Neoproterozoic III (i.e. Ediacarian/Vendian: ca 580-545 Ma) on delta(13)C and Sr-87/Sr-86 evidence. The rise in Sr-87/Sr-86 through the Smithton Dolomite (0.7079-0.7085) is consistent with previous work showing a monotonic rise in the ratio through the Vendian, Dolostones in the Block River Dolomite and lower Smithton Dolomite are syndepositional or early diagenetic and little altered in delta(13)C. In contrast, crystalline. isotopically altered massive dolostones comprise most of the upper two-thirds of the Smithton Dolomite, but minor interbedded limestones retain little-altered delta(13)C and Sr-87/Sr-86.
