Radiolarian age constraints on Mesotethyan ocean evolution, and their implications for development of the Bangong Nujiang suture, Tibet
by Alan Baxter
Published in the Journal of the Geological Society, London, 2009
Radiolarian discoveries indicate that deep-marine conditions prevailed in central Tibet from the early Middle Jurassic... more
Radiolarian discoveries indicate that deep-marine conditions prevailed in central Tibet from the early Middle Jurassic until well into the Early Cretaceous (late Hauterivian – early Aptian; 131 – 121 Ma) and help to constrain the temporal extent of oceanic conditions along the Bangong – Nujiang suture. These new fossils occur in chert or siliceous mudstone blocks associated with the Lagkor Tso ophiolitic mélange. Basin inversion associated with closure of Mesotethys between the Qiangtang and Lhasa terranes was accompanied by mélange formation and predated regionally widespread deposition of overlying shallow-marine late Aptian – Albian orbitolinid limestones.
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Seen by:Upper Jurassic radiolarians from the Naga Ophiolite, Nagaland, northeast India
by Alan Baxter
Alan T. Baxter, Jonathan C. Aitchison, Sergey V. Zyabrev, Jason R. Ali
Radiolarians, extracted from cherts collected from an ophiolitic mélange near Salumi, Nagaland, NE India, have... more Radiolarians, extracted from cherts collected from an ophiolitic mélange near Salumi, Nagaland, NE India, have well-preserved tests and can be assigned to the Upper Jurassic (Kimmeridgian–lower Tithonian). These are the first well-preserved and clearly imaged radiolarians reported from the Naga Ophiolite. They are significantly older than fossils previously reported from this mélange, and their ages are similar to those determined radiometrically from associated igneous units.
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