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This study delves into the ocean plate stratigraphy, examining basalt, chert, hemipelagic mudstone, and other key elements. It traces travel history from ridge to trench, showcasing meta-equivalents like amphibolite and quartzite. The research uncovers the fundamental structure of accretionary wedges and orogens, from Cenozoic to Archaean times. With examples from Japan, Indonesia, Alaska, and more, it reveals the geological evolution across different regions. Through geochemical data and detailed mapping, this work sheds light on ridge-trench transitions and repetitive thrusting processes. Despite challenges in recognizing modern analogues and pre-Mesozoic orogens, this research contributes valuable insights into Earth's complex geological past.
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Ocean Plate Stratigraphy: Conclusions • Basalt, chert, hemipelagic mudstone, clastic sst, turbidite, conglomerate • Records travel history from ridge to trench • Meta-equivalents: Amphibolite, quartzite, schist, Bi-Musc schist • Can record oceanic islands in mid-ocean • The fundamental structure of an accretionary wedge/orogen • Cenozoic to Archaean. Zeolite to granulite grade, • Can be repeated hundreds of times by thrusting (330 times in Alaska; > 150 times in Anglesey) • Geochemical data confirm ridge-trench transition • Poor understanding worldwide of classic modern analogues in Japan and Alaska. Still poorly recognized in pre-Mesozoic orogens.
Ocean Plate Stratigraphy: Examples Japan, Indonesia. SE Asia. Mesozoic-Cenozoic Alaska. Palaeogene. Chugach Peninsula. New Zealand. Mesozoic Lachlan; New England belt, Terra Australia orogen, Australia. Paleozoic Laohushan, Qilianshan, China. Palaeozoic Anglesey, Wales. Neoproterozoic Gairloch, NW Scotland. High-amphibolite facies. Palaeoproterozoic Pilbara. Australia. Early Archaean Isua. Greenland, Early Archaean
Anglesey, N. Wales, UK Neoproterozoic. The Mona Complex Classic accretionary orogen/complex with 580 Ma blueschists Type localiity for “mélange” coined by Edward Greenly in 1919. 150 repetitions of OPS recognized so far by Maruyama and his group
Geological map of the study area A-sec. F-sec. E-sec. B-sec. D-sec. C-sec. (after Kato and Nakamura, 2003)