15:45 〜 16:00
[SMP24-08] Insights into failed rift processes in the Archean, evidence from the Western Dharwar Craton, southern India.
キーワード：Archean, Failed rift, Basin tectonics
Field and structural geological information from different schist belts within Western Dharwar Craton (WDC), Dharwar Craton (DC), southern India are collected. Volcanic and sedimentary rocks of the WDC show characteristics evolved in a shallow-marine, narrow basin identical to a failed rift zone developed by the fracturing of basement rocks. 'Rift debris' type poorly sorted conglomerates are preserved in the boundary between Basement Gneiss and schist belts. Folded sequences of volcanic, volcanoclastic, and sedimentary rocks squeezed in between thrust/reverse faults summarizes the major structural association in the study area. This association is identical to a neotectonic inverted failed rift structure. Regional-scale strike-slip faults are also identified from the study area which is either associated with sinistral transpression or independent tectonic activity.
Geochemical signatures preserved in volcanic and volcaniclastic rocks also point to an intracratonic mafic to intermediate volcanism. The variation in the geochemical pattern can be attributed to the degree of crustal contamination during volcanism.
Field relations, structural association, and geochemical characteristics of WDC are pointing to the presence of well-preserved aborted rifts in the Archean DC. Post-3.0 Ga crustal growth throughout the Western Dharwar Craton is therefore initiated by similar failed rifting events. Multiple events of failed rifting and later basin inversion events associated with regional-scale shortening resulted in the current fold-and-thrust belt architecture of WDC. This shortening probably connected to the collision between Western Dharwar Craton and Eastern Dharwar Craton.
Geochemical signatures preserved in volcanic and volcaniclastic rocks also point to an intracratonic mafic to intermediate volcanism. The variation in the geochemical pattern can be attributed to the degree of crustal contamination during volcanism.
Field relations, structural association, and geochemical characteristics of WDC are pointing to the presence of well-preserved aborted rifts in the Archean DC. Post-3.0 Ga crustal growth throughout the Western Dharwar Craton is therefore initiated by similar failed rifting events. Multiple events of failed rifting and later basin inversion events associated with regional-scale shortening resulted in the current fold-and-thrust belt architecture of WDC. This shortening probably connected to the collision between Western Dharwar Craton and Eastern Dharwar Craton.