| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4722954 | Precambrian Research | 2014 | 18 Pages |
•Tectonic restoration of Archean Western Dharwar Craton (WDC), west coast, India.•Craton-limiting mid-crustal Paleoproterozoic transpressional orogens delineated.•2.3–2.5 Ga WDC-Coorg Block accretion extends as <2.5 Ga Betsimisaraka suture.•Northern Craton-limiting orogen extends into Madagascar as buried tectonic zone.•No evidence of Mesoproterozoic and younger accretion/tectonism within WDC.
New structural–mineralogical data and U–Th-total Pb monazite chemical ages in 27 samples in a 430 km long corridor along the west coast of India are combined with existing data to reconstruct the tectonic set up of the Meso/Neoarchean crystalline rocks in the Western Dharwar Craton (WDC). The data helps to delineate two NW-trending Paleoproterozoic ductile shear zones that limit the southern and the northern margins of the WDC. The southern shear zone (metamorphic age: 2.3–2.4 Ga) separates the greenschist facies supracrustal belts (2.5 and 3.3 Ga), foliated granitoids (2.5 and 2.9 Ga) and amphibolite facies anatectic gneisses (>3.0 Ga) of the WDC from the >2.9 Ga granulite facies ortho/para-gneisses of the Coorg Block. This shear zone is correlated with the ∼2.4 Ga Betsimisaraka suture zone in east-central Madagascar that demarcates the accretion zone between the Antongil Block (≈WDC) and the granulite facies lithologies of the Antananarivo domain (≈Coorg Block). The northern shear zone system (metamorphic age: 2.2–1.8 Ga) extending NW into Madagascar possibly exists as a hitherto undiscovered tectonic zone forming the basement of the Mesoproterozoic Sahantaha Formation underlying the Neoproterozoic Bemarivo Belt supracrustals in NE Madagascar.Within the WDC, the Meso/Neoproterozoic ages retrieved from poorly-defined margins in monazite are uncommon, dispersed within the craton, and do not define localized zones within the craton. The chemical ages of metamorphic monazites formed at greenschist/amphibolite facies conditions preclude metamorphism–deformation associated with accretion of crustal blocks within the WDC during the Rodinia assembly.
