Source provenance

Ahmad, S.A. & Chaudhary, M.N. (2007). Geochemical characterization and origin of the Karai gabbro from the Neoproterozoic Nagarparkar Complex, Pakistan. Geological Bulletin of the Punjab University, 42, 1-14.

Cited by 1 unit (1 published) · 0 field-level citations · 3 revision notes.

Full text reviewed (reviewer-supplied extract). Whole-rock major/trace/REE geochemistry of the Karai gabbro and associated dolerites of the Nagarparkar Complex (Pakistani part of the Kirana-Malani-Nagar basin). 'Within-plate' alkaline-to-subalkaline continental tholeiites (normative nepheline in alkaline gabbros), ring-shaped outcrops; discrimination diagrams (Ti-Zr-Y, Ti-V, Nb-Zr-Y) and chondrite-normalised REE (LREE-enriched, slight negative Nb anomaly) indicate non-subduction continental flood tholeiite. Neoproterozoic mantle-plume (hot-spot, ~1000-750 Ma) rifting during Rodinia break-up. Magmatic phases: Phase 1 Dhedvero gabbro/Karai dolerite -> Phase 2 grey/Churio granite + Wadlai adamellite -> Phase 3 Nagarparkar Granite -> Phase 4 basic/acid dykes; on Aravalli-Delhi basement, under Quaternary Bar Tala Formation.

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Units citing this source

• Precambrian Nagarparkar Igneous Complex Neoproterozoic
  • Lithology: Ahmad & Chaudhary (2007) characterised the Karai gabbro and associated dolerites as 'within-plate' alkaline-to-subalkaline continental tholeiites (normative nepheline in the more alkaline gabbros), forming ring-shaped outcrops. Discrimination diagrams (Ti-Zr-Y, Ti-V, Nb-Zr-Y) and chondrite-normalised REE (LREE-enriched with a slight negative Nb anomaly) confirm a non-subduction, continental flood-tholeiite character.
  • Geological significance: The magmatism is attributed to a Neoproterozoic mantle plume (hot-spot) active ~1000-750 Ma that drove continental rifting and Rodinia break-up along the western margin of the Trans-Aravalli belt, forming the bimodal Kirana-Malani-Nagar volcano-plutonic suite. The complex's phases run from Phase 1 Dhedvero gabbro/Karai dolerite through the Nagarparkar Granite (Phase 3) to late basic/acid dykes (Ahmad & Chaudhary 2007).
  • Coordinates: The complex crops out over ~450 sq km in the extreme SE Thar Desert near the Rann of Kutch (24°15'-24°30' N, 70°37'-71°07' E), resting unconformably on the Aravalli-Delhi basement and overlain by the Quaternary Bar Tala Formation (Ahmad & Chaudhary 2007).