Palaeoproterozoic U–Pb SHRIMP zircon age from basement rocks in Bangladesh: A possible remnant of the Columbia supercontinent

Abstract

We present new U-Pb SHRIMP zircon geochronological data for basement rocks in Bangladesh, and discuss the relationship with the formation of the Columbia supercontinent. Euhedral zircons from a diorite sample yield a concordia age of 1730 AE 11 Ma, which is interpreted as the crystallization age. The Palaeoproterozoic age of the examined basement rock and the common occurrences of similar $1.7-Ga geologic units in the Central Indian Tectonic Zone and Meghalaya-Shillong Plateau in Indian Shield suggest their apparent continuation. This, together with the occurrence of similar $1.7-Ga geologic units in the Albany-Fraser belt in Australia and East Antarctica, are used to suggest that the basement rocks in Bangladesh formed towards the final stages of the assembly of the Columbia supercontinent. To cite this article: I.

∼1.6 Ga ultrahigh‐temperature granulite metamorphism in the Central Indian Tectonic Zone: insights from metamorphic reaction history, geothermobarometry and monazite chemical ages

“…A pervasive Early Mesoproterozoic thermal event in the CGC was previously inferred from whole rock Rb-Sr systematics (see Acharyya, 2003). Recent studies of SHRIMP U-Pb zircon dating of tonalite and diorite from adjoining Bangladesh, in the eastern continuation of the CGC reveal a major Palaeoproterozoic ($1.7 Ga) magmatic event (Ameen et al, 2007;Hossain et al, 2007). Contrary to earlier predictions, Archaean ages are yet to be documented in the CGC.…”

Geothermobarometry and fluid inclusions of dioritic rocks in Bangladesh: Implications for emplacement depth and exhumation rate

“…Recent geochronological investigations on basement rocks in the northwestern part of Bangladesh indicate that Palaeoproterozoic (1.72-1.73 Ga; Ameen et al, 2007;Hossain et al, 2007) tonalitic to dioritic rocks, regarded as a continuation of the Central Indian Tectonic Zone in the Columbia supercontinent configuration (Hossain et al, 2007), occur in the Maddhapara area at a shallow depth (128 m) from the surface. The overlying cover consists of successive units of the Permian Gondwana Group, Pliocene Dupi Tila Formation, Pleistocene Barind Clay Formation and recent alluvium (Fig.…”

Abstract Volume of Sixth Nepal Geolgical Congress on Geology, Natural Resources, Infrastructures, Climate Change and Natural Disasters, 15 – 17 November 2010, Kathmandu, Nepal

“…The Palaeoproterozoic (~1.73 Ga) basement rocks from Maddhapara, Bangladesh, a remnant of Columbia supercontinent (Hossain et al 2007), show a large range of chemical variations (e.g., SiO 2 = 50.7-74.7%), including diorite, quartz diorite, monzodiorite, quartz monzonite and granite. Amphibole and biotite, dominant ferromagnesian minerals, have been analysed with an electron microprobe for major elements.…”