Rb-Sr age of Godhra and related granites, Gujarat, India

Abstract

Rubidium and strontium determinations are reported for Godhra and geographically related granites from central Gujarat. The whole rock data define a Rb-Sr isochron corresponding to a common age of 955 • 20 m.y. and initial Sr ratio of 0.7130• This age is distinctly older than the age of 735 m.y. reported for the Erinpura suite of rocks from Mount Abu in western Rajasthan and from Idar in northern Gujarat: There are at least two generations of post-Delhi intrusive rocks in the Gujarat precambrian. Biotites associated with these granites have the same age as the whole-rocks within experimental error indicating the absence of significant metamorphic heating since the time of emplacement. It is significant that rocks of similar age occur in the Rajasthan Precambrian mainly in the axial zone of the Aravalli Mountains.

The Mount Pavagadh volcanic suite, Deccan Traps: Geochemical stratigraphy and magmatic evolution

“…7b) the crustal end member is a western Indian granite with Sr = 145 ppm and 87 Sr/ 86 Sr = 0.7690 (Gopalan et al, 1979). This granite outcrops at Godhra (Fig.…”

The Chogat-Chamardi subvolcanic complex, Saurashtra, northwestern Deccan Traps: Geology, petrochemistry, and petrogenetic evolution

“…In comparison, the Chogat Gopalan et al, 1979). Contaminant in AFC model 2: Central Deccan granite mylonite xenolith (Sr = 170 ppm, 87 Sr/ 86 Sr = 0.78050, Ray et al, 2008).…”

“…In our first AFC model, the crustal end member was a western Indian granite (Gopalan et al, 1979), and in a second AFC model the crustal contaminant was a central Deccan granite mylonite xenolith from the Dhule area (Fig. 1a) (Ray et al, 2008).…”

Petrogenesis of lamprophyres from Chhota Udepur area, Narmada rift zone, and its relation to Deccan magmatism

“…However, no isotopic age data are available for these gneisses except for a metamorphic age (one of the strongest deformational event) of 1168 ± 30 Ma (Srimal and Das, 1997). These gneisses are overlain by the calc-silicate rocks of Champaner Group (Mesoproterozoic) which are intruded by Godhra granite of 955 ± 20 Ma (Gopalan et al, 1979). The Deccan basalts and associated alkaline rocks and sandstones (Bagh beds) of Late Cretaceous age rest on the Champaner and Pre-Champaner rocks.…”