Late Paleoproterozoic magmatism in Delhi Fold Belt, NW India and its implication: evidence from EPMA chemical ages of zircons

Record of Post-Collisional A-Type Magmatism in the Alwar Complex, Northern Aravalli Orogen, NW India

“…The lack of any intrusive relationship between granite and quartzite, but occurrence of conglomerate between them, indicates the basement nature of the granite. This interpretation supports the finding of Biju-Sekhar et al 14 who proposed that A-type granites in the Alwar complex formed basement for the Delhi sedimentation. Similarly, based on field observations and U-Pb detrital zircon age data from the Alwar quartzite, Kaur et al 35 advocated that the Khetri A-type granites formed the basement for sedimentation of the Delhi rocks.…”

“…Therefore, they provide significant information on the extensional magmatic processes that contribute to the chemical evolution of upper continental crust 10,12 . In the northern Aravalli orogen, a number of A-type intrusions occur in two igneous-metamorphic complexes, designated as the Alwar complex [13][14][15] and the Khetri complex [16][17][18][19][20] , also known as the Alwar basin or the Khetri basin. These rocks are late Palaeoproterozoic spanning an age range of 1.72-1.70 Ga (refs 14, 18, 19, 21).…”

“…The type of fold geometry and style, and the metamorphic history of the Alwar complex are apparently identical to that of the Khetri complex [27][28][29][30][31][32] . The igneous rocks, occurring in the area, are represented by mafic sills and dykes, granitoids and pegmatites 14,33 . The granitoid rocks of Dadikar and Harsora plutons are located in the NW of Alwar town (Figure 1).…”

“…The granitoid rocks of Dadikar and Harsora plutons are located in the NW of Alwar town (Figure 1). Biju-Sekhar et al 14 classified these granitoids as A-type granites and also reported their ages by zircon EPMA method at 1780-1726 Ma.…”

“…1.85 Ga, the timing of which is correlatable with the assembly of Columbia supercontinent [46][47][48][49][50] . The next phase of magmatic activity recorded in the Aravalli orogen is the 1.72-1.70 Ga Atype magmatism 14,18,19 . The relaxation phase following collision is often referred to as post-collisional period characterized by voluminous magmatism, whereas the within-plate settings are characterized by sparse but widespread magmatism 51 .…”