Mesoarchean gabbro-anorthosite complex from Singhbhum Craton, India

The Mayurbhanj composite granite pluton (MBG) surrounding the Simlipal volcano-sedimentary complex of Singhbhum Craton is associated with various phase of granites. The gabbros and noritic gabbro suite from Kuliana, Besoi, Jashipura and Sarat is composed of plagioclase, clinopyroxene and orthopyroxene as essential minerals with subordinate olivine, quartz and opaque minerals. The pressure and temperature conditions of Kuliana and Sarat suites indicated a range of 6.95–9.05 kbar and 1190-1203 °C and 8.56–9.92 kbar and 1155- 1216 °C respectively. The clinopyroxenes from the Jashipura reveals a pressure of 9.32–12.49 kbar and 1061-1183 °C temperature. Zircon U\Pb age data of gabbros from Jashipura yeld upper intercept ages in the range of 3099 Ma to 3047 Ma age, and the 3047 Ma is considered as the emplacement age.

 

The MgO, Ni and Cr, lower Al2O3, higher Fe2O3 and the REE patterns of these rocks reflect evolved nature of the magma which explains variable extent of partial melting and magmatic differentiation in the magma chamber. These rocks underwent crustal contamination displaying continental arc affinity. Based on the geochro- nological, geochemical and mineral chemical studies, it is proposed that these gabbros and noritic gabbro suite evolved synchronously with the Mayurbhanj granitic complex and played a significant role in the Mesoarchean crustal growth of the Singhbhum Craton.

 

Citation

C. Manikyamba, Arijit Pahari, M. Santosh, Jyotisankar Ray, C.S. Sindhuja, K.S.V. Subramanyam, Mutum Rajanikanta Singh (2020) Lithos, Volumes 366–367, 105541, ISSN 0024-4937, https://doi.org/10.1016/j.lithos.2020.105541.