Mafic rocks from Erinpura gneiss terrane in the Sirohi region: Possible ocean-floor remnants in the foreland of the Delhi Fold Belt, NW India

Abstract

A small isolated mafic body occurs to the south of Sirohi near village Daba within the Neoproterozoic Erinpura Granite in the southern sector of the Proterozoic Delhi Fold Belt in NW India. This mafic body occurs close to a 100 m wide NE-SW trending shear zone (Daba Shear Zone) which overprints the felsic rock fabrics. Further south, a small mafic body near village Kui was also sampled which forms the southern limit of the Phulad Ophiolite Suite which is a 300 km long major NE-SW trending lineament, described as Western Margin Fault. Some of the lithological components of the Daba mafic body show locally preserved magmatic fabric but completely transformed mineralogies under lower amphibolites facies metamorphic conditions where two-stage deformation has been inferred. Magnetic fabric analysis underlines a general correspondence of structural elements in both felsic and mafic lithologies. Binary correlations of Zr with other high field strength elements underline fractionation as the main process in the evolution of Daba and Kui rocks. Geochemical characteristics indicate subalkaline tholeiitic basalt affinity for these mafic rocks. The trace element characteristics, such as enriched LIL elements, high Th, absence of negative Nb anomalies and depletion in compatible elements in Daba samples suggest an enriched mantle source and lower degree of melting. The trace and rare earth element characteristics for Kui (Th anomaly, Nb-Ta trough and less spiked patterns, flat REE trends) indicate derivation from a refractory mantle source affected by fluids derived from subduction. Distinct differences in trace and REE characteristics between Daba and Kui can be interpreted in terms of different stages of ophiolite development.

Timing and genesis of Cu–(Au) mineralization in the Khetri Copper Belt, northwestern India: constraints from in situ U–Pb ages and Sm–Nd isotopes of monazite-(Ce)

“…1a). This event is recorded by evidence of metamorphism in the central and northern domains of the Aravalli-Delhi Fold Belt (e.g., Pant et al, 2008;Bhowmik et al, 2010;Hazarika et al, 2013;Ozha, 2016), and localized magmatism in the southern domain of this Fold Belt (e.g., Deb et al, 2001;Pandit et al, 2003Pandit et al, , 2011. Post-collisional intrusions, termed "Erinpura Granites", occur widely in the southern segment of the Aravalli-Delhi Fold Belt (Fig.…”

Discriminating Tectonic Setting of Igneous Rocks Using Biotite Major Element chemistry−A Machine Learning Approach

“…One group of workers relate the Neoproterozoic magmatism to subduction/Andean‐type active margin (Ashwal et al., 2013; De Wall et al., 2021). Some studies proposed emplacement of the Erinpura granite at late syn‐to post‐orogenic stage of the Delhi orogeny (Gupta et al., 1980; Pandit et al., 2011) as a result of subduction along the northern margin of the northwestern Indian craton and the South China block (De Wall et al., 2021). Many workers (e.g., Dhar et al., 1996; Eby & Kochhar, 1990; Kochhar, 1984; 2001; Kumar, Kumar, et al., 2021; Kumar, Sharma, et al., 2021; Kumar & Vallinayagam, 2014; Maheshwari et al., 2009; Sharma & Kumar, 2017) on the other hand, support the idea of hot spot‐driven magmatism in an extensional, anorogenic, continental intraplate setting for the formation of the subsequent late Neoproterozoic MIS.…”

In situ gamma radiation measurements in the Neoproterozoic rocks of Sirohi region, NW India

“…The Sirohi hills define a NE-SW trending about 20 km long, eyeshaped structure with a maximum width of 6 km. Deformation in the Sirohi region has been constrained at 770 Ma (Just et al 2011) overlapping with the timing of ∼770-750 Ma, Malani magmatism, the third largest felsic magmatic province in the world (Kochhar 1989;Bhushan 2000) spread over an area of >50,000 km 2 in NW India. The Malani Igneous Suite (MIS) comprises predominantly felsic plutonic and volcanic rocks and dykes.…”

“…Granitic rocks in this region can be broadly subdivided into two temporal settings, the 870-800 Ma Erinpura Granite and 770-750 Ma Malani Igneous Suite (MIS; Deb et al 2001;Gregory et al 2009;Just et al 2011). These rock suites show diverse petrogenetic and emplacement histories, clearly reflected in distinct differences in their chemical characteristics (Naik 1993;de Wall et al 2012de Wall et al , 2014.…”

“…The Sirohi region represents large scale faults and shear zones (Just et al 2011;Pandit et al 2011;de Wall et al 2012de Wall et al , 2014) that may have served as pathways for crustal fluids that are supposed to have caused enrichment or depletion of radiogenic elements. Locally elevated levels of uranium-related radioactivity were recently reported from Sindreth Group, by Somani et al (2012).…”