Original paper
Petrogenesis and tectonic environments for formation of peridotites and associated podiform chromite ore, southern part of Manipur Ophiolite Belt, Indo-Myanmar Orogenic Belt, NE India
Premi, Kshetrimayum; Sen, Amit Kumar; Singh, A. Krishnakanta; Lakhan, Nongmaithem
Neues Jahrbuch für Mineralogie - Abhandlungen Band 197 Heft 3 (2022), p. 209 - 232
66 references
published: Jan 25, 2022
published online: Oct 7, 2021
manuscript accepted: Aug 26, 2021
final revised version received: Aug 22, 2021
manuscript revision requested: Aug 20, 2021
manuscript received: Sep 23, 2020
ArtNo. ESP154019703000, Price: 29.00 €
Abstract
This article describes a new comprehensive study of mantle peridotites and associated podiform chromite ore from the southernmost part of Manipur Ophiolite Belt (MOB), northeast India. The ophiolitic suite of rocks exposed in the study area are comprised of well-preserved peridotite, chromite ore bodies with minor mafic (gabbro, basalt, mafic dyke) and felsic (plagiogranite) rocks, and oceanic pelagic sediments. The mantle peridotite consists chiefly of lherzolite with a lesser amount of harzburgite, whereas the chromite ore bodies (pods, lenses, veins) of variable sizes are hosted within the peridotites. The composition of chrome spinel in the peridotite is characterized by high Al2O3 (> 45 wt.%), Mg# (< 80) and low in Cr# (< 24). The chrome-spinel and olivine (Fo < 91) compositions and the characteristics of REE-distribution pattern resemble with the abyssal peridotites that preferentially generated in the mid-oceanic ridge tectonic setting by low degree of partial melting (< 12 %) of the mantle. Conversely, the chromite mineral in the ore is low in Al2O3 (11.15–21.13 wt.%), high in Cr# (61.94–77.86) with Mg# content in massive (60.23–71.47) and altered (13.15–54.02) chromite ores. These characteristics indicate their derivation from a boninitic melt by a higher degree of partial melting (> 20 %) at the supra-subduction zone tectonic environment. The results in the present study support that the magmatism in the mid-oceanic environment followed by subduction-related tectonic activity was responsible for the evolution of MOB. Later, the entire ophiolite sequence was obducted and emplaced along the eastern plate margin of the Indian subcontinent and the Indo-Myanmar Orogenic Belt during collisional orogeny.
Keywords
Mineral chemistry • geochemistry • peridotite • Cr-spinel • chromite ore • ophiolite • NE India