Geochemistry of mid-ocean ridge mafic intrusives from the Manipur Ophiolitic Complex,Indo-Myanmar Orogenic Belt,NE India |
| |
Authors: | A. Krishnakanta Singh N. Ibotombi Singh L. Debala Devi R. K. Bikramaditya Singh |
| |
Affiliation: | 1.Wadia Institute of Himalayan Geology,Dehradun,India;2.Department of Geology,D.M. College of Science,Imphal,India |
| |
Abstract: | Mafic intrusives emplaced within the mélange zone of the Manipur Ophiolitic Complex are subalkalinetholeiitic affinity with Fe-enrichment. Based on the field occurrences, textures-mineralogy and whole-rock compositions, these mafic intrusives can be identified as type-I (gabbro intrusives) and type-II (basalt-dolerite dykes). The type-I resembling enriched-type mid-ocean ridge basalt (E-MORB) shows moderate LREE enrichment (LaN/SmN = 2.5–2.6), slightly enriched MORB normalized HFSE patterns possibly represent melts derived from enriched MORB sub-oceanic mantle sources by small degree of partial melting. The other type-II has normal-type mid-ocean ridge basalt (N-MORB) geochemical features, as it exhibits nearly flat to depleted LREE (LaN/SmN = 1.0–0.6), flat MORB normalized HFSE patterns with slight LREE/HREE depletion (CeN/YbN = 1.37–0.46). It might have been derived from depleted MORB type sub-oceanic mantle source. The MORB signature displayed by these mafic intrusives indicates that they are dismembered fragments of oceanic crust generated at mid-ocean spreading ridge system and support the hypothesis that the Manipur ophiolites was initially formed in the divergent plate margin. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|