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Titolo:
Supra-subduction origin of the Nidar ophiolitic sequence, Indus Suture Zone, Ladakh, India: Evidence from mineral chemistry of upper mantle rocks
Autore:
Sachan, HK;
Indirizzi:
Wadia Inst Himalayan Geol, Dehra Dun 248001, Uttar Pradesh, India Wadia Inst Himalayan Geol Dehra Dun Uttar Pradesh India 248001 esh, India
Titolo Testata:
OFIOLITI
fascicolo: 1, volume: 26, anno: 2001,
pagine: 23 - 32
SICI:
0391-2612(200106)26:1<23:SOOTNO>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
TROODOS OPHIOLITE; ULTRAMAFIC ROCKS; PETROGENESIS; PERIDOTITE; GEOCHEMISTRY; CYPRUS; DISSOLUTION; CHROMITITES; EVOLUTION; PETROLOGY;
Keywords:
mineral chemistry; SSZ Ophiolite; Nidar Ophiolite; Ladakh; India;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Sachan, HK Wadia Inst Himalayan Geol, Dehra Dun 248001, Uttar Pradesh, India Wadia Inst Himalayan Geol Dehra Dun Uttar Pradesh India 248001
Citazione:
H.K. Sachan, "Supra-subduction origin of the Nidar ophiolitic sequence, Indus Suture Zone, Ladakh, India: Evidence from mineral chemistry of upper mantle rocks", OFIOLITI, 26(1), 2001, pp. 23-32

Abstract

The ultramafic rocks of Nidar ophiolitic sequence in the eastern part of the Ladakh (NW Himalaya) have been studied combining petrography and mineralchemistry data. The ultramafic rocks mainly consist oi spinel-harzburgite and spinel-dunite, that are intruded by spinel-bearing pyroxenites. The modal and chemical composition of minerals in hazburgite indicates a strongly-depleted nature consistent with a residual origin after the extraction of basaltic melt by single or multiple partial melting events. In contrast, dunite was probably formed as a consequence of interaction between harzburgiteand migrating melt(s), after the partial melting events. This is well corroborated by the petrographical and chemical evidence, e.g., the growth of secondary mineral aggregates and the large chromite component in the spinels. The mineral chemistry suggests that the melts percolating and interacting with harzburgite were rich in MgO and NiO and deficient in CaO, Al2O3, and TiO2. In particular, the low Ti content shown by clinopyroxenes and spinalswhich are cumulus phases in pyroxenites and secondary neoblastic phases inperidotites), in association with high Cr# (> 60) exhibited by ail the spinels, are consistent with parent melt of boninitic affinity. These melts are typical of island are environment. Therefore, this infers that the ultramafic units of Nidar ophiolite underwent melt percolation in a supra-subduction tectonic environment related to Fore-are setting.

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Documento generato il 11/07/20 alle ore 19:46:08