Geochemistry of platinum-group elements and mineral composition in chromitites and associated rocks from the Abdasht ultramafic complex,Kerman, Southeastern Iran |
| |
| Institution: | 1. Department of Geology, Payame Noor University, PO Box 19395-3697, Tehran, Iran;2. Department of Geology, Faculty of Science, Shahid Bahonar University, Kerman, Iran;1. Institute of Geophysics, China Earthquake Administration, 100081, Beijing, China;2. Centre for Tectonics, Resources and Exploration, Department of Earth Sciences, School of Physical Sciences, University of Adelaide, SA 5005, Australia;3. School of Earth Sciences and Resources, China University of Geosciences, 100083 Beijing, China;1. Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Campus do Vale, Porto Alegre, RS 91501-970, Brazil;2. Instituto de Geociências, Universidade de Brasília, Campus Universitário Darcy Ribeiro, Brasília, DF 70904-970, Brazil;3. Centro de Pesquisas Geocronológicas, Universidade de São Paulo, Rua Lago 562, Cidade Universitária, São Paulo, SP 05508-080, Brazil;4. Companhia de Pesquisas e Recursos Minerais, SGAN 603, Brasília, DF 70830-902, Brazil;1. Department of Geography and Geology, University of Turku, FIN-20014, Finland;2. Ödemarksvägen 107, FIN-49220 Broby, Finland;3. School of Chemical Engineering, University of Adelaide, Adelaide SA 5005, Australia;1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;2. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;1. State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Science and Resources, China University of Geosciences, Beijing 100083, China;2. Gold Geological Institute of CAPF, Langfang 065000, China;3. James Cook University, Townsville 4811, Queensland, Australia;1. Department of Mining Engineering, University of Tehran, Iran;2. Faculty of Health, Engineering and Science, Edith Cowan University, Perth, Australia;3. Department of Mining Engineering, University of Chile, Santiago, Chile;4. Advanced Mining Technology Center, University of Chile, Santiago, Chile |
| |
| Abstract: | The Abdasht complex is a major ultramafic complex in south-east Iran (Esfandagheh area). It is composed mainly of dunite, harzburgite, podiform chromitites, and subordinate lherzolite and wehrlite. The podiform chromitites display massive, disseminated, banded and nodular textures. Chromian spinels in massive chromitites exhibit a uniform and restricted composition and are characterized by Cr# = Cr / (Cr + Al)] ranging from 0.76 to 0.77, Mg# = Mg/(Mg + Fe2 +)] from 0.63 to 0.65 and TiO2 < 0.2 wt.%. These values may reflect crystallization of the chromian spinels from boninitic magmas. Chromian spinels in peridotites exhibit a wide range of Cr# from 0.48 to 0.86, Mg# from 0.26 to 0.56 and very low TiO2 contents (averaging 0.07 wt.%). The Fe3 +# is very low, (< 0.08 wt.%) in the chromian spinel of chromitites and peridotites of the Abdasht complex which reflects crystallization under low oxygen fugacities.The distribution of platinum group elements (PGE) in Abdasht chromitites displays a high (Os + Ir + Ru)/(Rh + Pt + Pd) ratio with strongly fractionated chondrite-normalized PGE patterns typical of ophiolitic chromitites. Moreover, the Pd/Ir value, which is an indicator of PGE fractionation, is very low (< 0.1) in the chromitites.The harzburgite, dunite and lherzolite samples are highly depleted in PGE contents relative to chondrites. The PdN/IrN ratios in dunites are unfractionated, averaging 0.72, whereas the harzburgites and lherzolites show slightly positive slopes PGE spidergrams, together with a small positive Ru anomaly, and their PdN/IrN ratio averages 2.4 and 2.3 respectively. Moreover, the PGE chondrite and primitive mantle normalized patterns of harzburgite, dunite and lherzolite are relatively flat which are comparable to the highly depleted mantle peridotites.The mineral chemistry data and PGE geochemistry indicate that the Abdasht chromitites and peridotites were generated from a melt with boninitic affinity under low oxygen fugacity in a supra-subduction zone setting. The composition of calculated parental melts of the Abdasht chromitites is consistent with the differentiation of arc-related magmas. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
