Carbon and nitrogen isotope, and mineral inclusion studies on the diamonds from the Pozanti–Karsanti chromitite, Turkey
- 22 Downloads
The Pozanti–Karsanti ophiolite (PKO) is one of the largest oceanic remnants in the Tauride belt, Turkey. Micro-diamonds were recovered from the podiform chromitites, and these diamonds were investigated based on morphology, color, cathodoluminescence, nitrogen content, carbon and nitrogen isotopes, internal structure and inclusions. The diamonds recovered from the PKO are mainly mixed-habit diamonds with sectors of different brightness under the cathodoluminescence images. The total δ13C range of the PKO diamonds varies between − 18.8 and − 28.4‰, with a principle δ13C mode at − 25‰. Nitrogen contents of the diamonds range from 7 to 541 ppm with a mean value of 171 ppm, and the δ15N values range from − 19.1 to 16.6‰, with a δ15N mode of − 9‰. Stacking faults and partial dislocations are commonly observed in the Transmission Electron Microscopy foils whereas inclusions are rather rare. Combinations of (Ca0.81Mn0.19)SiO3, NiMnCo-alloy and nano-sized, quenched fluid phases were observed as inclusions in the PKO diamonds. We believe that the 13C-depleted carbon signature of the PKO diamonds derived from previously subducted crustal matter. These diamonds may have crystallized from C-saturated fluids in the asthenospheric mantle at depth below 250 km which were subsequently carried rapidly upward by asthenospheric melts.
KeywordsOphiolite Diamonds Carbon isotope Nitrogen isotope Inclusion
We thank Fahui Xiong, Wenda Zhou and Prof. Ibrahim Uysal for assistance in the field work, Bin Shi for the assistance in CL imaging. Frédéric Couffignal conducted the SIMS analyses, Anja Schreiber cut the TEM foils of the diamonds, and Richard Wirth conducted TEM analyses. We appreciate their help very much. We would also like to thank Pengfei Zhang, Fei Liu, Paul T. Robinson and Vadim N. Reutsky for their valuable suggestions. We thank the editor and three anonymous reviewers for their thorough and valuable comments that improved this manuscript. This research was supported by the funded by Fundamental Research Funds for the Central Universities (020614380069, 020614380072), the Ministry of Science and Technology of China (2014DFR21270, 201511022, J1618), the National Science Foundation of China (Grants 41672063, 41773029, 41373029,), the China Geological Survey (DD20160023-01, DD20160022-01), and the IGCP-649 project. Y Dilek acknowledges the financial support for this project provided to him by a Lishiguang Scholarship through the Geological Survey of China and the Chinese Academy of Geological Sciences.
- Çelik ÖF, Michel D (2003) Origin of metamorphic soles and their post-kinematic mafic dyke swarms in the Antalya and Lycian ophiolites, SW Turkey. Geol J 3–4(38):235–256Google Scholar
- Das S, Basu AR et al (2017) In situ peridotitic diamond in Indus ophiolite sourced from hydrocarbon fluids in the mantle transition zone. Geology 45(8):755–758Google Scholar
- Gasparik T, Wolf K et al (1994) Experimental determination of phase relations in the CaSiOt system from 8 to 15 GPa. Am Mineral 79:1219–1222Google Scholar
- Keller RA, Taylor LA et al (1999) Detailed pull-apart of a diamondiferous eclogite xenolith: implications for mantle processes during diamond genesis. Proc 7th Int Kimberlite Conf 1:397–402Google Scholar
- Lian D, Yang J et al (2017a) Deep mantle origin and ultra-reducing conditions in podiform chromitite: diamond, moissanite, and other unusual minerals in podiform chromitites from the Pozanti–Karsanti ophiolite, southern Turkey. Am Mineral 102(5):1101–1113Google Scholar
- Ohashi Y, Finger LW (1978) The role of octahedral cations in pyroxenoid crystal chemistry; I, Bustamite, wollastonite, and the pectolite–schizolite–serandite series. Am Mineral 63(3–4):274–288Google Scholar