Petrology and geochemistry of amphibolites and greenschists from the metamorphic sole of the Muslim Bagh ophiolite (Pakistan): implications for protolith and ophiolite emplacement

© 2014, Saudi Society for Geosciences. Metamorphic sole rocks are exposed beneath both the Jang Tor Ghar Massif (JTGM) and Saplai Tor Ghar Massif (STGM) of the Muslim Bagh ophiolite. The sole rocks comprise the basal mylonitic part of the ophiolite peridotites and the sub-ophiolitic metamorphic rock series showing inverted metamorphic gradients. The latter mainly consist of garnetiferous amphibolites, amphibolites and greenschists. The mineralogy of the amphibolites (hornblende + plagioclase ± quartz ± biotite ± epidote ± apatite ± opaque) and garnet amphibolites in the metamorphic sole rocks of the Muslim Bagh ophiolite is similar except for the presence of garnet in the latter. Greenschists contain minerals such as chlorite + plagioclase + epidote ± actinolite ± quartz ± opaques. The mineral assemblages of these rocks suggest that they are meta-basites. Geochemical analyses indicate that the garnetiferous amphibolites are metamorphosed tholeiitic to alkaline basalts, akin to ocean island basalts (OIB). By contrast, the amphibolites and greenschists have geochemical signatures akin to mid-oceanic ridge basalts (MORB). Basalts of OIB type are also found in the hyaloclastite-mudstone unit (Bhm), while the MORB-type basalts are found in the basalt-chert unit (Bbc) of Bagh complex underlying the ophiolite nappe. Here, we interpret an early stage OIB-type basalt accretion to the base of the obducted plate associated with extrusion of volcanic rocks in the Bhm unit of Bagh complex followed by amphibolite facies metamorphism. During the later stage of the advancing ophiolitic thrust sheet, MORB-like basalts, such as those found in the Bbc unit of the Bagh complex, are underplated and metarmophosed to greenschist facies with subsequent accretion of the entire sequence of the Muslim Bagh ophiolite and the Bagh complex onto the Indian Platform sediments

Chromitite deposits of Turkey in Tethyan ophiolites

Some parts of the Tethyan ophiolites of Alpine-Himalayan suture belt are located within Turkey. The Tethyan belt splits into two branches in Turkey. The northern branch follows the İzmir-Ankara-Erzincan Zone, while the southern branch extends along the Anatolide-Tauride and Bitlis-Zagros suture zone. The subsections of the latter reach Iran in the east and Oman ophiolites in the south east. These ophiolites are also the only environments in which chromitite deposits occur. Consequently, the ophiolites in Turkey are significantly rich in terms of Alpine type chromitite occurrences and they are the oldest metallic mine products. There has been chromitite ore production in Turkey since the nineteenth century. With their refractory quality, chromitite produced in Turkey has always had a good standing in the market. Chromitite, which was exported as lump ore until mid-twentieth century, started to be used in the domestic market as the country’s industry developed, but still, even today an important part of the production is exported. In addition, since the chromitite developments near to the surface are almost completely exhausted, the chromitite ore production in the country has evolved to concentrated ore obtained from low grade deposits, through beneficiation. Although there are many active beneficiation plants in various parts of the country, there is still a significant amount of concentrate ore production; especially in the deposits of Adana-Aladağ region. In this chapter, the mentioned chromitite occurrences are discussed in a specific order from west to east, taking into account the ophiolite sequences to which they belong. The North Anatolian Ophiolites are introduced in the first three sections whereas the other three sections present the chromitite deposits of the South Anatolian Ophiolites. Nevertheless, considering the historical records and future production potentials, Turkey’s most important chromitite production regions could be listed in order of priority as Guleman (Elazığ), Kopdağ region (Erzincan), Muğla-Fethiye region, Aladağ-Pınarbaşı (Adana-Kayseri), Orhaneli-Harmancık (Bursa)-Eskişehir region and Hatay. It is clear that these should all be taken into consideration for further prospecting targeting. © Springer Nature Switzerland AG 2019