Mineralogy of different phases of Rodingite formation in dikes of Anarak upper Proterozoic Ophiolite (NE of Isfahan province, Iran)

In north of Anarak area, in the upper Proterozoic ophiolite, exist Massive and Vein type Rodingites. Vein type rodingites have formed in two phases. Massive or Static rodingites have formed during oceanic crust spreading and ophiolite formation, and Vein type or Dynamic rodingites have formed during Anarak ophiolite emplacement and tectonic activities. Abundance order of minerals in massive rodingites is Garnet (Chromian-Andradite), Idocrase, Chlorite, Diopside, Prehnite and Epidote (decreasing). In the first phase of vein type rodingites, the abundance order of minerals is Diopside, Chlorite, Idocrase, and Garnet (Ti-Andradite), and in the second phase is Diopside, Chlorite and Garnet (Andradite). Petrography and geochemical study of minerals show that, during the formation of massive type rodingites, the activity of Calcium, Iron, and Chromium ions in fluids, and during the formation of first phase of vein type rodingites, the activity of Calcium, Silicon, Magnesium, Aluminum, Titanium, and OH- ions in fluids, have been increased. Geochemistry of second phase of vein type rodingites is similar to first phase, but because of absence of Idocrase, and low Titanium in Andradite structure, the activity of Iron, Titanium, and Aluminum ions, is lower than first phase. Generally the diversity of minerals in massive type rodingites is more than vein type rodingites.