M Refoseh; A Shaker Ardakani; H Ranjbar
Abstract
Volcanic, sub-volcanic (dyke) and pyroclastic (agglomerate and tuff) rocks of Eocene age are located in the Kalmard block in the north and northeast of Kerman City. Petrographically, the lavas are basalt, andesite, rhyodacite and rhyolite, whereas the dykes and pyroclastic rocks are andesite and crystal ...
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Volcanic, sub-volcanic (dyke) and pyroclastic (agglomerate and tuff) rocks of Eocene age are located in the Kalmard block in the north and northeast of Kerman City. Petrographically, the lavas are basalt, andesite, rhyodacite and rhyolite, whereas the dykes and pyroclastic rocks are andesite and crystal tuff in composition respectively. The porphyritic, microlitic-porphyritic and trachytic are the main textures and mineralogically consist of plagioclase± quartz± K-feldspar ± biotite± amphibole± clinopyroxene± olivine+ opaque minerals. Plagioclases show evidences of disequilibrium textures such as sieve texture, resorption and zoning; whereas quartzes have resorbed margins, and amphiboles and biotites are only slightly opacitized. These textures can be resulted from magma mingling, PH2O variations, and decompression with minor loss of temperature during magmatic ascent. Geochemical studies revealed that the volcanic rocks belong to a sub-alkaline magmatic series with calc-alkaline nature. Furthermore, acidic volcanic rocks are metaluminous to peraluminous and show characteristics of I-type granitoids. The trace element discrimination diagrams along with chondrite-normalized rare earth element patterns show that the igneous rocks formed in an active continental arc environment.
A.R Shaker Ardakani; S Dargahi; H Amirpour
Abstract
The Ghaleh-Ganj dioritic- quartzdioritic massifs, Post early Eocene in age, located on the west side of the Makran Accretionary Prism and the Jazmurian Depression and the east side of the Jiroft fault, are part of the intrusives in the Ganj Complex, which itself is a part of the Jazmurian Ophiolitic ...
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The Ghaleh-Ganj dioritic- quartzdioritic massifs, Post early Eocene in age, located on the west side of the Makran Accretionary Prism and the Jazmurian Depression and the east side of the Jiroft fault, are part of the intrusives in the Ganj Complex, which itself is a part of the Jazmurian Ophiolitic Belt or the Inner Makran. The diorite- quartzdiorites are intruded into the Lower- Middle Eocene Bidak sedimentary units, which show spheroidal weathering and onion- skin erosion. The presence of feldspar, biotite and secondary minerals (such as clay minerals, secondary biotite and Fe oxides) in the study massifs played an important role in the occurrence of these features. Mineralogically the intrusives consist of plagioclase, clinopyroxene, amphibole, Biotite and opaques. Based on mineral chemistry studies, the plagioclases, oligoclase to labradorite in composition, show evidences of disequilibrium textures (e.g. sieve texture and oscillatory zoning). The clinopyroxenes are augite in composition and belonging to a tholeiitic magmatic series. Referring to linear relation between Ti and AlIV in clinopyroxenes, they seem to be formed in a pressure less than 5 kbs at a depth of less than 15 kilometers. Amphiboles are magnesiohornblende with tendency to actinolite in composition. Based on Zr/TiO2 versus Nb/Y and SiO2 versus Nb/Y diagrams, the intrusives plot in the fields of diorite- quartzdiorite and sub-alkaline, respectively. Their low Nb/Y ratio (0.14-0.16) also point out to their sub-alkaline (tholeiitic) nature. The intrusives are metaluminous and I-type, which referring to HFS and REE element contents, they belong to one group. The absence of a distinct Eu anomaly suggests the insignificance of plagioclase fractionation or oxidation state of the magma. The trace element discrimination diagrams together with chondrite-normalized rare earth element patterns show that the Ghaleh Ganj diorite- quartzdiorites formed in the Maturity Stage of a supra-subduction zone.
A Shaker Ardakani; M Arvin; B Oberhänsli
Abstract
The Lower Paleocene felsic plutonic rocks in the N- NE of Ghaleh-Ganj, are located on the western side of the Makran accretionary prism and the Jazmurian Depression and the east side of the Jiroft fault. They are parts of the intrusives in the Ganj complex, which itself is a part of the Jazmurian ophiolitic ...
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The Lower Paleocene felsic plutonic rocks in the N- NE of Ghaleh-Ganj, are located on the western side of the Makran accretionary prism and the Jazmurian Depression and the east side of the Jiroft fault. They are parts of the intrusives in the Ganj complex, which itself is a part of the Jazmurian ophiolitic belt or Inner Makran. Petrographically, the intrusives are quartz diorite, plagiogranite, tonalite, granodiorite, monzogranite and albite granite in composition with mainly equigranular to inequigranular textures and subordinate textures such as micrographic, granophyric, poikilitic and zoning. Mineralogically, the plutonic rocks consist of plagioclase, quartz, orthoclase, microcline, amphibole, biotite and opaques. The plagioclases show normal, reverse and oscillatory zoning and based on their mineral chemistry studies, are mainly albite to oligoclase in composition. Amphiboles are calcic type and magnesiohornblende in composition with affinity to actinolite. The geochemical studies show that the felsic plutonic rocks are trondhjemite to tonalite in composition and belonging to a sub-alkaline magmatic series with calc-alkaline nature, and have characteristics of peraluminous granitoids. Using trace element discrimination diagrams and ocean ridge granites-normalized multi-elements diagram clearly show that the Ganj felsic plutonic massifs are plotted in arc-related granites field with affinity towards ocean ridge granites field. These characteristics along with Nb-Ta negative anomalies are known as evidences for formation of Ganj felsic plutonic rocks in a supra-subduction zone environment.
