The granitoids-diroretic complex and associated volcanic suits of Malek Siah Kuh (eastern Iran) were examined by RS, XRD, XRF, AAS and ICP-MS methods. The Multispectral data were used for differentiating of lithologic...The granitoids-diroretic complex and associated volcanic suits of Malek Siah Kuh (eastern Iran) were examined by RS, XRD, XRF, AAS and ICP-MS methods. The Multispectral data were used for differentiating of lithological units, main alterations, structural trends, and hydrothermally altered minerals. Based on the results of remote sensing, field studies and petrographic data, the complex classified into three main groups: 1) mafic unit (gabbro-basalt), 2) intermediate rocks (diorite-andesite suite) and 3) felsic unit (granitoide rocks). The complex is characterized by high Al2O3 and Sr contents as well as high Sr/Y and La/Yb ratios, while low in Y and Yb contents. The geochemical characteristics of these rocks indicate that they are similar to adakite like rocks. The complex is high calc-alkaline to shoshonitic nature. The results indicated derivation from similar silicate melt source followed by differentiation and assimilation of crustal rocks. Based on set of petrological and geochemical relations, 3 distinct stages of mineralization process can be recognized. 1) It is differentiation during magma evolution as well as metal enrichment and subsolidus leaching by hot fluids. 2) It occurred by ascending of the gas-rich magma and release of S and As. 3) It was accompanied by hydrothermal activities leading to the generation of sulfidation and associated polymetallic (Cu, Au, Fe) mineralization.展开更多
In the Alborz Mountains of the eastern Roodbar (north of Iran), Tertiary volcanic rocks have a variety of composition between olivine basalt, basaltic andesite, pyroxene andesite and andesite. The presence of differen...In the Alborz Mountains of the eastern Roodbar (north of Iran), Tertiary volcanic rocks have a variety of composition between olivine basalt, basaltic andesite, pyroxene andesite and andesite. The presence of different xenoliths and xenocrysts is among the evidence of crustal contamination of these rocks. The positive correlations of CaO/Al<sub>2</sub>O<sub>3</sub> vs to MgO and Al<sub>2</sub>O<sub>3</sub> vs. SiO<sub>2</sub> are of signs of the olivine and clinopyroxene fractionation in the variation trend of the area rocks. Positive correlations K<sub>2</sub>O/P<sub>2</sub>O<sub>5</sub> vs with SiO<sub>2</sub> and La/Sm vs. K<sub>2</sub>O/P<sub>2</sub>O<sub>5</sub> demonstrate contamination of magma with the continental crust. The incompatible trace element patterns and their comparison with crustal contents indicate contamination of the rocks of the area with the lower and upper continental crust. Linear trends in the variation diagram of Nb/Y vs. Zr/Y, introduce two different source regions: a MORB source and the other continental crust for the rocks which are the genesis. The variations of Y/Nb vs. Zr/Nb and Rb/Y vs. Nb/Y reveal a crustal contamination of the magma originated from the MORB source. Geochemical studies represent that the area’s rocks were derived from the 15% melting of a mantle source of MORB type with spinel facies within a continental environment, which was contaminated by varying degrees of continental crustal rocks.展开更多
Area studied in this paper is located in the northwest of city of Alasht. The most important varieties of studied rocks are volcanic and semi-volcanic rocks of basic nature. These rocks, which form a distinguishable s...Area studied in this paper is located in the northwest of city of Alasht. The most important varieties of studied rocks are volcanic and semi-volcanic rocks of basic nature. These rocks, which form a distinguishable solid mass on 1:100,000 geological map, belong to Cretaceous period. According to results of petrographic study, rocks of this area include olivine basalt, dolerite, gabbro and microgabbro, and all have almost similar chemical compositions. According to chemistry-based naming process carried out through TAS method, these rocks are entirely basalt and basic and are all products of Sub-alkaline-Tholeiitic magma. According to Harker diagrams, a magmatic differentiation can be observed in all volcanic rocks;furthermore, basaltic magma erupted in this area has undergone an alteration and possibly a crustal contamination. The spider diagrams plotted in this paper show that basic rocks of Alasht area (basalts, andesite basalts, dolerites, gabbros and microgabbros) are all mostly similar to ocean island basalts (OIB). Once field study, sampling and microscopic study stages were complete, ten samples were selected for chemical analysis and were analyzed by XRF method.展开更多
Iran is a country that benefits from nice nature, diverse continent, areas full of unique geological phenomena. Thus, it is necessary to study these attractions for better recognition of them. In this regard, Hormoz I...Iran is a country that benefits from nice nature, diverse continent, areas full of unique geological phenomena. Thus, it is necessary to study these attractions for better recognition of them. In this regard, Hormoz Island with valuable geoheritage, biodiversity, cultural, historical and political diversity is very important. The accumulation of these attractions and its being located in Persian Gulf strategic area made it of considerable significance in national and international communities. Hormoz Island is a spherical salt dome which is located in Hormoz strait. This Island is composed of evaporites, igneous rocks and sedimentary rocks, and sediments mainly belong to Mishan and Aghajari formations and salt, gypsum and, to a lesser extent, limestone evaporites. In sedimentary formations of Hormoz, Aouthigenic minerals such as Pyrite, Dolomite, quartz, Anhydrite, gypsum and halite are frequently seen. Mineralization of volcanic leads to formation of high temperature minerals, such as oligiste, pyroxene, amphibole and low temperature and hydrothermal minerals such as Pyrite, quartz... in the tracks of igneous rocks. This unique geodiversity in rocks and mineral which made various colors in Hormoz Island made it a mineraogical reservoir. Beside considerable mineralogical attractions, there are other potentials like ochre mine, coral reefs, rock seashore, sea caves, salt caves, plant cover and wild life which have added to various tourism capabilities of this Island and made it a unique place in the world. This paper studies Hormoz Island in terms of geological features and geotourism potentials.展开更多
Koohrig intrusive mass is located in the east of Rafsanjan, Kerman Province, Iran and it is part of because it has cut the sandstone, limestone, shale units and conglomerate of Upper Cretaceous. Its intrusive rock inc...Koohrig intrusive mass is located in the east of Rafsanjan, Kerman Province, Iran and it is part of because it has cut the sandstone, limestone, shale units and conglomerate of Upper Cretaceous. Its intrusive rock includes quartz, plagioclase and alkali feldspar and its ferromagnesian mineral which is biotite has changed into chlorite. This Intrusive mass is characterized by the presence of metamorphic geochemical studies led to the detection of granite and granodiorite and quartz monzonite rocks.展开更多
Zarinkamar area is located in northeast of Shahrood, northeast of Iran, between latitudes of 36°37’ - 36°42’ and longitudes of 55°07’ - 55°12’. Different types of igneous rocks have an outcrop ...Zarinkamar area is located in northeast of Shahrood, northeast of Iran, between latitudes of 36°37’ - 36°42’ and longitudes of 55°07’ - 55°12’. Different types of igneous rocks have an outcrop on the region. Intrusive igneous rocks include a type of syenite with aegirine pyroxene and the other includes quartz from 5 to 20 percent. Moreover, aegirine syenite, ordinary syenite, and quartz syenite have been injected into Karaj Formation with an age of middle to early Eocene. Also, some parts of trachyte magma have given rise to produce trachyte outcrops after passing the crust and current flows. Studying major and rare elements shows that a magma separation has been caused by separation smelting or a crystal separation. These magmas are alkaline and shoshonites and they have been originated in a continental rift. The magma of Zarinkamar region has been combined with acidic continent crust as it rose to the surface. High amount of Th, and Rb and low amount of Ti, P, Sr, and Ba can prove this hypothesis.展开更多
Granitoid pluton in the north of Golpayegan is located in10 kmnorth of Golpayegan at SanandajSirjan zone. Dominant rocks of this region include granite, syenite, and gabbro. Granite type is granular with medium to coa...Granitoid pluton in the north of Golpayegan is located in10 kmnorth of Golpayegan at SanandajSirjan zone. Dominant rocks of this region include granite, syenite, and gabbro. Granite type is granular with medium to coarse crystals and its mineralogical composition contains alkali feldspar + quartz + plagioclase + biotite + secondary minerals (opaque + sphene + apatite). Granite rocks have calc-alkaline and?metaluminous to peraluminous nature, relative enrichment of Rb over Sr, and relative enrichment of LILE over HFSE elements. These granites, which are type I, are derived from the melting of metagreywackes and their tectonic setting is of upper continental crust and post-orogenic setting. Gabbroic type is older than other types of the pluton and is granular with medium to fine crystal. Mineralogical composition of these rocks is plagioclase + pyroxene + amphibole + biotite + secondary minerals (opaque). Based on geochemical characteristics of tholeiitic and metaluminous nature, relative enrichment of Ba and Sr elements over Rb, relative enrichment of LILE elements over HFSE, negative anomaly of Nb, Ba, and Ta, and positive anomaly of Pb are observed. Origin of this type is probably from enriched mantle and in-plane tectonic setting.展开更多
The Mianrahan’s ophiolitic complex out crops in the northeast of Kermanshah and along with the Zagros thrust zone. In Mianrahan sheet, these ophiolites are located along the NW-SE and parallel to the Zagros Thrust in...The Mianrahan’s ophiolitic complex out crops in the northeast of Kermanshah and along with the Zagros thrust zone. In Mianrahan sheet, these ophiolites are located along the NW-SE and parallel to the Zagros Thrust in the ground. The rocks of this ophiolite complex consist of peridotite, serpentinites, gabbro, dolerite dykes, basaltic lavas associated with marine sediments containing the cretaceous limestones, siliceous limestones and radiolarites. Stratification of this ophiolitic complex is similar to lithological facies sequence of the oceanic crust. However, in some parts, it could be seen as scattered and melanged in the ground. Petrographic study of Mianrahan’s ophiolitic complex started with the ultramafic sequence and followed by sedimentary rocks.展开更多
文摘The granitoids-diroretic complex and associated volcanic suits of Malek Siah Kuh (eastern Iran) were examined by RS, XRD, XRF, AAS and ICP-MS methods. The Multispectral data were used for differentiating of lithological units, main alterations, structural trends, and hydrothermally altered minerals. Based on the results of remote sensing, field studies and petrographic data, the complex classified into three main groups: 1) mafic unit (gabbro-basalt), 2) intermediate rocks (diorite-andesite suite) and 3) felsic unit (granitoide rocks). The complex is characterized by high Al2O3 and Sr contents as well as high Sr/Y and La/Yb ratios, while low in Y and Yb contents. The geochemical characteristics of these rocks indicate that they are similar to adakite like rocks. The complex is high calc-alkaline to shoshonitic nature. The results indicated derivation from similar silicate melt source followed by differentiation and assimilation of crustal rocks. Based on set of petrological and geochemical relations, 3 distinct stages of mineralization process can be recognized. 1) It is differentiation during magma evolution as well as metal enrichment and subsolidus leaching by hot fluids. 2) It occurred by ascending of the gas-rich magma and release of S and As. 3) It was accompanied by hydrothermal activities leading to the generation of sulfidation and associated polymetallic (Cu, Au, Fe) mineralization.
文摘In the Alborz Mountains of the eastern Roodbar (north of Iran), Tertiary volcanic rocks have a variety of composition between olivine basalt, basaltic andesite, pyroxene andesite and andesite. The presence of different xenoliths and xenocrysts is among the evidence of crustal contamination of these rocks. The positive correlations of CaO/Al<sub>2</sub>O<sub>3</sub> vs to MgO and Al<sub>2</sub>O<sub>3</sub> vs. SiO<sub>2</sub> are of signs of the olivine and clinopyroxene fractionation in the variation trend of the area rocks. Positive correlations K<sub>2</sub>O/P<sub>2</sub>O<sub>5</sub> vs with SiO<sub>2</sub> and La/Sm vs. K<sub>2</sub>O/P<sub>2</sub>O<sub>5</sub> demonstrate contamination of magma with the continental crust. The incompatible trace element patterns and their comparison with crustal contents indicate contamination of the rocks of the area with the lower and upper continental crust. Linear trends in the variation diagram of Nb/Y vs. Zr/Y, introduce two different source regions: a MORB source and the other continental crust for the rocks which are the genesis. The variations of Y/Nb vs. Zr/Nb and Rb/Y vs. Nb/Y reveal a crustal contamination of the magma originated from the MORB source. Geochemical studies represent that the area’s rocks were derived from the 15% melting of a mantle source of MORB type with spinel facies within a continental environment, which was contaminated by varying degrees of continental crustal rocks.
文摘Area studied in this paper is located in the northwest of city of Alasht. The most important varieties of studied rocks are volcanic and semi-volcanic rocks of basic nature. These rocks, which form a distinguishable solid mass on 1:100,000 geological map, belong to Cretaceous period. According to results of petrographic study, rocks of this area include olivine basalt, dolerite, gabbro and microgabbro, and all have almost similar chemical compositions. According to chemistry-based naming process carried out through TAS method, these rocks are entirely basalt and basic and are all products of Sub-alkaline-Tholeiitic magma. According to Harker diagrams, a magmatic differentiation can be observed in all volcanic rocks;furthermore, basaltic magma erupted in this area has undergone an alteration and possibly a crustal contamination. The spider diagrams plotted in this paper show that basic rocks of Alasht area (basalts, andesite basalts, dolerites, gabbros and microgabbros) are all mostly similar to ocean island basalts (OIB). Once field study, sampling and microscopic study stages were complete, ten samples were selected for chemical analysis and were analyzed by XRF method.
文摘Iran is a country that benefits from nice nature, diverse continent, areas full of unique geological phenomena. Thus, it is necessary to study these attractions for better recognition of them. In this regard, Hormoz Island with valuable geoheritage, biodiversity, cultural, historical and political diversity is very important. The accumulation of these attractions and its being located in Persian Gulf strategic area made it of considerable significance in national and international communities. Hormoz Island is a spherical salt dome which is located in Hormoz strait. This Island is composed of evaporites, igneous rocks and sedimentary rocks, and sediments mainly belong to Mishan and Aghajari formations and salt, gypsum and, to a lesser extent, limestone evaporites. In sedimentary formations of Hormoz, Aouthigenic minerals such as Pyrite, Dolomite, quartz, Anhydrite, gypsum and halite are frequently seen. Mineralization of volcanic leads to formation of high temperature minerals, such as oligiste, pyroxene, amphibole and low temperature and hydrothermal minerals such as Pyrite, quartz... in the tracks of igneous rocks. This unique geodiversity in rocks and mineral which made various colors in Hormoz Island made it a mineraogical reservoir. Beside considerable mineralogical attractions, there are other potentials like ochre mine, coral reefs, rock seashore, sea caves, salt caves, plant cover and wild life which have added to various tourism capabilities of this Island and made it a unique place in the world. This paper studies Hormoz Island in terms of geological features and geotourism potentials.
文摘Koohrig intrusive mass is located in the east of Rafsanjan, Kerman Province, Iran and it is part of because it has cut the sandstone, limestone, shale units and conglomerate of Upper Cretaceous. Its intrusive rock includes quartz, plagioclase and alkali feldspar and its ferromagnesian mineral which is biotite has changed into chlorite. This Intrusive mass is characterized by the presence of metamorphic geochemical studies led to the detection of granite and granodiorite and quartz monzonite rocks.
文摘Zarinkamar area is located in northeast of Shahrood, northeast of Iran, between latitudes of 36°37’ - 36°42’ and longitudes of 55°07’ - 55°12’. Different types of igneous rocks have an outcrop on the region. Intrusive igneous rocks include a type of syenite with aegirine pyroxene and the other includes quartz from 5 to 20 percent. Moreover, aegirine syenite, ordinary syenite, and quartz syenite have been injected into Karaj Formation with an age of middle to early Eocene. Also, some parts of trachyte magma have given rise to produce trachyte outcrops after passing the crust and current flows. Studying major and rare elements shows that a magma separation has been caused by separation smelting or a crystal separation. These magmas are alkaline and shoshonites and they have been originated in a continental rift. The magma of Zarinkamar region has been combined with acidic continent crust as it rose to the surface. High amount of Th, and Rb and low amount of Ti, P, Sr, and Ba can prove this hypothesis.
文摘Granitoid pluton in the north of Golpayegan is located in10 kmnorth of Golpayegan at SanandajSirjan zone. Dominant rocks of this region include granite, syenite, and gabbro. Granite type is granular with medium to coarse crystals and its mineralogical composition contains alkali feldspar + quartz + plagioclase + biotite + secondary minerals (opaque + sphene + apatite). Granite rocks have calc-alkaline and?metaluminous to peraluminous nature, relative enrichment of Rb over Sr, and relative enrichment of LILE over HFSE elements. These granites, which are type I, are derived from the melting of metagreywackes and their tectonic setting is of upper continental crust and post-orogenic setting. Gabbroic type is older than other types of the pluton and is granular with medium to fine crystal. Mineralogical composition of these rocks is plagioclase + pyroxene + amphibole + biotite + secondary minerals (opaque). Based on geochemical characteristics of tholeiitic and metaluminous nature, relative enrichment of Ba and Sr elements over Rb, relative enrichment of LILE elements over HFSE, negative anomaly of Nb, Ba, and Ta, and positive anomaly of Pb are observed. Origin of this type is probably from enriched mantle and in-plane tectonic setting.
文摘The Mianrahan’s ophiolitic complex out crops in the northeast of Kermanshah and along with the Zagros thrust zone. In Mianrahan sheet, these ophiolites are located along the NW-SE and parallel to the Zagros Thrust in the ground. The rocks of this ophiolite complex consist of peridotite, serpentinites, gabbro, dolerite dykes, basaltic lavas associated with marine sediments containing the cretaceous limestones, siliceous limestones and radiolarites. Stratification of this ophiolitic complex is similar to lithological facies sequence of the oceanic crust. However, in some parts, it could be seen as scattered and melanged in the ground. Petrographic study of Mianrahan’s ophiolitic complex started with the ultramafic sequence and followed by sedimentary rocks.
