Petrological Journal

Petrography, geochemistry and petrogenesis of basaltic rocks in Ali-Abad Garos area as a part of the Sahneh-Harsin ophiolitic complex (east of Kermanshah)

Siavash Omidianfar; Hesam Moeinzadeh; Mohsen Arvin; Mohammad Rahgoshay

Volume 13, Issue 1 , August 2022, , Pages 91-116

https://doi.org/10.22108/ijp.2021.125052.1203

Abstract

Introduction Mesozoic-Paleogene ophiolitic sequences in Iran are in association with opening and closing of Neo-Tethyan oceanic crust. Temporally and specially, these ophiolitic sequences ... Read More Introduction Mesozoic-Paleogene ophiolitic sequences in Iran are in association with opening and closing of Neo-Tethyan oceanic crust. Temporally and specially, these ophiolitic sequences subdivided into five different groups (or belts) (Shafaii Moghadam and Stern, 2014):Zagros outer belt (late Cretaceous-Paleogene);Zagros inner belt (late Cretaceous);Sabzevar- Torbat e Heydarieh belt (late Cretaceous-early Paleocene);Birjand-Nehbandan belt (early to late Cretaceous);Makran belt (late Jurassic-Cretaceous).The Zagros outer belt’s ophiolitic sequences cropped out along the NW-SE trending Zagros main thrust and including Maku-Khoy-Salmas, Kermanshah (-Kurdistan), Neyriz and Esfandagheh (or Haji-Abad) ophiolites. The Kermanshah ophiolite (KO) is an ophiolitic tectonic complex, which comprises imbricated dismembered fragments of mantle peridotites, gabbros, sheet dykes and basaltic rocks which generally occur as thrust-bound tectonic slices. The Sahneh-Harsin ophiolitic complex(SHOC) is the southeastern part of KO. Detail petrological study has not been carried out on the basaltic rocks from Ali-Abad Garos area(AGA) as a part of the SHOC. Thus, the present study focuses on the field observations, petrographic study as well as whole-rock geochemical analyses (XRF and ICP-MS) of the basaltic rocks widespread in AGA.Regional geologyKO cropped out in the northwest of Zagros main thrust (ZMT) where Zagros sedimentary belt join the Sanandaj-Sirjan magmatic-metamorphic belt. In SHOC as the southeastern part of Kermanshah ophiolites Triassic-Cretaceous limestone and radiolarites as well as Mesozoic metamorphic-sedimentary rocks are the oldest lithological units. In the following, ophiolitic sequence related lithological bodies such as peridotites, meta-peridotites, gabbros, meta-gabbros, diabasic dikes and volcanic rocks including pillow lava-massive basalts cropped out which are in accompanied by Eocene extrusive and intrusive rocks. Pliocene to Quaternary sedimentary rocks are the youngest lithological units in Sahneh-Harsin region. In Sahneh-Harsin region ophiolitic sequence related basaltic rocks cropped out in Ali-Abad Garos, Tamark, Gashor areas.Analytical methods We collected ~70 samples of both pillow lava and massive basaltic rocks in-AGA. Based on petrographic characteristics 10 of the freshest samples were analyzed for whole-rock major and trace elements by X-ray Fluorescence (XRF) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in ALS Chemex lab.Field observationsAli-Abad Garos ophiolitic sequence related basaltic rocks mostly show pillow lava structure. However, minor massive basaltic rocks are exist. In the northern part of the study area basaltic rocks are set atop of gabbroic units. However, gabbro-basalt boundary covered by Quaternary sediments. In some parts, basaltic bodies are in association with plagiogranites. Via a fault boundary upper Triassic-Cretaceous limestone units (Biston Formation) thrusted over basaltic rocks.PetrographyThe rocks under study are dominated by plagioclase (up to 20%), clinopyroxene (up to 10%) and opaque minerals (up to 2%) phenocrysts set in a fine-grained to glassy ground mass. Chlorite, calcite, epidote, quartz, zeolite and opaque minerals as secondary minerals formed by altered phenocrysts and groundmass. Massive basaltic rocks mostly show porphyritic texture and to lesser extent glomeroporphyritic, intergranular and amygdaloidal textures are present. The rocks studied are characterized by plagioclase (up to 10%), clinopyroxene (up to 20%) and opaque minerals (up to 5%) phenocrysts set in a fine grain to glassy groundmass. Secondary minerals in massive basaltic rocks are similar to those presented for pillow lava basaltic rocks.Whole-rock geochemistry, tectonic setting and source characteristicsThe studied basaltic rocks show tholeiitic signature. Major element oxides values against SiO2 values, as fractionation index, indicate fractional crystallization as an effective parameter in generation of these rocks. In chondrite-normalized REEs diagram, the basaltic rocks exhibit slight LREE enrichment relative to HREEs (LaN/YbN values ranging from 2.91 to 3.35 and Eu/Eu* values vary from 0.91 to 1.01). In primitive mantle-normalized multi-elements diagram, the patterns of basaltic rocks are consistent with plume related mid-oceanic ridge basalts (P-MORB), against within plate basalt (WPB or OIB), normal mid-oceanic ridge basalts (N-MORB) and enriched mid-oceanic ridge basalts (E-MORB). This case is in agreement with situation of the study samples in basaltic rocks with different geochemical signatures on discriminative diagrams. Parallel trends of the studying basaltic rocks on spider diagrams indicate that they are co-genetic. Also, different elemental ratios as well as the situation of the rocks under study in different geochemical diagrams reveal that parental magma (or magmas) could be formed by low degree partial melting (<3%) of a spinel peridotite as a source rock. Integration of our new presented geochemical data from the study basaltic rocks with other previously presented geochemical data from other ophiolitic sequence related basaltic outcrops within (SHOC) (Tamark and Gashor basaltic rocks) reveal that in this ophiolitic complex basaltic rocks are heterogeneous. Briefly, three different groups of basaltic rocks with P-MORB, E-MORB and OIB geochemical features exist in (SHOC). Comprehensive understanding of relation of these three different basaltic groups are needed to further elemental-isotopic geochemical data coupled with geochronological data.

the origin of Abgarm ultramafic complex (South of Kerman province)

Raziyeh Alipour; Hesam Moeinzadeh; Hamid Ahmadipour

Volume 11, Issue 3 , December 2020, , Pages 1-20

https://doi.org/10.22108/ijp.2020.122663.1174

Abstract

Abgarm ultramafic complex in the south of Kerman province is a part of Esfandagheh- Haji Abad ophiolite which is located in the northern edge of Zagros thrust. The complex contains ... Read More

The Study of amphibolites in‏ ‏Bahram Gor area (northwest of ‎Gol-e Gohar mine in Sirjan), with emphasis on mineral ‎paragenesis and whole rock chemical data

Seyyed Hesamaddin Moeinzadeh; Hadiseh Rahimisadegh; Mohssen Moazzen

Volume 9, Issue 4 , March 2019, , Pages 49-66

https://doi.org/10.22108/ijp.2018.106236.1052

Abstract

The study area is located northwest of Gol-e Gohar mine (Bahram Gur Protected Zone) in Sirjan, the Kerman Province, a part of the Sanandaj-Sirjan zone. The area is mainly dominated ... Read More

Origin of tourmaline in micaschists of ‎Gol-e-Gohar metamorphic complex from south-eastern Sanandaj-Sirjan Zone (Baft, Kerman Province)‎

Hosein Fatehi; Hamid Ahmadipour; Hesam Moeinzadeh

Volume 9, Issue 2 , September 2018, , Pages 81-100

https://doi.org/10.22108/ijp.2018.101553.1008

Abstract

In Gol-e-Gohar micaschists from south-east Sanandaj-Sirjan Zone (Kerman province), there are tourmaline crystals which are enriched in Mg and Na (Mg: 1.830 a.p.f.u and Na: 0.680 ... Read More

Geochemistry and Petrogenesis of lower to middle Paleozoic alkaline lamprophyre dikes of Hour Village, north east of Kerman

Davoud Raeisi; Seyed Hesam-aldin Moeinzadeh Mirhosseini

Volume 5, Issue 20 , January 2015, , Pages 147-162

Abstract

In the northeast of Kerman toward Ravar around Hour village, a series of rocks in the form of dike have been penetrated into the Lower-Middle Paleozoic Formations. The color of these ... Read More

Evaluation of evolution and emission of Gandom Berianâs basaltic flows-north of Shahdad, Kerman

Davoud Raeisi; Seyed Hesam-aldin Moeinzadeh Mirhosseini; Ahmad Abbasnejad; Sara Dargahi

Volume 4, Issue 13 , April 2013, , Pages 81-98

Abstract

Gandom Berian area is a basaltic messa composed of dark flows covering about 480 km2 of the western part of Lut desert in the northeast of Kerman. In this area, the fault system follows ... Read More Gandom Berian area is a basaltic messa composed of dark flows covering about 480 km2 of the western part of Lut desert in the northeast of Kerman. In this area, the fault system follows a north-south trend and, basaltic lavas have flowed along this trend. It seems that in Gandom Berian area, the activity of Nayband fault has created a tensional tectonic regime leading to the creation of open fractures in the crust which have conducted the flow of magma to the surface. Comparing maps of the lineation index factor of Nayband fault and also the related maps to situation of volcanic cones admit the role of fault in formation of Gandom Berian basaltic magma.The presence of coarse euhedral olivine crystals along with coarse crystals of clinopyroxenes and the absence of magmatic quartz, all reveal a fast deep ascending magma through fractures system and deep faults. The deep fracturing of Nayband fault has prevented the mixing of magma with crustal contamination. The high La/Nb value (with average 1.7) along with low ratio of Ce/Pb and Pb/Nd indicate low mixing of magma in the studied area. Also, none scattering compatible element plots show negligible magma mixing. Uniformity in crystal size distribution (CSD) plots and its constant slope indicate the low impact of physical processes such as magma mixing in basaltic magma which effects the crystallization of plagioclase microlites during its ascent to the surface. The main cause of steepness in CSD is the rapid quenching of basaltic magma during upwelling which leads to plagioclase fine microliths. The presence of olivine and clinopyroxene phenocrysts indicates that in the primary magma, crystallization had occurred before ascent and eruption. Based on Dy/Yb versus La/Yb plot the Gandom Beryian basalts were formed by 8 to 10% partial melting of a garnet-lehrzolite parental rock. In general, lower partial melting of upper mantle (less than 10%) leads to the creation of alkaline basaltic magma. On the other hand, Gandom Beryian basaltic magma has characteristics similar to a high magnesium parental magma with low degree of evolution.

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Author = Moeinzadeh, Seyyed Hesamaddin

Petrography, geochemistry and petrogenesis of basaltic rocks in Ali-Abad Garos area as a part of the Sahneh-Harsin ophiolitic complex (east of Kermanshah)

Abstract

the origin of Abgarm ultramafic complex (South of Kerman province)

Abstract

The Study of amphibolites in‏ ‏Bahram Gor area (northwest of ‎Gol-e Gohar mine in Sirjan), with emphasis on mineral ‎paragenesis and whole rock chemical data

Abstract

Origin of tourmaline in micaschists of ‎Gol-e-Gohar metamorphic complex from south-eastern Sanandaj-Sirjan Zone (Baft, Kerman Province)‎

Abstract

Geochemistry and Petrogenesis of lower to middle Paleozoic alkaline lamprophyre dikes of Hour Village, north east of Kerman

Abstract

Evaluation of evolution and emission of Gandom Berianâs basaltic flows-north of Shahdad, Kerman

Abstract