Petrogenesis of Amphibolite/Hornblendite Dikes in Qala-Diza Area, Iraqi Kurdistan Region

Abstract


Introduction
Amphibolite rocks are the most common mafic metamorphic rocks, consisting dominantly of amphibole and plagioclase (Frisch et al., 2010;Gill and Fitton, 2022).These rocks can be formed by metamorphic process of the magnesium-and iron-rich igneous rocks; such as basalt and gabbro during regional metamorphism under high temperature and high pressure conditions (Wilson, 2020).Most

Geologic and Tectonic Setting
Iraq forms the northeastern part of the Arabian plate which is tectonically controlled by the collision between the Iranian and Arabian plates (Fouad, 2015;Abdulnaby, 2019).The collision between these plates started during the lower Tertiary and is still going on which resulted in the formation of the foreland basin and the Zagros-Taurus Mountain belt (Mohajjel et al., 2003;Al-Qayim et al., 2012;Al humadi et al., 2019).According to Jassim and Buday (2006), Iraq is tectonically divided into three parts: (1) Stable Shelf which is subdivided into Salman, Mesopotamia, and Rutba-Jezira zones; (2) Unstable Shelf which is divided into Imbricated, High Folded and Foothill zones; and (3) Zagros Suture Zone (ZSZ) which is divided from southwest to northeast into the following three zones: • The Qulqula-Khwakurk Zone: The Qulqula Group consists mostly of Cretaceous radiolarian chert and limestone with imbricates of Permian, Triassic and Jurassic limestone.The Khwakurk Group consists of chert, volcanic and ultramafic rocks of the southern Neotethys (Jassim and Goff, 2006).
• 2The Penjween-Walash Zone which includes three Cretaceous intrusive complexes like Pushtashan, Mawat and Penjween as well as Paleogene Bulfat complex and the Cretaceous sedimentary and metamorphosed volcanic rocks, and unmetamorphosed Paleogene volcanic arc with mafic intrusions.These units were formed during the closure of the Neotethyan Ocean.• The Shalair Zone is composed of thrust sheets of metamorphosed pelitic rocks (mostly phyllites) of Shalair Group, Cretaceous volcanic arc, and meta-carbonates of Mesozoic age.Bulfat area is one of the disconnected fragments of oceanic lithosphere exposed at Jabal Bulfat in Zagros region, about 30 km east of Qala Dizah City, NE Iraq (Ali et al., 2012;Ali., 2017).It comprises volcano-sedimentary sequence of Gimo-Qandil Group (Jassim et al., 2006;Aswad et al., 2011) which originally named Bulfat Group (Jassim et al., 1987a;Karo, 2015).The Gimo group of Bulfat area includes regionally metamorphosed volcanics and volcano-sedimentary sequence (Jassim et al., 1982b), later it was intruded by igneous intrusion of Bulfat Complex (Buda, 1993).These intrusions mainly comprise pyroxene-hornblende and gabbros-diorite which are considered older intrusion intruded by younger olivine gabbro-diorites (Jassim et al., 2006a); as well as syenite and nepheline syenite formed during the late stage of the magmatic differentiation (Jassim et al., 2006a;Aswad et al., 2016).
Ultramafic igneous rocks in this area occur in the lower parts of complex, and can be divided into three occurrences like serpentinites, pyroxenites, and Pauza ultramafic body (Buday and Jassim, 1987).Ultramafic rocks of the Pauza Village are represented by peridotite affected by the serpentinization process, and forms 4% of the Bulfat ophiolite (Hamasalh, 2004).Discontinuous imbricated serpentinite occurs along the thrust zone between Halsho and Hero villages, separating the Eocene-Oligocene Walash-Naopurdan volcanic-sedimentary arc rocks from the metavolcano-sedimentary units of Gimo-Qandil Group (Albian˗Cenomanian) (Jassim et al., 2006;Karo, 2015).The geologic map of the Bulfat area and locations of the studied samples are shown in Fig. 1.Amphibolite and hornblendite rocks appeared in the area as dykes in contact with the other rocks mainly serpentinized and metacarbonates as host.It occurs in various forms ranging from massive bodies to banded.

Methodology and Field Description
Based on the field observations, amphibolite rocks are divided into banded and massive types.The studied rocks are mostly characterized by extremely heterogeneous grain size that occurs as dikes cutting host rocks which are mostly serpentinites with the exception of metacarbonates of Gere traverse (Fig. 2A).Banded amphibolite is marked by the foliation as a result of alternating segregated dark-coloured amphibole and light-coloured bands (Fig. 2B).Meanwhile, massive amphibolite is characterized by granoblastic texture with their main minerals (amphiboles and plagioclase) which are mixed and not affected by banding.The hornblendites are black and medium-to fine-grained in hand specimens (Figs.2C & 2D).These rocks occur as intrusions and dikes (Fig. 2C) cutting serpentinite host rocks; some samples are not collected from outcrops on the hill due to the presence of mine.therefore, the samples were collected under the hill (Fig. 2D).
More than 50 samples of amphibolite and hornblendite have been collected from five various localities (Fig. 1).In total 48 thin sections have been prepared, twenty-four from the banded amphibolite samples, seven from the massive amphibolites, and seventeen thin sections from the hornblendite samples.(Buda, 1993).Many hornblendite samples were taken long traverse called "Sh" lies 2 km northwest of Hero village.Six banded amphibolite samples were collected long "BJ" traverse lies 3.7 km southeast of Darishmana village.Two banded amphibolite samples, one massive amphibolite sample, and one hornblendite sample were collected from south of Hero village along the traverse called "GJ".Many hornblendite samples were taken along "HAJ" traverse which located 1.41 km northwest of Hero village.Five samples of massive amphibolite rocks were collected along "AhJ" traverse, located 2.41 km southeast of Hero.
These thin sections were examined in detail by polarized microscope for the identification of minerals and textures, and also to illustrate the effects of deformation and alteration/metamorphism on the studied rocks.The minerals percentage in studied samples are determined by using point counter method.Chemical compositions of minerals determined at Charles University in Prague with electron microprobe technique (EPMA) using a FEG-EPMA JXA-8530F (Jeol) microprobe under operating conditions of 15 kV accelerating potential and 20 nA beam current and the ZAF online program was used for data correction.Albite (Na), Corundum (Al), Apatite (P), Tugtupite (Cl), Diopside (Ca), Sanidine (K), Rutile (Ti), Chromium _Oxide (Cr), Barite (Ba), Vanadium (V), Magnetite (Fe), Rhodonite (Mn), Sphalerite (Zn), Ni (Ni), F-Topaz (F), Quartz (Si), and MgO (Mg) standards were used to measure elements indicated in brackets.
Whole-rock geochemistry (major and trace elements including the rare earth elements (REE) and loss-on-ignition were analyzed at ALS Laboratory Group in Seville, Spain using ICP-MS, ICP-AES, WST-SEQ with the Lithium Borate fusion method as a whole rock package encoding (ME-ICP06), (ME-MS 81D), (OA-GRA05) and (TOT-ICP06).The major elements were determined by ICP-MS (ME-ICP-06).Trace and REE elements were determined by ICP-MS ME-MS 81 TM plus method.Base metal reported with ME-MS 81 method by 4-acid digestion.Only available as an add on to ME-MS 81.

Petrography
Forty eight thin sections were examined in detail by polarized microscope for the identification of minerals and textures and also to show the effects of deformation and alteration and/or low-grade metamorphism on the studied rocks.Petrographically, both banded and massive amphibolites reveal that the main mineral constituents are amphibole and plagioclase; whereas, hornblendites contain >90% amphiboles.These rocks were affected by various degrees of alteration which resulted in the formation of secondary minerals such as chlorite, sericite, and epidote.These alterations resulted in changes of the original characteristics of the primary minerals such as veining.Both banded and massive amphibolite thin sections have granoblastic and porphyroblastic textures; whereas, the main textures displayed by hornblendites are equigranular, poikilitic, cataclastic, and intergranular.The description of these rocks is given below.
Green-coloured amphibole is the most abundant mineral in banded amphibolites (Fig. 3A) which show distinct pleochrois from yellow to green, and high relief.It is mostly anhedral-shaped of variable sizes ranging from coarse-grained (8mm) to fine grained (<1mm) with oxidation products along the cleavage traces and grains boundaries (Fig. 3A).Hornblende grains occurs as phenocrysts or tiny crystals in the groundmass and also as euhedral inclusion in secondary amphibole (Fig. 3A).Phenocrysts of amphibole contain small inclusions of plagioclase, opaque minerals, apatite, rutile, and zircon (Fig. 3B).The extinction angle of prismatic shaped crystals range from 14° to 25°.Most prismatic crystals are oriented along the foliation direction of these rocks (Figs.3B, D).Some grains show zoning due to the change of the composition from the core toward the rim indicating that the equilibrium conditions were not achieved (Downes et al., 2004), as well as undulose extinction, and are commonly twined.Plagioclase minerals are mostly fine-grained and appear mainly in groundmass, with subhedral or anhedral crystal habits and granular or elongate shape (Fig. 3B).Unlike the fine-grained crystal, most of the coarse-grained plagioclase grains show polysynthetic twining (Fig. 3B).Alteration of some plagioclase grains resulted in their partial to pervasive sericitization and/or epidotization.Plagioclase shows blasto-ophitic and blasto-subophitic textures where anhedral and subhedral crystals of plagioclase are completely or partially enclosed by the secondary amphiboles (Fig. 3B).
Some of the thin sections from the banded amphibolites show deformation where plagioclase displays undulose extinction and deformed twins.Pyroxene grains have mainly anhedral to subhedral habits, and form about 2-8% of the total volume of the rocks.The pyroxene grains are mostly altered to secondary amphibole and the relict pyroxene appear as inclusions within amphibole (Fig. 3C).Opaque minerals range in shape from anhedral to euhedral, occur as elongate, irregular and rhombic crystals along amphibole grain boundaries (Fig. 3D).The cores of some hornblende grains contain numerous, oriented, tiny opaques inclusions aligned along cleavage planes (Fig. 3E).According to backscattered image (BSE) of EPMA, Ilmenite also appears as an inclusion within amphibole (Fig. 5A).Ilmenite is sometimes surrounded by sphene (Fig. 5B), indicating that they have formed from it by alteration (Buda, 1993).
Occurrence of magnetite along amphibole boundaries (Fig. 5B) which are possibly related to metamorphic reactions and recrystallization (Polat et al., 2012).Rutile which is not common, occurs as inclusions within hornblende, sphene, and ilmenite.It is mostly produced from the alteration of other titaniferous minerals like Ilmenite and sphene (Demange, 2012).
Sphene is a common accessory mineral characterized by euhedral to anhedral crystal habit, very high relief, and pale brown colour (Fig. 3D).It occurs as small grains or as inclusion in amphibole.Sphene presence indicates high temperature condition (Hassan and Ridha, 2018).Apatite occurs as tiny six sided inclusion in amphibole and as grains in groundmass (Fig. 5A).Chlorite which is not common; has flaky shape, pale green colour and lacks pleochroism, and mainly found as retrograde chloritization alteration product (Fig. 5A).Biotite is not common, occurs as grains in the matrix or as inclusions in amphibole (Fig. 5B).
Plagioclase grains are mostly fine-grained, euhedral to anhedral in shape, or granular in within the groundmass (Fig. 3F).Based on extinction angle, some crystals are Na-rich (albite); meanwhile, the results of EPMA analysis also indicate the existence of anorthite.Large plagioclase grains show polysynthetic twinning which is lacking in the small-sized grains (Fig. 4B).Some crystals are replaced by sericite and minor epidote.Plagioclase displays undulose extinction and deformation twins.Blasto-Ophitic and sub-ophitic texture is also observed when a relatively individual crystal of plagioclase is completely enclosed by relic pyroxene or amphibole crystal (Figs.4A & 4B).Pyroxene has anhedral to subhedral habits, and medium-to fine-grained (Figs.3F & 4B).It is mostly diopside in the composition according to extinction angle.Proxenes are mostly altered to amphibole indicated by the presence of their remnants as inclusions within amphibole.Opaque grains range in shape from euhedral to anhedral, typically occur as oriented grains along crystal boundaries (Fig. 3F), and also occur as polygonal, and irregular inclusions within amphibole.Some hornblende grains contain numerous, oriented, and tiny opaque inclusions.EPMA-BSE images reveal that ilmenite occurs as fine crystals along amphibole boundaries and as inclusions in sphene and amphibole (Fig. 5D).Magnetite inclusions exist in amphibole and in altered plagioclase (Fig. 5C) or larger crystals/clusters associated with ilmenite.Ilmenite grains are mostly associated with titanite, and can be seen as inclusions in sphene (Fig. 5D).Inclusions of zircon and apatite occur in amphibole (Fig. 5D).(D) Amphibole grain contains apatite, ilmenite, zircon, and sphene inclusions; ilmenite grains occur along the amphibole boundaries and as inclusion in sphene within massive amphibolite; (E) Amphibole crystal contains tiny inclusions of apatite, chlorite, ilmenite, and magnetite in hornblendite; (F) Chlorite, apatite, epidote, and spinel + SiO2 inclusions within hornblende grains in hornblendite.
Amphibole crystals are euhedral to anhedral, equigranular, coarse-(5mm) to fine-grained (<1 mm) and contain quartz, apatite, rutile, and zircon inclusions.It is mostly green in colour, has strong pleochroism, symmetrical extinction and is commonly twinned (Fig. 4C).In some sample, hornblende grains are aligned along lineation direction (Fig. 4D).Sometimes, euhedral crystals of hornblende are enclosed in secondary amphibole.Some crystals show zoning or undulose extinction.Altered hornblendes show chlorite along the boundaries and fracture as a result of their chloritization (Figs.5E,  F).
Actinolite is characterized by yellow to pale bluish green pleochroism, medium relief, and high interference colors (Fig. 4E).Their extinction angle ranges between 0° to 20° parallel to the lineation of columnar crystal.Basal sections show rhombic crystals with symmetrical extinction, and two sets of cleavage at angles of 56° and 124° (Fig. 4F).Actinolite is the product of alteration of hornblende during retrograde metamorphism.Many actinolite crystals show twining (Fig. 4F).Pyroxene is rare and anhedral, and spread as small crystals around coarse-crystals of hornblende.Zircon occurs as an inclusion in amphibole crystals which are surrounded by pleochroic halos (Fig. 4F).
Opaque grains are euhedral to anhedral, typically oriented along hornblende boundaries, or as interstitial grains between amphibole grains (Fig. 4E).Opaque grains appear as small (<5 µm), rounded, polygon, or irregular inclusions within amphibole or as fine grains in groundmass (Fig. 4E).Based on EPMA-BSE image, ilmenite grains occur among amphibole crystals or as inclusions in amphibole (Fig. 5E), or replaced by sphene and rutile.Magnetite is rare and occurs along amphibole crystal boundaries (Fig. 5E).Cr-spinel (chromite) exists in amphibole as inclusion and is usually altered (altered parts/rims marked as Spinel and quartz.in the BSE images, spinel presents as Fe+Cr+Mg+Al and Si type, and it occurs between amphibole grains or as inclusions within amphiboles (Fig. 5F).Apatite is euhedral to anhedral, high relief, shows low interference colour, and occur as tiny inclusion in amphibole (Figs.5E  & 5F).Chlorite is restricted to the cracks, fractures, and grain boundaries and as inclusion (Figs.5E &  5F).

Mineral Chemistry
Major and minor element compositions of amphibole, plagioclase, pyroxene, and Fe-Ti oxides were analyzed on polished thin sections by EPMA.In total six samples have been chosen from banded amphibolite, massive amphibolite and hornblendite, (two samples from each group) and analysed to determine the chemical composition and to classify the rock samples.

Pyroxene
According to EPMA analysis, pyroxene was observed in two samples (GJ10 and GJ3).The compositions of pyroxenes are plotted on the wollastonite-enstatite-ferrosilite ternary diagram of Morimoto et al (1988).All the analyzed pyroxenes from banded and massive amphibolite are Mg-rich and classified as diopside with end-member formula (Wo 48 En37 Fs 14) in term of Fe-Mg ratio (Figs.7B).
The hornblendites are characterized amphibolites by having relatively lower concentrations of SiO 2 , MnO, Na 2 O, K2O, TiO2, Rb, Ba, Cs, Zr and HREEs, and higher concentrations of MgO, CaO, and Ni.The LREEs content in hornblendites are relatively higher than the banded amphibolites and lower than the massive amphibolites.They mostly have lower Sr content than the banded amphibolites, and higher than the massive amphibolites with the exception of one sample (HAJ9) which have very high concentration of Sr.
The primitive mantle-normalized trace elements spider diagram of Sun and McDonough (1989) shows that the banded amphibolites have positive Ba, K, Pb, Sr, Zr, and Ti anomalies, and negative Rb, Th, Nb, Pr, P, Eu, and Yb anomalies.In contrast, the massive amphibolites are characterized by negative Th, Nb, Sr, Zr, and Ti anomalies, and positive Rb, U, La, Sm, and Dy anomalies.The hornblendite relative to other both types of amphibolites is richer in Pr, Nd, P, U, La, Ce, Sm, Eu, and poorer in Cs, Rb, Nb, K, Ti, Y, and HREE, with distinct positive anomalies for Ba, U, Dy, and Sm and negative anomalies for Rb, Nb, Zr, Ti, and Sr (Fig. 8A).There is enrichment of LREE in hornblendites, such as La, Ce, Pr, and Nd.There are strong negative Ti anomalies and slight negative Zr anomalies in all samples.

Geothermobarometry
Amphiboles, particularly hornblende, are the most commonly utilized minerals for geothermobarometry because they can be found in a variety of calc-alkaline intrusive rocks (Sheikhi et al., 2020).Based on the mineral assemblages of amphibole and plagioclase from all banded amphibolite, massive amphibolite, and hornblendite, the temperature calculation was carried out using hornblende and hornblende-plagioclase geothermometers (Otten, 1984;Colombi, 1989;Blundy and Holland, 1990;Ernst and Liu, 1998).
Ti and Al in amphibole are used as temperature and pressure indicators by Ernst and Liu (1998) based on the TiO2-Al2O3 isopleth from amphibole composition.By using this geothermometer, the calculated temperature range is between 400 and 850 • C for banded amphibolite and 400-793 • C for massive amphibolite (Fig. 9).The majority of amphibolite lies between 3-5 kbar as average, while banded amphibolite gives higher pressure conditions due to the composition of Al2O3 in amphibole (Fig. 9).

Discussion
Based on the major element composition (Le Bas et al., 1986) (Fig. 10A), the banded amphibolites and massive amphibolites are classified as basalts with the exception of one sample which plots in the tephrite-basanite field; they are divided between alkaline and subalkaline/tholeiitic fields.The hornblendite rocks are divided between picrobasalts and foidites and the majority has alkaline affinity.On SiO 2 vs. FeO t /MgO diagram (Miyashiro, 1974) the majority of amphibolites are tholeiites (Fig. 10B).
According to MgO-FeO T -Al2O3 diagram (Pearce et al., 1977) (Fig. 11A), both banded and massive amphibolite, and hornblendites fall in the field of oceanic ridge and floor.The La/Yb -Th/Nb diagram   The petrographic study results showed that the studied rocks were affected by different degrees of alteration, which resulted in the formation of secondary minerals such as sericite, chlorite, and epidote.Plagioclase grains in amphibolites show polysynthetic twinning, but some lack twinning because of the small size of grains.This agrees with what mentioned by Nesse (2000) stating that twining of plagioclase can be absent in small grains, especially in metamorphic rocks.The undulose extinction in some amphibole and plagioclase crystals is a deformation feature (Hadi et al., 2013).Pleochroic halos in hornblendite is due to radiation from radioactive trace elements in zircon inclusions.
One sample of hornblendite (HAJ9) has a higher concentration of Sr than other hornblendite samples because of the presence of a plagioclase vein in this sample.Hornblendite generally has a lower Sr content than banded amphibolites and a greater Sr content than massive amphibolites.One sample of hornblendite (HAJ9) has a higher concentration of Sr than other hornblendite samples because of the presence of a plagioclase vein in this sample.In all samples, there are significant negative Ti anomalies and minor negative Zr anomalies, which show the retention of refractory minerals such zircon-rutile, apatite, and sphene (Hadi., 2013).Both amphibolites and hornblendite typically show negative Eu anomalies indicating either that plagioclase fractionation occurs during magma development, or there was presence of plagioclase in the mantle source where partial melting occurred.The geochemical characteristics of most amphibolite samples indicate their igneous origin of tholeiitic basalt affinity with sub-alkaline basalt protoliths that are produced by fractionation of pyroxene and plagioclase.
During the closure of the Neotethyan Ocean several oceanic fragments (ophiolites) were obducted in the Zagros Suture Zone (Al Humadi et al., 2019).The Zagros Suture Zone is characterized by different tectonic units in several nappes and thrust sheets (Ali et al., 2014).Bulfat area is part of the ophiolitebearing terranes (upper allochthon), which represents part of the second unit of the Penjween-Walash Subzone.
Geological history of the upper allochthon revealed that subduction was active during the Cretaceous period (Azizi and Jahangiri, 2008;Aswad et al., 2016).This was followed by, collision and obduction of the Cretaceous ophiolite complexes onto the northeastern margin of the Arabian Plate during the Late Cretaceous.However, The Bulfat Igneous Complex represents subduction zone of Eocene arc magmatism into the Cretaceous suprasubduction complex (Ali, 2017).Later rifting, led to ascending of the mantle upwelling and lithosphere to produce the melt that gave rise to the Wadi Rashid gabbro (Aswad et al., 2013) and olivine gabbro (Ali, 2017).N-MORB represents the main tectonic environment of most studied rocks, unlike previous studies that appeared E-MORB for rifting in Bulfat area (Aswad et al., 2013;Ali, 2017).Only two samples of banded amphibolite are plotted in the E-MORB field according to diagrams of wood (1980).
MORB geochemical signatures of the studied samples indicate that were they formed in an extensional tectonic environment, such as an intra-arc rift or a back arc.MORB are thought to be the products of comparatively large degree of partial melting; hence, their trace element patterns must reflect those of their mantle source.Therefore, the depletion of LILEs such as Rb, K, Sr, and Ba indicate to MORB character.Most banded amphibolite samples show the enrichment in LILES such as Cs, Ba, K, Pb, and Sr which is related to alteration (unrelated to magma origin).In hornblendite, depletion in Rb and Cs belonged to N-MORB; while, there is enrichment in LREE relative to other trace elements and this suggests assimilation of country rock by magma, or because of the rift in back arc.Depletion in Nb is related to the NMORB environment, and most of the studied samples have (La/Sm)n <1, which is another indicator of the NMORB environment.
Typically, the metamorphic paragenesis that occurs in any metamorphic rocks is based on pressure and temperature reached during metamorphism, and the bulk composition of the protolith.Experimental petrography, in which the researcher determined the equilibrium temperature and pressure in the lab to the modal natural geological system, allows for the estimation of the metamorphic condition for paragenesis during metamorphism.(Winter, 2010).
By employing different geothermobarometers for the Bulfat amphibolite and according to the mineral assemblage of studied amphibolites.These conditions are corresponding to amphibolite facies.

Conclusions
The predominant mineral constituents in the banded and massive amphibolites are calcic amphiboles and plagioclase with minor to accessory minerals such as diopside, iron oxides, titanite, quartz, apatite, and zircon.The predominant minaral in hornblendites is amphibole with accessory minerals such as iron oxides, apatite, rutile, zircon, titanate, and chlorite.
The electron microprobe analysis (EPMA) showed that the amphiboles of the banded amphibolite are nearly equally divided between tschermakite, magnesio-hornblende and pargasite; and those of the massive amphibolites range between magnesio-hornblende and less actinolite; meanwhile those of hornblendites are dominantly tschermakite with minor magnesio-hornblende and pargasite.The plagioclase of banded amphibolites are mostly andesine and albite, and those of the massive amphibolites are mostly anorthite, meanwhile those of hornblendites are albite.P-T condition of metamorphism revealed that the studied amphibolite rocks are within amphibolite facies grade.
Chemical classification diagrams showed that most amphibolites have tholeiitic basaltic affinity, meanwhile the hornblendites are divided between picrobasalts and foidites.
Tectonic discriminating diagrams indicated MORB origin for most amphibolites, and MORB as well as Islan Arc Tholeiite origin for most hornblendites.
Primitive mantle-normalized trace element diagram, chondrite-normalized-REE patterns and tectonomagmatic discrimination diagrams reflected MORB origin for the studied rocks.

Fig. 1 .
Fig.1.Geological map of Bulfat area showing the locations of the studied rock samples(Buda, 1993).

Fig. 5 .
Fig. 5. EPMA-BSE images illustrating the petrographic characteristics of the studied samples from Bulfat area: (A) magnetite grains along amphibole boundaries and fine grains of plagioclase, ilmenite, and apatite within the banded amphibolite matrix ; (B) Core of sphene contain inclusion of ilmenite, fine grains of biotite in groundmass next to amphibole, and sphene and plagioclase as inclusion in amphibole in banded amphibolite; (C) Amphibole phenocryst contains plagioclase which is partially altered to muscovite (sericite), and contains magnetite and ilmenite inclusions in massive amphibolite;(D) Amphibole grain contains apatite, ilmenite, zircon, and sphene inclusions; ilmenite grains occur along the amphibole boundaries and as inclusion in sphene within massive amphibolite; (E) Amphibole crystal contains tiny inclusions of apatite, chlorite, ilmenite, and magnetite in hornblendite; (F) Chlorite, apatite, epidote, and spinel + SiO2 inclusions within hornblende grains in hornblendite.
al (2012) (Fig.11B) reveal that most of the banded and massive amphibolites plot in the field of mid-oceanic ridge basalt (MORB).The hornblendites show a wide scatter between MORB and other fields including alkaline arc, oceanic islands, and oceanic arcs.Based on triangular diagrams of Wood (1980) (Figs.11C, D), the majority of banded and massive amphibolite fall in the field of N-MORB and fewer in E-MORB with few exceptions.Most hornblendite samples belonge to N-MORB with the exception of few samples which are scattered between the fields of island arc tholeiite basalt and E-MORB.

Table 1 .
amphibole composition and its formula in studied samples calculated to 23 Oxygen

Table 2 .
Electron microprobe analyses of feldspar in the studied rocks; their formula is calculated according to 32 Oxygen.

Table 3 .
Representative whole-rock geochemistry of amphibolite rocks in Bulfat area