Petrography study of the recent sediments in Hareer’s region at Basrah Governorate - Southern Iraq

Two sites of Hareer’s region is located in the southern part of Iraq, specifically in the northern Basrah Governorate. The sites are at a depth of 5 meters. The results of heavy mineral analysis showed that there are fifteen types include; Opaque grain (Iron Oxide), Chlorite, Muscovite mica, Biotite, Orthopyroxene, Clinopyroxene, Amphibole (Hornblende and Actinolite), Epidote, Garnet, Kyanite, Staurolite, Zircon, and Tourmaline. On the other hand the light minerals and the results of the mineral analyses revealed that they were primarily composed of rock fragments, with a variety of quartz minerals, feldspar minerals, evaporate minerals, clay-coated grains, and trace amounts of unidentified minerals. The abundance and diversity of heavy minerals indicate the diversity of the sources of the parent rocks, such as igneous, metamorphic and sedimentary rocks. The large amount of opaque and small amount of other minerals in the study area samples is due to the oxidation process where many of the ferromagnesian minerals such as pyroxenes, and hornblende decompose to form iron oxides (e.g. hematite, limonite). Light minerals were visible as irregular, sharp, or occasionally semi-sharp crystalline forms, which suggests that the sources were close by and that the light minerals originated from the sedimentary basin or within it through the processes of deposit erosion and re-deposition. The study area, which is a part of the Undissected Arc, is primarily distinguished by a high content of quartz (mono- and polycrystalline quartz, including chert), and feldspar, which can occur in fluvial environments.


Introduction
Study area is located in the southern part of Iraq, north of the Arabian Gulf, and depending on the physiographical divisions of Iraq, it is located within the Delta Plain sector [1].The study area is located in the southern part of the Iraqi marshes, specifically in the north of Basra Governorate, known as the Hareer's region.[2] divided the Basrah province into two regions, the eastern region, or what is known as the sedimentary plain region, and the western region, or what is known as Marwah Al-Batin region.The sedimentary plain area is described as being flat, consisting mainly of clay and silt deposited by the Tigris, Euphrates and Shatt al-Arab rivers, and it constitutes an area of 45% of the province of Basrah [3].The Iraqi marshes are unique in a balanced ecosystem, as they occupy large areas of the sedimentary plain in southern Iraq.The geographical location of the Mesopotamia basin, which mediates between the eastern mountains and the Arab plateau on the western side, helped to form two low basins that extend longitudinally parallel to the rivers of the Tigris and Euphrates.one east of the Tigris and the other west of the Euphrates.The Tigris and Euphrates receive sediments dredged during the rivers' long march as well as dusty sediments carried by the wind.This is one of the most important deposits in the region.North westerly, south easterly and south westerly winds beat the region, as it blows.The region is affected by dust storms that contain high levels of soil and dust with fine sizes, the thickness of which reaches 8 meters / 1000 years, and whose source is either local soils or transferred from neighbouring countries [4].The aim of this study is distinguishing the sedimentary environment of the study area and the source of the sediment from which the minerals came.

Materials and Methods
Ten samples collected from two locations were picked for sampling in order to accomplish the study's aim (Fig. 1).The first location (site 1) is at Longitude and Latitude 47• 41 ˋ 11.4 ˋˋ E and 30 • 36ˋ 54.1 ˋˋ N and the second location (site 2), which is situated at Longitude 47• 41 ˋ33.8 ˋˋ E and Latitude 30 • 36 ˋ 67. 4 ˋˋN.By employing a galvanized metal tube driven into the sediment one meter by one meter by a mechanical vibrator, the first borehole was drilled in site one and the second borehole was drilled in site two at a depth of around 5m below the ground surface of the area.In the laboratory, the tubes of the cores were cute a length for both sides to open their longitudinally.The first step involved creating a detailed visual description of the sediments, which included their texture, colour, and any existing sedimentary structures (Figs. 2).According to the variations in sediment colour, the heavy and light minerals were separated using Griffiths and Carver methods [5] and [6] at the Marine Sciences Center, University of Basrah.

-Iron oxides group
Iron oxides in site one ranging between 37.7-41.7%with an average 39.12%, while in site two is ranging between 37.2-42.8%with an average 39.4%.
-Ultra-Stable Group This group was found in the study area is represented by three minerals: Tourmaline and Zircon.

Tourmaline Mineral
It is characterized by forms rounded -sub rounded crystalline with brown to yellowish brown colour (Fig. 3).With an average 5.08% and 5.02% of sites one and two respectively.

Zircon Mineral
Zircon mineral in this the study with form a semi-round colorless granule (plate 1).With an average 5.72% and 5.82% of sites one and two respectively.

Muscovite Mineral
Muscovite available in pale green (Fig. 3).The results of the analysis recorded a rate of 6% and 6.44% of sites one and two respectively.

Light minerals
Light minerals studies focused on the mineralogical study of the main components of study area (all types of quartz, feldspar and rock fragments, carbonate, chert, evaporates, and coated grains) (Table 2), (Fig. 4).Quartz Two types of quartz were recognized, monocrystalline and polycrystalline quartz.

A-Monocrystalline quartz
Monocrystalline quartz represents the major quartz type that observed in all studied samples.Monocrystalline quartz in site one ranging between 15.3-19.3%, with an average 17.2%, while in site two is ranging between 16.3-20.4%,with an average 18.2%.Monocrystalline quartz grain is sub rounded in shape (Fig. 4).

B-Polycrystalline Quartz
Polycrystalline quartz grain is rounded to sub rounded in shape (Fig. 4).Polycrystalline quartz ranging between 2.4-5.1% and 3.6-6.3% of sites one and two respectively with average 3.78% and 5.16% of sites one and two respectively (Table 2).

Feldspar
Feldspar minerals are divided into two groups' alkali feldspar and plagioclase feldspar.a-Alkali feldspar: These minerals include microcline and orthoclase.

-Microcline
The average of microcline in site one 3.4%.While in site two 4.1%.Microcline grains are sub rounded to sub angular in shape (Fig. 4).

b-Plagioclase feldspar
Plagioclase feldspar in site one ranging between 1.7-2.7%,with an average 2.22%, while in site two is ranging between 1.7-2.9%,with an average 2.24%.Plagioclase grains are angular to sub angular in shape (Fig. 4).

Carbonate minerals
Carbonate minerals are angular to sub rounded in shape (Fig. 4).Carbonate minerals in site one ranging between 21.2-31.8%,with an average 28.72%, while in site two is ranging between 27.4-32.4%,with an average 29.82% (Table 2).

Rock Fragments:
These include Chert fragments, igneous rock fragments, metamorphic rock fragments, and Mudstone rock fragments.a-Chert rock fragments Chert rock fragments in site one ranging between 7.7 -10.7%, with an average 8.8%, while in site two is ranging between 8.4-12.7%,with an average 10.34% (Table 2).Chert grains are sub angular to rounded in shape (Fig. 4).

b-Igneous rock fragments
Igneous rock fragments are sub rounded to sub angular in shape (Fig. 4).Igneous rock fragments in site one ranging between 2.5-3.4%, with an average 2.92%, while in site two is ranging between 2.5-3.3%, with an average 2.9% (Table 2).

c-Metamorphic rock fragments
Metamorphic rock fragments in site one ranging between 3.2-3.9%,with an average 3.48%, while in site two is ranging between 2.7-3.7%, with an average 3.18% (Table 2).The shapes of these grains are elongated (Fig. 4).

d-Mudstone rock fragments
Mudstone rock fragments in site one ranging between 2.7-3.8%, with an average 3.44%, while in site two is ranging between 2.4-3.8%, with an average 3.12% (Table 2).Mudstone rock fragments are sub rounded to sub angular shape (Fig. 4).

Coated clay
Coated clay in site one ranging between 1.7-2.7%,with an average 2.32%, while in site two is ranging between 2.4-3.1%, with an average 2.7% (Table 2).

Light Muscovite
Light muscovite in site one ranging between 3.4-3.9%,with an average 3.84%, while in site two is ranging between 3.2-3.9%,with an average 3.48% (   Separating and diagnosing the minerals in the studied samples showed that there are fifteen types of the heavy minerals, the abundance and diversity of these minerals indicate the diversity of the sources of the parent rocks, such as igneous, metamorphic and sedimentary rocks.Thus, it is suggested that the studied heavy minerals aggregates are derived from sedimentary rocks (mono or multi cyclic), metamorphic, and acidic, basic igneous rocks.Opaque heavy minerals are the main component in all from the study area samples it is represented by iron oxides, with a rate of 39.26%.Confirmed the increase of opaque minerals in beach sand dunes and derived from sediment recycling processes .The presence of chlorite, pyroxene, hornblende, iron oxide minerals and biotite is evidence that basic and ultra-basic, igneous and acidic igneous rocks have mainly contributed to processing the sediments of the study area, as mentioned in .As for tourmaline and zircon minerals, they are minerals derived from reworked Sediments from windmoved sediments, and the evidence for this is their appearance in round-shaped crystals And the fact that these minerals come from the weathering of ancient rocks, which can remain for several sedimentary cycles, and the possibility of the emergence of new deposits by the process of scattering (reworking) of the ancient sediments.Thus, it can be considered as evidence of the occurrence reworking of sediment.On the other hand, the rutile mineral indicates the composition of the source rocks, as it is characterized by a richness of elements titanium, which is a stable element; therefore, it is suggested that it is derived from the felsic rocks The minerals muscovite, biotite, and chlorite, which are concentrated in the study area, that is, in the direction of Shat al-Arab, and this was confirmed by .In areas close to the study area, the percentage is high compared to what we found in our study area, and this means that the increase is in the direction of the Shatt Al-Arab.The group of unstable minerals was represented by amphiboles and pyroxenes, as they constitute a major constituent of heavy minerals, which can give a good indication of the proximity of sediment sources.The presence of these two minerals indicates rapid erosion, with the help of the region's dry climate, which causes mechanical corrosion occurring and the lack of chemical erosion .Confirmed that hornblende and pyroxene is an indicator of the dominance of mechanical erosion of the rocks and evidence of arid climate in the past.On the other hand, hornblende may be concentrated in fine sand deposits, as confirmed by The mineral Epidote was found with pale yellow granules that tend to be greenish, semi-circular, and these types are rich in with iron And because of the similarity of the main mineral groups reached in this study with the major heavy mineral groups in the study of in the Shatt Al-Arab region.Whereas, this match in heavy mineral aggregates indicates the possibility transmission of sediments are in this area by the influence of river and tidal processes.This is indicated by that the Epidote is found in higher proportions in the ancient than the modern sediments of both rivers.These sediments moved to the region from the influence of the Shatt al-Arab by transport processes of tidal currents and discharge of the Tigris and Euphrates rivers at the mid-Holocene sea level drop .As for the study of light minerals, the results of the mineral analyzes were presented, and they were in the first place, The rock fragments, followed by an array of quartz minerals, feldspar minerals, evaporate minerals, clay-coated grains, and trace amounts of unknown minerals.Where it found diversity in rock fragment minerals, represented by sedimentary, metamorphic and igneous rocks, which dominated the proportions of the region's sediments, with an average of 72.9%.And the shapes of these grains are a good indication of nature of the sedimentation and transport distances .These minerals appeared in irregular, sharp, or sometimes semi-sharp crystalline forms, which indicates the proximity of the sources and that it originated from within the sedimentary basin by the processes of erosion of the semi-solidified carbonate deposits and their re-deposition.According to the scarcity of metamorphic rocks in the supply source due to transportation.As for the igneous rock fragments, they were distinguished by their dark colours and the shape of their grains, which are circular and sharp, this indicates that the transportation distance is close and that it is derived from reworking sediments.Also, the results showed polycrystalline quartz grain shapes, which indicates diversity of sources, as the presence of monocrystalline quartz alongside polycrystalline quartz is a good indication of a different source.And that the proportion of monocrystalline is greater than that of polycrystalline, due to the poor stability of granules Polycrystalline quartz during the transfer process .This increase also reflects on transport of grains in more than one sedimentary cycle This is consistent with the study of which confirms that sedimentation in more than one sedimentary cycle is a characteristic inherent in the appearance of monocrystalline quartz grains.Which is characterized by a variety of roundness from round to sharp, as well as the presence of impurities such as mica and iron oxides is characteristic of re-deposited monocrystalline quartz.
The origin of these deposits is either volcanic or weathered rocks or storm deposits dusty, and then the monocrystalline quartz is of igneous, felsic, volcanic and terrestrial origin Polycrystalline quartz probably refers to sources of plutonic igneous rocks and metamorphic rocks, such as schist, gneiss, and Metaquartzite is derived from a variety of sources .Feldspar is one of the main minerals in the group of light minerals found in studied area sediments, as the feldspar minerals include two groups of alkali feldspars (orthoclase and microcline) and sodium feldspar (plagioclase).The round grains in which feldspar appeared indicate a dry climate, as mentioned that the round grains indicate a dry climate, or the sharp grains indicate a humid climate.On the other hand, it is considered as an indication of the length of time available and thus the rates of erosion; Hence, it is strong evidence of the intensity of wind activity , and this is clear evidence of the dryness of the climate during sedimentation processes.In this study, the proposed diagram was used by as shown in (Fig. 5) to determine the origin of the dominant source sediments at the time of sedimentation by determining the tectonics of the source area.The study area is located within Undissected Arc, this happens when they contain varieties of quartz (mono-and polycrystalline quartz, including chert) and feldspar, It is mainly characterized by a high content of unstable rock fragments such as volcanic fragments, this can occur in fluvial environments.The disaggregation of igneous and metamorphic rock pieces, along with rapid erosion of the source area and rapid deposition, may be the causes of the increase in weight% in the samples from the studied area.The distribution of heavy minerals is affected by several factors; it includes processes such as weathering, transfer factor hydrodynamics, and diagenetic process.The shapes of heavy minerals found in the study area are indicators of corrosion intensity.The study area is located within Undissected Arc; it is mainly characterized by a low content of quartz (mono-and polycrystalline quartz, including chert) and feldspar, this can occur in fluvial environments.

K
J Al-Sudani a , B N Albadran b , A S Y Al-hadadi a* , M H Al-Jaberi a and J R Pournelle c a Department of Geology, College of Science-University of Basrah, Basrah, Iraq b Almaaqal University, Basrah, Iraq c University of South Carolina School of Earth, Ocean, and Environment,

Fig. 5 :
Fig.5: Determination of source area tectonics to determine the origin of the dominant source sediments at the time of sedimentation by4.ConclusionThe disaggregation of igneous and metamorphic rock pieces, along with rapid erosion of the source area and rapid deposition, may be the causes of the increase in weight% in the samples from the studied area.The distribution of heavy minerals is affected by several factors; it includes processes such as weathering, transfer factor hydrodynamics, and diagenetic process.The shapes of heavy minerals found in the study area are indicators of corrosion intensity.The study area is located within Undissected Arc; it is mainly characterized by a low content of quartz (mono-and polycrystalline quartz, including chert) and feldspar, this can occur in fluvial environments.ReferencesAl-Sayyab, A., al-Ansari, N., al-Rawi, D., al-Jassim,J.,A., al-Amri,F.,S., and Zuhair al-Sheikh,Z., 1982.Geology of Iraq, Dar Al-Kutub for printing and publishing, Mosul, 280 pages.