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New Data about the Tectonic Structure of the Arabian Plate by Interpretation of Space images
Dr. Eng. M. Rukieh
General Organization of Remote Sensing
Director General
Introduction
This research aims to study the tectonics of the Arabian plate using space images data of distinguished characteristics, especially the multispectral TM of resolution 30m, where we can take benefit from the important specifications of these images such as:
1- Synoptic Coverage
These images enable us to see, in the same time, the Arabian Plate completely, and study its general tectonic characteristics.
2- The multi-spectral characteristics of these digital images give more information about the specifications of the plate.
3- The possibility of processing these images by the different digital processing methods through modern software as IRDAS and merging of different channels.
Through this research we prepared several tectonic schemes (13/1 million) and less, and we get important data about the structure of the Arabian Plate, the most important of them are:
- Identifying three annular structures of different dimensions (big and very big).
- Identifying five tectonic systems which extend for hundreds of kilometers towards western north, starting from Alaqaba gulf in the western south till the Arabian gulf in the eastern north. As well as identifying another fault systems.
- Identifying the general characteristics of the Arabic Rift System, which forms the western borders of the Arabian Plate
- Identifying the erupted volcanic rocks inside the plate, especially in the area of Harrat Asham, Jordan, Wadi Sarhan, Jadah and Almedina in Saudi Arabia and the wind phenomena in it.
The Location of the Arabian Plate:
The Arabian Plate forms the northern part of the African plate where it was separated from it during the Miocene by the Red Sea rift. The southern part named Arabian Peninsula where three seas surround it from three directions: the Red sea from the western south, Addan gulf and Arab sea from the south and the eastern south, and the Arabian Gulf from the eastern north. It is bordered by a bend belt and the faults of AlAnadoul, Zagharous and Tebles (fig.1). In its western south parts the Precambrian Arabian shield rocks are revealed, and covered by recent sedimentary rocks to north and eastern north from Paleozoic till Quaternary. The rocks thickness exceeds 10kms in the north of Iraq and Syria.
The General Tectonic Characteristics of the Arabian Plate:
The following main annular and linear structures have been identified through the interpretation of the space images (13/1 million – 1/5 million scales) (fig.2)
1- Annular structures:
The annular structures represent the geological shapes and phenomena which have central symmetry, and of ring, circular or oval shapes and they are different, in their structures, from other surrounding phenomena. Also, these structures differ in their dimensions, origin and the characteristics of their identification on earth or space images. They form one of the most important structural elements in the earth crust. Their dimensions range from many meters till hundred or thousands kms.
Our study has shown the following main annular structures:
The first one: (no.1 in fig.2)
It covers the most important part of the western plate on the eastern south side of the Red Sea, its northern borders reach Alaqaba gulf. It is composed of many concentric rings which take an oval-oblate shape; its radius reaches more than 900km. It seems that the rift of the Red sea has divided it into two parts (right and left); the right one appears in the Arabian plate, it is very big and forms one of the most known regional structures on the glob.
We can notice inside this structure many smaller structures such as the one which exists to the east of Alaqaba gulf (no.1-B), where its diameter reaches about 150km. The rocks of the Arabian shield form the central core of this structure, these rocks reveal in the east of the Red sea and appear in the space images as a bow, its depression reaches about 700km in its middle part, then it gradually confined towards north for less than 100km in Jordan, and less than 200km in the south of Yemen, after that it disappears under the recent sediments (Abed 2000). The rocks of the Arabian shield are composed of two main groups (Ashanti 1993): the first group is composed of igneous rocks, which can found as intrusive batholith and dyks, they are composed of basic and ultrabasic rocks as Gabbro, Pyredotite, Dunite, or middle as Diorite or acidic as Granite which exposed to metaphorism and deformation. The second group is composed of metamorphic rocks as schist, Gneiss, slate, and others which were resulted from the transformation of sedimentary pyroclastics layered rocks.
The researchers agree that the age of the Arabian Nubian shield rocks range between 1000-450 million years (Bentror 1985, Mc Court 1990, Ashanti 1993) in spite of the fact that there are some signs refer that their age may reach 1600 million year.
The second structure (no.2, fig.2):
It is located on the northern borders of the first structure; it is concentric and composed of core and outer ring and covers the areas of west of Iraq, south of Syria, east of Jordan and north of Saudi Arabia. It conforms , geologically, part of Arrotbah uplift, its radius reaches 350km, and the radius of its core is about 70km. The volcanic eruptions have deformed its western south side in the south of Syria, north of Jordan.
Inside this structure, we have noticed several smaller oval annular structures, it is complex tectonically and affected by a big number of faults, of north, western north or eastern north direction, for example Akfan and Alolab faults, they are of right lateral displacement (Rukieh and others 2002) which extend on areas of more than 150km. in addition to several faults and fissures which take the mentioned directions and they form small depressions.. Arrotba uplift is considered as one of the most important tectonic phenomena in the north of Arabian Plate, it was originated during the Paleozoic and continues till the following ones, where it formed positive high starting from the Carboniferous, the most occurrences of the early Paleozoic are concentrated in this uplift (Sawaf etal.1993).
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