SEGURIDAD y RIESGO COMO COMPONENTE DEL DERECHO A LA VIDA 28

The Syrian territory belongs to the northern edge of the Arabian Platform (Krasheninnikov et. al. 1996) consisting of the inner zone of a stable shelf and a more mobile zone in the north belonging to the mobile shelf. The stable inner zone comprises the southern part of Syria with the Jordan uplift, the Drouz depression and the Rutba anteclise. The study region belongs to the mobile shelf, where the Ad-Dauw basin and the Balas uplift (Fig. 4.12) can be differentiated within the folded area of the Palmyrides (aulacogene). The folded zone is surrounded by the Northern Palmyrian fault and the Southern Palmyrian fault which is the most prominent with vertical displacements up to 1000 m. The northern part of the zone is composed of large folds complicated by smaller anticlines (Fig. 4.12).

The southern subzone shows asymmetrical linearly extended anticlines (10 – 25 km) with gentle sloping western limbs (10 to 20 °) and steep south-eastern limbs (up to 30 ° to 40 °) and faulty. Cretaceous sediments and Jurassic rocks are present in the core, Paleogene sediments are characteristic for the limbs. The subzone is bordered by the Dimachq fault in the southwest and the Ad-Dauw Basin, filled with neogene-quaternary sediments in the north.

In the Northern Palmyrides mainly sediments of Cretaceous age are found. The oldest sediments outcropping in the Palmyrides belong to the Jurassic age. A section of about 60 to 100 m of dolomites, the largest outcrops in Syria of the Middle and Upper Jurassic are found in the Palmyrides at Jebel Naqnaniyeh (Bajocian sediments: dolomites of about 180 m) and Jebel Ash Shath (Callovian sediments, several 10 m thick: limestones and marls and Oxfordian beds, consisting of dolomites and clayey limestones of about 60 m) (Ponikarov et al. 1967). The upper slopes of the Palmyrides are mainly constituted of Cretaceous sediments. The lower slopes are constituted of Paleogene age. The rock outcrops of the younger and middle Cretaceous are limestones and dolomites. The layers of Upper Cretaceous are characterized by mergelic limestones with glauconites and geodes.

Fig. 4.12 Tectonic subdivision (Krasheninnikov et al. 1996)

The outcrops of the Cretaceous formation are between 200 to 300 m thick in the Northern and Southern Palmyrides. The lithofacies is mainly limestones and sandstones, intercalated partly with gypsum beds and organo-granular phosphate intercalations. In the other areas the Cretaceous rocks are overlaid by Paleogene sediments.

The series of the Paleogene, exposed southeast of Tadmor, are dated according to planktonic and benthonic small foraminifera. The Paleogene consists of calcareous marls and clayey limestone. The clay content is highest in this lower Palaeogene sequence.

Flintstones of nodular type are mainly found here in nodular type. The Palaeogene formation is mainly consistent in depressions like in the Wadi El-Bardeh. The Lower Eocene sequence of limestones, marls, alternating with flints can be differentiated from the Upper Cretaceous. The Middle Eocene is characterized by softlike chalky limestones and organic limestones with large nummulites sometimes with beds of marls with glauconite and phosphate nodules and flint streaks. In the upper part of the Middle Eocene chalk-like

4.3 Soilscape units 96

limestones with block-jointing are present, in some places containing large baryte concretions. The Upper Eocene is composed of chalk like limestones and nummulitic limestones.

According to the investigations based on geochronological methods (radiometric: K-Ar isotopes, Rb-Sr, and foraminifera zones) (Krasheninnikov et. al. 1996) the Paleaogene of Syria is characterized as follows: Lower Eocene sediments comprise foliated calcareous clays, marls. The uppermost Lower Eocene and Middle Eocene show an alternation of limestones with black and brown cherts forming independent questas or ridges. The flints are mainly chalcedonic which means that the transition from gel-liquid to calcedony is complete. Nevertheless the chert content of some of the Eocene formations do not exceed 3% (Krasheninnikov et al. 1996). White and grey chalky limestones and marls with planktonic microorganisms typifies the Middle Eocene and an alternation of chalky massive biogenic and softer fine-grained pelitic limestones can be distinguished for the Upper Eocene. Oligocene sediments with a thickness of about 120 m are present on the southern and northern footslopes of the Northern Palmyrides and in the region of the Ad-Dauw Basin. The lithofacies is characterized by massive coarse layered limestones containing coral colonies, pelecypods, foraminifera, intercalated especially in the higher layers with sandy limestones, sandstones and clays.

In the area of Wadi El-Bardeh the Oligocene sediments consist of sandy limestones and sandstones with vertical burrows of different shapes filled with siliceous concretions.

Oligocene sediments consist of shallow water massive coarse – layered, fine-grained, aphanitic and biogenic limestones with terrigeneous sediments like sand and clay rocks at the top. Facies and thicknesses varies with respect to tectonic structure. Most of the sediments comprises glauconite horizons and the planktonic foraminifera allows subdivision of the sediments according to the 26 subglobal based on the Paleogene formainiferal zonal scale of the Caribbean basin within deep sea drilling project research in 1968.

The Lower Miocene sediments present west of Tadmor comprises continental, sometimes silicified sandstones and limestones. Middle Miocene sediments are gypsum beds, limestones and sandstones nearby and west of Tadmor. Upper Miocene sediments are not present in the project area. Pliocene sediments, mainly conglomerates and sandstones with small beds of clays and marls, containing freshwater mollusks shells fill depressions in the mountain ranges like the Ad-Dauw basin.

Proluvial quaternary sediments are mainly found in the southeastern part of the study area and the intermontane basin of Ad-Dauw. They are composed of debris cones, i.e.

pebble and gravel beds, comprising local rocks. Upper Quaternary proluvial deposits are

most widespread within the quaternary deposits consisting of rocks with loam debris and pebbles. Bedded clay, loam and sandy marls form the Upper Quaternary sediments in the Tadmor basin.

Miocene volcanic rocks probably from ocean floor volcanism are found in the Wadi Mihassa where a dolerite sill, detectable for 4 km, within the Middle Miocene Series . Pliocene basalt cone is found on Paleogene sediments near Mihassa. These are remnants of volcanic cones in dissected tableland and consist of numerous interbedded lava flows 4 – 50 m thick. The basaltic outflows form very blocky material which obstructs water flow.

The red sands on the road Palmyra-El Basiri-Damascus seem to be decomposed basalt remnants. The red sands are quite abundant and can be used as construction material