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The Sultani oil shale (OS) deposit is considered as a major fossil fuel source in Jordan. Applying various petrographic and geochemical techniques, this paper aims to study the Sultani OS geochemical and organic petrographic features. Results show that Sultani OS is a bituminous limestone consisting of very fine-grained matrix with rippled micro-laminated texture and muddy material of cryptocrystalline micrite. The rock is rich in Cretaceous microfossil shells filled in organic matter (OM). The fillingOMis bitumen of the migrabitumen type. TheOMcontent reaches up to 17 wt.% with high oil-yielding capacity (up to 12 wt.%). High TOC values suggest that the Sultani OS has a very good source rock potential. Organic petrography shows lowOMmaturity level and reveals two varieties of vitrinite, namely primary and oxidized vitrinite. The latter is derived from terrestrial plant tissues. Additionally, liptinite macerals including alginite and to a lesser extent cutinite, also participate. Various diagenetic features such as pyrite replacement and bitumen thermal alteration have been recorded. Results suggest that Sultani OS is a marinite formed under marine conditions with limited contribution of terrestrialOMinput.

This work represents the first detailed study of an oil shale (OS) section from the Upper Campanian Amman Silicified Limestone (ASL) Formation in south-western part of Jordan. More than five meters of oil shale have been recorded. Using the petrography and geochemistry, this study aims to focus on such non-conventional types of oil shale rocks in Jordan and to shed some light on their composition and formational environment. Unlike oil shale from Maastrichtian to early Tertiary, this type of oil shale is highly dolomitized. The dolomite is diagenetic in origin. This oil shale type contains considerable amount of OM and remarkably enriched in some trace elements and shows quite low sulfur content. Results suggest that the formation of dolomite appears to be limited by the rate of organic matter oxidation.

Quartz geodes are spectacularly displayed at Ras En Naqab where hundreds of geodes have weathered from their host chalky limestone and sandstone beds and scattered on slope surfaces. Geodes of different sizes, shapes and fillings appear in four horizons of the shallow marine sediments of the Upper Cretaceous Wadi Umm Ghudran Formation in South Jordan. They are characterised by a wide areal extent, but limited stratigraphic distribution, and as such, they represent a distinctive stratigraphic marker horizon. Ghudran geodes are mostly milky white in colour, botryoidally and crystalline in shape and range in diameter from 3 to 30 cm or more. It is believed that the formation of geodes took place in cavities, after complete dissolution of pre-existing fossils, which left no trace of their internal microstructures but only faint appearance of external moulds. Chalcedony and microcrystalline quartz occur as cavity linings and in some samples as cavity filling. The structure of the silica geodes begins with chalcedony in its outer rim followed, internally, by microcrystalline quartz and ends with prismatic quartz crystals in the central part. Spot analysis indicates that the geodes composed totally of Si and O with traces of Al (0.05 %). The silica-rich solutions that formed the geodes were possibly derived from the weathering of the overlying Amman Silicified Limestone Formation and the infiltration of chemical products by the action of groundwater. Investigations showed that the crystallization went slowly under equilibrium conditions and formed from the same silica source.

Surface sediments of Ziqlab Reservoir, northwest Jordan, were evaluated to characterize trace element distributions and sources related to various physicochemical variables. Trace element distribution is determined by texture, parent material in the catchment, and anthropogenic activities. The suitability of reservoir sediment for replacing or amending soil was assessed by comparing sediment characteristics to natural soils. Results suggest that the sandy facies can be used as artificial soils, whereas clayey facies can be utilized as fertilizer for poor quality soils in Jordan. The fine-grained sediment fraction is associated with (1) high abundance of clay minerals with high cation exchange capacity and available micronutrients; (2) occurrence of kaolinite, montmorillonite–illite, vermiculite, and smectite; and (3) optimal pH values for availability of most micronutrients. Among the trace elements measured, total nickel and cadmium slightly exceeded recommended safe levels for soils, but the hi...

This work discusses status of the geologic and economic potentials of minerals and industrial rocks in Jordan. The major mineral resources are presented in details and the paper is designed to cover the lack of published data in this field. Geologically, the structural framework of Jordan is controlled largely by Arabian Nubian Shield in the south, block—faulted areas in the east, upwarping in north and east, and Wadi Araba-Dead Sea Transform Fault in the western part. The geologic environments include Precambrian crystalline basement (Late Proterozoic) of Arabian Nubian Shield (ANS) that is composed of igneous and metamorphic rocks at south-western part. Paleozoic rocks at southern and southeastern part consist of clastic minerals which are dominated by sandstone, whereas Mesozoic sedimentary rocks are widespread throughout southwestern, northern to southeastern parts of the country. They mainly consist of major industrial rocks and minerals such as phosphate, oil shale, limestone, dolomite, chalk, marble, gypsum, diatomite and tripoli. Cenozoic Era is composed of sedimentary and volcanic rocks in different parts of Jordan. There are more than twenty nonmetallic minerals and four main metallic deposits within the various geologic environments. This paper summarizes their distribution, chemical and mineralogical characteristics, in addition to their production statistics.

Phosphorite concretions are recorded for the first time within the lower part of the Umm Rijam Chert Limestone Formation (Eocene) in the Ma'an area, southern Jordan. The phosphorite concretions are typically hosted and encountered as individual layer in moderately lithified sediments of marl, chalk and chalky marl. The phosphorite concretions are present in thin layer (10–30 cm thick). They are localized on a hardground surface that formed as a result of cementation of soft ground by bioclastic materials. Light grey and brownish to black colors are encountered with isometric, ellipsoid, elongated, subangular to subrounded phosphorite concretions (up to 6 cm in length). Most of the phosphorite concretions preserve bioturbation structures; they also include fecal pellets of various sizes. The main biogenic components are fragments of macrofossils (bivalves) and microfossils (planktonic foraminifera) in different proportions. Petrographic examinations reveal that the phosphorite concretions are composed of cryptocrystalline apatite that characteristically appears in cross-polarized light almost as isotropic phosphate and minor anisotropic phosphate. Apatite and calcite are the main mineral constituents of the phosphorite concretions identified by XRD. The apatite is identified as francolite (carbonate-flour-apatite). Chemical analyses of the phosphorite concretions using X-ray florescence indicate that the P2O5 content ranges from 18.8 to 31.19%, whereas SEM–EDS analyses indicate that the phosphorus proportion is around 14% by volume. It could be argued that the phosphorite concretions were transported after being reworked, or were derived from carbonate and chalk pebbles that were later phosphatized and subjected to erosion, forming residual lag deposit along the hardground surface.

K–Ar dates, petrographic and chemical data were obtained from representative samples from three NW–SE trending basaltic dikes in the Harrat Ash Shaam Volcanic Field, northeast Jordan. Compared with other NE–SW trending dikes in Jordan, three phases of activity were determined for the studied dikes starting from the oldest (around 23 Ma) to the youngest at around 1.7 Ma. Three dominant petrotypes of basalt were distinguished and related to the three phases. During the Early Miocene, there was emplacement of a pyroxene–iddingsite basalt (23%), which is characterized by a tholeiitic composition. Later, in the Middle to Late Miocene, the composition was that of pyroxene olivine basalt (34%) with an increase in the alkaline character of the magma chamber. In the final stage, the dikes comprised olivine basalt (22%) with a basanite composition. It is reasonable to assume that the emplacement of the dikes was part of the same volcanic phase and regional tectonic regime associated with the phases of volcanic activity of the Red Sea System.

Degradation and subsequent calcitization of phosphate grains from the upper part of the Late Cretaceous Amman Formation at southeast Irbid in northern part of Jordan have been petrographically verified. A number of calcitization patterns were observed. The variety in calcitization patterns reflects the replacing nature of calcite. Filamentous schizophytes are assisted, through borings, in early degradation of bone fragments into phosphomicrite fillings and dark envelopes (haloes) around grains. Calcitization process is more likely attributed to the availability of calcite, restriction of apatite formation, nature and composition of phosphate grains, varying pH of sediment and pore-fluids and physico-chemical conditions of the depositional site. Diagenetic replacement of phosphate grains by calcite as a result of calcitization process resulted in poorer grade of phosphate deposits where the P2O5 is less than 15.2%.

Fault zones are the locations where motion of tectonic plates, often associated with earthquakes, is accommodated. Despite a rapid increase in the understanding of faults in the last decades, our knowledge of their geometry, petrophysical properties, and controlling processes remains incomplete. The central questions addressed here in our study of the Dead Sea Transform (DST) in the Middle East are as follows: (1) What are the structure and kinematics of a large fault zone? (2) What controls its structure and kinematics? (3) How does the DST compare to other plate boundary fault zones? The DST has accommodated a total of 105 km of left-lateral transform motion between the African and Arabian plates since early Miocene (similar to 20 Ma). The DST segment between the Dead Sea and the Red Sea, called the Arava/Araba Fault (AF), is studied here using a multidisciplinary and multiscale approach from the mu m to the plate tectonic scale. We observe that under the DST a narrow, subvertical zone cuts through crust and lithosphere. First, from west to east the crustal thickness increases smoothly from 26 to 39 km, and a subhorizontal lower crustal reflector is detected east of the AF. Second, several faults exist in the upper crust in a 40 km wide zone centered on the AF, but none have kilometer-size zones of decreased seismic velocities or zones of high electrical conductivities in the upper crust expected for large damage zones. Third, the AF is the main branch of the DST system, even though it has accommodated only a part (up to 60 km) of the overall 105 km of sinistral plate motion. Fourth, the AF acts as a barrier to fluids to a depth of 4 km, and the lithology changes abruptly across it. Fifth, in the top few hundred meters of the AF a locally transpressional regime is observed in a 100-300 m wide zone of deformed and displaced material, bordered by subparallel faults forming a positive flower structure. Other segments of the AF have a transtensional character with small pull-aparts along them. The damage zones of the individual faults are only 5-20 m wide at this depth range. Sixth, two areas on the AF show mesoscale to microscale faulting and veining in limestone sequences with faulting depths between 2 and 5 km. Seventh, fluids in the AF are carried downward into the fault zone. Only a minor fraction of fluids is derived from ascending hydrothermal fluids. However, we found that on the kilometer scale the AF does not act as an important fluid conduit. Most of these findings are corroborated using thermomechanical modeling where shear deformation in the upper crust is localized in one or two major faults; at larger depth, shear deformation occurs in a 20-40 km wide zone with a mechanically weak decoupling zone extending subvertically through the entire lithosphere.

The volcanism in the western Arabian plate extends from the Red Sea through the Harrat Ash Shaam system to western Syria, as far north as the Bitlis suture in the Taurides. The Harrat Ash Shaam volcanic system in Jordan consists of northwest-trending dikes and a volcanic field that together encompass a width of 220 km. In terms of width, direction, and age of the main volcanic phases, the system is similar to the Red Sea dike belt. About 130 new K-Ar age determinations show that the ages of the Harrat Ash Shaam system (dikes and flows) range from Oligocene to Quaternary. However, there is a distinct gap in the ages between ∼22 and 13 Ma. This gap coincides with an apparent decrease in volcanism in the Red Sea region from around 20 to 12 Ma. We interpret this 9 m.y. gap as a quiescent period interrupting the volcanic activity in the region and suggest that from ∼22 to 13 Ma, tectonic activity in the Arabian plate was mainly restricted to the Red Sea region. A renewal of volcanism along the western margins of the Arabian plate at 13 Ma was very likely associated with the sinistral movement along the north-trending Dead Sea transform. This renewal of volcanism and tectonic activity may reflect the emergence of upper-mantle upwelling beneath the western Arabian plate at that time.