http://www.sciencedirect.com/science/article/pii/S1674987115001516

The Semail ophiolite of Oman and the United Arab Emirates(UAE) provides the best preserved large slice of oceanic lithosphere exposed on the continental crust,and offers unique opportunities to study processes of ocean crust formation,subduction initiation and obduction.Metamorphic rocks exposed in the eastern UAE have traditionally been interpreted as a metamorphic sole to the Semail ophiolite.However,there has been some debate over the possibility that the exposures contain components of older Arabian continental crust.To help answer this question,presented here are new zircon and rutile U-Pb geochronological data from various units of the metamorphic rocks.Zircon was absent in most samples.Those that yielded zircon and rutile provide dominant single age populations that are 95-93 Ma,partially overlapping with the known age of oceanic crust formation(96.5-94.5 Ma),and partially overlapping with cooling ages of the metamorphic rocks(95-90 Ma).The data are interpreted as dating high-grade metamorphism during subduction burial of the sediments into hot mantle lithosphere,and rapid cooling during their subsequent exhumation.A few discordant zircon ages,interpreted as late Neoproterozoic and younger,represent minor detrital input from the continent.No evidence is found in favour of the existence of older Arabian continental crust within the metamorphic rocks of the UAE.     

Palaeoenvironmental Reconstruction of the Early to Middle Miocene Sequence in West Central Sinai,Egypt, as Revealed from Fossil Diatoms

A detailed analysis of the diatoms from the sedimentary sequence exposed in Abu Qada basin, west central Sinai, was used to determine the palaeoenvironmental changes during the Lower to Middle Miocene. A total of 85 diatom species and varieties belonging to 37 genera were identified from 154 samples collected throughout the stratigraphic succession. The lithological characters of the studied samples varied between sandstone, silty interbeds, sandy shales, shales, and terminated with anhydrite and limestones. These rock units are included in two lithostratigraphic formations (Rudies and Kareem), which are separated by a marked unconformity. The distribution and preservation of fossil diatoms in the sedimentary record are examined with the aim of outlining the temporal and spatial variation in the composition of the diatom assemblages, in order to estimate the changes in depositional environments during the Lower to Middle Miocene. The distributional pattern of the recorded diatom taxa distinguished four diatom eco-zones. The environment of each eco-zone is deduced and a proposed paleobathymetric change and depositional history of the Miocene sediments in the studied area are given.     

Geochemistry and Petrogenesis of Intracontinental Basaltic Volcanism on the Northwest Arabian Plate,Gaziantep Basin,Southeast Anatolia,Turkey

Volcanism along the northwest boundary of the Arabian Plate found in the Gaziantep Basin, southeast Turkey, is of Miocene age and is of alkaline and calc-alkaline basic composition. The rare earth element data for both compositional series indicates spinel–peridotite source areas. The rare earth and trace elements of the alkaline lavas originate from a highly primitive and slightly contaminated asthenospheric mantle; those of the calc-alkaline lavas originate from a highly heterogeneous, asthenospheric, and lithospheric mantle source. Partial melting and magmatic differentiation processes played a role in the formation of the petrological features of these volcanics. These rocks form two groups on the basis of their ~(87) Sr/~(86) Sr and ~(143) Nd/~(144) Nd isotopic compositions in addition to their classifications based on their chemical compositions(alkaline and calc-alkaline). These isotopic differences indicate a dissimilar parental magma. Therefore, high Nd isotope samples imply a previously formed and highly primitive mantle whereas low Nd isotope samples may indicate comparable partial melting of an enriched heterogeneous shallow mantle. Other isotopic changes that do not conform to the chemical features of these lavas are partly related to the various tectonic events of the region, such as the Dead Sea Fault System and the Bitlis Suture Zone.     

The First Discovery of the Easternmost Jehol Biota from Southeastern Jilin,China

正Objective The Jehol Biota,a world-famous Early Cretaceous fossil Lagerst?tte characterized by the traditional Eosestheria-Ephemeropsis-Lycoptera(EEL)assemblage,has a wide distribution over most parts of northern China,the coastal area of southeastern China,southeastern Mongolia,Transbaikalian area of Russia,Korea and Japan(Shao et al.,2017).The Baishan Basin,situated in     

Is Ziarat a Potential Site for Conventional or Unconventional Energy Resources?

A structural interpretation of the Ziarat block in the Balochistan region (a part of the Suleiman Fold and Thrust Belt) has been carried out using seismic and seismological data. Seismic data consists of nine 2.5D pre‐stack migrated seismic lines, whereas the seismological data covers the Fault Plane Solution and source parameters. Structural interpretation describes two broad fault sets of fore and back thrusts in the study area that have resulted in the development of pop‐up structures, accountable for the structural traps and seismicity pattern in terms of seismic hazard. Seismic interpretation includes time and depth contour maps of the Dungan Formation and Ranikot group, while seismological interpretation includes Fault Plane Solution, that is correlated with a geological and structural map of the area for the interpretation of the nature of the subsurface faults. Principal stresses are also estimated for the Ranikot group and Dungan Formation. In order to calculate anisotropic elastic properties, the parameters of the rock strength of the formations are first determined from seismic data, along with the dominant stresses (vertical, minimum horizontal, and maximum horizontal). The differential ratio of the maximum and minimum horizontal stresses is obtained to indicate optimal zones for hydraulic fracturing, and to assess the potential for geothermal energy reservoir prospect generation. The stress maps indicate high values towards the deeper part of the horizon, and low towards the shallower part, attributed to the lithological and structural variation in the area. Outcomes of structural interpretation indicate a good correlation of structure and tectonics from both seismological and seismic methods.