Statistics for Spatial Data.

Late Cryogenian-Ediacaran history of the Arabian-Nubian Shield: A review of depositional, plutonic, structural, and tectonic events in the closing stages of the northern East African Orogen

Today it is generally recognized that the particular behaviour of trace metals in the environment is determined by their specific physicochemical forms rather than by their total concentration. Several chemical speciation and fractionation methods for heavy metal analysis in soils and sediments have been and are still being developed and applied. They primarily are intended to understand the particular environmental behaviour of metals, present in a variety of forms and in a variety of matrices. Analytical developments, modifications of existing methods, and recent new approaches are reviewed and discussed. Techniques used include chemical extractions, ion-exchange/gel chromatography, filtration, centrifugation and sieving, selective solvent extraction. Moreover, the application of these various techniques in different research fields over the last years is explored. The value and the limitations of speciation and fractionation techniques applied in specific experimental work is outlined. It is d...

Chemical Speciation and Fractionation in Soil and Sediment Heavy Metal Analysis: A Review

Two distinct phases of continental magmatism are evident in western Arabia The first, from about 30 to 20 Ma, produced tholeiitic-to-transitional lavas emplaced along NW trends The second, from about 12 Ma to Recent, produced transitional-to-strongly-alkalic lavas emplaced along N-S trends The older phase is attributed to passive-mantle upwelling during extension of the Red Sea Basin, whereas the younger phase is attributed to active-mantle upwelling but was facilitated by minor continental extension perpendicular to plate collision The younger magmatic phase is largely contemporaneous with a major period of crustal uplift to produce the West Arabian Swell after about 14 Ma A variety of evidence suggests that the West Arabian Swell is thermally supported by hot, upwelling asthenosphere In contrast to the distinct asymmetry of uplift and magmatism on opposing sides of the Red Sea Basin, these processes were symmetric across a N-S line marking the central axis of the West Arabian Swell This axis coincides with two fundamental features: the Ha'il-Rutbah Arch in the north, and the Makkah-Madinah-Nafud (MMN) volcanic line in the south The symmetry of magmatism is demonstrated by petrochemical evidence that the MMN harrats were derived by greater degrees of partial melting, at shallower depths, than those harrats lying to the west and east of the MMN line The potential temperature of the asthenosphere is estimated to be about 1436°C beneath the MMN line and about 1354°C beneath the flanking, more undersaturated harrats The source of upwelling is either a mantle plume centrally located beneath the West Arabian Swell or an elongated and extended lobe of hot asthenosphere emanating from the Ethiopian mantle plume Convective flow may have been channelled along a preexisting, regional flexure in the continental lithosphere which concentrated hot asthenosphere beneath the central axis of the AfroArabian Dome This crest of mantle upwelling underlies the MMN line in the north and the Danakil Depression and Ethiopian rift system in the south It also passes through the Red Sea Basin at the midpoint of an unusual, doubly propagating rift system where axial seafloor spreading began 4–5 my ago The NW trend of the Red Sea Basin was well established by crustal attenuation during the older magmatic phase The Pliocene invasion of this basin by a N-S zone of mantle upwelling has resulted in seafloor spreading parallel to the preexisting structure along a rift system that has continued to propagate away from its eccentric mantle source in two opposing directions

Upwelling asthenosphere beneath western Arabia and its regional implications

\n The regularly spaced, N-trending Summan Platform, Khurais-Burgan Anticline, En Nala (Ghawar) Anticline and Qatar Arch in the eastern part of the Arabian Plate appear to have formed during the Precambrian Amar Collision between about 640 and 620 million years ago. This collision occurred along the N-trending Amar Suture (that bisects the Arabian Peninsula at about longitude 45 E) when the Rayn micro-plate in the east was fused to the western part of the Arabian Craton. The great anticlines are bounded by the NE-trending Wadi Batin Fault and NW-trending Abu Jifan Fault that converge on the Amar Suture. Deep wells drilled into these anticlines intersected deformed metasediments that are dated as syn-collisional. The Amar Collision was followed by a widespread extensional collapse of the Arabian-Nubian Shield between about 620 and 530 million years ago. During the final extensional stage, between about 570 and 530 million years ago, the NW-trending Najd Fault System dislocated the Arabian Shield left-laterally by about 250 to 300 kilometers. This dislocation appears to complement NE-oriented intra-continental rifts in Oman, Pakistan, Zagros Mountains and the Arabian Gulf. In these rift basins there accumulated thick sequences of clastic and carbonate rocks and salt, such as the Ara Group in Oman, Salt Range Formation in Pakistan, and Hormuz Series in the Arabian Gulf and Zagros Mountains. During the extensional collapse, the N-trending anticlines probably remained elevated as elongated horsts bounded by normal faults. The intervening subsiding grabens accumulated syn-rift sediments including the Hormuz Salt, and form an inter-fingering pattern between the great N-trending anticlines. The Precambrian anticlines, together with the syn-rift salt form the foundations of most of the hydrocarbon traps in the Arabian Plate.

Origin of the Arabian Plate Structures: Amar Collision and Najd Rift

http://www.utdallas.edu/~rjstern/pdfs/Jarraretal.pdf

Late- and post-orogenic Neoproterozoic intrusions of Jordan: implications for crustal growth in the northernmost segment of the East African Orogen

The main objective of this study was to assess the spatial and temporal variability of groundwater level fluctuations in the Amman–Zarqa basin, during the period 2001–2005. In the year 2003, as a consequence of war, there was a sudden increase in the population in this basin. Knowing that the basin is already heavily populated and witnesses most of the human and industrial activities in Jordan, this study was prompted to help make wise water resources management decisions to cope with the new situation. Data from 31 fairly distributed wells in the upper aquifer of the basin were subjected to geostatistical treatment. Kriging interpolation techniques have indicated that the groundwater flow directions remained almost constant over the years. The two main directions are SW–NE and E–W. Kriging mapped fluctuations have also showed that drop and rise events are localized in the basin. Forecasting possibilities for management purposes were tackled using autocorrelation analysis. The constructed autocorrelograms indicated, in general, the temporal dependence of seasonal water level fluctuations, and that forecasting can be carried out within a period of 3–21 months. Several suggestions were made to mitigate the drop and rise hazards in the detected sites.

Geostatistical analysis of spatiotemporal variability of groundwater level fluctuations in Amman–Zarqa basin, Jordan: a case study

A late Proterozoic bimodal volcanic/subvolcanic suite from Wadi Araba, southwest Jordan

Large tectonic and lithospheric structures of the Red Sea region

The evolution of a Pan-African (c. 900–550 Ma) suite of composite dikes, with latite margins and rhyolite interiors, from southwest Jordan is discussed. The dikes cut the Neoproterozoic calc-alkaline granitoids and high-grade metamorphic rocks (c. 800– 600 Ma) of the northern Arabian-Nubian Shield in Jordan and have been dated by the Rb-Sr isochron method at 566 � 7 Ma. The symmetrically distributed latite margins constitute less than one-quarter of the whole dike thickness. The rhyolite intruded a median fracture within the latite, while the latter was still hot but completely solidified. The dikes are alkaline and bimodal in composition with a gap in SiO2 between 61 and 74 wt%. Both end members display similar chondrite-normalized rare earth element patterns. The rhyolites display the compositional signature of A-type granites. The (La/Lu)N values are 6.02 and 4.91 for latites and rhyolites, respectively, and the rhyolites show a pronounced negative Eu anomaly, in contrast to the slight negative Eu anomaly of the latites. The chemical variability (e.g. Zr/Y, Zr/Nb, K/Rb) within and between latites and rhyolites does not support a fractional crystallization relationship between the felsic and mafic members of the dikes. We interpret the magma genesis of the composite dikes as the result of intrusion of mantle-derived mafic magma into the lower crust in an extensional tectonic regime. The mafic magma underwent extensive fractional crystallization, which supplied the necessary heat for melting of the lower crust. The products of the initial stages of partial melting (5–10%) mixed with the fractionating mafic magma and gave rise to the latite melts. Further partial melting of the lower crust (up to 30%) produced a felsic melt, which upon 50% fractional crystallization (hornblende 15%, biotite 5%, feldspars 60%, and quartz 20%) gave rise to the rhyolitic magma. Copyright # 2004 John Wiley & Sons, Ltd. Received 20 March 2002; revised version received 2 March 2003; accepted 20 March 2003

/pdf/origin-age-and-petrogenesis-of-neoproterozoic-composite-250csoq74a.pdf

G. Saffarini

Papers

Late- and post-orogenic Neoproterozoic intrusions of Jordan: implications for crustal growth in the northernmost segment of the East African Orogen

Geostatistical analysis of spatiotemporal variability of groundwater level fluctuations in Amman–Zarqa basin, Jordan: a case study

A late Proterozoic bimodal volcanic/subvolcanic suite from Wadi Araba, southwest Jordan

Large tectonic and lithospheric structures of the Red Sea region

Origin, age and petrogenesis of Neoproterozoic composite dikes from the Arabian‐Nubian Shield, SW Jordan