Les enclaves du volcanisme recent du rift syrien

2001 ◽  
Vol 172 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Ahmad Bilal ◽  
Jacques L. R. Touret
Keyword(s):  
Dead Sea ◽  
Mantle Metasomatism ◽  
Arabian Plate ◽  
Spinel Peridotite ◽  
Quaternary Volcanism ◽  
The North ◽  
Exact Position ◽  
Limited Degree ◽  
Tubular Inclusions ◽  
Lateral Displacements

Abstract In direct continuity with the Dead Sea fault, the Syrian rift, which links the rigid Arabian plate to the mobile ophiolite belt of Cyprus-southern Turkey, plays a very important role in the regional geodynamic structure. Its exact position, as well as the related fracture system, has been documented from the analysis of a complete aerial photo coverage of the whole Syrian territory. The rift corresponds to a transform fault, with lateral displacements decreasing from more than 100 km, to the south, to less than 30 km to the north. Several major episodes of volcanic activity have occurred since early Mesozoic times, with eruptive centers located in three major domains, southern (S), center (M) and northern (N), respectively. The recent (Neogene-Quaternary) volcanism is compared to the Cretaceous one (Bhannes-Tayasir episode). Erupted lavas are in general very basic (picrobasalts, basanites), with rather primitive magmas, except for one occurrence at El Kafr (southern Syria) which corresponds to a silica-undersaturated, strongly differentiated phonolite. Major and partial (Rb, Ba, Nb, Sr, Y, Lu) trace-element data show overall similarities between recent and Cretaceous volcanisms, with however a more distinct alkaline trend and stronger variations of LILE-elements for recent lavas. Few volcanoes contain a number of ultrabasic xenoliths, notably lherzolites, harzburgites and pyroxenites. Rare garnet-bearing varieties have also been observed in M and S-domains, including few grenatites. Xenolith texture is protogranular or granular, with a variable (mostly limited) degree of local melting by the enclosing basalt. Olivines are Mg-rich (mg (super *) = 0.93-0.83), as are ortho-and clinopyroxene. This last mineral, which may show spectacular Opx and spinel exsolution lamellae, is relatively abundant, as shown by the frequent occurrence of pyroxenite (Cpx-Opx) and Cpx-rich lherzolite (wehrlite). Because of the possible occurrence of Cretaceous rocks with kimberlitic affinities [Nabi Mata, Sharkov et al., 1993], garnet has been studied in detail. On the garnet triangle, most analyses plot well away from high-pressure mantle rocks, notably kimberlites, but close to infracrustal garnet-bearing rocks (granulites). Very few analytical points (3 out of a total of 20) could correspond to garnet peridotite. All other rocks are equilibrated in the field of spinel peridotite or infracrustal granulites. Pure CO 2 -bearing fluid inclusions have been found in olivine and pyroxenes from xenoliths and in phenocrysts from enclosing basalts. Highest density fluids (up to 1.15 g/cm 3 ), are observed in pyroxenites, especially from M-domain. They occur in primary, tubular inclusions adjacent to or even containing minute spinel grains, oriented along the exsolution lamellae of the clinopyroxene-host. P-T conditions of mineral equilibration in the xenoliths have been estimated from the pyroxene thermometer [Bertrand and Mercier, 1986; Brey and Kohler, 1990] and maximum density of fluid trapped in primary inclusions. They correspond to about 1 100-1 300 degrees C for the temperature, 10-13 kb for the pressure. These P-T conditions do not show any significant variation between different regional occurrences, but well between various petrographical types, the maximum conditions being recorded in pyroxenites. These results suggest that some clinopyroxene at least has been formed by mantle metasomatism caused by ephemeral carbonate magmas, in a mantle plume located under the Arabic plate.

A review of the tectonics of the northern Middle East region

1984 ◽  
Vol 121 (6) ◽  
pp. 577-587 ◽  
Author(s):  
P. E. R. Lovelock
Keyword(s):  
Late Cretaceous ◽  
Kinematic Model ◽  
Continental Collision ◽  
Dead Sea ◽  
Plate Motion ◽  
Arabian Plate ◽  
Southern Boundary ◽  
The North ◽  
The Dead ◽  
Two Stages

AbstractThe structure of the northern part of the Arabian platform is reviewed in the light of hitherto unpublished exploration data and the presently accepted kinematic model of plate motion in the region. The Palmyra and Sinjar zones share a common history of development involving two stages of rifting, one in the Triassic–Jurassic and the other during late Cretaceous to early Tertiary times. Deformation of the Palmyra zone during the Mio-Pliocene is attributed to north–south compression on the eastern block of the Dead Sea transcurrent system which occurred after continental collision in the north in southeast Turkey. The asymmetry of the Palmyra zone is believed to result from northward underthrusting along the southern boundary facilitated by the presence of shallow Triassic evaporites. An important NW-SE cross-plate shear zone has been identified, which can be traced for 600 km and which controls the course of the River Euphrates over long distances in Syria and Iraq. Transcurrent motion along this zone resulted in the formation of narrow grabens during the late Cretaceous which were compressed during the Mio-Pliocene. To a large extent, present day structures in the region result from compressional reactivation of old lineaments within the Arabian plate by the transcurrent motion of the Dead Sea fault zone and subsequent continental collision.

Early to Middle Miocene intra-continental basaltic volcanism in the northern part of the Arabian plate, SE Anatolia, Turkey: geochemistry and petrogenesis

2007 ◽  
Vol 144 (5) ◽  
pp. 867-882 ◽  
Author(s):  
MUSA ALPASLAN
Keyword(s):  
Trace Elements ◽  
Melt Inclusions ◽  
Crustal Contamination ◽  
Dead Sea ◽  
Major And Trace Elements ◽  
Garnet Peridotite ◽  
Arabian Plate ◽  
Magma Ascent ◽  
Primitive Mantle ◽  
Spinel Peridotite

Continental basalts ranging in age from 16.5 to 19.08 Ma crop out throughout the northern part of the Arabian plate. The basalts have distinctive petrographic characteristics such as rounded and skeletal olivine phenocrysts with abundant melt inclusions, implying the mixing of two distinct magmas. All of the analysed basalts are tholeiitic in composition. The presence of quartz xenocrysts with clinopyroxene rims in some samples indicates that crustal assimilation was probably an important process during magma ascent to the surface, and low Mg number and high SiO2 contents of the basalts clearly show that they have experienced fractional crystallization as well as crustal contamination. Variations of the major and trace elements versus MgO show that olivine+clinopyroxene+plagioclase were the main fractionating minerals. In terms of incompatible trace elements, the basalts have OIB-like signatures with a slight depletion at Nb–Ta on primitive-mantle-normalized diagrams. The basalts have slightly LREE enriched patterns with La/YbN = 5.5 to 6.7. La/Nb ratios are close to unity, suggesting the melts may have originated in the asthenospheric mantle. Partial melting modelling based on REE data imply that the melts were not produced from a single mantle source depth, which is either purely a spinel- or garnet-peridotite end member. The samples lie on a binary mixing line between low-degree melts (<5%) from garnet-peridotite and higher-degree melts (>10%) from spinel-peridotite sources on a plot of La/Yb v. Dy/Yb, requiring interaction of melts derived from both garnet- and spinel-peridotite fields. Melts originating from both sources were initially tapped by distinct magma chambers, which subsequently hybridized into a single flow. Hybridized magma ascended to the surface along Neogene strike-slip faults, which are linked to the Dead Sea Fault Zone.

The Metasomatized Mantle beneath the North Atlantic Craton: Insights from Peridotite Xenoliths of the Chidliak Kimberlite Province (NE Canada)

2019 ◽  
Vol 60 (10) ◽  
pp. 1991-2024 ◽  
Author(s):  
M G Kopylova ◽  
E Tso ◽  
F Ma ◽  
J Liu ◽  
D G Pearson
Keyword(s):  
North Atlantic ◽  
Thermal State ◽  
Mineral Chemistry ◽  
Mantle Metasomatism ◽  
Labrador Sea ◽  
The North ◽  
Rock Types ◽  
History Of ◽  
The North Atlantic ◽  
North Atlantic Craton

Abstract We studied the petrography, mineralogy, thermobarometry and whole-rock chemistry of 120 peridotite and pyroxenite xenoliths collected from the 156–138 Ma Chidliak kimberlite province (Southern Baffin Island). Xenoliths from pipes CH-1, -6, -7 and -44 are divided into two garnet-bearing series, dunites–harzburgites–lherzolites and wehrlites–olivine pyroxenites. Both series show widely varying textures, from coarse to sheared, and textures of late formation of garnet and clinopyroxene. Some samples from the lherzolite series may contain spinel, whereas wehrlites may contain ilmenite. In CH-6, rare coarse samples of the lherzolite and wehrlite series were derived from P = 2·8 to 5·6 GPa, whereas predominant sheared and coarse samples of the lherzolite series coexist at P = 5·6–7·5 GPa. Kimberlites CH-1, -7, -44 sample mainly the deeper mantle, at P = 5·0–7·5 GPa, represented by coarse and sheared lherzolite and wehrlite series. The bulk of the pressure–temperature arrays defines a thermal state compatible with 35–39 mW m–2 surface heat flow, but a significant thermal disequilibrium was evident in the large isobaric thermal scatter, especially at depth, and in the low thermal gradients uncharacteristic of conduction. The whole-rock Si and Mg contents of the Chidliak xenoliths and their mineral chemistry reflect initial high levels of melt depletion typical of cratonic mantle and subsequent refertilization in Ca and Al. Unlike the more orthopyroxene-rich mantle of many other cratons, the Chidliak mantle is rich (∼83 vol%) in forsteritic olivine. We assign this to silicate–carbonate metasomatism, which triggered wehrlitization of the mantle. The Chidliak mantle resembles the Greenlandic part of the North Atlantic Craton, suggesting the former contiguous nature of their lithosphere before subsequent rifting into separate continental fragments. Another, more recent type of mantle metasomatism, which affected the Chidliak mantle, is characterized by elevated Ti in pyroxenes and garnet typical of all rock types from CH-1, -7 and -44. These metasomatic samples are largely absent from the CH-6 xenolith suite. The Ti imprint is most intense in xenoliths derived from depths equivalent to 5·5–6·5 GPa where it is associated with higher strain, the presence of sheared samples of the lherzolite series and higher temperatures varying isobarically by up to 200 °C. The horizontal scale of the thermal-metasomatic imprint is more ambiguous and could be as regional as tens of kilometers or as local as &lt;1 km. The time-scale of this metasomatism relates to a conductive length-scale and could be as short as &lt;1 Myr, shortly predating kimberlite formation. A complex protracted metasomatic history of the North Atlantic Craton reconstructed from Chidliak xenoliths matches emplacement patterns of deep CO2-rich and Ti-rich magmatism around the Labrador Sea prior to the craton rifting. The metasomatism may have played a pivotal role in thinning the North Atlantic Craton lithosphere adjacent to the Labrador Sea from ∼240 km in the Jurassic to ∼65 km in the Paleogene.

Displacement and stress field along part of the Cobequid Fault, Nova Scotia

1969 ◽  
Vol 6 (5) ◽  
pp. 1095-1104 ◽  
Author(s):  
Gerhard H. Eisbacher
Keyword(s):  
Stress Field ◽  
Fault Zone ◽  
Maximum Compressive Stress ◽  
Clastic Rocks ◽  
The North ◽  
Total Displacement ◽  
Displacement Vectors ◽  
Lateral Displacements ◽  
Fault Trace ◽  
Southern Flank

The east-trending Cobequid Fault separates pre-Carboniferous rocks of the Cobequid Mountains to the north from Carboniferous clastic rocks along the southern flank of the mountains. A detailed study of the fault zone revealed tie predominance of right-lateral displacements. The orientation of the stress field that existed during deformation along the fault trace was determined by the study of systematic fractures in pebbles within Carboniferous conglomerate. Maximum compressive stress was aligned in a NW–SE direction, being compatible with the orientation of the displacement vectors in the fault zone. Transcurrent movement along the Cobequid Fault occurred in late Pennsylvanian time and involved both Carboniferous and pre-Carboniferous rocks; total displacement is unknown.

Bathymetry and uplift rate of the Gulf of Aqaba, Dead Sea Fault.

2021 ◽  
Author(s):  
Matthieu Ribot ◽  
Yann Klinger ◽  
Edwige Pons-Branchu ◽  
Marthe Lefevre ◽  
Sigurjón Jónsson
Keyword(s):  
High Resolution ◽  
Tectonic Evolution ◽  
Active Faults ◽  
Major Change ◽  
Dead Sea ◽  
Fault System ◽  
Arabian Plate ◽  
Gulf Of Aqaba ◽  
Uplift Rate ◽  
The Dead

&lt;p&gt;Initially described in the late 50&amp;#8217;s, the Dead Sea Fault system connects at its southern end to the Red Sea extensive system, through a succession of left-stepping faults. In this region, the left-lateral differential displacement of the Arabian plate with respect to the Sinai micro-plate along the Dead Sea fault results in the formation of a depression corresponding to the Gulf Aqaba. We acquired new bathymetric data in the areas of the Gulf of Aqaba and Strait of Tiran during two marine campaigns (June 2018, September 2019) in order to investigate the location of the active faults, which structure and control the morphology of the area. The high-resolution datasets (10-m posting) allow us to present a new fault map of the gulf and to discuss the seismic potential of the main active faults.&lt;/p&gt;&lt;p&gt;We also investigated the eastern margin of the Gulf of Aqaba and Tiran island to assess the vertical uplift rate. To do so, we computed high-resolution topographic data and we processed new series of U-Th analyses on corals from the uplifted marine terraces.&lt;/p&gt;&lt;p&gt;Combining our results with previous studies, we determined the local and the regional uplift in the area of the Gulf of Aqaba and Strait of Tiran.&lt;/p&gt;&lt;p&gt;Eventually, we discussed the tectonic evolution of the gulf since the last major change of the tectonic regime and we propose a revised tectonic evolution model of the area.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

New insights into the Hercynian Orogeny, and their implications for the Paleozoic Hydrocarbon System in the Arabian Plate

GeoArabia ◽  
2009 ◽  
Vol 14 (3) ◽  
pp. 199-228 ◽  
Author(s):  
Mohammad Faqira ◽  
Martin Rademakers ◽  
AbdulKader M. Afifi
Keyword(s):  
Oil And Gas ◽  
Seismic Imaging ◽  
Structural Features ◽  
Source Rocks ◽  
Arabian Plate ◽  
Arabian Shield ◽  
Tectonic Event ◽  
Angular Unconformity ◽  
The North ◽  
Hercynian Orogeny

ABSTRACT During the past decade, considerable improvements in the seismic imaging of the deeper Paleozoic section, along with data from new well penetrations, have significantly improved our understanding of the mid-Carboniferous deformational event. Because it occurred at the same time as the Hercynian Orogeny in Europe, North Africa and North America it has been commonly referred to by the same name in the Middle East. This was the main tectonic event during the late Paleozoic, which initiated or reactivated many of the N-trending block uplifts that underlie the major hydrocarbon accumulations in eastern Arabia. The nature of the Hercynian deformation away from these structural features was poorly understood due to inadequate seismic imaging and insufficient well control, along with the tectonic overprint of subsequent deformation events. Three Hercynian NE-trending arches are recognized in the Arabian Plate (1) the Levant Arch, which extended from Egypt to Turkey along the coast of the Mediterranean Sea, (2) the Al-Batin Arch, which extended from the Arabian Shield through Kuwait to Iran, and (3) the Oman-Hadhramaut Arch, which extended along the southeast coast of Oman and Yemen. These arches were initiated during the mid-Carboniferous Hercynian Orogeny, and persisted until they were covered unconformably by the Khuff Formation during the Late Permian. Two Hercynian basins separate these arches: the Nafud-Ma’aniya Basin in the north and Faydah-Jafurah Basin in the south. The pre-Hercynian Paleozoic section was extensively eroded over the arches, resulting in a major angular unconformity, but generally preserved within the basins. Our interpretation suggests that most of the Arabian Shield, except the western highlands along the Red Sea, is the exhumed part of the Al-Batin Arch. The Hercynian structural fabric of regional arches and basins continue in northern Africa, and in general appear to be oriented orthogonal to the old margin of the Gondwana continent. The Hercynian structure of arches and basins was partly obliterated by subsequent Mesozoic and Cenozoic tectonic events. In eastern Saudi Arabia, Qatar, and Kuwait, regional extension during the Triassic formed N-trending horsts and graben that cut across the NE-trending Hercynian mega-structures, which locally inverted them. Subsequent reactivation during the Cretaceous and Neogene resulted in additional growth of the N-trending structures. The Hercynian Arches had major impact on the Paleozoic hydrocarbon accumulations. The Silurian source rocks are generally preserved in the basins and eroded over the arches, which generally confined Silurian-sourced hydrocarbons either within the basins or along their flanks. Furthermore, the relict Hercynian paleo-topography generally confined the post-Hercynian continental clastics of the Unayzah Formation and equivalents to the Hercynian basins. These clastics contain the main Paleozoic oil and gas reservoirs, particularly along the basin margins where they overlie the sub-crop of the Silurian section with angular unconformity, thus juxtaposing reservoir and source rock.

On the Chloride Waters of Great Britain

1945 ◽  
Vol 82 (6) ◽  
pp. 267-273 ◽  
Author(s):  
W. Anderson
Keyword(s):  
Great Britain ◽  
The South ◽  
Very Old ◽  
North East ◽  
The North ◽  
Exact Position ◽  
The Many ◽  
The Village ◽  
Made In

Formerly there were several surface brine springs in the North-East Coalfield; to-day there are none. From the many accounts of their occurrence nothing has been learned of their exact position, and very little of the composition of their waters. The earliest record, made in 1684, described the Butterby spring (Todd, 1684), and then at various times during the next two centuries brine springs at Framwellgate, Lumley, Birtley, Walker, Wallsend, Hebburn, and Jarrow were noted. In particular the Birtley salt spring is often mentioned, and on the 6-in. Ordnance map, Durham No. 13, 1862 edition, it is sited to the south-east of the village. Although no record has been found there must have been either a brine spring or well at Gateshead, for the name of the present-day suburb, Saltwell, is very old, and brine springs are still active in the coal workings of that area.

Numerical simulation of structural growth in the Lebanese restraining bends, Dead Sea fault system

2021 ◽  
Author(s):  
Jakub Fedorik ◽  
Francesco E. Maesano ◽  
Abdulkader M. Alafifi
Keyword(s):  
Numerical Simulation ◽  
Lateral Displacement ◽  
Dead Sea ◽  
Geometrical Model ◽  
Experimental Models ◽  
Strike Slip ◽  
Boundary Element Methods ◽  
Fault System ◽  
Arabian Plate ◽  
Restraining Bend

&lt;p&gt;Strike-slip structures are rarely validated because commonly used 2D restoration techniques are not applicable. Here we present the results of 3D numerical simulation of the restraining bends in Lebanon using boundary element methods of fault deformation implemented in MOVE&amp;#8482;. The Lebanon restraining bend is the largest transpressional feature along the Dead Sea Transform (DST), and consists of two mountain ranges: Mount Lebanon on the west, dominated by the active Yammouneh fault, and the Anti-Lebanon Range to the east, influenced by the Serghaya and other faults. We built a new 3D geometrical model of the fault surfaces based on previous mapping of faults onshore and offshore Lebanon, complemented by interpretation of satellite images and DEM, and analogy with experimental models of restraining bend or transpressional structures. The model was simulated in response to the regional stress produced by the left-lateral displacement of the Arabian plate. The simulation accurately predicted the shape and magnitude of positive and negative topographic changes and faults slip directions throughout Lebanon. Furthermore, this simulation supports the hypothesis that the formation of the Anti-Lebanon Range was influenced by the intersection of the DST with the older Palmyrides belt, resulting in failed restraining bend. In contrast, the structure of Mt. Lebanon is similar to laboratory experiments of a restraining bend without inheritance. In addition, our simulation presents an approach of how strike-slip structural models may be validated in areas where subsurface data are limited.&lt;/p&gt;

Part II. The Perseia Fountain House

1953 ◽  
Vol 48 ◽  
pp. 19-29 ◽  
Author(s):  
A. J. B. Wace ◽  
M. R. Holland ◽  
M. S. F. Hood ◽  
A. G. Woodhead
Keyword(s):  
Soft Rock ◽  
The South ◽  
South Side ◽  
The North ◽  
North Side ◽  
Exact Position ◽  
Fountain House ◽  
East West

In 1892 Tsountas in the course of exploration on the top of the ridge between the ‘Tomb of Clytemnestra’ and the Lion Gate found a painted circular cap of poros (o·61 m. in diameter), which from the cuttings in it clearly seems to have been connected with some form of installation for water (Plate 14, b). It bears an inscription which as restored refers to Perseus. This inscribed cap Tsountas says he found among later ruins, but he did not specify the exact position. In 1922 therefore we investigated the ruins of apparently Hellenistic date which lie directly to the south of the modern carriage road on the top of the ridge to the north of the ‘Tomb of Clytemnestra’. A long terrace wall of ashlar work in poros was found running in an east-west direction along the south side of the modern road. In front of it, against its north side, lie two cement-lined basins (Plate 14, a). When these were first found and partially examined in 1922 it was suggested that they might be part of a gymnasium of Hellenistic date. At the same time a trial trench XIa by side of the steps was dug down about 0·25 m. into the soft rock below. In 1939 further trials were made behind (to the south of) the western part of the main terrace wall. Trench VII, which was dug to rock, was part of this work. At the same time the curved wall was exposed and part of the ‘votive deposit’ was excavated. The pottery then found, which was lost in the Nauplia Museum during the war, was of the same character as that found in 1952 and described below. In 1952, as part of the programme of exploration on the top and sides of the ridge which runs westward from the Lion Gate, it was decided to clear these ruins completely and study and plan them afresh.

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