bluuebunny/crossref_metadata_2025_split huggingface dataset:
The evolution of the Oman Mountains Foreland Basin
Authors: Warburton J. , Burnhill T. J. , Graham R. H. , Isaac K. P. 
Published: April 2008

Abstract
The Late Cretaceous fill of the Oman Mountains foredeep is subdivided into four sub-sequences using seismic stratigraphic principles based on seismic, well and outcrop data. Sub-sequence FD-a (Late Coniacian to Early Santonian) was overriden by the Hawasina allochthon on the sea bed of the foredeep. FD-b (Early to Late Santonian) was deposited during thrusting and slices of foredeep sediment were tectonically accreted onto the allochthon during the final stages of thrusting. FD-c and FD-d (Late Santonian to Late Coniacian) were deposited after the emplacement of the allochthon into the foredeep. Subsidence curves for the foredeep area show that an emergent peripheral bulge bounded the cratonic side of the foredeep throughout the Late Cretaceous. There is no evidence that the forebulge migrated with time ahead of the advancing Hawasina thrust sheets. Instead the bulge remained in situ while the basin narrowed during thrusting. During the Maastrichtian, after infill of the foredeep, the Oman Mountains area subsided beneath sea level. Clastic supply from the drowned hinterland ceased and carbonate deposition followed. The main Oman Mountain building episode was during the Late Miocene when continent-continent collision occurred in the Zagros Mountains.
Structures associated with nappe emplacement and culmination collapse in the Central Oman Mountains
Authors: Coffield D. Q. 
Published: April 2008

Abstract
The Fanjah Saddle, in the Central Oman Mountains, forms a structural and topographic depression between two major culminations which expose parautochthonous rocks in windows through the overlying allochthon. Two styles of normal faulting are present in the culminations: high-angle faults which dip toward the saddle core and cut the plunging noses of the culminations, and low-angle faults around the culmination flanks which include bedding-parallel detachments, reactivated thrust planes and surge zones. This second set of faults verge down-dip radially away from the culmination flanks.
The high-angle normal faults are interpreted to be accommodation structures resulting from the differential uplift of the parautochthon between the culminations and the saddle. The low-angle normal faults are interpreted to be gravity-driven culmination collapse structures resulting from oversteepening of the culmination flanks.
Post-orogenic late Campanian to Maastrichtian sediments adjacent to the culminations indicate that the culminations were initialy emergent during this time, acting as a clastic source. These same sediments, and the underlying nappe pile, are folded by compression from displacements on the normal faults which implies culmination uplift was reactivated after the Maastrichtian, possibly during post-middle Eocene Zagros orogeny.
Maastrichtian to early Tertiary stratigraphy and palaeogeography of the Central and Northern Oman Mountains
Authors: Nolan S. C. , Skelton P. W. , Clissold B. P. , Smewing J. D. 
Published: April 2008

Abstract
Maastrichtian to Tertiary sedimentary rocks outcrop extensively around the periphery of the Oman Mountains. They form part of a geologically distinct suite of strata deposited after obduction of the Semail ophiolite and thrusting of the Hawasina and Sumeini imbricates onto the eastern edge of the Arabian plate. The lithostratigraphy of Maastrichtian and early Tertiary rocks of the central and northern Oman Mountains is revised and a number of new formations are erected. The proto-Oman Mountains were emergent in the early Maastrichtian and were subject to subaerial erosion and weathering. NW and W of the mountains, gradual subsidence followed during the Maastrichtian, allowing for formation of a transgressive, onlapping sequence represented by the Qahlah (fluviatile to shallow marine terrigenous clastics) and Simsima (shallow shelf carbonate) Formations. More rapid subsidence NE of the mountains produced fan delta and submarine debris flow/turbidite apron sequences comprising the Al Khawd and Thaqab Formations respectively. A low-angle unconformity separates Tertiary strata from older units. During the Palaeogene, basinal and slope facies with debris flows and turbidite sequences were deposited directly upon the unconformity surface in rapidly subsiding basins NW (Muthaymimah Formation) and NNE (Ruwaydah Formation) of the Oman Mountains. Elsewhere, shallow carbonate shelf facies were extensively developed in less rapidly subsiding areas during the Palaeogene. The Palaeocene and early Eocene is represented by the Jafnayn Limestone Formation. This is succeeded and overlapped by a variety of later Eocene units. ENE and E of the mountains early Eocene regression is marked by restricted facies of the Rusayl Formation. Overlying the Rusayl Formation are shallow, open shelf limestones of the Seeb Formation which is rich in alveolinid and nummulitic foraminifera. On the Arabian side of the mountains the Rusayl Formation is not developed and the Jafnayn Formation is succeeded either by the Seeb Formation or fine-grained, faunally restricted limestones and marls of the Fahud Beds, which represent intra-shelf facies.
Cenozoic alluvial fan systems of interior Oman: palaeoenvironmental reconstruction based on discrimination of palaeochannels using remotely sensed data
Authors: Maizels J. , McBean C. 
Published: April 2008

Abstract
Sequences of exhumed, superimposed palaeochannel generations exposed on a Cenozoic alluvial fan in interior Oman are discriminated using a range of different remote sensing techniques. While lithological composition has been demonstrated to vary systematically with relative age of the deposit, ground radiometry has confirmed a relationship between spectral response and percentage cherts in the alluvial deposits. This relationship has allowed up to 14 palaeochannel generations to be discriminated from tonal contrasts on black and white air photographs, and up to five generations on black and white air photo mosaics and SIR-A imagery, and on Landsat MSS false colour imagery. Mapping of successive palaeochannel generations has highlighted the contrasts in channel extent, morphology and pattern during long-term evolution of the fan. These changes in palaeochannel characteristics are interpreted in terms of changes in humidity and continentality of the catchment, changes in eustatic level and in the watertable, and progressive expansion of the drainage network during the Cenozoic.
Structures in the Huqf-Haushi Uplift, east Central Oman
Authors: Ries A. C. , Shackleton R. M. 
Published: April 2008

Abstract
The extensive, very gentle Huqf-Haushi Uplift shows the effects of intraplate deformation from Infracambrian times onwards. The Uplift itself, apparently complementary to subsidence of the Ghaba Salt Basin to the west and the Masirah Trough to the east, began in the Infracambrian and continued intermittently until the Late Cretaceous. Local open folds are shown to be Palaeozoic, probably pre-Ordovician. The main deformation in the Uplift is by faulting. Two closely related sets, one NNE-SSW, the other N-S are essentially strike-slip in sense. The NNE-SSW faults, associated with half-domes and with folds making a small angle clockwise from the faults, are transpressional left-lateral strike-slip faults and the N-S set are probably also mainly left-lateral strike-slip faults. The array of faults is associated with the Masirah Fault, itself interpreted as a left-lateral transform fault. The faulting occurred in the Late Cretaceous. Subsequent deformation was slight.
The structure of Masirah Island, Oman
Authors: Moseley F. 
Published: April 2008

Abstract

The Masirah Ophiolite, extending over 1000 km
2
and now believed to be of Tithonian age, is cut by an extensive melange of uncertain age. The melange has been interpreted as representing a former transform fault zone. Later pre-Tertiary cross-cutting tectonic zones exist, within which ophiolite units have been tilted to the vertical and strongly folded. In one zone there are granites with continental affinities suggesting that Masirah was thrust against continental Arabia, probably late in the Cretaceous. Limestone of presumed early Tertiary age rests with strong unconformity upon the ophiolite, and is itself folded and faulted.
Tectonics of the Masirah Fault Zone and eastern Oman
Authors: Shackleton R. M. , Ries A. C. 
Published: April 2008

Abstract
Previously known but undescribed ophiolites on Ras Madrakah and Ras Jibsch and the ophiolite forming Masirah Island define an upthrust linear zone now separated from the Oman continental margin by the Masirah Fault. West of this, in the Batain coast, are the allochthonous Batain Melange and the Hawasina Complex of Mesozoic basinal deposits, mainly cherts. The Melange, like the Semail Melange with which it is correlated, contains ophiolite and Permian limestone exotics with Tethyan faunas. These allochthonous rocks are intensely deformed by WNW-vergent thrusts and folds. This Batain fold and thrust belt widens and becomes more complex northwards. It appears to have been continuous with the deformation south of the Semail Ophiolite, although now separated by the Jebel Ja’alan Uplift. The tectonics are intrepreted to be the result firstly of northward motion, along the Masirah Fault, of the Helmand Block of Afghanistan, away from the Oman continental coast, and during this motion, upthrust of the Masirah Ophiolite. Then, later in the Cretaceous, southwestward obduction of oceanic coast, including the Semail Ophiolite and the Masirah Ophiolite Zone, onto the Arabian continental plate. The oblique obduction across the NNE-trending Batain margin produced the Batain fold and thrust belt and reversed the strike-slip motion on the Masirah Fault.
Neogene tectonics and sedimentation of the SE Oman continental margin: results from ODP Leg 117
Authors: Prell Warren L. ,   shipboard party of ODP Leg 117
Published: April 2008

Abstract
The primary objective of Leg 117 of the Ocean Drilling Program was to test ideas about the origin and variability of the Asian summer monsoon and its influence on depositional patterns and the oxygen minimum zone (OMZ) in the northwestern Indian Ocean. The western Arabian Sea currently is characterized by intense summer monsoonal upwelling that induces high primary productivity and distinctive planktonic assemblages. The planktonic indicators of upwelling conditions, as well as aeolian detritus from deserts and highlands of adjacent lands, are preserved in the sediments deposited on the Owen Ridge and the Oman Margin. A second objective was to resolve questions about the tectonic history of the Owen Ridge and Oman Margin.
Inter-relationship of Makran-Oman Mountains belts of convergence
Authors: Glennie K. W. , Hughes Clarke M. W. , Boeuf M. G. A. , Pilaar W. F. H. , Reinhardt B. M. 
Published: April 2008

Abstract
Mid Permian rifting and crustal separation along the northern margin of Arabia led to initiation of the Neo-Tethys ocean and deposition of sediments typified by the Hawasina. Subsequently, the Neo-Tethyan oceanic crust was consumed in a late Cretaceous subduction zone, generally easterly dipping in the Oman sector, and its sedimentary cover built up an accretion wedge (Hawasina; Coloured Melange) until the late Campanian, when the buoyant crust of the Arabian continental margin seemingly choked the subduction process.
Continuing convergence caused increased activity on, or the creation of, another subduction trench running between and extending south and east of the Central Iran-Lut and Sanandaj-Sirjan microcontinents (the proto-Makran trench). The resulting crustal relaxation on the earlier subduction site permitted uplift of the half-buried Oman continental margin; the overlying Hawasina and former hanging wall of Semail ophiolite then spread gravitationally further onto the Arabian shelf.
The Makran accretion wedge of Mesozoic Coloured Melange-type rocks and a thick pile of Maastrichtian to Eocene flysch underlies an ophiolitic hanging wall. Post-Eocene collisions between Arabia, Eurasia and intervening microcontinents resulted in: movement of the Naiband Fault in Iran and associated change in trend of the main subduction trench from NW-SE to E-W; thrusting of the Kahnu-Daragar and Alpine-type ophiolite over the SE Sanandaj-Sirjan Zone and rotation of part of its basement; westward thrusting of Musandam, and was associated with the Oligocene uplift of the Oman Mountains. The Zagros plicate folds began their main development in the Pliocene. Continent-continent collision has not occurred between Oman and the Makran.
Ophiolites and their modern oceanic analogues
Authors: Parson L. M. , Murton B. J. 
Published: April 2008

Abstract
Conventional studies of oceanis structure and evolution are inevitably hampered by the difficulties with sampling the crust in the third dimension. Remote sensing of surficial structure, topography and morphotectonics has become easier and of higher resolution with the advent of more sophisticated techniques such as GLORIA long range sidescan sonar, as well as multibeam swath bathymetric mapping systems. Subsurface studies, however, have enjoyed less of this progress, and although deep drilling, electromagnetic surveys and deep seismic techniques still provide some measure of understanding below the seafloor, these data are few and relatively widely spaced. The integration of studies of ophiolite, therefore, can offer the marine community the benefits of a vast body of knowledge with regard to deeper structure and crustal compositions, which is unattainable in the deep sea. In turn, many of the regional and detailed structures which have been recently identified in active mid-ocean spreading systems, such as ridge segmentation patterns and ridge axis discontinuities, now form a significant contribution to recent studies of ophiolite complexes. The complementary work of the two schools is clear and ripe for development.
Ridge axial segmentation in the Oman ophiolite: evidence from along-strike variations in the sheeted dyke complex
Authors: MacLeod C. J. , Rothery D. A. 
Published: April 2008

Abstract

Evidence from along-strike variations in the sheeted dyke complex shows that the spreading axis at which the Oman ophiolite formed was segmented by first- and/or second-order discontinuities, most probably propagating rifts and overlapping spreading centres. We identify at least four, possibly up to seven, of these discontinuities along the
c.
500 km ridge-parallel length of the ophiolite, but recognize no unequivocal transform fault structures. We show that the discontinuities in the sheeted dyke complex can be related to aspects of segmentation previously deduced from mantle flow fabrics and deep crustal structure, and conclude that the Oman palaeo-spreading axis was segmented on a scale of 50–100 km, comparable with that of a modern fast-spreading axis such as the East Pacific Rise.
Geochemical control on the evolutionary history of the Ballantrae Complex, SW Scotland, from comparisons with recent analogues
Authors: Smellie J. L. , Stone P. 
Published: April 2008

Abstract
A combination of geochemical and field investigations of the Ballantrae Complex allows some control on the relative timing of events in its tectono-magmatic history. In particular, the presence of boninitic lava and hyaloclastite confirms an oceanic, supra-subduction zone origin for this early Ordovician ophiolite assemblage. Boninite eruption was preceded by a substantial phase of late Tremadoc island-arc volcanicity and the boninitic units themselves are interbedded with early Arenig primitive island-arc tholeiites. Various supra-subduction zone extensional processes have been invoked to explain boninite occurrences in recently active oceanic island arcs; interarc rifting as a precursor to marginal basin formation is preferred as a model for the Ballantrae Complex. Evidence to support this preference is drawn from the early to mid-Arenig part of the Complex where sandstones derived from mature volcanic arc lavas are conformably overlain by tholeiitic lavas erupted in a back-arc basin; a possible analogue is seen in the active Bransfield Strait marginal basin. Thus, an evolutionary sequence can be envisaged for the Ballantrae Complex which begins with the establishment of an oceanic island arc where supra-subduction zone extension led to the genesis of boninitic lavas. Next, as extension continued, a marginal basin developed wherein sandstones derived from the arc lavas were deposited and tholeiites of ocean island type were erupted. Imbrication of the back arc sequence and accretion of the ophiolite terrane was initiated in the late Arenig by arc-continent collision.
Influence of the partial melting regime on the formation of ophiolitic chromitite
Authors: Roberts Stephen 
Published: April 2008

Abstract

The mantle sequence of the Vourinos ophiolite is composed of a highly depleted peridotite. Indices of depletion including the MgO content of the whole rock (40 wt% MgO), the CaO and Al
2
O
3
contents of the orthopyroxene (<3.00 and 1.5 wt% respectively) and the Cr# value (100Cr/(Cr + Al)) of the spinels (54–80) all indicate a high degree of depletion, consistent with the removal of one or more melt fractions. The extensive chromite mineralization of the mantle sequence also shows a highly restricted chemistry with all but one chromite segregation falling in the range Cr# 75–82. By comparing the geochemistry of the Vourinos mantle sequence with other depleted (Semail) and more fertile mantle (Appenine) sequences, it can be shown that the melting of increasingly depleted residua results in chromium-rich magmas due to the
D
Cr
peridotite-melt
of 1 or less. These chromium-rich magmas undergo extensive olivine plus spinel fractionation and result in chromium-rich chromite segregations partly due to the chromium content of the liquid but also to the relatively high silica content of the magmas concerned. Although chromite mineralisation is unlikely to be taking place within the ocean basins at the present time, modern oceans do contain evidence of sites of likely former chromite mineralisation within the oceanic crust.
Peridotite intrusions emplaced in the fossil suprasubduction zone environment of Cyprus
Authors: Laurent Roger 
Published: April 2008

Abstract
The layered ultramafic and mafic rocks forming the early plutonic assemblage of the Troodos ophiolite are crosscut by intrusive bodies of poikilitic perioditite. These late intrusions of lherzolitic composition congregate near the base of the crust and rim the diapiric mantle dome (Mount Olympus) of harzburgite which outcrops in the core of the plutonic complex. Their parental magma consisted of extensively melted mantle peridotite with addition of basaltic melt. This mixture or crystal-liquid suspension of high ‘yield strength’ is assumed to have been generated in a mantle diapir within the subduction zone environment. The mantle diapir has reached the base of the Troodos crust, deformed the crust and released crystal mushes resulting in the intrusion of peridotite bodies into the crust.
Evidence for plagioclase-lherzolite intrusion in the Mid-Atlantic Ridge, DSDP Leg 37
Authors: Girardeau Jacques , Mercier Jean-Claude C. 
Published: April 2008

Abstract
From studies of ophiolites, it is thought that plagioclase-peridotites represent a non-negligible constituent of the oceanic lithosphere that reflects magmatism at oceanic ridges. To date, very few of them have been described from the abundant peridotites recovered from oceanic domains at present day oceanic ridges, except from transform faults. However, some plagioclase-lherzolites, interpreted as cumulate rocks, were drilled at Site 334 of DSDP Leg 37 on the Mid-Atlantic Ridge.
These plagioclase-lherzolites display poikilitic textures with oikocrysts of clinopyroxene and interstitial plagioclase that include xenocrysts of strained and partly annealed olivine crystals and subidiomorphic spinels. Petrofabric data for olivine point to a plastic deformation stage for these rocks as they display weak lattice fabrics which may have resulted from high-temperature plastic flow. Mineral compositions bear a strong resemblance to ophiolitic and oceanic rocks interpreted as residues from partial melting, except for clinopyroxenes which show a slight titanium enrichment. It is considered that these plagioclase-lherzolites represent residual harzburgites which have been pervasively impregnated by a melt from which clinopyroxene and plagioclase crystallized. Due to this impregnation episode, the primary structure and chemical composition of olivines were partly modified. It is suggested that these peridotites were locally so sufficiently lubricated by interstitial melt that they behaved as a crystal mush that had intruded the high-level crustal gabbros of the Mid-Atlantic Ridge. Their formation reflects pervasive magma percolation in the upper-most residual upper mantle at the Mid-Atlantic Ridge axis.
The validity of whole-rock geochemistry in the study of the oceanic crust: a case study from ODP Hole 504B.
Authors: Brewer T. S. , Pelling R. , Lovell M. A. , Harvey P. K. 
Published: April 2008

Abstract
Attempts to interpret the geochemistry of the oceanic crust are constrained by the representative nature, quality, and amount of material recovered from an individual site. The most effective sampling method has been that of continuous coring while drilling, although the amount of material recovered from a single hole can vary with depth from 0 to 100%, and is often, though not necessarily, low. Observations suggest there is inevitably a biasing towards the recovery of unaltered material. DSDP/ODP Hole 504B has been successfully drilled in a series of stages and a 1500 m section of the oceanic crust has been sampled. The core recovery in Hole 504B is, however, generally poor; consequently the study of both igneous and alteration processes at this site is limited. An alternative to this scenario is offered by down-hole geochemical (nuclear) measurements. The nuclear responses provide a limited but near-continuous geochemical dataset within this hole. The derived chemo-stratigraphy correlates well with that based upon conventional geophysical measurements. Alteration has played an important role in producing the observed chemical signatures and may partly explain the poor core recovery within the hole. Downhole nuclear measurements in the ocean crust provide a novel geochemical dataset in the study of both primary and secondary processes. This information must be integrated with lithological, petrological and geophysical data to produce the most complete appraisal yet of the oceanic crust.