The Carboniferous Baralacha La basaltic dykes (Upper Lahul, Ladakh): remnants of an early rifting event along the Indian northern plate

The Lower Carboniferous Baralacha La basaltic dykes were emplaced along transtensional faults. The basalts exhibit tholeiitic and alkaline affinities. The tholeiites are TiO2-poor, moderately enriched in light rare earth (LREE), and display Nb and Ta negative and Th positive anomalies. The alkali basalts, compared to the tholeiites, have higher TiO2, rare earth and highly incompatible trace element contents and greater LREE enrichments. The Nd and Pb isotope compositions of the Baralacha La basalts suggest that they derive from the partial melting of an enriched OIB mantle source. characterized by a HIMU component, and contaminated by the lower continental crust. The Baralacha La dyke swarm represent the remnants of an early rifting event on the northern Indian passive margin.

The value of adding mirror therapy for upper limb motor recovery of subacute stroke patients: a randomized controlled trial.

BACKGROUND: Upper limb paresis remains a relevant challenge in stroke rehabilitation. AIM: To evaluate if adding mirror therapy (MT) to conventional therapy (CT) can improve motor recovery of the upper limb in subacute stroke patients. DESIGN: Prospective, single-center, single-blind, randomised, controlled trial. SETTING: Subacute stroke patients referred to a Physical and Rehabilitation Medicine Unit between October 2009 and August 2011. POPULATION: Twenty-six subacute stroke patients (time from stroke <4 weeks) with upper limb paresis (Motricity Index â0/00¤ 77). METHODS: Patients were randomly allocated to the MT (N.=13) or to the CT group (N.=13). Both followed a comprehensive rehabilitative treatment. In addition, MT Group had 30 minutes of MT while the CT group had 30 minutes of sham therapy. Action Research Arm Test (ARAT) was the primary outcome measures. Motricity Index (MI) and the Functional Independence Measure (FIM) were the secondary outcome measures. RESULTS: After one month of treatment patients of both groups showed statistically significant improvements in all the variables measured (P<0.05). Moreover patients of the MT group had greater improvements in the ARAT, MI and FIM values compared to CT group (P<0.01, Glass's Î" Effect Size: 1.18). No relevant adverse event was recorded during the study. CONCLUSION: MT is a promising and easy method to improve motor recovery of the upper limb in subacute stroke patients. CLINICAL REHABILITATION IMPACT: While MT use has been advocated for acute patients with no or negligible motor function, it can be usefully extended to patients who show partial motor recovery. The easiness of implementation, the low cost and the acceptability makes this therapy an useful tool in stroke rehabilitation.

Hémorragie digestive haute: utilité des scores pronostiques [Upper gastrointestinal bleeding: usefulness of prognostic scores].

Upper gastrointestinal bleeding is a potentially serious event, usually requiring urgent endoscopic treatment. Better stratification of the risk of complication or death could optimize management and improve patient outcomes, while ensuring adequate resource allocation. Several prognostic scores have been developed, in order to identify high risk patients, who require immediate treatment, and patients at low risk for whom endoscopy may be delayed. An ideal prognostic score should be accurate, simple, reproducible, and prospectively validated in different populations. Published scores meet these requirements only partially, and thus can only be used as part of an integrative diagnostic and therapeutic process.

Sedimentary record of the northward flight of India and its collision with Eurasia (Ladakh Himalaya, India)

Stratigraphic and petrographic analysis of the Cretaceous to Eocene Tibetan sedimentary succession has allowed us to reinterpret in detail the sequence of events which led to closure of Neotethys and continental collision in the NW Himalaya. During the Early Cretaceous, the Indian passive margin recorded basaltic magmatic activity. Albian volcanic arenites, probably related to a major extensional tectonic event, are unconformably overlain by an Upper Cretaceous to Paleocene carbonate sequence, with a major quartzarenite episode triggered by the global eustatic sea-level fall at the Cretaceous/Tertiary boundary. At the same time, Neotethyan oceanic crust was being subducted beneath Asia, as testified by calc-alkalic volcanism and forearc basin sedimentation in the Transhimalayan belt. Onset of collision and obduction of the Asian accretionary wedge onto the Indian continental rise was recorded by shoaling of the outer shelf at the Paleocene/Eocene boundary, related to flexural uplift of the passive margin. A few My later, foreland basin volcanic arenites derived from the uplifted Asian subduction complex onlapped onto the Indian continental terrace. All along the Himalaya, marine facies were rapidly replaced by continental redbeds in collisional basins on both sides of the ophiolitic suture. Next, foreland basin sedimentation was interrupted by fold-thrust deformation and final ophiolite emplacement. The observed sequence of events compares favourably with theoretical models of rifted margin to overthrust belt transition and shows that initial phases of continental collision and obduction were completed within 10 to 15 My, with formation of a proto-Himalayan chain by the end of the middle Eocene.

Geological transect across the Northwestern Himalaya in eastern Ladakh and Lahul (A model for the continental collision of India and Asia)

The detailed geological mapping and structural study of a complete transect across the northwestern Himalaya allow to describe the tectonic evolution of the north Indian continental margin during the Tethys ocean opening and the Himalayan Orogeny. The Late Paleozoic Tethys rifting is associated with several tectonomagmatic events. In Upper Lahul and SE Zanskar, this extensional phase is recorded by Lower Carboniferous synsedimentary transtensional faults, a Lower Permian stratigraphic unconformity, a Lower Permian granitic intrusion and middle Permian basaltic extrusions (Panjal Traps). In eastern Ladakh, a Permian listric normal fault is also related to this phase. The scarcity of synsedimentary faults and the gradual increase of the Permian syn-rift sediment thickness towards the NE suggest a flexural type margin. The collision of India and Asia is characterized by a succession of contrasting orogenic phases. South of the Suture Zone, the initiation of the SW vergent Nyimaling-Tsarap Nappe corresponds to an early phase of continental underthrusting. To the S, in Lahul, an opposite underthrusting within the Indian plate is recorded by the NE vergent Tandi Syncline. This structure is associated with the newly defined Shikar Beh Nappe, now partly eroded, which is responsible for the high grade (amphibolite facies) regional metamorphism of South Lahul. The main thrusting of the Nyimaling-Tsarap Nappe followed the formation of the Shikar Beh Nappe. The Nyimaling-Tsarap Nappe developed by ductile shear of the upper part of the subducted Indian continental margin and is responsible for the progressive regional metamorphism of SE Zanskar, reaching amphibolite facies below the frontal part of the nappe, near Sarchu. In Upper Lahul, the frontal parts of the Nyimaling-Tsarap and Shikar Beh nappes are separated by a zone of low grade metamorphic rocks (pumpellyite-actinolite facies to lower greenschist facies). At high structural level, the Nyimaling-Tsarap Nappe is characterized by imbricate structures, which grade into a large ductile shear zone with depth. The related crustal shortening is about 87 km. The root zone and the frontal part of this nappe have been subsequently affected by two zones of dextral transpression and underthrusting: the Nyimaling Shear Zone and the Sarchu Shear Zone. These shear zones are interpreted as consequences of the counterclockwise rotation of the continental underthrusting direction of India relative to Asia, which occurred some 45 and 36 Ma ago, according to plate tectonic models. Later, a phase of NE vergent `'backfolding'' developed on these two zones of dextral transpression, creating isoclinal folds in SE Zanskar and more open folds in the Nyimaling Dome and in the Indus Molasse sediments. During a late stage of the Himalayan Orogeny, the frontal part of the Nyimaling-Tsarap Nappe underwent an extension of about 15 km. This phase is represented by two types of structures, responsible for the tectonic unroofing of the amphibolite facies rocks of the Sarchu area: the Sarchu high angle Normal Fault, cutting a first set of low angle normal faults, which have been created by reactivation of older thrust planes related to the Nyimaling-Tsarap Nappe.

Upper Triassic to Cretaceous radiolaria from Nicaragua and northern Costa Rica - The Mesquito composite oceanic terrane

We propose a new terrane subdivision of Nicaragua and Northern Costa Rica, based on Upper Triassic to Upper Cretaceous radiolarian biochronology of ribbon radiolarites, the newly studied Siuna Serpentinite Mélange, and published 40Ar/39Ar dating and geochemistry of mafic and ultramafic igneous rock units of the area. The new Mesquito Composite Oceanic Terrane (MCOT) comprises the southern half of the Chortis Block, that was assumed to be a continental fragment of N-America. The MCOT is defined by 4 corner localities characterized by ultramafic and mafic oceanic rocks and radiolarites of Late Triassic, Jurassic and Early Cretaceous age: 1. The Siuna Serpentinite Mélange (NE-Nicaragua), 2. The El Castillo Mélange (Nicaragua/Costa Rica border), 3.The Santa Elena Ultramafics (N-Costa Rica) and, 4. DSDP Legs 67/84. 1. The Siuna Serpentinite Mélange contains, high pressure metamorphic mafics and Middle Jurassic (Bajocian-Bathonian) radiolarites in original, sedimentary contact with arc-metandesites. The Siuna Mélange also contains Upper Jurassic black detrital chert formed in a marginal (fore-arc?) basin shortly before subduction. A phengite 40Ar/39Ar -cooling age dates the exhumation of the high pressure rocks as 139 Ma (earliest Cretaceous). 2. The El Castillo Mélange comprises a radiolarite block tectonically embedded in serpentinite that yielded a diverse Rhaetian (latest Triassic) radiolarian assemblage, the oldest fossils recovered so far from S-Central America. 3. The Santa Elena Ultramafics of N-Costa Rica together with the serpentinite outcrops near El Castillo (2) in Southern Nicaragua, are the southernmost outcrops of the MCOT. The Santa Elena Unit (3) itself is still undated, but it is thrust onto the middle Cretaceous Santa Rosa Accretionary Complex (SRAC), that contains Lower to Upper Jurassic, highly deformed radiolarite blocks, probably reworked from the MCOT, which was the upper plate with respect to the SRAC. 4. Serpentinites, metagabbros and basalts have long been known from DSDP Leg 67/84 (3), drilled off Guatemala in the Nicaragua-Guatemala forearc basement. They have been restudied and reveal 40Ar/39Ar dated Upper Triassic to middle Cretaceous enriched Ocean Island Basalts and Jurassic to Lower Cretaceous depleted Island arc rocks of probable Pacific origin. The area between localities 1-4 is largely covered by Tertiary to Recent arcs, but we suspect that its basement is made of oceanic/accreted terranes. Earthquake seismic studies indicate an ill-defined, shallow Moho in this area. The MCOT covers most of Nicaragua and could extend to Guatemala to the W and form the Lower (southern) Nicaragua Rise to the NE. Some basement complexes of Jamaica, Hispaniola and Puerto Rico may also belong to the MCOT. The Nicoya Complex s. str. has been regarded as an example of Caribbean crust and the Caribbean Large Igneous Province (CLIP). However, 40Ar/39Ar - dates on basalts and intrusives indicate ages as old as Early Cretaceous. Highly deformed Jurassic and Lower Cretaceous radiolarites occur as blocks within younger intrusives and basalts. Our interpretation is that radiolarites became first accreted to the MCOT, then became reworked into the Nicoya Plateau in Late Cretaceous times. This implies that the Nicoya Plateau formed along the Pacific edge of the MCOT, independent form the CLIP and most probably unrelated with he Galapagos hotspot. No Jurassic radiolarite, no older sediment age than Coniacian-Santonian, and no older 40Ar/39Ar age than 95 Ma is known from S-Central America between SE of Nicoya and Colombia. For us this area represents the trailing edge of the CLIP s. str.

The roles of flux- and decompression melting and their respective fractionation lines for continental crust formation: Evidence from the Kohistan arc

Delamination and foundering of the lower continental crust (LCC) into the mantle is part of the crust-forming mechanism. However, knowledge of the composition and mineralogy of the preserved or delaminated LCC over geological timescales remains scarce. We provide a synopsis of recent research within the Kohistan arc (Pakistan) and demonstrate that hydrous and less hydrous liquid lines of descent related to flux assisted and decompression mantle melting, respectively, produce compositionally different lower crustal rocks. The argument refers to two lower crustal sections exposed in Kohistan, the older Southern Plutonic Complex (SPC) and the younger Chilas Complex. The SPC typifies a hydrous, high-pressure fractionation sequence of olivine-pyroxenes-garnet-Fe/Ti-oxide-amphibole-plagioclase. The Chilas Complex illustrates a less hydrous fractionation sequence of olivine-clinopyroxene-orthopyroxene-plagioclase-amphibole. Despite the similarity of the Chilas Complex rocks to proposed lower crust compositions, the less hydrous fractionation results in unrealistically small volumes of silica-rich rocks, precluding the Chilas Complex gabbros to represent the magmatic complement to the upper crust. The composition of the SPC lower crust differs markedly from bulk lower crust estimates, but is complementary to silica-rich rocks exposed along this section and in the Kohistan batholith. These observations inspire a composite model for the formation of continental crust (CC) where the negatively buoyant delaminated and the buoyant preserved lower continental crusts (LCC) differ in genesis, mineralogy, and composition. We propose that the upper, non-sedimentary subsequent removal of the complementary, negatively buoyant garnet-pyroxene-amphibole-plagioclase-rich cumulates. In contrast, the LCC, which is buoyant and preserved over geological timescales, is formed by less hydrous parental mantle melts. We suggest that the bulk continental crust composition is related to mixing of these petrologically not directly related end members. Published by Elsevier B.V.

Migration of sharks into freshwater systems during the Miocene and implications for Alpine paleoelevation

Trace-element and isotopic compositions of fossilized shark teeth sampled from Miocene marine sediments of the north Alpine Molasse Basin, the Vienna Basin, and the Pannonian Basin generally show evidence of formation in a marine environment under conditions geochemically equivalent to the open ocean. In contrast, two of eight shark teeth from the Swiss Upper Marine Molasse locality of La Moliere have extremely low delta O-18 values (10.3% and 11.3%) and low Sr-87/Sr-86 ratios (0.707840 and 0.707812) compared to other teeth from this locality (21.1%,22.4%o and 0.708421-0.708630). The rare earth element (REE) abundances and patterns from La Moliere not only differ between dentine and enameloid of the same tooth, but also between different teeth, supporting variable conditions of diagenesis at this site. However, the REE patterns of enameloid from the ``exotic'' teeth analyzed for O and Sr isotopic compositions are similar to those of teeth that have O and Sr isotopic compositions typical of a marine setting at this site. Collectively, this suggests that the two ``exotic'' teeth were formed while the sharks frequented a freshwater environment with very low O-18-content and Sr isotopic composition controlled by Mesozoic calcareous rocks. This is consistent with a paleogeography of high-elevation (similar to 2300 m) Miocene Alps adjacent to a marginal sea.

Underutilization of upper gastrointestinal endoscopy.

BACKGROUND & AIMS: Efforts to reduce costs in health care may raise concerns about underuse of medical procedures. This study prospectively assessed underuse of upper gastrointestinal endoscopy in a cohort of patients in whom we have recently published data on overuse of endoscopy. METHODS: Underuse was identified by formal necessity criteria for endoscopy, obtained by an explicit panel process. Outpatients were consecutively included in two clinical settings. Setting A consisted of 20 primary care physicians and 7215 patient visits that occurred within 1 month. Setting B consisted of 920 visits that occurred during 3 weeks at an outpatient clinic. RESULTS: During these 8135 visits, 611 patients complained of upper digestive symptoms; 63 of them underwent endoscopy. Underuse was identified in 72 patients (11.8%). The two clinical situations mainly responsible for underuse of endoscopy were uninvestigated peptic symptoms resistant to treatment and dysphagia. At first follow-up, 29 of the patients with initial underuse still fulfilled criteria of necessity (underuse rate, 4.7%). One-year follow-up showed underuse of endoscopy in 5 patients. CONCLUSIONS: This prospective evidence shows that underuse of a medical procedure exists. The estimated overuse and underuse of endoscopy in this cohort were approximately equal (5%). Improving quality of care will require reductions of both overuse and underuse of medical procedures.

New palaeontological investigations in the Jurassic of western Thailand

The paleontological investigations of the Jurassic of Western Thailand, districts of Mae Sot (Tak-Mae Sot highway, Padaeng Tak and Ban Mae Kut Luang Zinc mines) and Umphang (Klo Tho), provide age constraints for the Late Indosinian orogeny, the Paleotethys closure and the timing of the marine Jurassic inundation of Sundaland. The basal conglomerate of the Jurassic is derived from the pelagic Triassic Mae Sariang substratum. Stratigraphy, microfacies and paleontology of the Jurassic marine strata focus especially on ammonites, bivalves, large benthic foraminifera and algae. Among ammonites, the Tethyan Catulloceras perisphinctoides Gemmellaro marks the Upper Toarcian (Aalensis Zone) along the Tak-Mae Sot highway and Riccardiceras longalvum (Vacek). Malladaites pertinax (Vacek), Abbasites sp. and Vacekia sp. indicate Middle Aalenian to lowermost Bajocian in the Padaeng Mine (SE of Mae Sot) and Klo-Tho (Umphang). Vacekia sp., Spinammatoceras schindewolfi Linares and Sandoval and Malladaites vaceki Linares and Sandoval indicate Middle Aalenian to lowermost Upper Aalenian at Ban Mae Kut Luang (NE of Mae Sot). Among foraminifers, the large benthic foraminifer Timidonella sarda Bassoullet, Chabrier and Fourcade in the Western Tethys is indicative for Aalenian-Bajocian times, as characterized in the section at the Tak-Padaeng Zinc mine and the Klo-Tho Formation near Umphang. The endemic foraminifer Gutnicella kaempferi characterizes the Pu Khloe Khi Formation near Umphang. Among bivalves, shallow marine, dominantly endemic fauna includes Parvamussium donaiense (Mansuy) and Bositra ornate (Quenstedt), from the Toarcian to the Early Bajocian. A consideration of the faunal affinity shows that the fauna is partly endemic with Northern Tethyan (Eurasian) affinity. Crown Copyright (C) 2010 Published by Elsevier B.V. on behalf of International Association for Gondwana Research. All rights reserved.

The oceanic base of slope record of the Permian-Triassic crisis: view from Tethys (Oman)

The Oman Mountains provide some of the best sections of Permian and Triassic sediments from ocean sea floor to base-of-slope environments related to the distal South Tethyan margin. The central part of the range exposes the Buday'ah section of oceanic sediments in the so-called "Hawasina allochtons". The locality of Wadi Maqam in the north-western part of the Oman Mountains is among places where the thick Permian-Triassic base-of-slope sediments is exposed (Baud et al., 2001). Overlying 400 m of middle Permian limestones and dolomites, the upper Permian sediments consist of 50 m of ≈ 10 cm thick beds of cherts and dolomites rich in sponge spicules. The top of the Permian units is well bioturbated lime mudstone-wackestone, devoid of cherts and dated as late Changhsingian (Krystyn in Richoz et al., 2005). The boundary yellow shales are overlain by very thinly bedded, laminated microbial platy lime mudstone with H. parvus. The dramatic loss of the burrowing infauna indicates the appearance of oxygen-poor water. These Induan sediments are about 25 m thick and show at the top the first calcirudites, commonly clast-supported (edge-wise conglomerates), and are characterized by tabular clasts representing the sub- in situ reworking of the laminated, platy calcilutite. The very thick Smithian overlying litho-unit (up to 900 m) marks the onset on the base-of-slope of a deep-marine basin in which carbonate submarine fan deposits developed This very thick unit consists essentially of platy limestones, calcarenites and calcirudites. It comprises mainly grey-beige calcilutite, laminated and flaggy, interbedded with sparse beds of fine-grained calcarenite in cm beds. Channelized beds of intraformational calcirudite are also part of this succession which constitutes the greater part of the outcrop available. During the Spathian to Anisian, the sedimentation changes to terrigenous mudstone and siltstone that ended with Ladinian radiolarites.

The Anarak, Jandaq and Posht-e-Badam metamorphic complexes in central Iran: New geological data, relationships and tectonic implications

The Anarak, Jandaq and Posht-e-Badam metamorphic complexes occupy the NW part of the Central-East Iranian Microcontinent and are juxtaposed with the Great Kavir block and Sanandaj-Sirjan zone. Our recent findings redefine the origin of these complexes, so far attributed to the Precambrian-Early Paleozoic orogenic episodes, and now directly related to the tectonic evolution of the Paleo-Tethys Ocean. This tectonic evolution was initiated by Late Ordovician-Early Devonian rifting events and terminated in the Triassic by the Eocimmerian collision event due to the docking of the Cimmerian blocks with the Asiatic Turan block. The ``Variscan accretionary complex'' is a new name we proposed for the most widely distributed metamorphic rocks connected to the Anarak and Jandaq complexes. This accretionary complex exposed from SW of Jandaq to the Anarak and Kabudan areas is a thick and fine grain siliciclastic sequence accompanied by marginal-sea ophiolitic remnants, including gabbro-basalts with a supra-subduction-geochemical signature. New Ar-40/Ar-39 ages are obtained as 333-320 Ma for the metamorphism of this sequence under greenschist to amphibolite facies. Moreover, the limy intercalations in the volcano-sedimentary part of this complex in Godar-e-Siah yielded Upper Devonian-Tournaisian conodonts. The northeastern part of this complex in the Jandaq area was intruded by 215 +/- 15 Ma arc to collisional granite and pegmatites dated by ID-TIMS and its metamorphic rocks are characterized by Some Ar-40/Ar-39 radiometric ages of 163-156 Ma. The ``Variscan'' accretionary complex was northwardly accreted to the Airekan granitic terrane dated at 549 +/- 15 Ma. Later, from the Late Carboniferous to Triassic, huge amounts of oceanic material were accreted to its southern side and penetrated by several seamounts such as the Anarak and Kabudan. This new period of accretion is supported by the 280-230 Ma Ar-40/Ar-39 ages for the Anarak mild high-pressure metamorphic rocks and a 262 Ma U-Pb age for the trondhjemite-rhyolite association of that area. The Triassic Bayazeh flysch filled the foreland basin during the final closure of the Paleo-Tethys Ocean and was partly deposited and/or thrusted onto the Cimmerian Yazd block. The Paleo-Tethys magmatic arc products have been well-preserved in the Late Devonian-Carboniferous Godar-e-Siah intra-arc deposits and the Triassic Nakhlak fore-arc succession. On the passive margin of the Cimmerian block, in the Yazd region, the nearly continuous Upper Paleozoic platform-type deposition was totally interrupted during the Middle to Late Triassic. Local erosion, down to Lower Paleozoic levels, may be related to flexural bulge erosion. The platform was finally unconformably covered by Liassic continental molassic deposits of the Shemshak. One of the extensional periods related to Neo-Tethyan back-arc rifting in Late Cretaceous time finally separated parts of the Eocimmerian collisional domain from the Eurasian Turan domain. The opening and closing of this new ocean, characterized by the Nain and Sabzevar ophiolitic melanges, finally transported the Anarak-Jandaq composite terrane to Central Iran, accompanied by large scale rotation of the Central-East Iranian Microcontinent (CEIM). Due to many similarities between the Posht-e-Badam metamorphic complex and the Anarak-Jandaq composite terrane, the former could be part of the latter, if it was transported further south during Tertiary time. (C) 2007 Elsevier B.V. All rights reserved.

Geochemical and H-O-Sr-Nd isotope evidence for magmatic processes and meteoric-water interactions in the basal complex of La Gomera, Canary Islands

The plutonic rocks of the Basal Complex of La Gomera, Canary Islands, Spain, were studied by means of major and trace element contents and by H-O-Sr-Nd isotope compositions in order to distinguish primary magmatic characteristics and late-stage alteration products. Deciphering the effects of alteration allowed us to determine primary, plume-related compositions that indicated D- and (18)O-depletion relative to normal upper mantle, supporting the conclusions of earlier studies on the plutonic rocks of Fuerteventura and La Palma. Late-stage alteration took place during the formation of the intrusive series induced by interaction with meteoric water. Inferred isotopic compositions of the meteoric water indicate that the water infiltrated into the rock edifice at a height of about 1500 m above sea level, suggesting the existence of a subaerial volcano which was active during the intrusive activity and that it has been either distroyed or remain buried by later volcanic and landslide events.