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[Display omitted] • Detrital zircon data show an extensive Cadomian arc magmatism in Iran-Anatolia. • Abundant 2.6–2.4 Ga zircons show exhumation of a local crust during the Ediacaran. • Zircon and bulk-rock isotope data show Gondwana rifting in early Paleozoic. Understanding crustal growth, reworking, and geodynamics of the northern continental margin of Gondwana during Ediacaran to Silurian times plays an important role in Gondwana's paleogeographic reconstruction. This study uses a combination of bulk-rock geochemistry, magmatic and detrital zircon geochronology, zircon trace element, and O-Hf isotope data to evaluate the Ediacaran-early Paleozoic magmatic history of northern Gondwana. Our detrital zircon data from Ediacaran to Ordovician sedimentary successions of central Iran show that the 620–500 Ma detrital zircon likely originates from the erosion of the Cadomian arcs in Iran and Anatolia. This zircon shows variable εHf (t) and δ18O values and Nb/Yb, U/Yb, and U/Nb, resembling arc rocks. The Cryogenian (1000–620 Ma) detrital zircon with juvenile εHf (t) and mantle-like δ18O values could have been supplied from erosion of the juvenile crust of the ANS. The youngest age peaks of 488–450 Ma for detrital zircon, in upper Cambrian-Ordovician sedimentary rocks, are considered to show the rifting of Gondwana and Paleotethys opening. Abundant unrounded 2.5 Ga detrital zircon from Ediacaran sandstones probably shows uplift and exhumation of a local source, i.e., the Archean crust of Iran. The Neoproterozoic igneous rocks formed firstly during the subduction of oceanic lithosphere (Mozambique Ocean) beneath northern Gondwana around 880 Ma to form the ANS juvenile crust. Later, the magmatism moved from the ANS toward the northern territories of Gondwana, with peak magmatism at 570–525 Ma. In Cambrian to Ordovician, the Cadomian magmatic arc was uplifted and eroded, and the geodynamic setting switched into juvenile magmatism following rifting of northern Gondwana. [ABSTRACT FROM AUTHOR]

[Display omitted] • Many dated phases are xenocrysts, giving only maximum ages of intrusion. • Most examples of KKAC magmas intruded coevally between 60 and 88 Ma, peaking at 81 Ma. • Their timing and location link the KKAC magmas to the South Atlantic's opening. Kimberlitic, kamafugitic and alkaline-carbonatitic (KKAC) rocks have been proposed to be directly related to supercontinent cycles. However, the hybrid nature of KKAC magmas complicates the geochronological studies required to understand their mutual relationships. Robust evaluation of their history depends on appropriate choice of dating techniques and careful attention to the nature of the dated material. Extensive KKAC outcrops in the magmatic province on the south-western margin of the São Francisco Craton (SW-SFC) are heavily weathered and most existing ages are based on residual perovskite, phlogopite, apatite and zircon. A multi-methodological appraisal (in situ U-Pb on perovskite and zircon, in situ Rb-Sr on phlogopite; major and trace elements) shows that both primary minerals and entrained xenocrysts (perovskite, phlogopite, zircon) can be found within the same pipe. Most xenocrysts can be recognised from microstructural features, chemical/isotopic differences and/or the petrological incompatibility of a phase (e.g., zircon) that cannot be cognate in the KKAC melts. Xenocrysts of phlogopite and a few apatites suggest that the KKAC magmatism may have begun as early as ca 110 Ma but is cryptic, i.e. poorly expressed in surface eruptions. When the (maximum) ages derived from xenocrysts are filtered out, accepted intrusion ages group almost entirely in the period of 76–88 Ma, with mean ages of 80, 79 and 83 Ma for kimberlites, kamafugites and alkaline-carbonatite rocks, respectively. This timing, and the location of the KKAC eruptions 400–900 km from the continental shelf margin, are consistent with a geodynamic model in which far-field mantle melting and magmatism is driven by the migration of convective instabilities from the margin of an opening ocean, beneath the adjacent craton roots. The refined geochronological framework thus suggests that the KKAC magmatism in the SW-SFC is best interpreted as a far-field effect of the South Atlantic opening (ca 127 Ma). [ABSTRACT FROM AUTHOR]

[Display omitted] • Eclogitization kinetics of oceanic crust layers controlled Precambrian subduction. • Discrete eclogitization induced flat subduction in Precambrian. • Flat subduction builds short-lived overthickened layered mantle. Flat (shallow) subduction is mainly proposed as an Archean-Paleoproterozoic process, contributing to the growth of continental lithosphere. However, numerical models of Precambrian subduction commonly show steep subduction. Here we investigate the effects of lithology-dependent eclogitization (minor for gabbroic lower crust, strong for basaltic upper crust) of oceanic crust during subduction. We performed 2D petrological-thermomechanical modeling of subduction at potential mantle temperatures up to 250 °C warmer than present, using a numerical approach that accounts for buoyancy effects from both mantle depletion and eclogitization. The modeling reveals that increases in mantle potential temperature and the related thickness of oceanic crust and depleted mantle may induce transition to the flat subduction regime at ΔT ≥ 150 °C but only when a delayed eclogitization of gabbroic compared to basaltic crust is taken into account. Otherwise, subduction operates in the steep slab regime. Flat Precambrian subduction models show episodic bimodal magmatism within arcs located > 400 km from the trench, caused by short-lived (1–4 Myr) subduction transients consisting of three consecutive stages: (1) twisting downward of the eclogitized slab portion, (2) subvertical descent and break-off of this twisted portion, (3) rising of the remnant non-eclogitised slab tip and continuation of flat subduction. Limited formation of TTG-series granitoids is caused by partial melting of the subducting basaltic layer but becomes less pronounced at ΔT = 250 °C. Flat subduction produces an overthickened, layered keel-like continental mantle root, with an intermediate layer of subducted oceanic crust. However, construction of long-lived mantle keels by this mechanism might be limited by peeling off of the gradually eclogitizing oceanic crust and the underlaying mantle when plate convergence ends. At elevated mantle temperatures flat subduction produces voluminous hydration of the mantle wedge, forming a subcrustal serpentinite mélange layer that becomes a potential source of fluids in the subsequent evolution of the overlying continental crust. [ABSTRACT FROM AUTHOR]

[Display omitted] • A magmatic flare-up occurred in NE Iran during the Early to Middle Eocene. • Magmatic flare-up was dominated by melts from a metasomatized mantle wedge. • Change in slab dip and upwelling of the asthenosphere caused the magmatic flare-up. Most continental arcs are built up over a long time (≥100 myr), and while subduction may be ongoing throughout this interval, magmatism appears to be highly episodic. This episodic behaviour is characterized by high-flux magmatic events but an overall low rate of magmatism. The causes of high-flux magmatic events ("flare-ups") are enigmatic in many continental arcs. Bulk-rock Sr, Nd, and Pb isotopes, as well as zircon O and Hf isotopes, imply that the mantle and the continental crust can be involved in magmatic flare-ups. However, the relative contributions of mantle vs. crust with changes in eruption rates can differ from arc to arc. The Cenozoic magmatic arcs of Iran, built on mature continental crust, are an excellent candidate for studying the geochemical-isotopic feedback of magmatic pulses to understand the triggers for a flare-up. Our new data constrain the timing of the flare-up in NE Iran to the Early to Middle Eocene (51–43 Ma). This flare-up is characterized by the outpouring of high-K calc-alkalic to shoshonitic magmas at ∼110 ± 8 km3/myr - km. Geochemical modelling using the "Arc Basalt Simulator version 3″ shows that the high-K trachybasalts, moderately to extremely depleted in high-field strength elements, can be derived from the shallower (3.0 GPa; 870 °C) to deeper parts (5.0–5.4 GPa; 965–980 °C) of a subducting slab with ∼1.0 to 5.5 % slab melt flux. Mixing modelling using Sr, Nd, and Pb isotope data indicates that the Torud mafic-intermediate magmatic rocks can be generated by adding ∼ 1% to <6% of slab components (50% AOC: 50% sediment) to an Indian MORB-like mantle. Our results suggest that the high magmatic fluxes in NE Iran were instigated mainly by Eocene slab steepening after Paleocene flat-slab subduction, resulting in enhanced upwelling and melting of a volatile-enriched asthenospheric mantle. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low density craton-like core lithosphere in Zagros. • Arabian lithosphere underthrusts beneath Eurasia (Iran) due to density excess. • Cold and relatively dense sub-lithospheric body beneath the Iranian plateau. The tectonic evolution of the Arabia-Eurasia collision zone is enigmatic due to our poor knowledge of the compositional structure of the Zagros keel and the sub-lithospheric mantle beneath the Iranian plateau. Here, we present a thermochemical model for the upper mantle, starting from the Arabian plate toward the Zagros keel (in SW Iran) and the Iranian plateau to the Kopet Dagh Mountains in NE Iran. The crustal and (sub) lithospheric mantle structure is constrained using receiver functions and high-resolution seismic tomography. The crustal density is obtained by converting local Vp velocity profiles to density. The presumed mantle composition/density of different tectonic units has been inferred from the composition of mantle-derived xenoliths in Pleistocene alkaline basalts of NE Iran, mantle xenoliths from Eastern Arabia, and integrated geophysical-petrological modeling of seismic tomography as well as Bouguer and geoid anomalies. Our results indicate that the lower part of the lithosphere in the Arabian plate is ∼ +25 kg/m3 denser than the sub-lithospheric mantle, which allows underthrusting of the Arabian lithosphere beneath the Iranian plateau. The Zagros core–an ultra-positive seismic velocity anomaly in the tomographic models– is modeled assuming a refractory "craton-like" composition, leading to a ∼-60 kg/m3 density contrast with its underlying fertile lithospheric mantle. We hypothesize that at least the upper ∼100 km of the hydrous Arabian lithosphere was compositionally cratonic before the collision-related shortening processes. In contrast, the anhydrous Iranian lithosphere has been refertilized during asthenosphere upwelling and mantle flows. The Iranian plateau is underlain by a cold sub-lithospheric body characterized by ∼ +25 kg/m3 density contrast with respect to the ambient asthenosphere. [ABSTRACT FROM AUTHOR]

[Display omitted] • The phlogopites in Bairong lamprophyres reveal asthenospheric components. • The asthenosphere upwelling is the main mechanism for heat and material exchange. • The mafic magmas expelled volatiles and metals to form ore-bearing magmas. The lithosphere provides a reservoir for ore-forming elements introduced by repeated fertilisation during asthenosphere-lithosphere interaction by the slab subduction. Here we use the Gangdese copper metallogenic belt to show how mineralogical study can help to interpret these mantle signatures. We present insights into the in-situ geochronological, geochemical and whole-rock isotopic analyses of minerals from mantle-derived lamprophyres that intruded the Bairong Cu-porphyry deposit in the Gangdese metallogenic belt. Zircon U-Pb dating yields weighted-mean concordant 206Pb/238U ages of 11.69 ± 0.27 Ma to 12.41 ± 0.83 Ma. These zircons show juvenile ε Hf (t) (+1.0 ∼ +10.9) and low δ18O (5.5‰ ∼ 7.7‰) values. Variable initial 87Sr/86Sr ratios (0.7073–0.7080), ε Nd (t) values (−6.3 ∼ −5.0) and initial 187Os/188Os ratios (0.1382–0.1591) suggest hybridization between lithosphere mantle and asthenospheric melts. Phlogopites in the lamprophyres reflect partial dissolution and incipient melting with low Mg# values but high Al 2 O 3 contents in core. And these phlogopites are surrounded by a zone with high Mg# values. We interpret this as superheating and hybridization of refractory lithosphere mantle and asthenosphere. The 3-D magnetotelluric and seismic signature of the Gangdese mineral belt reflect a mantle source region comprising asthenosphere, old refractory lithosphere, ponded mafic melts near the crust-mantle boundary, and higher-level magma chambers where more extensive mixing between crust- and mantle-derived melts occurs. The asthenospheric upwelling provides a mechanism for heat transfer and the expulsion of volatile elements. It is generating a new young, fertile lithosphere beneath the southeast Lhasa block, which has driven the mineralization processes in the Gangdese metallogenic belt. [ABSTRACT FROM AUTHOR]

Background: Standard treatment for periprosthetic joint infection (PJI) involves 2-stage exchange with placement of an antibiotic-impregnated cement spacer (ACS). Conflicting evidence exists on the role of ACS in development of acute kidney injury (AKI) after first-stage surgery. In this randomized clinical trial, we aimed to compare the incidence of AKI between the first-stage of a planned 2-stage exchange vs 1-stage exchange. This study design isolates the effect of the ACS in otherwise identical treatment groups.Methods: The primary outcome variable was AKI, defined as a creatinine ≥1.5 times baseline or an increase of ≥0.3 mg/dL. Risk factors for AKI were evaluated using bivariate statistical tests and multivariable logistic regression.Results: Patients who underwent the first stage of a planned 2-stage exchange were significantly more likely to develop AKI compared with the 1-stage exchange group (15 [22.7%] vs 4 [6.6%], P = .011). On multivariable regression analysis, ACS placement (odds ratio 7.48, 95% confidence limit 1.77-31.56) and chronic kidney disease (odds ratio 3.84, 95% confidence limit 1.22-12.08) were independent risk factors for AKI.Conclusion: Our study provides evidence that high-dose antibiotic cement spacers for treatment of PJI are an independent risk factor for AKI. Therefore, efforts to minimize nephrotoxicity should be employed in revision for PJI when possible. [ABSTRACT FROM AUTHOR]

The Trans-North China Orogen (TNCO) is a major Paleoproterozoic collisional orogen exposed within the North China Craton (NCC). The orogen has undergone a complex tectonic evolution, but its role in the growth of continental crust is contentious. High-grade metamorphic rocks may carry key information required to clarify these issues. Here, using petrography, mineral chemistry, and zircon U–Pb–Hf isotopes, we investigate a suite of Neoarchean–Paleoproterozoic high-grade metamorphic rocks in the Hengshan Complex within the central TNCO. Garnet-bearing mafic granulites and amphibolites occur as lenses or dikes within tonalite–trondhjemite–granodiorite (TTG) gneisses. Three stages of metamorphic mineral assemblages are identified in a mafic granulite from the northern Hengshan Complex: (1) the prograde assemblage is preserved as small plagioclase and apatite inclusions within garnet porphyroblasts; (2) the peak mineral assemblage is recorded by a high-Ca garnet core coexisting with clinopyroxene, plagioclase, hornblende, biotite, and quartz; and (3) the retrograde assemblage is represented mainly by vermicular symplectites of hornblende + plagioclase and plagioclase coronae surrounding low-Ca garnet rims. Phase equilibria modeling and conventional geothermobarometry suggest that the mafic granulite records a clockwise P–T path, including decompression and cooling from the granulite-facies peak (12.5–14 kbar and >750 °C) to amphibolite-facies conditions during retrogression (7.3–8.3 kbar and 615–721 °C). In contrast, the amphibolite in the southern Hengshan Complex preserves only amphibolite-facies assemblages (hornblende + plagioclase + quartz), consistent with the metamorphic pressures of <7.1 kbar and temperatures below 720 °C. Zircon U--Pb dating of magmatic zircons shows that the protoliths of the TTG gneisses and amphibolite were emplaced at ca. 2.5 and 2.1 Ga, respectively. The metamorphic zircons reveal ages of 1.92–1.80 Ga for the mafic granulite (weighted mean of ca. 1.87 Ga) and 1.92–1.83 Ga for the amphibolites (weighted mean of ca. 1.88 Ga). These 1.88–1.87 Ga metamorphic ages are interpreted to represent the time when the rocks cooled to the solidus. By comparing Paleoproterozoic metamorphic ages across the TNCO, we infer that the subduction–collision–amalgamation between the Western and Eastern Blocks of the NCC lasted from 1.95 to 1.80 Ga at least, marking the final cratonization of the NCC. The ca. 2.5 Ga magmatic zircons within the TTG gneisses show positive ε Hf (t) values (+0.49 to +7.12) with model ages of 2.8–2.7 Ga, suggesting that the protoliths were derived from the partial melting of Neoarchean juvenile mafic crust. Zircon Hf model ages (T DM = 2.1–2.0 Ga) of the mafic granulite may represent the approximate time at which the mafic magma was generated in the mantle. Thus, the Hengshan Complex within the central TNCO records two episodes of crustal growth at 2.8–2.7 and 2.1–2.0 Ga, respectively. To further understand the processes involved in crustal evolution, we reconstructed a layered crust model for the Hengshan Complex, and the layered crust was strongly influenced by Paleoproterozoic thermal events. [Display omitted] • The Hengshan Complex witnessed multistage tectonomagmatic-metamorphic events. • A clockwise P-T path is constrained for the garnet-bearing mafic granulite. • 2.8–2.7 and 2.1–2.0 Ga crustal growth events are recognized in the central TNCO. • The layered crustal structure model is retrieved in the Hengshan Complex. [ABSTRACT FROM AUTHOR]

New geochronological and geochemical data for Late Neoproterozoic to Mesozoic intrusive rocks from NW Iran define major regional magmatic episodes and track the birth and growth of one of the Cimmerian microcontinents: the Persian block. After the final accretion of the Gondwanan terranes, the subduction of the Prototethyan Ocean beneath NW Gondwana during the Late Neoproterozoic was the trigger for high magmatic fluxes and the emplacement of isotopically diverse arc-related intrusions in NW Gondwana. The Late Neoproterozoic rocks of NW Iran belong to this magmatic event which includes intrusions with highly variable εHf(t) values. This magmatism continued until a magmatic lull during the Ordovician, which led to the erosion of the Neoproterozoic arc, and then was followed by a rifting event which controlled the opening of Paleotethys. In addition, it is supposed that a prolonged pulse of rift magmatism in Persia lasted from Devonian-Carboniferous to Early Permian time. These magmatic events are geographically restricted and are mostly recorded from NW Iran, although there is some evidence for these magmatic events in other segments of Iran. The Jurassic rocks of NW Iran are interpreted to be the along-strike equivalents of a Mesozoic magmatic belt (the Sanandaj-Sirjan Zone; SaSZ) toward the NW. Magmatic rocks from the SaSZ show pulsed magmatism, with high-flux events at both ~176–160 Ma and ~130 Ma. The SaSZ magmatic rocks are suggested to be formed along a continental arc but a rift setting is also considered for the formation of the SaSZ rocks based on the plume-related geochemical signatures. The arc signatures are represented by Nb-Ta depletion in the highly contaminated (by upper continental crust) plutonic rocks whereas the plume-related signature of less-contaminated melts is manifested by enrichment in Nb-Ta and high εHf(t) values, with peaks at +0.6 and +11.2. All these magmatic pulses led to pre-Cimmerian continental growth and reworking during the Late Neoproterozoic, rifting and detachment of the Cimmerian blocks from Gondwana in Mid-Late Paleozoic time and further crustal growth and reworking of Cimmeria during the Mesozoic. Unlabelled Image • U-Pb zircon ages define Late Neoproterozoic, Paleozoic and Mesozoic magmatic events in NW Iran. • Late Neoproterozoic magmatism is characterized by highly variable εHf(t) values. • Late Paleozoic magmatic pulses show rift-related geochemical signatures with radiogenic εHf(t) values. [ABSTRACT FROM AUTHOR]

Background: Posterior-stabilized total knee arthroplasty (TKA) with gradually variable radii (G-curve) femoral condylar geometry is now available. It is believed that a G-curve design would lead to more mid-flexion stability leading to reduced incidence of paradoxical anterior slide. The objective of this study was to assess the in vivo kinematics for subjects implanted with this type of TKA under various conditions of daily living.Methods: Tibiofemoral kinematics of 35 patients having posterior-stabilized TKA with G-curve design were analyzed using fluoroscopy while performing three activities: weight-bearing deep knee bend, gait, and walking down a ramp. The subjects were assessed for range of motion, condylar translation, axial rotation, cam-spine engagement, and condylar lift-off.Results: The average weight-bearing flexion during deep knee bend was 111.4°. On average, the subjects exhibited 5.4 mm of posterior rollback of the lateral condyle and 2.0 mm of the medial condyle from full extension to maximum knee flexion. The femur consistently rotated externally with flexion, and the average axial rotation was 5.2°. Overall movement of the condyles during gait and ramp-down activity was small. No incidence of condylar lift-off was observed.Conclusion: Subjects in this study experienced consistent magnitudes of posterior femoral rollback and external rotation of the femur with weight-bearing flexion. The variation is similar to that previously reported for normal knee where the lateral condyle moves consistently posterior compared to the medial condyle. Subjects experienced low overall mid-flexion paradoxical anterior sliding and no incidence of condylar lift-off leading to mid-flexion stability. [ABSTRACT FROM AUTHOR]

Background: We sought to evaluate the outcomes of cementless acetabular components used in patients with Crowe II and III dysplasia, and to compare outcomes between cups placed within vs outside of an "anatomic" zone. Our specific aims were to (1) plot hip centers in these patients at our institution to characterize "anatomic" vs "nonanatomic" positions, (2) evaluate the association between hip center and radiographic loosening, (3) determine whether hip center was associated with acetabular component revision, and (4) compare patient-reported outcome scores between groups.Methods: We retrospectively reviewed 88 primary cementless total hip arthroplasties at a mean follow-up of 10 years (range 2-26 years). Patients were 85% female, with a mean age of 44 years (range 28-61 years) and a body mass index of 27 kg/m2 (range 19-42 kg/m2). Medical records and radiographs were reviewed, and a survey was conducted for all patients. Anatomic hip center was defined using the 4-zone system, wherein centers are "anatomic" if they are <1 cm superior and <1 cm lateral to the approximate femoral head center. Cox proportional analyses were used to compare outcomes between groups.Results: Seventy hips (80%) had an anatomic hip center. Anatomic hips had a lower incidence of radiographic acetabular loosening (0% vs 17%, P = .007) and cup revision (0% vs 28%, P = .0002). There were no differences in Hip Disability and Osteoarthritis Outcome and Joint Replacement Scores (96.2 ± 5 vs 91.9 ± 12, P = .7).Conclusion: The incidence of aseptic loosening and cup revision were lower when hip center was <1 cm superior and 1 cm lateral to the approximate femoral head center. [ABSTRACT FROM AUTHOR]

Kimberlites are not only the most economically important source of diamonds; they also carry unique information encapsulated in rock fragments entrained as the magma traverses the whole thickness of the lithosphere. The Nurbinskaya pipe in the Siberian kimberlite province (Russia) is one of several intruded along the Vilyui Rift, a major terrane boundary. The pipe contains three populations of mantle-derived zircon xenocrysts: Archean (mean age 2709 ± 9 Ma), Devonian (mean age 371 ± 2.3 Ma), and a subset of grains with evidence of brittle deformation and rehealing, and a range of ages between 370 and 450 Ma. The Hf-isotope, O-isotope and trace-element signatures of the last group provide a link between the Archean and Devonian events, indicating at least three episodes of magmatic activity and zircon crystallization in the lithosphere beneath the pipe. The emplacement of the Nurbinskaya pipe ca 370 Ma ago was only the youngest activity in a magma plumbing system that has been periodically reactivated over at least 2.7 billion years, controlled by the lithosphere-scale structure of the Vilyui Rift. [ABSTRACT FROM AUTHOR]

Background: Data addressing risk factors predictive of mortality and reoperation after periprosthetic femur fractures (PPFxs) are lacking. This study examined survivorship and risk ratios for mortality and reoperation after surgical treatment for PPFx and associated clinical risk factors.Methods: A retrospective review was performed for 291 patients treated surgically for PPFx between 2004 and 2013. Primary outcomes were death and reoperation.Results: Mortality at 1 year was 13%, whereas the rate of reoperation was 12%. Greater span of fixation and revision arthroplasty (vs open reduction internal fixation) trended toward a lower likelihood of reoperation.Conclusion: After PPFx, patients have a 24% risk of either death or reoperation at 1 year. Factors contributing to increased mortality are nonmodifiable. Risk of reoperation is minimized with greater span of fixation and performance of revision arthroplasty. [ABSTRACT FROM AUTHOR]

Podiform chromitites occur in the meta-dunite horizon of the Dobromirtsi ultramafic massif, in the Central Rhodope metamorphic core complex (southern Bulgaria). Although these were deformed and metamorphosed together with their host rocks several chromite cores from massive chromitite samples still preserve compositions unaffected by metamorphism – at least in terms of major elements . In situ laser ablation ICP-MS analyses of these chromite cores show a bimodality in the composition of chromite between high-Cr and high-Al {Cr# = [Cr/(Cr + Al)], atomic ratio = 0.74–0.55} with Mg# between 0.69 and 0.60 [Mg# = Mg/(Mg + Fe 2 + ), atomic ratio]. These compositions of chromite and the whole rock enrichment of Os–Ir–Ru relative to Pt–Pd in the chromitites resemble that reported for podiform chromitites in ophiolites elsewhere. Magmatic platinum-group minerals (PGM), including laurite (RuS 2 ), Os–Ir alloys and sulfarsenides (irarsite, IrAsS), exhibit a wide range of 187 Os/ 188 Os (from 0.1097 to 0.1272) whereas 187 Re/ 188 Os is nearly zero. The distribution of the Os model ages calculated for these PGM ranges between 0.13 and 2.6 Ga, with age peaks at 0.25, 0.4, 0.7, 2.1 and 2.6 Ga. Two xenocrystic zircons were identified in the chromitites and yield concordant U–Pb age of 2257 ± 80 Ma (2σ) and 1952 ± 82 Ma (2σ). The oldest zircon exhibits a depleted-mantle Hf model age ( T DM ) of 2.77 Ga and a “crustal” Hf model age ( T C DM ) of 3.1 Ga, whereas the youngest has a T DM of 2.21 Ga and a T C DM of 2.35 Ga. We interpret the coexistence of both types of chromitites in a horizon of meta-dunites as the result of their precipitation from fractionating island arc tholeiite melts. The first reactions produced dunite; later the batches of magma were isolated from reaction with the peridotite wall-rocks and progressively fractionated in a network of dunite channels developed in the upper mantle beneath the back-arc spreading centre. The Os and Hf model ages suggest that the ultramafic protolith of the Dobromirtsi ophiolite was derived from an original Archean mantle at least 3 Ga old, which underlay a continental crust and was reworked in the Paleo-proterozoic and possibly even younger times. [ABSTRACT FROM AUTHOR]

The Phanerozoic tectonic evolution of the Kutch region (NW India) has been attributed to rifting processes. In situ U-Pb perovskite dates (all data = 124 ± 4 Ma, MSWD = 42) obtained on three samples of a newly discovered lamproite dyke emplaced in the Kutch rift setting identify a previously unknown and relatively young (Mid-Cretaceous) magmatic event in this part of India. The dyke was emplaced into the Katrol Formation of Upper Jurassic to very early Cretaceous age. The presence of xenocrystic garnet and fractionated REE distribution patterns (low HREE/LREE) in the lamproite, along with high contents of transition metals and low Al 2 O 3 , suggest that it was derived from the garnet stability field in the mantle. Extreme impoverishment in HREE and HFSE suggest a mantle source region that has experienced both depletion and later enrichment. In situ analysis of Nd isotopes in perovskite of three samples gives a mean εNd = 0.4 ± 1 and a T DM model age of 598 ± 64 Ma, while in situ Sr-isotope analysis gives a mean 87 Sr/ 86 Sr = 0.70388 ± 2 (2SE), corresponding to εSr = 8.6 ± 0.3; both datasets suggest mixing between lithospheric-mantle and depleted-mantle components. The fault-controlled emplacement of this body highlights the role of deep-penetrating fault systems in providing a pathway and initiating decompressional melting of the mantle source rocks. The lamproite represents an earlier phase of rift related magmatism, different from the emplacement of the melanephelinite–basanites and basalts that dominate the igneous activity related to the Deccan volcanism in the Kutch mainland. [ABSTRACT FROM AUTHOR]

Abstract: Lithospheric thinning beneath the North China Craton is widely recognized, but whether the Yangtze block has undergone the same process is a controversial issue. Based on a detailed petrographic study, a suite of xenoliths from the Lianshan Cenozoic basalts have been analyzed for the compositions of minerals and whole rocks, and their Sr–Nd isotopes to probe the nature and evolution of the subcontinental lithospheric mantle beneath the lower Yangtze block. The Lianshan xenoliths can be subdivided into two Types: the main Type 1 xenoliths (9–15% clinopyroxene and olivine-Mg#<90) and minor Type 2 peridotites (1.8–6.2% clinopyroxene and olivine-Mg#>90). Type 1 peridotites are characterized by low MgO, high levels of basaltic components (i.e., Al2O3, CaO and TiO2), LREE-depleted patterns in clinopyroxenes and whole rocks, and relatively high 143Nd/144Nd (0.513219–0.513331) and low 86Sr/87Sr (0.702279–0.702789). These features suggest that Type 1 peridotites represent fragments of the newly accreted fertile lithospheric mantle that have undergone ~1% of fractional partial melting and later weak silicate–melt metasomatism, similar to Phanerozoic lithospheric mantle beneath the eastern North China Craton. Type 2 peridotites may be shallow relics of the older lithospheric mantle depleted in basaltic components, with LREE-enriched and HREE-depleted patterns, relatively low 143Nd/144Nd (0.512499–0.512956) and high 86Sr/87Sr (0.703275–0.703997), which can be produced by 9–14% partial melting and subsequent carbonatite–melt metasomatism. Neither type shows a correlation between equilibration temperatures and Mg# in olivine, indicating that the lithospheric mantle is not compositionally stratified, but both types coexist at similar depths. This coexistence suggests that the residual refractory lithospheric mantle (i.e., Type 2 peridotites) may be irregularly eroded by upwelling asthenosphere materials along weak zones and eventually replaced to create a new and fertile lithosphere mantle (i.e., Type 1 xenoliths) as the asthenosphere cooled. Therefore, the subcontinental lithospheric mantle beneath the lower Yangtze block shared a common evolutional dynamic environment with that beneath the eastern North China Craton during late Mesozoic–Cenozoic time. [Copyright &y& Elsevier]

Abstract: The Carboniferous tectonic setting of the Junggar terrane, northern Xinjiang, NW China, has long been a matter of debate. Voluminous Carboniferous volcanic rocks are widely distributed in the Karamaili area, the southern part of the eastern Junggar terrane. Early Carboniferous rocks comprise basalts and basaltic andesites, with enrichment of LREE and LILE and depletion of HFSE, and uniformly high ε Nd(t) (+3.7 to +4.0). Late Carboniferous rocks consist of basalts, basaltic andesites, rhyolites and minor dacites, and can be subdivided into basic and felsic groups. The basic rocks are depleted in HFSE, and show variable high ε Nd(t) (+4.8 to +6.9). They have higher Cr and Ni and lower Na2O, U and Th contents than early Carboniferous basic rocks. The felsic rocks show A-type affinity, with typical enrichment of alkalis, LREE and HFSE and strong depletion in Ba, Sr, Eu and Ti. They have high values of ε Nd(t) and zircon ε Hf(t) (+11.6 to +17.9). New LA-ICPMS zircon U–Pb analyses constrain their emplacement to late Carboniferous time (306.5–314.3Ma). The Carboniferous basic rocks show negative Zr-Hf anomalies and low Th/Ce (<0.07) and Th/La (0.06–0.16), excluding significant crustal contamination during magma evolution. They have low La/Ba (0.03–0.12), Ce/Y (<3) and (Tb/Yb)N (<2) and variable Ba/Th (28–318) and Ba/La (3.1–34), suggesting that they were derived from a main spinel with minor garnet lherzolite mantle source metasomatized by slab-derived fluids. The late Carboniferous felsic rocks were produced when upwelling asthenosphere triggered partial melting of juvenile lower crust. The early Carboniferous volcanism occurred in an island-arc setting related to the southward subduction of the Paleo-Junggar Ocean plate, whereas the late Carboniferous rocks erupted in a post-collisional extensional setting. Thus, a rapid tectonic transition from arc to post-collisional extension may have occurred between early and late Carboniferous, and probably resulted from slab break-off or lithospheric delamination. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to determine if cobalt and chromium ion levels can predict soft tissue damage at total hip revision. This study included 90 metal-on-metal total hip patients with preoperative cobalt and chromium ion levels. Tissue damage noted at revision surgery was graded on a 4-point scale. Sensitivity, specificity, and predictive values were calculated for various threshold values. Receiver operating characteristic analysis was conducted. Using 7 ppb as a threshold, cobalt and chromium ion levels had poor sensitivity and specificity (Co, 65% and 56%; Cr, 29% and 75%). Positive predictive values for cobalt and chromium were only 48% and 26% respectively. The area under the curve was 0.37 for cobalt and 0.44 for chromium. The length of time to revision significantly correlated with tissue damage (P = .001). Ion levels are unreliable predictors of periarticular soft tissue damage and should not be used in isolation as surgical intervention triggers. [Copyright &y& Elsevier]

Abstract: The success of metal bearings is dependent on several parameters. The effects of in vivo forces on the deformation of monoblock acetabular components have yet to be determined. The purpose of our study was to assess the amount of deformation with press-fit fixation of 1-piece metal acetabular components. Four manufacturers provided 1-piece metal acetabular components in each size (30 cups). Testing was conducted using a custom vise to simulate press-fit fixation, and measurements were performed with a Mitutoyo Test device (Aurora, Ill). Previously determined in vivo forces were used in the press-fit simulation. All components deformed under simulated in vivo applied loads. Component deformation ranged from 15 to 300 µm. Larger cups with thinner walls to accommodate larger heads had the greatest deformation and often exceeded the range of reported clearances from the manufacturers (76-227 µm). [Copyright &y& Elsevier]

Abstract: Podiform chromite deposits occur in the mantle sequences of many ophiolites that were formed in supra-subduction zone (SSZ) settings. We have measured the Re–Os isotopic compositions of the major chromite deposits and associated mantle peridotites of the Dongqiao Ophiolite in the Bangong–Nujiang suture, Tibet, to investigate the petrogenesis of these rocks and their genetic relationships. The 187Os/188Os ratios of the chromite separates define a narrow range from 0.12318 to 0.12354, less variable than those of the associated peridotites. Previously-reported 187Os/188Os ratios of the Os-rich alloys enclosed in the chromitites define two clusters: 0.12645±0.00004 (2s; n=145) and 0.12003 to 0.12194. The ultra-depleted dunites have much lower 187Os/188Os (0.11754, 0.11815), and the harzburgites show a wider range from 0.12107 to 0.12612. The average isotopic composition of the chromitites (187Os/188Os: 0.12337±0.00001) is low compared with the carbonaceous chondrite value (187Os/188Os: 0.1260±0.0013) and lower than the average value measured for podiform chromitites worldwide (0.12809±0.00085). In contrast, the basalts have higher 187Os/188Os, ranging from 0.20414 to 0.38067, while the plagioclase-bearing harzburgite and cumulates show intermediate values of 187Os/188Os (0.12979~0.14206). Correspondingly, the basalts have the highest 187Re/188Os ratios, up to 45.4±3.2, and the chromites have the lowest 187Re/188Os ratios, down to 0.00113±0.00008. We suggest that melts/fluids, derived from the subducting slab, triggered partial melting in the overlying mantle wedge and added significant amounts of radiogenic Os to the peridotites. Mass-balance calculations indicate that a melt/mantle ratio of approximately 15:1 (melt: 187Re/188Os: 45.4, 187Os/188Os: 0.34484; mantle peridotite: 187Re/188Os: 0.0029, 187Os/188Os: 0.11754) is necessary to increase the Os isotopic composition of the chromitite deposits to its observed average value. This value implies a surprisingly low average melt/mantle ratio during the formation of the chromitite deposits. The percolating melts probably were of variable isotopic composition. However, in the chromitite pods the Os from many melts was pooled and homogenized, which is why the chromitite deposits show such a small variation in their Os isotopic composition. The results of this study suggest that the 187Os/188Os ratios of chromitites may not be representative of the DMM, but only reflect an upper limit. Importantly, the Os-isotope compositions of chromitites strongly suggest that such deposits can be formed by melt/mantle mixing processes. [Copyright &y& Elsevier]

Abstract: The Malay Peninsula lies on two continental blocks, Sibumasu and East Malaya, which are intruded by granitoids in two provinces: the Main Range and Eastern. Previous models propose that Permian–Triassic granitoids are subduction-related and syn-to post-collisional. We present 752 U–Pb analyses that were carried out on zircons from river sands in the Malay Peninsula; of these, 243 grains were selected for Hf-isotope analyses. Our data suggest a more complex Sibumasu–East Malaya collision history. 176Hf/177Hfi ratios reveal that Permian–Triassic zircons were sourced from three magmatic suites: (a) Permian crustally-derived granitoids, (b) Early-Middle Triassic granitoids with mixed mantle–crust sources, and (c) Late Triassic crustally-derived granitoids. This suggests three Permian–Triassic episodes of magmatism in the Malay Peninsula, two of which occurred in the Eastern Province. Although the exact timing of the Sibumasu–East Malaya collision remains unresolved, current data suggest that it occurred before the Late Triassic, probably in Late Permian–Early Triassic. Our data also indicate that Sibumasu and East Malaya basements are chronologically heterogeneous, but predominantly of Proterozoic age. Some basement may be Neoarchaean but there is no evidence for basement older than 2.8Ga. Finally, we show that Hf-isotope signatures of Triassic zircons can be used as provenance indicators. [Copyright &y& Elsevier]

The location of magmatic Ni-Cu-PGE sulfide deposits is related to lithospheric architecture, particularly that of the subcontinental lithospheric mantle (SCLM). At crustal levels, this relationship is manifest by a close proximity to craton and paleocraton margins. Deposits are associated with mafic-ultramafic rocks and many show a close spatial relationship with a coeval large igneous province (LIP). Meted quantities and tenors observed in deposits require segregation of a magmatic sulfide melt from a large volume of parental ultramafic melt. Generation of these parental melts requires melting of upwelling mantle rising to depths of 100 km or less. The timing and tectonic setting of deposits indicates that this most likely occurs when mantle plumes impact on the base of the SCLM and are channeled laterally to areas of thinnest SCLM, where they undergo decompression melting. Alternatively, the setting of some smaller deposits suggests that upwelling may be induced by syn- to post-collisional lithospheric delamination. Craton margins are generally zones of relatively thin lithosphere and are the focus of strain during regional tectonism, providing points of dilation along active translithospheric faults. These faults facilitate melt introduction into the crust. The craton margin zone of thin lithosphere and active faulting may be adjacent to a neighboring block of continental lithosphere (paleocraton margin) or adjacent to a flanking narrow marginal basin (underlain by asthenosphere). All deposits form during periods of active regional tectonism, most commonly under mildly compressional to transpressional conditions. These different settings and conditions may result in differing depths of melting and differing depths and degrees of crustal interaction. The latter is believed to be a key factor for the development of a metal-rich sulfide melt, which is ultimately emplaced in the deposit environment. These variations can account for the observed range of ore and host rock types. Most large deposits are associated with intracontinental settings or with (former) passive margins at the edge of small marginal basins. No significant deposits are associated with the margins of large oceans or with supra-subduction zone environments, possibly reflecting poor preservational potential or (with the latter) limitations to plume interaction with continental lithosphere. A craton-margin model for the genesis of magmatic Ni-Cu-PGE deposits is proposed. This model provides a framework for further examination of deposit-forming processes and also provides a coherent predictive framework for mineral exploration. [ABSTRACT FROM AUTHOR]

Abstract: The study purpose was to analyze current results of modern cementless femoral components in young patients having total hip arthroplasty (THA) or hip resurfacing. Twenty-two studies (n = 5907; hips = 6408) evaluating modern cementless THA in young patients and 15 studies evaluating hip resurfacing (n = 3002; hips = 3269) were included. Meta-analysis techniques were used to pool failure rates. The pooled failure rate for THA using femoral revision for mechanical failure as an end point was 1.3% (95% confidence interval [CI], 1.0%-1.7%) at a mean 8.4 years of follow-up. At a mean of 3.9 years of follow-up, the pooled mechanical failure rate of the femoral component for hip resurfacing was 2.6% (95% CI, 2.0-3.4). In conclusion, the enthusiasm for hip resurfacing should be tempered by these data. Longer follow-up and direct comparison trials are required to confirm these findings. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to asses the fate of incomplete seating of press-fit acetabular components. From 1990 to 2002, 587 hip arthroplasties were performed using a single-design acetabular component inserted with a press-fit technique with no additional fixation. Complete radiographic follow-up at a mean 9.2 years was available for 343 cases. One hundred thirty-three acetabular components had incomplete seating on the initial postoperative radiograph and 210 cases had complete seating. Of 133 components, 125 (94%) had evidence of complete zone 2 filling. Zone 2 focal osteolysis was present in 22 patients. There were no intraoperative fractures. No acetabular components were revised for loosening. Incomplete seating of press-fit acetabular components is safe and effective in achieving initial and long-term fixation. Zone 2 lucencies when present initially are not associated with increased failure risks. Vigorous attempts to completely seat the acetabular component appear to be unwarranted. [Copyright &y& Elsevier]

Abstract: Infection is an unfortunate complication of total knee arthroplasty. Current literature supports 2-stage reimplantation as the gold standard. Controversy exists whether static or articulating spacers are the best interim treatment method. Seventy-six 2-stage reimplantation procedures met the study inclusion criteria. There were 28 static spacers and 48 articulating spacers. The eradication rate was 94.7% in the articulating group compared with 92.1% in the static group (P = 0.7). There were no significant differences in postoperative Knee Society Scores pain scores. There were 28 (58%) good to excellent function scores in the articulating group and 10 (36%) in the static group (P = .05). Interim use of an articulating spacer maintains excellent infection eradication rates and may improve function over the use of static spacers. [Copyright &y& Elsevier]

Abstract: Hip instability is a common postoperative complication after revision surgery. This study sought to define the prevalence of hip instability after 2-stage reimplantation without an articulating spacer. A joint registry review identified 110 patients undergoing 2-stage reimplantation. Fifty-five patients (56 hips) were alive at the time of data collection. Instability was documented and risk factors were analyzed. Of the 56 hips, 14 (25%) dislocated. Five of these 14 patients had chronic abduction insufficiency. Six patients required rerevision to attain stability. There were no significant differences between dislocators and nondislocators in abduction angle, head size, cup size, liner type, or leg length. The 25% (14/56) dislocation rate reported here is unacceptable. Interim articulating spacers, postoperative bracing, large head technology, and constrained liners are treatment methods that should be considered in this group of patients. [Copyright &y& Elsevier]

Abstract: A retrospective review of patients with joint arthroplasty was performed to determine if body mass index has increased with time and if the body mass index of patients with arthroplasty was significantly different than that of the general population. We also sought to determine if reimbursement kept pace with this growing cohort. The number of obese patients increased from 30.4% in 1990 to 52.1% in 2005 (P < .0001). In 2005, 24% of the general population was obese, whereas 52.1% of arthroplasty patients were obese. Physician reimbursement decreased 38% for knee arthroplasty and 46% for hip arthroplasty and the need for total joint arthroplasty because of these confounding variables will increase exponentially beyond scheduled expectations. Patients and health policy forecasters must understand the interrelationship between obesity and the need for arthroplasty. [Copyright &y& Elsevier]