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The alkalinity of ocean island basalts (OIB), which form by upwelling thermo-chemical instabilities in the mantle, is often associated with the degree of melting. Yet it remains to be tested if alkalinity and the degree of melting are systematically associated with enriched mantle components. The Tasmantid Seamounts, which are fossil remnants of the Tasmantid mantle plume, comprise a north-south age-progressive submarine volcanic chain in the Coral and Tasman Seas East of Australia. Dredged seafloor lavas from nine seamounts along the seamount chain, ranging in age from 50 to 6.5 Ma, show a dichotomy in alkalinity, similar to those observed in other hotspot areas such as Hawai’i or Pitcairn. In radiogenic Sr-Nd-Hf-Pb isotope systematics, Tasmantid Seamount lavas form a continuum between EM1 and PREMA and are thus part of the prevalent EM1-PREMA association in the Pacific. However, their radiogenic Pb isotope systematics mark the Tasmantid plume as an individuum with no resemblance to any other plume. In stable Fe isotopes (expressed as δ57FePrim, which is the Fe isotopic composition calculated to primitive lavas along a liquid line of descent) alkali basalts are, on average, isotopically heavier than tholeiitic lavas, ranging in δ57FePrim from +0.10 to +0.21‰, unrelated to radiogenic isotope systematics, but with co-variations of δ57FePrim and Ti* (which is the primitive melt Ti content). These systematics point towards residual garnet as a key factor and thus indicate a solely petrologic relation between degrees of melting and Fe isotopes. Tholeiitic lavas exhibit a near-depleted mantle like isotopic composition (ranging in δ57FePrim from −0.01 to +0.22‰, median at δ57FePrim + 0.04‰), yet with values of up to δ57FePrim + 0.22‰ that require an isotopically heavy source of unknown origin. The lack of systematics between alkalinity and radiogenic isotope signatures indicates that temperature is the likely driving force for variable melting degrees in some samples over others. Based on these observations, we surmise that tholeiitic lavas form in the plume centre whereas alkaline lavas form at the cooler rim of the conduit. Mixing between melts and associated enriched components in the Tasmantid mantle plume may occur but, at least for alkaline lavas, only on a small scale.

To better understand volcanism on planetary bodies other than the Earth, the quantification of physical processes is needed. Here, the petrogenesis of the achondrite Martian Yamato (Y) nakhlites (Y 000593, Y 000749, and Y 000802) is reinvestigated via quantitative analysis of augite (high-Ca clinopyroxene) phenocrysts: crystal size distribution (CSD), spatial distribution patterns (SDP), and electron backscatter diffraction (EBSD). Results from CSD and EBSD quantitative data sets show augite to have continuous uninterrupted growth resulting in calculated minimum magma chamber residence times of either 88–117 ± 6 yr or 9–12 yr. All samples exhibit low-intensity S-LS type crystallographic preferred orientation. Directional strain is observed across all samples with intracrystalline misorientation patterns indicative of (100)[001]:(001)[100] (Y 000593 and Y 000802) and {110}or {110}1/2 (Y 000749) slip systems. SDP results indicate phenocryst-bearing crystal-clustered rock signatures. Combined findings from this work show that the Yamato nakhlites formed on Mars as individual low-viscosity lava flows or sills. This study shows that through combining these different quantitative techniques over multiple samples, one can more effectively compare and interpret resulting data to gain a more robust, geologically contextualized petrogenetic understanding of the rock suite being studied. The techniques used in this study should be equally applicable to igneous achondrites from other parent bodies.

Understanding the quantity and isotopic composition of water that has been delivered to Earth over its history is crucial for models our planet’s evolution, and predicting habitability across the solar system. Here we have used stepwise pyrolysis to measure the hydrogen inventory of CM carbonaceous chondrites, which are likely to have been a major source of volatiles for the early Earth. Stepwise pyrolysis potentially enables the carriers of pre-terrestrial hydrogen to be identified, and distinguished from hydrogen that may have been added during the meteorite’s time on Earth. Twelve CM meteorites were analysed, and from their bulk hydrogen composition, petrologic type and nature of parent body processing, they can be divided into three subsets. The CMs of subset A have been mildly aqueously altered. Their hydrogen is hosted by isotopically light phyllosilicate, isotopically heavy organic matter, and adsorbed terrestrial water that is comparable to or slightly heavier than phyllosilicate. The subset B meteorites have been heavily aqueously altered and their hydrogen is also in phyllosilicate, organic matter and adsorbed terrestrial water. Their pyrolysis profiles differ from subset A in that the phyllosilicates dehydroxylate at higher temperatures owing to differences in mineralogy and chemical composition. The hydrogen that was evolved from organic matter may also have been isotopically lighter owing to loss of deuterium during aqueous alteration. Subset C meteorites were heated on their parent body after aqueous alteration, leading to loss of hydrogen from phyllosilicates and organic matter such that half of the water that they evolve was added after falling to Earth. Taking the 12 CMs together, an average of 0.20 wt. % H (21 % of total H) is terrestrial, and recalculation of bulk compositions without this component can raise bulk δD of individual meteorites by up to 73 ‰. Carbonaceous chondrites in our collections differ in the abundance and isotopic composition of hydrogen relative to their parent asteroid(s). An accurate understanding of the nature of water that was delivered to early Earth can only come from the analysis of materials that have been isolated from the terrestrial atmosphere, such as those returned from Ryugu and Bennu.

Volcanism associated with the Kerguelen Large Igneous Province is found scattered in southwestern Australia (the ca 136 to ca 130 Ma Bunbury Basalts, and ca 124 Ma Wallaby Plateau), India (ca 118 Ma Rajmahal Traps and Cona Basalts), and Tibet (the ca 132 Ma Comei Basalts), but apart from the ∼70 000 km2 Wallaby Plateau, these examples are spatially and volumetrically minor. Here, we report dredge, geochronological and geochemical results from the ∼90 000 km2 Naturaliste Plateau, located ∼170 to ∼500 km southwest of Australia. Dredged lavas and intrusive rocks range from mafic to felsic compositions, and prior geophysical analyses indicate these units comprise much of the plateau substrate. 40Ar/39Ar plagioclase ages from mafic units and U–Pb zircon ages from silicic rocks indicate magmatic emplacement from 130.6 ± 1.2 to 129.4 ± 1.3 Ma for mafic rocks and 131.8 ± 3.9 to 128.2 ± 2.3 Ma for silicic rocks (2σ). These Cretaceous Naturaliste magmas incorporated a significant component of continental crust, with relatively high 87Sr/86Sr (up to 0.78), high 207Pb/204 Pb ratios (15.5–15.6), low 143Nd/144Nd (0.511–0.512) and primitive-mantle normalised Th/Nb of 11.3 and La/Nb of 3.97. These geochemical results are consistent with the plateau being underlain by continental basement, as indicated by prior interpretations of seismic and gravity data, corroborated by dredging of Mesoproterozoic granites and gneisses on the southern plateau flank. The Cretaceous Naturaliste Plateau igneous rocks have signatures indicative of extraction from a depleted mantle, with trace-element and isotopic values that overlap with Kerguelen Plateau lavas reflect crustal contamination. Our chemical and geochronological results therefore show the Naturaliste Plateau contains evidence of an extensive igneous event representing some of the earliest voluminous Kerguelen hotspot magmas. Prior work reports that contemporaneous correlative volcanic sequences underlie the nearby Mentelle Basin, and the Enderby Basin and Princess Elizabeth Trough in the Antarctic. When combined, the igneous rocks in the Naturaliste, Mentelle, Wallaby, Enderby, Princess Elizabeth, Bunbury and Comei-Cona areas form a 136–124 Ma Large Igneous Province covering >244 000 km2.

Meteorite Hills (MET) 01075 is unique among the CM carbonaceous chondrites in containing the feldspathoid mineral sodalite, and hence it may provide valuable evidence for a nebular or parent body process that has not been previously recorded by this meteorite group. MET 01075 is composed of aqueously altered chondrules and calcium‐ and aluminum‐rich inclusions (CAIs) in a matrix that is predominantly made of serpentine‐ and tochilinite‐rich particles. The chondrules have been impact flattened and define a foliation petrofabric. Sodalite occurs in a 0.6 mm size CAI that also contains spinel, perovskite, and diopside together with Fe‐rich phyllosilicate and calcite. By analogy with feldspathoid‐bearing CAIs in the CV and CO carbonaceous chondrites, the sodalite is interpreted to have formed by replacement of melilite or anorthite during alkali‐halogen metasomatism in a parent body environment. While it is possible that the CAI was metasomatized in a precursor parent body, then excavated and incorporated into the MET 01075 parent body, in situ metasomatism is the favored model. The brief episode of relatively high temperature water–rock interaction was driven by radiogenic or impact heating, and most of the evidence for metasomatism was erased by subsequent lower temperature aqueous alteration. MET 01075 is very unusual in sampling a CM parent body region that underwent early alkali‐halogen metasomatism and has retained one of its products.

The nakhlite meteorites characteristically contain iddingsite, a hydrous iron–magnesium silicate that formed by aqueous alteration on Mars. Iddingsite is most abundant in Northwest Africa (NWA) 817, and alteration products in this meteorite also have the lowest deuterium/hydrogen ratio of any nakhlite. Taken together, these distinctive properties could be interpreted to show that NWA 817 was altered under different physico‐chemical conditions than the other nakhlites and by liquid water from a separate reservoir. Here this interpretation is tested through a petrographic, mineralogical, chemical, and isotopic study of NWA 817. We find that its iddingsite occurs as olivine‐hosted veins of nanocrystalline smectite and Fe‐oxyhydroxide. Strong similarities in the mineralogy of iddingsite between NWA 817 and other nakhlites suggest that these meteorites were altered under comparable physico‐chemical conditions, with the Fe‐rich composition of NWA 817 olivine grains rendering them especially susceptible to aqueous alteration. Analyses of NWA 817 bulk samples by stepwise pyrolysis confirm that its iddingsite has unusually low deuterium/hydrogen ratios, but owing to terrestrial weathering of this meteorite, the hydrogen isotopic data cannot be used with confidence to infer the origin of Martian aqueous solutions. NWA 817 was most probably altered along with the other nakhlites over a short time period and in a common aqueous system. One interpretation of a correlation between the eruption ages of three of the nakhlites and the chemical composition of their iddingsite is that water originated from close to the surface of Mars and flowed through the nakhlite lava pile under the influence of gravity.

Lewis Cliff (LEW) 85311 is classified as a Mighei-like (CM) carbonaceous chondrite, yet it has some unusual properties that highlight an unrealised diversity within the CMs, and also questions how many parent bodies are sampled by the group. This meteorite is composed of rimmed chondrules, chondrule fragments and refractory inclusions that are set in a fine-grained phyllosilicate-rich matrix. The chondrules are of a similar size to those in the CMs, and have narrow fine-grained rims. LEW 85311 has been mildly aqueously altered, as evidenced by the preservation of melilite and kamacite, and X-ray diffraction results showing a low phyllosilicate fraction and a high ratio of cronstedtite to Fe,Mg serpentine. The chemical composition of LEW 85311 matrix, fine-grained rims, tochilinite and P-rich sulphides is similar to mildly aqueously altered CMs. LEW 85311 is enriched in refractory elements and REEs such that its CI-normalised profile falls between the CMs and CVs, and its oxygen isotopic composition plots in the CV-CK-CO field. Other distinctive properties of this meteorite include the presence of abundant refractory inclusions, and hundreds of micrometer size objects composed of needle-fibre calcite. LEW 85311 could come from part of a single CM parent body that was unusually rich in refractory inclusions, but more likely samples a different parent body to most other members of the group that accreted a subtly different mixture of materials. The mineralogical and geochemical evolution of LEW 85311 during subsequent aqueous alteration was similar to other CMs and was arrested at an early stage, corresponding to a petrologic subtype of CM2.7, probably due to an unusually low proportion of accreted ice. The CM carbonaceous chondrites sample multiple parent bodies whose similar size and inventory of accreted materials, including radiogenic isotopes, led to a comparable post-accretionary evolution.

Evidence for impact-generated water on Mars ~633 Ma ago predicts two craters at the nakhlite meteorite’s ejection site., Nakhlite meteorites are ~1.4 to 1.3 Ga old igneous rocks, aqueously altered on Mars ~630 Ma ago. We test the theory that water-rock interaction was impact driven. Electron backscatter diffraction demonstrates that the meteorites Miller Range 03346 and Lafayette were heterogeneously deformed, leading to localized regions of brecciation, plastic deformation, and mechanical twinning of augite. Numerical modeling shows that the pattern of deformation is consistent with shock-generated compressive and tensile stresses. Mesostasis within shocked areas was aqueously altered to phyllosilicates, carbonates, and oxides, suggesting a genetic link between the two processes. We propose that an impact ~630 Ma ago simultaneously deformed the nakhlite parent rocks and generated liquid water by melting of permafrost. Ensuing water-rock interaction focused on shocked mesostasis with a high density of reactive sites. The nakhlite source location must have two spatially correlated craters, one ~630 Ma old and another, ejecting the meteorites, ~11 Ma ago.

The upcoming Mars Sample Return (MSR) mission aims to deliver small quantities of Martian rocks to the Earth. Investigating these precious samples requires the development and application of techniques that can extract the greatest amount of high quality data from the minimum sample volume, thereby maximising science return from MSR. Atom probe tomography (APT) and transmission electron microscopy (TEM) are two complementary techniques that can obtain nanoscale structural, geochemical and, in the case of atom probe, isotopic information from small sample volumes. Here we describe how both techniques operate, as well as review recent developments in sample preparation protocols. We also outline how APT has been successfully applied to extraterrestrial materials in the recent past. Finally, we describe how we have studied Martian meteorites using TEM and APT in close coordination in order to characterise the products of water/rock interactions in t h e cru st of Ma r s – a k ey sc ie n ce goal of MSR. Our results provide new insights into the Martian hydrosphere and the mechanisms of anhydrous-hydrous mineral replacement. In light of the unique results provided by these tools, APT and TEM should form a crucial part at the culmination of a correlative analytical pipeline for MSR mission materials.

In order to validate calculated ages of the Martian crust we require precise radiometric dates from igneous rocks where their provenance on the Martian surface is known. Martian meteorites have been dated precisely and quantitatively, but the launch sites are currently unknown. Inferring the formation environment of a correlated suite of Martian meteorites can constrain the nature and complexity of the volcanic system they formed from. The nakhlite meteorites are such a suite of augite-rich rocks that sample the basaltic crust of Mars, and as such can provide unique insights into its volcanic processes. Using electron backscatter diffraction we have determined the shape-preferred and crystallographic-preferred orientation petrofabrics of four nakhlites (Governador Valadares, Lafayette, Miller Range 03346 and Nakhla) in order to understand the conditions under which their parent rocks formed. In all samples, there is a clear link between the shape-preferred orientation (SPO) and crystallographic-preferred orientation (CPO) of augite phenocrysts. This relationship reveals the three-dimensional shape of the augite crystals using CPO as a proxy for 3D SPO, and also enables a quantitative 3-dimensional petrofabric analysis. All four nakhlites exhibit a foliation defined by the CPO of the augite axis in a plane, although individual meteorites show subtle textural variations. Nakhla and Governador Valadares display a weak CPO lineation within their axis foliation that is interpreted to have developed in a combined pure shear/simple shear flow regime, indicative of emplacement of their parent rock as a subaerial hyperbolic lava flow. By contrast, the foliation dominated CPO petrofabrics of Lafayette and Miller Range 03346 suggest formation in a pure shear dominated regime with little influence of hyperbolic flow. These CPO petrofabrics are indicative of crystal settling in the stagnant portion of cooling magma bodies, or the flattening area of spreading lava flows. The CPO foliation of Lafayette's is substantially weaker than Miller Range 03346, probably due to its higher phenocryst density causing grain-grain interactions that hindered fabric development. The CPO petrofabrics identified can also be used to determine the approximate plane of the Martian surface and the line of magma flow to within ∼20°. Our results suggest that the nakhlite launch crater sampled a complex volcanic edifice that was supplied by at least three distinct magmatic systems limiting the possible locations these rocks could have originated from on Mars.

Many volcanoes worldwide still have poorly resolved eruption histories, with the date of the last eruption often undetermined. One such example is Ascension Island, where the timing of the last eruption, and consequently, the activity status of the volcano, is unclear. Here, we use the 40Ar/39Ar dating technique to resolve ages of the three youngest lava flows on the island, which are hawaiites and mugearite with 1.5 – 1.9 wt% K2O. In dating these lavas, we provide the first evidence of Holocene volcanic activity on Ascension (0.51 ± 0.18 ka; 0.55 ± 0.12 ka; 1.64 ± 0.37 ka), determining that it should be classed as an active volcanic system. In addition, we demonstrate that the 40Ar/39Ar method can reproducibly date mafic lava flows younger than 1 ka, decreasing the gap between recorded history and geological dating. These results offer new prospects for determining patterns of late-Holocene volcanic activity; critical for accurate volcanic hazard assessment.

Basement structure is known to exert strong magmatic and morphological control on continental volcanoes, but relatively little is known about the structural control of submarine volcanoes. Here we investigate the morphology of the Tasmantid Seamounts, a >2400 km long chain of age‐progressive intraplate volcanoes, ranging from 56 to 7 Ma. The seamounts are emplaced over the extinct Tasman Sea spreading centre, which was active between 84 and 52 Ma. While thick sediment (∼1 km) obscures much of the basement, detailed morphological and geophysical analyses of the seamounts reveal a strong correlation between tectonic setting, seamount orientation, and volcanic structure, despite the ≥20 Ma interval between spreading cessation and seamount emplacement. Seamounts emplaced on fracture zones or spreading segment‐transform fault inside corners are typically large and elongate. Where original morphology is preserved, they often appear rugged and predominantly fissure‐fed. By contrast, comparatively smooth, conical seamounts with isolated dyke‐fed flank cones are often found mid‐segment and at outside corners. Volcanic fabrics also align closely with the expected principal stress directions for strong mechanical coupling across transform faults. This behaviour suggests the lithosphere is dissected by numerous deep faults, channelling magma along pre‐existing structural trends. Generally low effective elastic thicknesses (

The metamorphic history of martian meteorite NWA 7034 suggests that the martian crustal dichotomy may have formed within 100 million years of planetary formation., Martian meteorite Northwest Africa (NWA) 7034 and its paired stones are the only brecciated regolith samples from Mars with compositions that are representative of the average martian crust. These samples therefore provide a unique opportunity to constrain the processes of metamorphism and alteration in the martian crust, which we have investigated via U-Pu/Xe, 40Ar/39Ar, and U-Th-Sm/He chronometry. U-Pu/Xe ages are comparable to previously reported Sm-Nd and U-Pb ages obtained from NWA 7034 and confirm an ancient (>4.3 billion years) age for the source lithology. After almost 3000 million years (Ma) of quiescence, the source terrain experienced several hundred million years of thermal metamorphism recorded by the K-Ar system that appears to have varied both spatially and temporally. Such protracted metamorphism is consistent with plume-related magmatism and suggests that the source terrain covered an areal extent comparable to plume-fed edifices (hundreds of square kilometers). The retention of such expansive, ancient volcanic terrains in the southern highlands over billions of years suggests that formation of the martian crustal dichotomy, a topographic and geophysical divide between the heavily cratered southern highlands and smoother plains of the northern lowlands, likely predates emplacement of the NWA 7034 source terrain—that is, it formed within the first ~100 Ma of planetary formation.

Cohen was supported by STFC grant ST/N000846/1. The funds for 40Ar/39Ar dating were supplied by the SUERC Argon Isotope Facility. NERC are thanked for the continued funding of the Argon Isotope Facility. The Rochechourt impact structure in south-central France, with maximum diameter of 40–50 km, has previously been dated to within 1% uncertainty of the Triassic–Jurassic boundary, at which time ~30% of global genera became extinct. To evaluate the temporal relationship between the impact and the Triassic–Jurassic boundary at high precision, we have re-examined the structure's age using multicollector ARGUS-V 40Ar/39Ar mass spectrometry. Results from four aliquots of impact melt are highly reproducible, and yield an age of 206.92 ± 0.20/0.32 Ma (2σ, full analytical/external uncertainties). Thus, the Rochechouart impact structure predates the Triassic–Jurassic boundary by 5.6 ± 0.4 Ma and so is not temporally linked to the mass extinction. Rochechouart has formerly been proposed to be part of a multiple impact event, but when compared with new ages from the other purported “paired” structures, the results provide no evidence for synchronous impacts in the Late Triassic. The widespread Central Atlantic Magmatic Province flood basalts remain the most likely cause of the Triassic–Jurassic mass extinction. Publisher PDF

40Ar/39Ar laser incremental heating analyses of supergene K-Mn oxides from weathering profiles at the Baye Mn deposit, southern Yunnan Plateau, SW China, were carried out to place constraints on the timing of weathering and derive insights into local paleoclimatic and landscape evolution. Weathering profiles in the Baye Mn mine are dominated by 20–30 m thick saprolites, which are locally covered by unconsolidated alluvial deposits. We analyzed 70 grains from 35 hand samples collected from four sites located at distinct elevations. In most cases, different grains from the same hand sample and different samples from the same site have reproducible 40Ar/39Ar plateau ages. The plateau ages of individual grains are also consistent with the respective isochron, integrated, and ideogram ages. This age consistency attests to the reliability of the geochronological results as numerical constraints on the formation and evolution of these weathering profiles. Sixty-four grains from 32 hand samples collected from weathering profiles at four sites (A to D) yield well-defined plateau or pseudoplateau ages ranging from 2.98 ± 0.07 to

The Daye District represents one of the largest concentrations of Cu–Fe–Au skarn deposits in China, with additional porphyry Cu–Mo deposits. These deposits are closely associated with late Mesozoic intrusions of intermediate to felsic composition. Previous studies have yielded important age constraints for several deposits, timing and history of metallogenesis for the entire district, however, remain not well understood. In this paper, we present twenty-five new ages (Re–Os, 40Ar/39Ar, and U–Pb) to better understand the temporal framework of the district-wide polymetallic mineralization. These ages, when combined with existing data, indicate a prolonged history of mineralization lasting 25 million years from late Jurassic to early Cretaceous (157–132 Ma), and that most ore deposits of the district are results of multistage hydrothermal activity. Discrete episodes of ore formation coincide well with emplacement ages of granitoid intrusions within the district as revealed by recent zircon U–Pb dating. This age consistency substantiates a genetic relationship between ore formation and intrusive magmatism. Prolonged and episodic magmatic and hydrothermal activities must have played significant roles in the formation of polymetallic ore deposits in the district by repeatedly supplying heat, fluids, and metals. Previous studies have demonstrated that the Daye District was dominated by lithospheric extension during late Jurassic to early Cretaceous, when extensive magmatism and mineralization took place. Under the extensional setting, the area could have experienced significant uplift or extensional exhumation that would have brought early-stage intrusions and associated ore deposits to shallower levels, with ore bodies formed by subsequent magmatic–hydrothermal events tending to be localized at greater depth. This in turn indicates potentials to find new ore bodies at depth of known deposits, especially for those formed by episodic magmatic–hydrothermal processes. This view is partly confirmed by the recent success in deep exploration beneath the Tieshan Fe–Cu and Tonglushan Cu–Au–Fe deposits.

Reconstruction of bony defects in the surgical management of vertebral osteomyelitis is a challenging endeavor. Our objective is to report the use of intra-abdominal vessels as the recipient vessels for microanastomosis of vascularized bone graft and the use of a spinal cage for fixation. Three patients failed conservative treatment for vertebral osteomyelitis and suffered pathologic fracture. Their treatment consisted of staged posterior irrigation and debridement with segmental fixation, followed by a thoracoabdominal approach multiple-level corpectomy. Reconstruction was performed with a free vascularized fibular graft placed within a custom, expandable cage. The vascularized fibular graft was anastomosed to an intra-abdominal recipient vessel. All patients improved clinically with no neurologic deficits noted. All showed evidence of successful fusion. Free vascularized bone grafts continue to be an excellent option for multi-level spinal defects related to osteomyelitis. Intra-abdominal recipient vessels are appropriate recipient vessels, as their diameter, length, and accessibility allow vascularized bone graft reconstruction of vertebral column defects of the thoracolumbar region. These vessels are also easily accessible and the anastomoses can be performed in the superficial operating incision. © 2013 Wiley Periodicals, Inc. Microsurgery 33:560–566, 2013.

Here we use geochronology of Australian intraplate volcanoes to construct a high-resolution plate-velocity record and to explore how tectonic events in the southwest Pacific may have influenced plate motion. Nine samples from five volcanoes yield ages from 33.6 ± 0.5 to 27.3 ± 0.4 Ma and, when combined with published ages from 30 to 16 Ma, show that the rate of volcanic migration was not constant. Instead, the results indicate distinct changes in Australian plate motion. Fast northward velocities (61 ± 8 and 57 ± 4 km/Ma) prevailed from 34 to 30 (±0.5) and from 23 to 16 (±0.5) Ma, respectively, with distinct reductions to 20 ± 10 and 22 ± 5 km/Ma from 30 to 29 (±0.5) Ma and from 26 to 23 (±0.5) Ma. These velocity reductions are concurrent with tectonic collisions in New Guinea and Ontong Java, respectively. Interspersed between the periods of sluggish motion is a brief 29-26 (±0.5) Ma burst of atypically fast northward plate movement of 100 ± 20 km/Ma. We evaluate potential mechanisms for this atypically fast velocity, including catastrophic slab penetration into the lower mantle, thermomechanical erosion of the lithosphere, and plume-push forces; none are appropriate. This period of fast motion was, however, coincident with a major southward propagating slab tear that developed along the northeastern plate margin, following partial jamming of subduction and ophiolite obduction in New Caledonia. Although it is unclear whether such an event can play a role in driving fast plate motion, numerical or analogue models may help address this question. Key Points We determine nine 40Ar/39Ar ages from five Cenozoic volcanoes in Australia Slow velocities correlate with New Guinea and Ontong Java collisions Anomalously fast velocity of 100 +/- 20 km/Ma is identified from 29-26 Ma

Intraplate volcanism was widespread in southeastern Queensland during the mid Cenozoic, leaving a legacy of variably eroded volcanoes and rugged topography known locally as "The Scenic Rim". These plume-derived volcanoes provide a detailed record of northward Australian plate velocity, and indicate a major slowdown commencing at 26 Ma and persisting until 23 Ma, correlated with initial collision of the massive Ontong Java plateau with the northern subduction margin of the Australian plate. Despite traversing over 36 km of continental crust, trace element and isotopic signatures indicate little or only minor contamination for most units, with the exception of rhyolites formed during the period of slow plate velocity. Nevertheless, the thick continental crust allowed magmas to stall and fractionate during ascent, often producing highly evolved rocks (e.g., comendites) containing extreme concentrations of incompatible elements, including >2000 ppm Zr. Meanwhile, isotopic and trace element results from mafic units are consistent with melting and mixing of depleted upper mantle and an EM1-like source. Alkaline mafic eruptions also often contain abundant upper mantle and lower crustal xenoliths, providing excellent samples of these otherwise inaccessible regions. Denudation has produced good exposures of the subsurface magmatic architecture, a variety of landscapes, and diverse wildlife habitats; as a result many of the volcanoes are contained in National Parks, including the World Heritage listed Gondwana Rainforests of Australia.

Six tuffaceous beds within the Omo Group of the Omo–Turkana Basin have been dated using the 40 Ar/ 39 Ar single crystal total fusion method on anorthoclase, yielding eruption ages. The Omo Group constitutes up to 800 m of subaerially exposed sediments surrounding Lake Turkana within the East African Rift system in northern Kenya and southern Ethiopia. Rhyolitic explosive eruptions produced tuffs and pumice clasts that are considered to have been deposited shortly after eruption. The new age data on feldspars from the pumice clasts range from 4.02 ± 0.04 Ma for the Naibar Tuff of the Koobi Fora Formation to 1.53 ± 0.02 Ma for Tuff K of the Shungura Formation. The Orange Tuff in the KBS Member of the Koobi Fora Formation was dated at 1.76 ± 0.03 Ma, providing good control in this part of the sequence where formerly there was a >200 ka gap. Data are consistent with earlier measurements and significantly improve age resolution within the Omo Group, which has yielded many vertebrate fossils, including hominin fossils comprising a number of species. We suggest new age estimates for a limited number of hominin specimens. Supplementary material: Eleven tables and nine figures are available at www.geolsoc.org.uk/SUP18506.

The Yangzhaiyu gold deposit is one of numerous lode gold deposits in the Xiaoqinling district, southern margin of the North China Craton. Gold mineralization is hosted in Neoarchean to early Paleoproterozoic amphibolite facies metamorphic rocks and consists of auriferous quartz veins and subordinate disseminated ores in the vein-proximal alteration zone. Ore-related hydrothermal alteration is dominated by sericite + quartz + sulfide assemblages close to gold veins, and biotite + quartz + pyrite ± chlorite ± epidote alteration generally distal from mineralization. Pyrite is the predominant sulfide mineral, locally coexisting with minor amounts of chalcopyrite, sphalerite, and galena. Gold occurs mostly as free gold enclosed in or filling microfractures of pyrite and quartz and is also present in equilibrium with Au-bearing tellurides, mainly petzite and calaverite coexisting with hessite, tellurobismuthite, and altaite. Fluid inclusion studies suggest that gold veins were deposited at intermediate temperatures (175°–313°C) from aqueous or aqueous-carbonic fluids with moderate salinity (5–14 wt % NaCl equiv). δ 34S values of sulfide minerals range mainly from 2.0 to 4.4‰, whereas auriferous quartz vein samples have δ 18O values of 12.4 to 9.6‰, with calculated δ 18OH2O values of 6.0 to 3.2‰. Gold-related pyrite grains yield elevated 3He/4He ratios (1.51-0.32 Ra) relative to crustal reservoirs and mantle-like 20Ne/22Ne and 21Ne/22Ne ratios (9.90-9.68 and 0.029, respectively). The stable and noble gas isotopes thus suggest deep-seated, most likely magmatic and mantle-derived, sources for the ore fluids, sulfur and, by inference, other components in the ore system. 40Ar/39Ar dating of ore-related sericite and biotite separates indicates two episodes of gold genesis at 134.5 to 132.3 and 124.3 to 123.7 Ma. The mineralization ages overlap zircon U-Pb ages of 141.0 ± 1.6 to 125.8 ± 1.4 Ma (2 σ ) for the Wenyu and Niangniangshan monzogranite Plutons and a number of mafic to intermediate dikes intruding these Plutons, all being proximal to the Yangzhaiyu gold deposit. The synchronism of gold genesis and magmatism provides additional weights of evidence for a magmatic derivation of ore fluids and sulfur. The geochronologic data also suggest that gold veining took place billions of years after the stabilization of the North China Craton and associated metamorphism in the Late Archean to early Paleoproterozoic. This contrasts sharply to lode gold deposits in other Precambrian cratons that formed predominantly in Late Archean to Paleoproterozoic, temporarily and genetically related to regional high-grade metamorphism and compressional or transpressional tectonism. Available data have demonstrated that the North China Craton was reactivated in the late Mesozoic, as marked by voluminous igneous rocks, faulted-basin formation, high crustal heat flow, and widespread metamorphic core complexes in the eastern part of the craton. It is thus suggested that the Yangzhaiyu gold deposit, together with other deposits of similar ages in the Xiaoqinling district, were products of this craton reactivation event. Lithospheric extension and extensive magmatism related to the craton reactivation may have provided sufficient heat energy, fluid, and sulfur required for the formation of the gold deposits.

We present 40Ar/39Ar ages for four volcanic bodies from a group of volumetrically minor alkaline plugs, necks, and dikes in northeastern Brazil, previously ascribed to passage over the purported Fernando de Noronha plume. The rocks are relatively primitive (9.5–14.7 wt.% MgO), typically nepheline-normative basanites with ocean island basalt (OIB)-like trace-element compositions similar to alkalic basalts from the Fernando de Noronha archipelago. Highly fractionated REE coupled with relative depletions of K and Rb indicates that the silica undersaturated magmas were generated by small degrees of melting in the presence of residual garnet and a hydrous metasomatic phase. Three of the four units (Caracarazinho, Cabugizinho da Arara and Serra Preta de Bodo) were heretofore undated. The fourth body (Cabelo de Negro) was included to facilitate comparison with published K–Ar dates. 40Ar/39Ar age determinations by the laser incremental-heating method on duplicate grains of groundmass reveal the youngest continental volcanism in Brazil, with emplacement ages between 8.9 ± 0.5 and 7.1 ± 0.3 Ma. Our age for Cabelo de Negro (7.9 ± 0.3 Ma) is roughly 20 Ma younger than the published K–Ar date for this plug. The reproducibility of our duplicate analyses and the consistency of the plateau, ideogram and isochron ages for this sample attest to the reliability of the new 40Ar/39Ar results. Our geochronological results show that volcanic activity on the continent did not shut down prior to the onset of volcanism on the island of Fernando de Noronha. Both areas were active contemporaneously for at least 5 Ma. We argue that the extended duration, small volume and lack of a clear age progression suggest that this example of alkaline intraplate volcanism is more likely the surface manifestation of the upwelling flow seen in an edge-driven convection mode, rather than tracking passage over a deep-seated mantle plume. This hypothesis is supported by xenolith thermobarometery, heat-flow data and seismic tomography, which collectively provide evidence for a mild thermal anomaly (upwelling) in the upper mantle under the eastern-most equatorial Brazil that extends into the Atlantic and appears to travel with the plate. Small-scale convection is also consistent with the seismic evidence for a downwelling to about 600 km depth in the mantle beneath the cratonic margin of eastern Brazil. Given the inherently sluggish upwelling associated with such small-scale convection, it appears that the entrainment of metasomatically enriched lithospheric mantle is likely vital to melt generation. If so, the spatial distribution of edge-driven magmatism may provide a tool for mapping fertility of the subcontinental lithospheric mantle.

Aesthetic reduction of the labia minora has gained popularity, and a number of different techniques have been described. Each procedure has its own set of advantages and disadvantages. However, no algorithm has been defined for pairing the degree of deformity with the optimal surgical procedure.Patients were stratified into one of four groups based on labial size. The surgeon chose one of three reduction techniques based on the degree of labial hypertrophy and the patient's aesthetic preferences for labial edge color and contour. Three reduction techniques were used including the edge excision technique, the inferior wedge resection technique, and deepithelialization reduction labioplasty. The success of aesthetic reduction was evaluated, as was symptomatic relief.The 12 procedures performed included five deepithelialization techniques, four edge excision techniques, and three inferior wedge resection techniques. As reported, 92% of the patients were "very satisfied" with their aesthetic and functional results. The complications were minimal, with three patients experiencing minor wound healing difficulties that resolved spontaneously. One patient who underwent the edge excision technique was "not satisfied" and complained of overreduction.The authors found all three techniques for labia minora reduction to be useful in different clinical situations. A novel algorithm is described for matching the optimal surgical technique for each patient based on her degree of hypertrophy and aesthetic goals.

The development and application of geochronological tools suitable for dating Cenozoic rocks and processes have been instrumental to our understanding of the modern history of Australia. Geochronology reveals a dynamic continent that traced a long and rapid trajectory from a position adjacent to Antarctica in the early Cenozoic to its present position near the tropics. The average travel velocity along this path is revealed by the age of hotspot volcanoes, derived by the K–Ar method, and is complemented by measured geomagnetic pole positions on dated igneous rocks and sedimentary deposits. K–Ar dating of volcanic rocks also provided constraints on rates of landscape evolution before and after volcanism and the timing and pattern of dispersion of life—including human inhabitation. K–Ar geochronological results reveal a history of faunal and floral evolution suggestive of a continent undergoing progressive cooling and dehydration with a few brief warm and humid excursions. In contrast, 40Ar/39Ar, SHRIMP U–P...

Laser incremental-heating 40Ar/39Ar geochronology of seven leucitites from southeastern Australia indicates that leucite-bearing lavas in individual geographic clusters were erupted in one million years or less. The eruption ages range from 17.9 ± 0.3 Ma (2σ) at El Capitan in northern-central New South Wales to 8.9 ± 0.2 Ma (2σ) at Cosgrove in northern Victoria. The 40Ar/39Ar results demonstrate that the southward migration of leucite-bearing lavas was near-contemporaneous with age-progressive central-volcano magmatism in southeastern Australia. As such, the 40Ar/39Ar results are consistent with a hotspot-related origin for the leucitites. However, the question of whether single or multiple hotspots are required to explain these volcanic chains, which are separated by a distance of about 300 km, awaits a more complete geochronological picture of the onset, duration and migration of leucitite and central-volcano magmatism in eastern Australia.

Background: Recently, pain infusion pumps for postoperative pain control have gained popularity in many surgical specialties. This investigation was designed to evaluate the efficacy of a local anesthetic pain infusion pump in management of postoperative pain in abdominoplasty patients. Methods: A retrospective study of 38 abdominoplasty patients with local anesthetic pain pumps and 35 abdominoplasty patients without pain pumps was performed. Pain pumps were loaded with 0.25% or 0.5% bupivacaine and infused at a constant rate of 4 ml/hour. All patients were admitted postoperatively and started on a narcotic patient-controlled analgesia. Postoperative patient-controlled analgesia narcotic use and pain scores were recorded every 2 hours by the nursing staff. For the first 24 hours of postoperative hospital stay, pain medication, pain scores, and antiemetic use were determined from the patients’ charts. Hospital stay was also reviewed. Results: In the pain pump group, there was a small but not statistically significant reduction in pain medication use (2.65 versus 3.04 pain units) (p = 0.34). Interestingly, pain scores were higher in the pain pump group but not significantly (2.73 versus 2.31) (p = 0.17). There was no statistically significant difference in the use of antiemetics (0.8 versus 0.6) (p = 0.60). Hospital length of stay averaged 2.2 days in the pain pump group and 2.5 days in the group without pain pumps (p = 0.09). Conclusions: The postoperative use of pain pumps in abdominoplasty patients does not significantly improve pain management. Further investigation into this application of the pain pump is necessary before recommending their routine use in abdominoplasty patients.

Laser Ar-40/Ar-39 analyses were undertaken on Oligocene bimodal intraplate volcanic rocks from five volcanic areas spanning 320 km along a north-northeast-trending belt in southeast Queensland, Sixty-one mineral grains and groundmass fragments from 21 samples were analysed by incremental heating, while 99 mineral grains from 10 samples were analysed by total fusion. Fourteen samples are from localities dated previously by the K-Ar method. The 40Ar/39Ar ages are reproducible among different aliquots from the same sample and different samples from the same location, and correlate with latitude, ranging from 30.6 +/- 0.3 Ma on Fraser Island in the north (25 degrees S) to 25.8 +/- 0.2 Ma at Flinders Peak in the south (27.7 degrees S). This age progression is not evident from K-Ar ages compiled for the same region. The decrease of Ar-40/Ar-39 ages with latitude is consistent with previous suggestions for a hotspot origin for east Australian central volcanoes and yields an Australian Plate velocity, relative to the postulated fixed hotspot reference, frame, of 71 (+7, -4) mm/y at an azimuth of N10 degrees E for the period of ca 31-26 Ma. This velocity agrees within error with the values of about 65 +/- 3 mm/y obtained from previously reported K-Ar analyses of east Australian central volcano provinces active in the last 35 million years. These results demonstrate that the improved accuracy and precision of the Ar-40/Ar-39 method permit resolution of age versus latitude relationships for narrower time windows, which may potentially provide constraints on changing plate velocities with time. This improved temporal resolution may also contribute to resolving current debate over the existence and the stationary versus mutable position of postulated mantle plumes and hotspots.

The role of prophylactic antibiotics in reduction mammaplasty remains controversial. However, most surgeons choose to use antibiotics. In addition to cost and potential allergic reactions, unnecessary administration of antibiotics can suppress host natural flora and produce resistant organisms.Fifty patients were sequentially assigned to one of three study limbs: (1) no antibiotics, (2) preoperative antibiotics only, or (3) preoperative and postoperative antibiotics. The study was designed to include approximately 17 patients in each group. Cephalosporin antibiotics were used unless there was any question of allergy, in which case an alternative antibiotic regimen was used. Preoperative data collected on patients included age, body mass index, history of diabetes mellitus, peripheral vascular disease, previous breast surgery, steroid therapy, and tobacco use. Operative data included specimen weight, operative time, estimated blood loss, prolonged intraoperative hypotension, adjunctive axillary and breast tail liposuction, and intraoperative breast tissue culture.The patient population in the three limbs of the study was similar. Thus, there was no significant difference among the groups insofar as the preoperative data were concerned (p0.20): age, body mass index, diabetes mellitus, peripheral vascular disease, previous breast surgery, and steroid or tobacco use. Furthermore, no significant difference (p0.12) was noted among intraoperative data in the three groups: specimen weight, operative time, estimated blood loss, prolonged hypotension, adjunctive breast liposuction, and positive bacterial culture from intraoperative breast tissue samples. Ninety percent of positive intraoperative breast tissue cultures revealed Staphylococcus epidermidis. Using strict criteria, the infection rate ranged from 19 to 20 percent. There was no significant difference (p0.91) in rate of infection among the three study limbs. There was, however, a significant reduction (p = 0.002) in delayed wound healing in the group that received preoperative antibiotics only. Among the studied risk factors for infection, only positive intraoperative culture of breast tissue was significant (p = 0.008) for development of infection. There was a significant association between delayed wound healing and infection (p = 0.003).This prospective study did not find that prophylactic antibiotics in reduction mammaplasty have an effect on infection; however, a single preoperative dose significantly improved wound healing.

Once botulinum toxin type A is reconstituted, the manufacturer recommends that it be used in approximately 4 hours. As a result, a significant amount of this costly drug is often discarded because it is not completely used in the recommended period. The purpose of the present study was to compare fresh versus stored reconstituted botulinum toxin type A for (1) initial potency, (2) duration of action, and (3) bacterial colonization. Using a rabbit model, 20 New Zealand White rabbits were divided into four groups (I to IV). All rabbits had an injection of 2.5 U of reconstituted botulinum toxin into the right anterior auricular muscle. The first group was injected with botulinum toxin type A that was freshly reconstituted and served as the control. The second, third, and fourth groups were injected with botulinum toxin type A that had been reconstituted and stored for 2, 6, and 12 weeks, respectively, in a conventional freezer. Each rabbit had daily visual evaluation of the ear, with the position of auricle being graded from I to III. In addition, each rabbit had a nerve conduction study performed on the right anterior auricular muscle before injection and every 2 weeks after injection. Amplitude was chosen as the principal variable in the data analysis because it is the best predictor of physiologic changes at the muscle motor unit level. The endpoint of the study was defined as the time at which the nerve conduction studies and the visual inspections returned to baseline, preinjection levels. Botulinum toxin type A was also cultured before injection into each group.Overall, the nerve conduction data revealed a trend with a faster recovery (return to baseline) with the stored botulinum toxin. Groups IV and III returned to baseline first, followed by groups II and I. However, there was no significant difference among the groups at 2 and 4 weeks after injection, indicating that initial potency was unchanged. The differences between the groups became significant (p < 0.05) at 6 weeks and onward, suggesting that the duration was affected. Group I (fresh botulinum toxin) and group II (toxin stored for 2 weeks) had comparable outcomes and were not significantly different at any time period. Under visual inspection, the mean recovery time for each group was as follows: group IV, 5.4 weeks; group III, 7.0 weeks; group II, 6.75 weeks; and group I, 7.80 weeks. The results showed significance (p < 0.05) beginning after 3 weeks among some groups. Again, there was an overall quicker trend to return to baseline with the longer storage of the botulinum toxin (groups III and IV). These results support the authors' conduction study data, which suggest that the initial potency is not affected but the duration of action is. Again, groups I and II had comparable results. Microbiology cultures showed no growth of either aerobic or anaerobic bacteria at 7 days. In conclusion, using the rabbit model, it seems that reconstituted and stored botulinum toxin type A has the same initial potency but the duration of action is affected sometime after 2 weeks of storage. No bacterial contamination was associated with storing unpreserved reconstituted botulinum toxin type A for up to 12 weeks.

Many patients are now consulting plastic surgeons for evaluation of their silicone gel breast implants. This study assesses the accuracy of a clinician's ability to determine if a silicone gel breast implant has failed. In addition, it sheds light on the long-term integrity of the silicone gel breast implant. This study examined the condition of 350 silicone gel breast implants in a group of 159 of the authors' patients who previously had undergone augmentation mammaplasty or breast reconstruction. These women underwent secondary open procedures including capsulotomy or capsulectomy for fibrous capsule contractures, exchange of implants, or other revisional surgery. The condition of the implant was noted at the time of this secondary operation. The preoperative evaluation, which included the patient's history and physical examination and often mammography, was then matched against the operative findings to determine the pertinent factors that predict the integrity of a silicone gel breast implant. A history of trauma and/or a reported change in shape of a patient's breast correlated with implant failure. An analysis of implant failure as a function of implant age revealed that 63 percent of silicone gel breast implants in place 12 years or greater in this study population were not intact. A change in the patient's physical examination, including a softened breast consistency and/or the presence of a nodule or mass adjacent to an implant, also was suggestive of implant failure. Several different mammographic presentations of implants that were not intact were identified. This modality predicted implant failure in 89 percent of implants studied. It is hoped that this information will help clinicians to make a more accurate assessment of the condition of a patient's silicone gel breast implant. It should be noted that all women in our study underwent secondary procedures, as stated above. The results obtained apply to this patient group but may not specifically pertain to the general implant-bearing population.

This study compares the acute intraoperative arterial elongation technique with the interposition vein-graft method for the closure of small arterial gaps that cannot be repaired by undermining alone. Ten conditioned female mongrel dogs were divided into two groups: a vein graft interposition group and an acute expansion-elongation group. In ten cases, a 25-mm segment of the superficial femoral artery was excised. The resultant defect, measuring 45 to 60 mm, was repaired by an interpositional graft of a comparable size segment of the superficial femoral vein. In ten other cases, a same-size defect was repaired by a tension-free end-to-end anastomosis, following acute intraoperative arterial elongation. The animals were explored at various intervals. Overall results revealed a 100 percent patency rate with the acute expansion-elongation group vs. 80 percent with the vein-graft interposition group. The versatility, time saving, and ease of technique, plus previous clinical experience, is encouraging enough to recommend this method for the sound repair of small arterial defects in clinical cases.

In this study, the 3M microvascular anastomotic system was utilized for the first time to perform an end-to-end anastomosis in a non-vascular tubular structure, which was compared to the conventional microvascular suture method. The bicornuate rat uterus was the preferred structure because of its anatomic similarity to the human fallopian tube. Thirty Sprague-Dawley rats underwent 3M and conventional end-to-end anastomoses of their bicornuate uteri. At different intervals, the animals were explored and biopsies were taken for examination under light microscopy. Overall patency rate with the 3M technique was 68 percent vs. 96 percent with the conventional technique. Complication rates were 40 percent with the 3M device and 12 percent with the conventional method. This study concludes that, if this method is to be used on non-vascular tubular structures, further modifications to the system and additional research are mandatory, in order to recommend this technique for clinical application.

The Louisville Seamount Trail is a 4300 km long volcanic chain that has been built in the past 80 m.y. as the Pacific plate moved over a persistent mantle melting anomaly or hotspot. Because of its linear morphology and its long-lived age-progressive volcanism, Louisville is the South Pacific counterpart of the much better studied Hawaiian-Emperor Seamount Trail. Together, Louisville and Hawaii are textbook examples of two primary hotspots that have been keystones in deciphering the motion of the Pacific plate relative to a set of "fixed" deep-mantle plumes. However, drilling during Ocean Drilling Program (ODP) Leg 197 in the Emperor Seamounts documented a large ~15° southward motion of the Hawaiian hotspot prior to 50 Ma. Is it possible that the Hawaiian and Louisville hotspots moved in concert and thus constitute a moving reference frame for modeling plate motion in the Pacific? Alternatively, could they have moved independently, as predicted by mantle flow models that reproduce the observed latitudinal motion for Hawaii but that predict a largely longitudinal shift for the Louisville hotspot? These two end-member geodynamic models were tested during Integrated Ocean Drilling Program (IODP) Expedition 330 to the Louisville Seamount Trail. In addition, existing data from dredged lavas suggest that the mantle plume source of the Louisville hotspot has been remarkably homogeneous for as long as 80 m.y. These lavas are predominantly alkali basalts and likely represent a mostly alkalic shield-building stage, which is in sharp contrast to the massive tholeiitic shield-building stage of Hawaiian volcanoes. Geochemical and isotopic data for the recovered lavas during Expedition 330 will provide insights into the magmatic evolution and melting processes of individual Louisville volcanoes, their progression from shield-building to postshield and (maybe) posterosional stages, the temperature and depth of partial melting of their mantle plume source, and the enigmatic long-lived and apparent geochemical homogeneity of the Louisville mantle source. Collectively, this will enable us to characterize the Louisville Seamount Trail as a product of one of the few global primary hotspots, to better constrain its plume-lithosphere interactions, and to further test the hypothesis that the Ontong Java Plateau formed from the plume head of the Louisville mantle plume around 120 Ma. During Expedition 330 we replicated the drilling strategy of Leg 197, the first expedition to provide compelling evidence for the motion of the Hawaiian mantle plume between 80 and 50 Ma. For that reason we targeted Louisville seamounts that have ages similar to Detroit, Suiko, Nintoku, and Koko Seamounts in the Emperor Seamount Trail. In total, five seamounts were drilled in the Louisville Seamount Trail: Canopus, Rigil, Burton, Achernar, and Hadar Guyots (old to young). By analyzing a large number of time-independent in situ lava flows (and other volcanic eruptive products) from these seamounts using modern paleomagnetic, 40Ar/39Ar geochronological, and geochemical techniques, we will be able to directly compare the paleolatitude estimates and geochemical signatures between the two longest-lived hotspot systems in the Pacific Ocean. We drilled into the summits of the five Louisville guyots and reached volcanic basement at four of these drilling targets. In two cases we targeted larger seamount structures and drilled near the flanks of these ancient volcanoes, and in the other three cases we selected smaller edifices that we drilled closer to their centers. Drilling and logging plans for each of these sites were similar, with coring reaching 522.0 meters below seafloor (mbsf) for Site U1374 and 232.9, 65.7, 11.5, 182.8, and 53.3 mbsf for Sites U1372, U1373, U1375, U1376, and U1377, respectively. Some Expedition 330 drill sites were capped with only a thin layer of pelagic ooze between 6.6 and 13.5 m thick, and, if present, these were cored by using a low-rotation gravity-push technique with the rotary core barrel to maximize recovery. However, at Sites U1373 and U1376 no pelagic ooze was present, and the holes needed to be started directly into cobble-rich hardgrounds. In all cases, the bulk of the seamount sediment cover comprised sequences of volcanic sandstones and various kinds of basalt breccia or basalt conglomerate, which often were interspersed with basaltic lava flows, the spatter/tephra products of submarine eruptions, or other volcanic products, including auto-brecciated flows or peperites. Also several intervals of carbonate were cored, with the special occurrence of a ~15 m thick algal limestone reef at Site U1376 on Burton Guyot. In addition, some condensed pelagic limestone units were recovered on three of the other seamounts, but these did not exceed 30 cm in thickness. Despite their limited presence in the drilled sediment, these limestones provide valuable insights for the paleoclimate record at high ~50° southern latitudes since Mesozoic times. Several Louisville sites progressed from subaerial conditions in the top of volcanic basement into submarine eruptive environments, or drilling of the igneous basement immediately started in submarine volcanic sequences, as was the case for Sites U1376 and U1377 on Burton and Hadar Guyots. At three sites we cored >100 m into the igneous basement: 187.3 m at Site U1372, 505.3 m at Site U1374, and 140.9 m at Site U1376. At the other sites we did not core into basement (Site U1375) or we cored only 38.2 m (Site U1377) because of unstable hole conditions. Even so, drilling during Expedition 330 resulted in a large number of in situ lava flows, pillow basalts, or other types of volcanic products such as auto-brecciated lava flows, intrusive sheets or dikes, and peperites. In particular, the three holes on Canopus and Rigil Guyots (the two oldest seamounts drilled in the Louisville Seamount Trail), resulted in adequate numbers of in situ lava flows to average out paleosecular variation, with probable eruption ages estimated at ~78 and 73 Ma, respectively. Remarkably, at all drill sites large quantities of hyaloclastites, volcanic sandstones, and basaltic breccias were also recovered, which in many cases show consistent paleomagnetic inclinations compared to the lava flows bracketing these units. For Site U1374 on Rigil Guyot we also observed a magnetic polarity reversal in the cored sequence. Overall, this is very promising for determining a reliable paleolatitude record for the Louisville Seamounts following detailed postcruise examinations. The deeper penetrations of several hundred meters required bit changes and reentries using free-fall funnels. Basement penetration rates were 1.8–2.5 m/h depending on drill depth. In total, 1114 m of sediment and igneous basement at five seamounts was drilled, and 806 m was recovered (average recovery = 72.4%). At Site U1374 on Rigil Guyot, a total of 522 m was drilled, with a record-breaking 87.8% recovery. Most outstandingly, nearly all Expedition 330 core material is characterized by low degrees of alteration, providing us with a large quantity of samples of mostly well-preserved basalt, containing, for example, pristine olivine crystals with melt inclusions, fresh volcanic glass, unaltered plagioclase, carbonate, zeolite and celadonite alteration minerals, various micro- and macrofossils, and, in one case, mantle xenoliths and xenocrysts. The large quantity and excellent quality of the recovered sample material allow us to address all the scientific objectives of this expedition and beyond.

Study design Clinical case series. Objective To show the efficacy of prophylactic inferior vena cava (IVC) filters in preventing venous thromboembolic event (VTE) in high-risk patients undergoing major spinal surgery. Summary of background data Patients undergoing major spinal surgery are at increased risk for VTEs. Recent studies have shown IVC filters are effective in preventing clinically significant pulmonary embolism (PE), but have not documented the frequency of all emboli prevented. Methods Patients undergoing major spinal surgery from 2006 to 2009, having IVC filters placed for VTE prophylaxis, were reviewed. Patients with 2 or more risk factors for VTE were included and their perioperative courses were reviewed for PE and device-related complications. Cavograms obtained at the time of attempted filter retrieval identified intercepted emboli. The rates of intercepted emboli and clinical PEs were compared with those of similar populations undergoing similar procedures. Results Approximately 17% of patients had entrapped thrombus present at attempted filter retrieval. An additional 17% of filters were unable to be retrieved due to change in position within the IVC. No patients experienced symptomatic PE. One patient developed a deep vein thrombus requiring pharmacologic treatment and another patient developed superficial phlebitis. There were no complications related to IVC filter use. Conclusions These findings show that the decreased rate of PE observed in this and other series is likely because of the use of IVC filters, rather than sampling bias inherent when studying a relatively rare problem. The safety of IVC filters in this population is also confirmed. The observed rate of clinical PE is consistent with other published series. Emboli intercepted by filters may more accurately estimate clinically significant emboli prevented. Therefore, cavograms may prove to be a valuable method of assessing the efficacy of these devices in future studies.

Sir:The number of patients who undergo labia minora reduction continues to rise at an alarming rate. Affected women most commonly complain of social embarrassment and aesthetic concern; however, most women also report some functional limitation, including chronic infections or pain with sexual inter

A consecutive series of 73 patients underwent tissue expansion for breast reconstruction between 1980 and 1986. The cases were reviewed, and preoperative risk factors, postoperative complications, and aesthetic results were assessed. Cigarette smoking correlated with a higher incidence of complications and unfavorable results. Similar correlations were found among patients with histories of significant medical disorders or alcohol abuse, although patient numbers were small in these categories. Subpectoral and suprapectoral placement of expanders yielded similar complication rates and aesthetic results. Surgical techniques contributing to improved aesthetic results are described.

Earth's largest and thickest oceanic plateau, the Ontong Java plateau, is currently colliding with the Australian plate, but it has been difficult to date the start of this momentous event with much accuracy. Now a team from the University of Queensland presents strong evidence for a collision starting about 26 million years ago. The dating comes from geochronological data on hotspot volcanoes in the Tasman Sea, east of Australia, which reveal a link between collision of the plateau with the Melanesian arc and motion of the Australian plate. The timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks in the Pacific, including the archetypal Hawaiian chain, suggesting that immense oceanic plateaus, like Ontong Java, can contribute to initiating rapid change in plate boundaries and motions on a global scale. Geochronological data on hotspot volcanoes in eastern Australia are presented, which reveal a strong link between collision of the plateau with the Melanesian arc and motion of the Australian plate. The timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks in the Pacific, including the archetypal Hawaiian chain, and thus provide strong evidence that immense oceanic plateaus can contribute to initiating rapid change in plate boundaries and motions on a global scale. The subduction of oceanic plateaux, which contain extraordinarily thick basaltic crust and are the marine counterparts of continental flood-basalt provinces, is an important factor in many current models of plate motion1,2,3,4 and provides a potential mechanism for triggering plate reorganization5. To evaluate such models, it is essential to decipher the history of the collision between the largest and thickest of the world’s oceanic plateaux, the Ontong Java plateau, and the Australian plate, but this has been hindered by poor constraints for the arrival of the plateau at the Melanesian trench. Here we present 40Ar–39Ar geochronological data on hotspot volcanoes in eastern Australian that reveal a strong link between collision of the Greenland-sized Ontong Java plateau with the Melanesian arc and motion of the Australian plate. The new ages define a short-lived period of reduced northward plate motion between 26 and 23 Myr ago, coincident with an eastward offset in the contemporaneous tracks of seamount chains in the Tasman Sea east of Australia. These features record a brief westward deflection of the Australian plate as the plateau entered and choked the Melanesian trench 26 Myr ago. From 23 Myr ago, Australia returned to a rapid northerly trajectory at roughly the same time that southwest-directed subduction began along the Trobriand trough6. The timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks on the Pacific plate, including the archetypal Hawaiian chain7, and thus provide strong evidence that immense oceanic plateaux, like the Ontong Java, can contribute to initiating rapid change in plate boundaries and motions on a global scale.

Until now, aesthetic goals in parotid surgery have seldom been addressed because oncologic concerns have largely overshadowed aesthetic issues for patients with parotid masses. Fortunately, the majority of parotid masses are benign pleomorphic adenomas that rarely recur, leaving a large group of patients healthy after their parotid surgery, with some desiring aesthetic improvement in their facial appearance. Traditional parotidectomy incisions leave a visible scar on the neck as well as a visible hollow in the retromandibular region, which can extend onto the cheek. A rhytidectomy approach to the parotid gland allows for a more concealed, aesthetically appealing scar while maintaining good visibility and access to the parotid gland. By performing bilateral sub-SMAS (superficial musculoaponeurotic system) rhytidectomy after a parotidectomy, facial symmetry and balance is enhanced, and these aesthetic deformities can be minimized. The SMAS flap can help to fill the hollow and form a tissue barrier over the resected gland to prevent gustatory sweating. Finally, the incision scarring is minimized with a rhytidectomy-type approach. Two cases are reported in which patients underwent both rhytidectomy and parotidectomy. In the one case, the procedures were performed in the same surgical setting. In the other case, they were performed in a delayed fashion. These cases exemplify the possibility of addressing facial aesthetic goals of rejuvenation in a patient requiring parotid resection.

Donor site seroma continues to be the most common complication of latissimus dorsi flap reconstruction. Numerous preventive methods and treatments have been described. The use of fibrin sealant in the donor site before closure may be an effective means of seroma prevention. The authors evaluated the efficacy of fibrin sealant in conjunction with closed suction drainage in a series of 17 latissimus flap donor sites. They also determined their approximate institutional seroma rate with a retrospective chart review of 20 donor sites. The fibrin sealant patients had a seroma rate of 11.8% compared with a rate of 35% among the untreated patients (P = 0.047). This compares favorably with seroma rates as high as 79% described in the literature. In conclusion, the use of fibrin sealant in the latissimus flap donor site appears to be effective in preventing seroma.

Despite great advances in modern medicine, postoperative nausea and vomiting (PONV) continue to be a significant problem without a definitive cure. This article describes a prospective study conducted with 143 plastic surgery patients at a single institution between 1998 and 2000 to identify preoperative risk factors for PONV that may be specific to plastic surgery patients. In addition, a prophylactic regimen was identified that demonstrated a decrease in the incidence of PONV from the published incidence of 22% to 3%. The regimen includes the use of multiple antiemetic agents including ondansetron (Zofran) promethazine (Phenergan), and metoclopramide (Reglan), with the addition of dexamethasone (Decadron) in selected cases

After performing a chart review, the authors identified 120 patients who underwent breast cancer-related reconstruction. All charts were evaluated with regard to breast mound reconstruction type, nipple-areola reconstruction type, the interval between breast mound and nipple-areola reconstruction, the number of procedures needed to achieve nipple-areola reconstruction, patient history of radiation therapy, and complications. A questionnaire was then developed and mailed to all of the patients who underwent both breast mound and nipple/areola reconstruction (n = 105) to evaluate their level of satisfaction. Of the 43 patients who returned the questionnaire, 41 completed all portions correctly. The questionnaire evaluated patient satisfaction with breast mound reconstruction; patient satisfaction with nipple-areola reconstruction; what the patient disliked most about the nipple-areola reconstruction; and whether or not the patient would choose to have breast reconstruction again. Several parameters were then tested statistically against the reported patient satisfaction.A review of all patients who underwent breast reconstruction revealed that their breast mound reconstructions were done using either a TRAM flap (59 percent), a latissimus dorsi flap and an implant (19 percent), an expander followed by an implant (9 percent), an implant only (4 percent), or other means (9 percent). The nipple-areola was reconstructed in these patients with either a star flap (36 percent), nipple sharing (10 percent), a keyhole flap (9 percent), a skate flap (9 percent), an S-flap (8 percent), a full-thickness skin graft (6 percent), or by another means (22 percent). The number of procedures needed to achieve nipple-areola reconstruction was either one (in 66 percent of the patients), two (in 32 percent of the patients), or three or more (2 percent of the patients). Eleven percent of the patients experienced the complication of nipple necrosis. Satisfaction with breast mound reconstruction was reported by 81 percent of patients to be excellent/good, by 14 percent of patients to be fair, and by 5 percent of patients to be poor. Reported satisfaction with nipple-areola reconstruction was excellent/good for 64 percent of patients, fair for 22 percent of patients, and poor for 14 percent of patients. The factors patients disliked most about their nipple-areola reconstruction were, in descending order, lack of projection, color match, shape, size, texture, and position. Statistical analysis of the data revealed inferior patient satisfaction when there was a longer interval between breast mound and nipple areola reconstruction (p = 0.003). No significant difference was observed in nipple/areola reconstruction satisfaction ratings when compared with breast mound reconstruction type (p = 0.46), nipple-areola reconstruction type (p = 0.98), and history of radiation therapy (p = 0.23). There was also no significant difference when breast mound reconstruction was compared with technique (p = 0.51) and history of radiation therapy (p = 0.079). Overall, there was a greater satisfaction with breast mound reconstruction than with nipple-areola reconstruction (p = 0.0001).

A single institution's experience in the simultaneous reconstruction of both breasts using bilateral latissimus dorsi myocutaneous flaps is presented. The procedure was performed on 24 patients by the attending staff of the department of plastic surgery at St. Joseph Hospital in Houston, Texas, between 1979 and 1999. Of the 24 patients reviewed, six had immediate reconstructions, 13 had delayed primary reconstructions, and five had secondary reconstructions of failed or unsatisfactory primary procedures. In the group with delayed reconstructions, the average time between mastectomy and reconstruction was 46.4 months, with a range from 7 days to 21 years. The operative method, results, and outcomes of our experience in these patients is presented.