In the aftermath of the end‐Permian extinction: the microbialite refuge?

We present the first study of micro‐crustaceans (ostracods) associated with microbial crusts in the aftermath of the most devastating extinction, the end‐Permian extinction (EPE). These post‐extinction microbialites dominated shallow shelf marine environments and were traditionally considered as devoid of any associated fauna. We present a micro‐palaeontological analysis of a large record from microbial and non‐microbial settings following the EPE. This dataset documents the proliferation of ostracods strictly associated with microbialites. Based on the diet of extant ostracods and uniformitarianism, we propose that the abundant microbes in the mats served as an unlimited food supply. Photosynthetic cyanobacteria may also have locally provided oxygen under low oxygen conditions interpreted by others for the microbialites. Microbialites provided a specialised environment that may have acted as refuge for ostracods in the immediate aftermath of the EPE. The surviving faunas may have been progenitors for the starting of the latter radiation.     

Transnational labour migration and the politics of care in the Southeast Asian family

Recent increases in female labour migration in and from Asia have triggered a surge of interest in how the absence of the mother and wife for extended periods of time affects the left-behind family, particularly children, in labour-sending countries. While migration studies in the region have shown that the extended family, especially female relatives, is often called on for support in childcare during the mother’s absence it is not yet clear how childcare arrangements are made. Drawing on in-depth interviews with non-parent carers of left-behind children in Indonesia and Vietnam, the paper aims to unveil complexities and nuances around care in the context of transnational labour migration. In so doing it draws attention to the enduring influence of social norms on the organisation of family life when women are increasingly drawn into the global labour market. By contrasting a predominantly patrilineal East Asian family structure in Vietnam with what is often understood as a bilateral South-East Asian family structure in Indonesia, the paper seeks to provide interesting comparative insights into the adaptive strategies that the transnational family pursues in order to cope with the reproductive vacuum left behind by the migrant mother.     

Numerical modeling of the hydraulic signatures of horizontal and inclined faults

Pumping tests in discontinuous media are commonly interpreted using radial/non-radial flow analytical models, which do not account for a large range of multistage real signatures that combine both flow types. The term radial is employed in Barker??s sense, referring to the cross-flow area growth with a flow dimension (n) equal to 2, while multistage refers to a flow response of several time periods with successive n values. Synthetic domains are used to numerically investigate the flow behaviour of faulted media, specifically the effect of fault inclination on multistage signatures. Simulations are performed using single faults surrounded by a permeable matrix to characterize drawdown series and to identify hydrodynamic scenarios associated with some diagnostic multistage n sequences. The n sequence 2 ?C <?2 ?C 2 results from interactions between the matrix and a horizontal to weakly inclined fault, while 2 ?C 1.5 ?C 2 corresponds to a higher fault inclination and is a combination of the generalized horizontally and vertically faulted models. These results improve the interpretation of ambiguous drawdown series from long-term pumping tests. This provides a better hydraulic characterization of faulted environments, allowing assessment of fault and matrix properties such as fault inclination. The approach is successfully tested on real datasets.     

Vulnerability of laptop computers to volcanic ash and gas

Laptop computers are vital components of critical infrastructure sectors and a common tool in broader society. As they become more widely used, their exposure to volcanic hazards will increase. Therefore, understanding how laptops will function in volcanic environments is necessary to provide suitable mitigation options. In this study, laptop computers were subjected to volcanic ash and gas in both laboratory and field settings. None of the laptops sustained permanent damage in laboratory experiments; however, ash contamination did reduce the functionality of keyboards, CD drives, and cooling fans. Several laptops shut down temporarily due to overheating following ash contamination. In field experiments, laptops were exposed to high concentrations of volcanic gases at White Island, New Zealand. These laptops did not sustain permanent damage as only a small amount of gas was able to enter the laptops. However, metal components on the outside of the laptop did sustain minor corrosion. Re-examination of the laptops after 6?months indicated they were in full working order. Printed circuit boards suffered significant corrosion damage and ceased working only when in direct and sustained contact with volcanic gases. Simple mitigation techniques such as isolating laptops inside heavy duty polyethylene bags were effective. Overall, our experiments demonstrate that laptops have a relatively low risk of damage from volcanic ash and gas exposure, but have a low-medium risk of loss of functionality in ash environments. We think this has implications for other electronic equipment used extensively in critical infrastructure services.     

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The investigations were carried out in order to evaluate change of the beaches profile during the period 1993–2008 and to elucidate main trends of the coastal dynamics. Morphometric indicators (beach width, height and inclination) were measured every year during the period 1993–2008 in 70 measuring stations located along the coastline. It was determined that the dynamic shoreline of the mainland during 1993–2008 receded by 10.2 m and the dynamic shoreline of the Curonian Spit advanced into the sea by 8.3 m. The different morphometric beach indicators changed to varying extents over the period 1993–2008, but comparison of values for 1993 and 2008 showed that those changes were small. The average beach width increased by 1.2 m on the mainland coast and by 0.5 m on the Curonian Spit coast. The average beach height also increased negligibly: by 0.5 m on the mainland coast and by 0.1 m on the Curonian Spit coast. The average beach slope inclination increased by 0.012 (from 0.065 to 0.077) on the mainland coast and by 0.005 (from 0.073 to 0.078) on the Curonian Spit coast. The measurements show that, despite being the most dynamic elements in the coastal system, these beaches managed to retain their morphometric indicators almost unchanged during the period of observation.     

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The geothermal gradient of Io: Consequences for lithosphere structure and volcanic eruptive activity

We solve numerically the equations describing the transfer of heat through the lithosphere of Io by a mixture of conduction and volcanic advection as proposed by O’Reilly and Davies (O’Reilly, T.C., Davies, G.F. [1981]. Geophys. Res. Lett. 8, 313-316), removing the requirement that average material properties must be used. As expected, the dominance of advective heat transfer by volcanic eruptions means that Io’s geothermal gradient well away from volcanic centres is very small, of order 1 K km⁻¹. This result is independent of any reasonable assumptions about the radiogenic heating rate in the lithosphere. The lithosphere temperature does not increase greatly above the surface temperature until the base of the lithosphere is approached, except in limited areas around shallow magma bodies. As a consequence, solid volatile sulphur compounds mobilized by volcanic processes and re-deposited on the surface of Io commonly remain solid until they reach great depths as they are progressively buried by ongoing activity. For current estimates of the volcanic heat transfer rate, melting of SO₂ does not begin until a depth of ∼20 km and sulphur remains solid to a depth of ∼26 km in a 30 km thick lithosphere. Rising magmas can incorporate fluids from these deep sulphur compound aquifers, and we quantify the major influence that this can have on the bulk density of the magma and hence the resulting possible intrusion and eruption styles.     

The global distribution of pyroclastic deposits on Mercury: The view from MESSENGER flybys 1–3

We present a global survey of candidate pyroclastic deposits on Mercury, derived from images obtained during MESSENGER flybys 1–3 that provided near-global coverage at resolutions between 5 and 0.5 km/pixel. Thirty-five deposits were identified and characterized and are located principally on the floors of craters, along rims of craters, and along the edge of the Caloris basin. Deposits are commonly centered on rimless, often irregularly shaped pits, mostly between 5 and 45 km in diameter. The deposits identified are generally similar in morphology and absolute reflectance to lunar pyroclastic deposits. Spectrally the deposits appear brighter and redder than background Mercury terrain. On the basis of the available coverage, the candidate pyroclastic deposits appear to be essentially globally distributed. The diameters of the deposits, when mapped to lunar gravity conditions, are larger than their lunar counterparts, implying that more abundant volatiles were present during the typical eruptive process than on the Moon. These observations indicate that if these deposits resulted from hawaiian-style eruptions, the volatile contents required would be between ～1600 and 16,000 ppm CO or an equivalent value of H₂O, CO₂, SO₂, or H₂S (for a more oxidizing interior), or N₂, S₂, CS₂, S₂Cl, Cl, Cl₂, or COS (for a more reducing interior). These abundances are much greater than those predicted by existing models for Mercury's formation. An apparent lack of small deposits, compared with the Moon, may be due to resolution effects, a topic that can be further assessed during the orbital phase of the MESSENGER mission. These results provide a framework within which orbital observations by MESSENGER and the future BepiColombo mission can be analyzed.     

Bolla Bollana boulder beds: A Neoproterozoic trough mouth fan in South Australia?

The Bolla Bollana Formation is an exceptionally thick (ca 1500 m), rift‐related sedimentary succession cropping out in the northern Flinders Ranges, South Australia, which was deposited during the Sturtian (mid Cryogenian) glaciation. Lithofacies analysis reveals three distinct facies associations which chart changing depositional styles on an ice‐sourced subaqueous fan system. The diamictite facies association is dominant, and comprises both massive and stratified varieties with a range of clast compositions and textures, arranged into thick beds (1 to 20 m), representing stacked, ice‐proximal glaciogenic debris‐flow deposits. A channel belt facies association, most commonly consisting of normally graded conglomerates and sandstones, displays scour and fill structure of ca 10 m width and 1 to 3 m depth: these strata are interpreted as channelized turbidites. Rare mud‐filled channels in this facies association bear glacially striated lonestones. Finally, a sheet heterolithics facies association contains a range of conglomerates through sandstones to silty shales arranged into clear, normally graded cycles from the lamina to bed scale. These record a variety of non‐channelized turbidites, probably occupying distal and/or inter‐channel locations on the subaqueous fan. Coarsening and thickening‐up cycles, capped by dolomicrites or mudstones, are indicative of lobe build out and abandonment, potentially as a result of ice lobe advance and stagnation. Dropstones, recognized by downwarped and punctured laminae beneath pebbles to boulders in shale, or in delicate climbing ripple cross‐laminated siltstones, are clearly indicative of ice rafting. The co‐occurrence of ice‐rafted debris and striated lonestones strongly supports a glaciogenic sediment source for the diamictites. Comparison to Pleistocene analogues enables an interpretation as a trough mouth fan, most probably deposited leeward of a palaeo‐ice stream. Beyond emphasizing the highly dynamic nature of Sturtian ice sheets, these interpretations testify to the oldest trough mouth fan recorded to date.