Geological setting of the Rapu Rapu gold-rich volcanogenic massive sulfide deposits,Albay Province,Philippines

Gold-rich Fe–Cu–Zn volcanogenic massive sulfide deposits occur within strata of probable Jurassic age on Rapu Rapu Island in Albay Province, Philippines. Massive sulfides at the Ungay Malobago and Hixbar deposits are spatially associated with dacitic volcanic rocks within a highly-deformed sequence of mafic volcanic and quartzofeldspathic sedimentary rocks. The massive sulfide deposits formed at the stratigraphic contact between footwall dacites and hangingwall mafic volcanic and quartzofeldspathic rocks. The deposits and their host strata have undergone regional metamorphism with strong penetrative deformation. Metamorphic mineral assemblages and textural evidence suggest that peak metamorphism was upper-greenschist to lower-amphibolite grade and syn-D₁ deformation. Based on the age of regional metamorphism, deformation is inferred to be mid-Tertiary in age. Deformation at Rapu Rapu resulted in reorientation of the strata into a broad antiform with strong shallow-plunging elongation fabrics, overturning of the volcanic sequence that hosts the Ungay Malobago deposit, and complex folding of the mineralized zones. The present highly linear form of the Ungay Malobago deposit is mainly a product of this ductile strain.Immobile element ratios for a given lithology generally remain constant in saprolitic samples, and thus provide an effective identification tool even in strongly weathered rocks. Lithogeochemical data define a bimodal volcanic suite that is comparable to bimodal assemblages that occur in several modern back-arc basins in the southwestern Pacific Ocean, including those behind the Vanuatu and the New Britain arcs. On Rapu Rapu, the dacitic rocks are enriched in light REE and have high Zr/Y ratios, which indicates a calc–alkaline affinity and suggests a mature island-arc setting. The quartzofeldspathic sedimentary rocks are more widespread than the dacites and have notably lower Zr/Y ratios; they may have been derived from erosion of a distant volcanic arc. The mafic volcanic rocks are dominantly low-K arc tholeiites of basaltic to andesitic composition, but with modest enrichment in the light REE; comparable rocks can be found in the Vanuatu and New Britain back-arc basins.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00126-003-0349-0An erratum to this article can be found at Editorial handling: O. Christensen     

Habitat disturbance and marina development: An assessment of ecological effects. I. Changes in primary production due to dredging and marina construction

Potential impacts on primary production were estimated for an 800-slip marina previously planned for Davids Island, located in the extreme western portion of Long Island Sound, New York. Macroalgal and microalgal production in the area of the proposed marina was analyzed on the basis of six depth zones ranging from an existing seawall (at about +2.2 m MLW) seaward to a depth of ?2.4 m MLW. Productivity measurements were based on in situ ¹⁴C uptake studies, chlorophyll a determinations, and varying light exposures within the euphotic zone that were the estimate of daily production calculated for eight dominant macroalgae and microalgae, and summed to estimate existing production in the proposed marina. Similarly, post-construction production was estimated by applying the calculated daily production to the appropriate areas of hard substrate (breakwater, pilings, etc.) in the euphotic zone. Pre- and post-construction macroalgal production values were 50,608 and 42,152 g C d^?1, respectively. This represents a 17% reduction in macroalgal production. It should be noted, however, that production on the seafloor of the marina was not accounted for. Consquently, reductions in macroalgal production that might occur are likely overestimated. Microalgal production constituted less than 3% of total primary production in the nearshore areas of Davids Island. The pre- and post-construction microalgal production values were 1,542 and 743 g C d^?1, respectively. This represents a 48% reduction in microalgal production in unconsolidated sediment. However, micoalgal production would likely occur on hard substrates in the marina. Overall, pre- and post-construction estimates of primary production were remarkably similar, suggesting that production on hard substrates in the marina would compensate for lost production from deepening of the nearshore zone during construction. *** DIRECT SUPPORT *** A01BY074 00012     

Alongshore variation in the rip current hazard at Pensacola Beach, Florida

Many drowning and near drownings at Pensacola Beach, Florida are attributed to rip currents, the strong seaward-flowing currents that extend from the shoreline to the line of breakers and sometimes beyond. While surf forecasts assume that the rip hazard is uniform alongshore and that the (erosion) rips are ephemeral features, evidence is presented to suggest that the rip hazard at Pensacola Beach is not uniform alongshore. Rather the rip current “hotspots” develop as a consequence of an alongshore variation in the surf similarity parameter and nearshore state on the order of ~1,450 m. The variation is forced by transverse ridges on the inner shelf that force wave refraction and focusing at the ridge crests. This creates a more dissipative, rhythmic bar and beach morphology at the ridges and rougher surf. Between ridges, where wave heights and periods are smaller and the outermost bar is forced closer to the shoreline, the nearshore is in a (more reflective) bar and rip state during red flag conditions. Drownings between 2000 and 2009 are shown to be clustered between transverse ridges and in the years following a hurricane or tropical storm (2000–2003 and 2005–2008) when the bar and rip morphology first develops as the shore face recovers. This continues until the innermost bar attaches to the beach face unless the bar system is reset by another tropical storm or hurricane. It is argued that the rip hazard is dependent on the alongshore covariation of the environmental forcing with the individual and group behavior in both time and space, even on what appears to be a relatively uniform beach environment.     

Axial and transverse deep-water sediment supply to syn-rift fault terraces: Insights from the West Xylokastro Fault Block,Gulf of Corinth,Greece

Deep-water syn-rift systems develop in partially- or transiently-linked depocentres to form complicated depositional architectures, which are characterised by short transport distances, coarse grain sizes and a wide range of sedimentary processes. Exhumed systems that can help to constrain the tectono-stratigraphic evolution of such systems are rare or complicated by inversion tectonics. Here, we document a mid-Pleistocene deep-water syn-rift system fed by Gilbert-type fan deltas in the hangingwall of a rift margin fault bounding the West Xylokastro Horst block, on the southern margin of the Gulf of Corinth, Greece. Structural and stratigraphic mapping combined with digital outcrop models permit observations along this syn-rift depositional system from hinterland source to deep-water sink. The West Xylokastro Fault hangingwall is filled by two distinct sediment systems; an axial system fed by coarse-grained sediment gravity flows derived from fault-tip Gilbert-type fan deltas and a lateral system dominated by mass transport deposits fed from an evolving fault-scarp apron. Abrupt changes in stratigraphic architecture across the axial system are interpreted to record changes in relative base level, sediment supply and tectonics. Locally, depositional topography and intra-basinal structures controlled sediment dispersal patterns, from bed-scale infilling of local rugose topography above mass transport complexes, to basin-scale confinement from the fault scarp apron. These acted to generate a temporally and spatially variable, heterogeneous stratigraphic architecture throughout the basin-fill. The transition of the locus of sedimentation from a rift margin to a fault terrace through the syn-sedimentary growth of a basinward fault produced regressive surfaces updip, which manifest themselves as channels in the deep-water realm and acted to prograde the system. We present a new conceptual model that recognises coeval axial and transverse systems based on the stratigraphic architecture around the West Xylokastro fault block that emphasizes the lateral and vertical heterogeneity of rift basin-fills with multiple entry points.     

Evidence for cold-based glacial activity in the Allan Hills,Antarctica

Evidence is presented for cold-based glacial erosion, deposition and deformation from the Allan Hills, South Victoria Land, Antarctica. Different erosional features such as scrapes, striae and grooves, depositional features including till, isolated boulders and ice-cored debris cones and three scales of glaciotectonism resulting from cold-based glacial advance are described, and conceptual models are presented based on these observations and those of advancing cold-based glaciers elsewhere. The models entail: (i) ice block apron overriding and entrainment, and (ii) ice-bed separation leading to the formation of a cavity on the down-glacier side of escarpments. The models are most applicable to a horizontally stratified, lithified sedimentary bedrock substrate, but our criteria may assist in correctly interpreting features such as boulder trains, modified bedrock tors and complex cosmogenic exposure histories which have been noted in several regions that may have experienced cold-based glaciation during Pleistocene glacial maxima.     

Link between climate change mitigation and resource efficiency: A UK case study

This paper provides an in-depth analysis of the links between dematerialisation and climate change mitigation. Methods used for material flow analyses (MFA) within the wider context of industrial ecology (which includes a focus on all resource flows in an economy, not purely material tonnage) tend to focus either on detoxification and pollution reduction or dematerialisation and resource productivity. An environmentally extended input–output (EEIO) model incorporates both aspects, which need to be dealt with when looking at how to meet challenging greenhouse gas (GHG) emission targets. The approach understands both production systems and consumption patterns and has the ability through scenarios to analyse the (GHG) effectiveness of a wide range of material efficiency options. This analysis adopts an environmentally extended input–output approach to assess the role of material efficiency measures in reducing UK GHG emissions by 2050. A method for projecting the variables and parameters in the model, including the supply of and demand for materials and products, is presented and applied to investigate thirteen material efficiency strategies in the UK.     

Local level climate justice? Adaptation finance and vulnerability reduction

Climate change creates a double inequality through the inverse distribution of risk and responsibility. Developed states are responsible, but are forecast to confront only moderate adverse effects; least developed states are not culpable and yet experience significant threats to livelihoods, assets and security. Adaptation finance addresses inequity by developed states facilitating/funding behaviour adjustments necessary for exposed communities to lessen climate risk. This article investigates the ground-level effectiveness of adaptation finance in climate vulnerable villages across Malawi, while controlling for disparities in vulnerability. Malawi and selected districts are both climate vulnerable and significant recipients of adaptation finance. This concludes a larger top–down multi-scalar analysis of climate justice, which applies the distribution and effectiveness of adaptation finance as a proxy. The study avails of participatory assessments to compare actions of villages receiving adaptation finance with those engaging in autonomous and informal adaptations. Adaptation finance villages: (a) address more climate related risks; and (b) enhance agency, security and sustainably lessen climate vulnerability. Conversely, informal practice villages attend to a lower proportion of climate risks and often develop short-term strategies with less enduring vulnerability reduction. Vulnerable communities receiving adaptation finance do change behaviours to reduce climate risk and thus secure local level climate justice.     

Variability of precipitation and temperature in Guanajuato,Mexico

Variability of precipitation and temperature was examined on multiple time scales using data from five surface observing stations in the center of Guanajuato state, Mexico, as well as gridded data from the North American Regional Reanalysis (NARR). Frequency of days with total precipitation exceeding the 90th percentile was not found to have increased from 1979-2011. However, frequency of days with maximum temperature above the 90th percentile more than doubled from 1979-2011, and frequency of days with maximum temperature below the 10th percentile decreased by almost half over the same period, an important result given the scarcity of water resources for the agriculture-based economy. Precipitation within the growing season was found to vary by phase of the Madden-Julian oscillation (MJO), with MJO phases 1-3 associated with above-normal rainfall and MJO phases 4-7 with normal or below normal rainfall. Composite anomalies of precipitation, surface pressure, surface wind, surface temperature, and 700 mbar height showed that days with rainfall in Guanajuato were associated with on-shore, upslope flow, reduced surface temperatures, and reduced potential evaporation. Composites for MJO phases 1-3 and 8 agreed well with these anomalies. Similarly, composite anomalies for days without rainfall in Guanajuato showed warm surface temperatures, broad anticyclonic flow over much of northern Mexico, and enhanced potential evaporation. Composites for MJO phases 4-7 agreed well with these anomalies.