Integrating geochemistry and micromorphology to interpret feature use at Dust Cave,a Paleo‐Indian through middle‐archaic site in Northwest Alabama

The authors develop an integrated method using geochemistry and micromorphology to examine the use of archaeological features at Dust Cave, a Paleo‐Indian through Middle Archaic (10,650–3600 cal. B.C.) site in northwest Alabama. Samples analyzed using ICP‐AES for aluminum (Al), barium (Ba), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorous (P), strontium (Sr), sulfur (S), and zinc (Zn) and suggest that cultural features differ chemically from geogenic sediments in several ways: (a) K‐means cluster analyses indicate that features of known origin and suspected features of the same origin cluster together, thereby allowing for a preliminary separation into discrete functionalities; (b) phosphorus serves as an indicator of human occupation intensity; and (c) Sr/Ca and K/P ratios help identify anthropogenic materials. Micromorphological observations allow for a finer subdivision of feature types and help highlight postdepositional processes affecting cave sediments, and interpretation of activity at the site. These findings show that feature diversity and occupation intensity increased through time, peaking during the Middle Archaic. © 2006 Wiley Periodicals, Inc.     

Metadolerite age relationships in the Dalradian of northwest Donegal,Ireland and their orogenic significance

The structural relationships of several intrusive sheets belonging to the extensive metadolerite suite of the Appin (lower) Dalradian rocks of the Creeslough area, northwest Donegal, Ireland have been examined. It is concluded that, relative to the regional chronology of deformation of the enclosing metasediments, sheet emplacement has occurred: pre-D2; syn-D2; between D2 and D3; and syn-D3. The height of activity came in the post-D2, pre-D3 interval and coincided with the peak of regional metamorphism in the area. These relationships in Donegal are compared with those of the pretectonic basic rocks of the southwest Highlands and models are discussed.     

Deglacial to postglacial palaeoenvironments of the Celtic Sea: lacustrine conditions versus a continuous marine sequence

Recent work on the last glaciation of the British Isles has led to an improved understanding of the nature and timing of the retreat of the British?Irish Ice Sheet (BIIS) from its southern maximum (Isles of Scilly), northwards into the Celtic and Irish seas. However, the nature of the deglacial environments across the Celtic Sea shelf, the extent of subaerial exposure and the existence (or otherwise) of a contiguous terrestrial linkage between Britain and Ireland following ice retreat remains ambiguous. Multiproxy research, based on analysis of 12 BGS vibrocores from the Celtic Deep Basin (CDB), seeks to address these issues. CDB cores exhibit a shell‐rich upward fining sequence of Holocene marine sand above an erosional contact cut in laminated muds with infrequent lonestones. Molluscs, in situ Foraminifera and marine diatoms are absent from the basal muds, but rare damaged freshwater diatoms and foraminiferal linings occur. Dinoflagellate cysts and other non‐pollen palynomorphs evidence diverse, environmentally incompatible floras with temperate, boreal and Arctic glaciomarine taxa co‐occurring. Such multiproxy records can be interpreted as representing a retreating ice margin, with reworking of marine sediments into a lacustrine basin. Equally, the same record may be interpreted as recording similar conditions within a semi‐enclosed marine embayment dominated by meltwater export and deposition of reworked microfossils. As assemblages from these cores contrast markedly with proven glaciomarine sequences from outside the CDB, a glaciolacustrine interpretation is favoured for the laminated sequence, truncated by a Late Weichselian transgressive sequence fining upwards into fully marine conditions. Reworked rare intertidal molluscs from immediately above the regional unconformity provide a minimum date c. 13.9 cal. ka BP for commencement of widespread marine erosion. Although suggestive of glaciolacustrine conditions, the exact nature and timing of laminated sediment deposition within the CDB, and the implications this has on (pen)insularity of Ireland following deglaciation, remain elusive.     

Petrogenesis of Volcanic Rocks from Saipan and Rota, Mariana Islands, and Implications for the Evolution of Nascent Island Arcs

An ⁴⁰Ar/³⁹Ar age of 45·1 Ma determined for lavas fromnorthern Saipan confirms that these high-silica rhyolites eruptedduring the ‘proto-arc’ stage of volcanism in theIzu–Bonin–Mariana system, which is characterizedelsewhere by eruption of boninitic lavas. Incompatible traceelement concentrations and Sr, Hf, Nd, and Pb isotope ratiosfor these rhyolites are transitional between those of c. 48Ma boninitic lavas and post-38 Ma ‘first-arc’ andesitesand dacites from Saipan and Rota that have typical subduction-relatedcompositions. These transitional compositions are modeled bycrystal fractionation of parental tholeiitic basalt combinedwith assimilation of young boninitic crust. A second stage ofRayleigh fractionation in the upper crust is required by SiO₂concentrations that exceed 77 wt % and near-zero compatibleelement concentrations. First-arc magma compositions are consistentwith fractionation of basalt and assimilation of crust similarin composition to the first-arc magmas themselves. The mantlesources of the proto-arc and first-arc lavas from Saipan andRota are similar to those of Philippine back-arc basin basaltsbased on Nd and Hf isotopic compositions. The Pb isotope compositionsof these lavas are between those of Pacific sea-floor basaltsand Jurassic and younger cherty and clay-rich sediments. Thiscontrasts with the boninitic proto-arc volcanic rocks from Guamand Deep Sea Drilling Project Sites 458 and 459 that have Pbisotope compositions similar to Pacific basin basalts and volcaniclasticsediments. The preferred explanation for the difference in thenature of proto-arc volcanism between Saipan and other fore-arclocations is that the crust ceased extending 3–4 Myr earlierbeneath Saipan. This was caused by a change from mantle upwelling,fore-arc extension, and shallow melting to an environment dominatedby more normal mantle wedge convection, stable crust, and deepermelting. KEY WORDS: rhyolite; andesite; Mariana arc; isotope ratios; trace elements     

“A Place of Pain and Gain”: Exploring the Dynamics of Resistance in the Creation of Sengwe Tshipise Wilderness Corridor,Southeast Zimbabwe

This article examines the relationship between place attachment and resistance during participatory planning of the Sengwe Tshipise Wilderness Corridor, located in southeast Zimbabwe, a region that falls within the Great Limpopo Transfrontier Conservation Area. Field research was conducted from July to December 2013 using 69 semistructured interviews, seven focus-group discussions, and analysis of secondary data. By following the dominant narratives articulated by villagers affected by this Corridor, we illustrate the multiple ways in which place attachment becomes part of everyday politics of resistance. Results show that a strong place-based identity is at the center of narratives deployed by villagers displaced by war, conservation, and veterinary fencing restrictions. Through deploying this place-based identity, communities collectively influenced both the spatial extent of the corridor and institutional governance arrangements. This article contributes to debates on the role of community agency in the implementation of transfrontier conservation areas.     

Isotope characteristics of submarine lavas from the Philippine Sea: implications for the origin of arc and basin magmas of the Philippine tectonic plate

Igneous rocks from the Philippine tectonic plate recovered on Deep Sea Drilling Project Legs 31, 58 and 59 have been analyzed for Sr, Nd and Pb isotope ratios. Samples include rocks from the West Philippine Basin, Daito Basin and Benham Rise (40–60 m.y.), the Palau-Kyushu Ridge (29–44 m.y.) and the Parece Vela and Shikoku basins (17–30 m.y.). Samples from the West Philippine, Parece Vela and Shikoku basins are MORB (mid-ocean ridge basalt)-like with ⁸⁷Sr/⁸⁶Sr= 0.7026−0.7032, ¹⁴³Nd/¹⁴⁴Nd= 0.51300−0.51315, and ²⁰⁶Pb/²⁰⁴Pb= 17.8−18.1. Samples from the Daito Basin and Benham Rise are OIB (oceanic island basalt)-like with ⁸⁷Sr/⁸⁶Sr= 0.7038−0.7040, ¹⁴³Nd/¹⁴⁴Nd= 0.51285−0.51291 and ²⁰⁶Pb/²⁰⁴Pb= 18.8−19.2. All of these rocks have elevated ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb compared to the Northern Hemisphere Regression Line (NHRL) and have δ²⁰⁷Pb values of 0 to +6 and δ²⁰⁸Pb values of +32 to +65. Lavas from the Palau-Kyushu Ridge, a remnant island arc, have ⁸⁷Sr/⁸⁶Sr= 7032−0.7035, ¹⁴³Nd/¹⁴⁴Nd= 0.51308−0.51310 and ²⁰⁶Pb/²⁰⁴Pb= 18.4−18.5. Unlike the basin magmas erupted before and after them, these lavas plot along the NHRL and have Pb-isotope ratios similar to modern Pacific plate MORB's. This characteristic is shared by other Palau-Kyushu Arc volcanic rocks that have been sampled from submerged and subaerial portions of the Mariana fore-arc.At least four geochemically distinct magma sources are required for these Philippine plate magmas. The basin magmas tap Source 1, a MORB-mantle source that was contaminated by EMI (enriched mantle component 1 [31]) and Source 2, an OIB-like mantle source with some characteristics of EMII (enriched mantle component 2 [31]). The arc lavas are derived from Source 3, a MORB-source or residue mantle including Sr and Pb from the subducted oceanic crust, and Source 4, MORB-source or residue mantle including a component with characteristics of HIMU (mantle component with high U/Pb [31]). These same sources can account for many of the isotopic characteristics of recent Philippine plate arc and basin lavas. The enriched components in these sources which are associated with the DUPAL anomaly were probably introduced into the asthenosphere from the deep mantle when the Philippine plate was located in the Southern Hemisphere 60 m.y.b.p.     

Trouble in paradise: resilience and Vancouver’s second life in the “new economy”

Resilience is an increasingly important concept within urban studies, economic geography, and evolutionary economics for measuring the capacity of city-regions to respond to economic shocks. In this article, we provide a sympathetic critique of the resilience metaphor in urban studies, which we explicate through an analysis of the recent history of the Vancouver economy. On the surface, Vancouver seemingly showed resilience when it overcame the abrupt decline of its resource-based economy in the 1980s, and established an alternative flourishing “new economy” by the 1990s. But over the last five years, the key local “creative” industries such as video game development and film production have suffered, with a number of large firms leaving Vancouver, and industry employment declining sharply. Drawing on more than 40 interviews conducted over a five-year period with members of the local video game community, our paper documents the rise and more recent decline of Vancouver’s “new economy” sector. Our research raises questions about the value of the resilience metaphor in urban studies and highlights the difficulties facing city-regions reliant on highly mobile “new economy” industries.     

Modeling Nonprofit Resilience in Long-Term Recovery in Christchurch,New Zealand

Following the 2010–2011 earthquakes in Christchurch, New Zealand, many nonprofit organizations changed or expanded services to address emergent or compounded risks. This research is based on interviews with thirty local community nonprofit managers and discussions with five staff focus groups conducted in 2014. Preexisting nonprofits with flexible organizational structures and emergent nonprofits succeeded in providing services during the emergency response and early recovery phases; nonprofits contracted with the government were better suited for long-term recovery. Shared resources among nonprofit agency connections contributed to successful transitions from response to recovery. Similar organizational resilience factors might occur in other major cities following disasters.     

The stratigraphic evolution of the Indus Fan and the history of sedimentation in the Arabian Sea

The Indus Fan records the erosion of the western Himalayas and Karakoram since India began to collide with Asia during the Eocene, 50 Ma. Multi-channel seismic reflection data from the northern Arabian Sea correlated to industrial well Indus Marine A-1 on the Pakistan Shelf show that sedimentation patterns are variable through time, reflecting preferential sedimentation in deep water during periods of lower sea-level (e.g., middle Miocene, Pleistocene), the diversion of sediment toward the east following uplift of the Murray Ridge, and the autocyclic switching of fan lobes. Individual channel-levee systems are estimated to have been constructed over periods of 10⁵–10⁶ yr during the Late Miocene. Sediment velocities derived from sonobuoys and multi-channel stacking velocities allow sections to be time-depth converted and then backstripped to calculate sediment budgets through time. The middle Miocene is the period of most rapid accumulation, probably reflecting surface uplift in the source regions and strengthening of the monsoon at that time. Increasing sedimentation during the Pleistocene, after a late Miocene-Pliocene minimum, is apparently caused by faster erosion during intense glaciation. The sediment-unloaded geometry of the basement under the Pakistan Shelf shows a steep gradient, similar to the continent-ocean transition seen at other rifted volcanic margins, with basement depths on the oceanward side indistinguishable from oceanic crust. Consequently we suggest that the continent-ocean transition is located close to the present shelf break, rather than >350 km to the south, as previously proposed.     

Application of a coupled ice‐ocean model to the Labrador Sea

Abstract

The steady, coupled ice‐ocean circulation model of Willmott and Mysak (1989) for a meridional channel is applied to the Labrador Sea for the winter season. The model consists of a thermodynamic reduced‐gravity ocean combined with a variable thickness ice cover that is in thermal equilibrium. Upon specifying the forcing fields of surface air temperature, wind stress and water temperature along the open southern boundary, the winter climatological ice‐edge position, ice thickness, ocean circulation and temperature fields are determined in the channel domain. The sensitivity of the results to the various model parameters is examined. In particular, the optimum heat exchange coefficients for the interfaces of air‐water, ice‐water and air‐ice are found.

The model ice‐edge position compares favourably with the 50% winter climatological ice concentration isoline obtained from an analysis of 32 years (1953–84) of sea‐ice concentration data. The simulations of the ocean temperature and ice thickness are also quite realistic according to the observed records available. The model is also applied to two specific winters (1981 and 1983) during which anomalous sea‐ice and weather conditions prevailed in the Labrador Sea.