Evidence for middle Cretaceous accretion at Santa Elena Peninsula (Santa Rosa Accretionary Complex), Costa Rica

An oceanic assemblage of alkaline basalts, radiolarites and polymictic breccias forms the tectonic substratum of the Santa Elena Nappe, which is constituted by extensive outcrops of ultramafic and mafic rocks of the Santa Elena Peninsula (NW Costa Rica). The undulating basal contact of this nappe defines several half-windows along the south shores of the Santa Elena Peninsula. Lithologically it is constituted by vesicular pillowed and massive alkaline basaltic flows, alkaline sills, ribbon-bedded and knobby radiolarites, muddy tuffaceous and detrital turbidites, debris flows and polymictic breccias and megabreccias. Sediments and basalt flows show predominant subvertical dips and occur in packages separated by roughly bed-parallel thrust planes. Individual packages reveal a coherent internal stratigraphy that records younging to the east in all packages and shows rapid coarsening upwards of the detrital facies. Alkaline basalt flows, pillow breccias and sills within radiolarite successions are genetically related to a mid-Cretaceous submarine seamount. Detrital sedimentary facies range form distal turbidites to proximal debris flows and culminate in megabreccias related to collapse and mass wasting in an accretionary prism. According to radiolarian dating, bedded radiolarites and soft-sediment-deformed clasts in the megabreccias formed in a short, late Aptian to Cenomanian time interval. Middle Jurassic to Lower Cretaceous radiolarian ages are found in clasts and blocks reworked from an older oceanic basement. We conclude that the oceanic assemblage beneath the Santa Elena Nappe does not represent a continuous stratigraphic succession. It is a pile of individual thrust sheets constituting an accretionary sequence, where intrusion and extrusion of alkaline basalts, sedimentation of radiolarites, turbidites and trench fill chaotic sediments occurred during the Aptian-Cenomanian. These thrust sheets formed shortly before the off-scraping and accretion of the complex. Here we define the Santa Rosa Accretionary Complex and propose a new hypothesis not considered in former interpretations. This hypothesis would be the basis for further research

Emplacement of Jurassic-Lower Cretaceous radiolarites of the Nicoya Complex (Costa Rica)

We present a new model to explain the origin, emplacement and stratigraphy of the Nicoya Complex in the NW part of the Nicoya Peninsula (Costa Rica) based on twenty-five years of field work, accompanied with the evolution of geochemical, vulcanological, petrological, sedimentological and paleontological paradigms. The igneous-sedimentary relation, together with radiolarian biochronology of the NW-Nicoya Peninsula is re-examined. We interpret the Nicoya Complex as a cross-section of a fragment of the Late Cretaceous Caribbean Plateau, in which the deepest levels are exposed in the NW-Nicoya Peninsula. Over 50% of the igneous rocks are intrusive (gabbros and in less proportion plagiogranites) which have a single mantle source; the remainder are basalts with a similar geochemical signature. Ar39/Ar40 radioisotopic whole rock and plagioclase ages range throughout the area from 84 to 83 Ma (Santonian) for the intrusives, and from 139 to 88 Ma (Berriasian-Turonian) for the basalts. In contrast, Mn-radiolarites that crop out in the area are older in age, Bajocian (Middle Jurassic) to Albian (middle Cretaceous). These Mn-radiolaritic blocks are set in a "matrix" of multiple gabbros and diabases intrusions. Chilled margins of magmatites, and hydrothermal baking and leaching of the radiolarites confirm the Ar39/Ar40 dating of igneous rocks being consistently younger than most of the radiolarian cherts. No Jurassic magmatic basement has been identified on the Nicoya Peninsula. We interpret the Jurassic-Cretaceous chert sediment pile to have been disrupted and detached from its original basement by multiple magmatic events that occurred during the formation of the Caribbean Plateau. Coniacian-Santonian (Late Cretaceous), Fe-rich radiolarites are largely synchronous and associated with late phases of the Plateau

Characterization and tectonic implications of Mesozoic-Cenozoic oceanic assemblages of Costa Rica and Western Panama

The Pacific face of Costa Rica and western Panama has been extensively studied because of the wide occurrence of oceanic assemblages. In Northern Costa Rica, the Santa Elena Nappe made by ultramafic and mafic associations overthrusts the Santa Rosa Accretionary Complex. The Nicoya Complex corresponds to a pre-Campanian oceanic plateau association, cropping out in the Nicoya Peninsula and the outer Herradura Block. The 89 Ma high MgO Tortugal Komatiitic Suite corresponds to 14-km long, 1.5-km wide body, with no clear relation with to the Nicoya Complex. The Tulín Formation (Maastrichtian to Lower Eocene) forms the main edifice of an accreted ancient oceanic island of the Herradura Block. The Quepos Block was formed by the accretion of a late Cretaceous-Paleocene seamount. In the Osa and Burica peninsulas, Caño Island and Golfito area, a series of Upper Cretaceous to Eocene accreted plateau and seamount blocks crop out. In western Panama, the oceanic assemblages range from Upper Cretaceous to Miocene, and their geochemical signature show their oceanic plateau association. The Costa Rica and western Panama oceanic assemblages correspond to a fragmentary and disrupted Jurassic to Miocene sequences with a very complicated geological and geotectonic history. Their presence could be interpreted as a result of accretionary processes rather than tectonic erosion; despite this last process is nowadays active in the Middle American Trench. The whole picture has not been completed yet, but apparently, most of the igneous rocks have a geochemical signature similar to the Galapagos mantle plume. The later has been acting in pulses, or otherwise the outcropping occurrences could be part of several plateaus somehow diachronically formed in the Pacific basin

Anti-inflammatory activity of Punica granatum L. (Pomegranate) rind extracts applied topically to ex vivo skin

Coadministered pomegranate rind extract (PRE) and zinc (II) produces a potent virucidal activity against Herpes simplex virus (HSV); however, HSV infections are also associated with localised inflammation and pain. Here, the objective was to determine the anti-inflammatory activity and relative depth penetration of PRE, total pomegranate tannins (TPT) and zinc (II) in skin, ex vivo. PRE, TPT and ZnSO4 were dosed onto freshly excised ex vivo porcine skin mounted in Franz diffusion cells and analysed for COX-2, as a marker for modulation of the arachidonic acid inflammation pathway, by Western blotting and immunohistochemistry. Tape stripping was carried out to construct relative depth profiles. Topical application of PRE to ex vivo skin downregulated expression of COX-2, which was significant after just 6 h, and maintained for up to 24 h. This was achieved with intact stratum corneum, proving that punicalagin penetrated skin, further supported by the depth profiling data. When PRE and ZnSO4 were applied together, statistically equal downregulation of COX-2 was observed when compared to the application of PRE alone; no effect followed the application of ZnSO4 alone. TPT downregulated COX-2 less than PRE, indicating that tannins alone may not be entirely responsible for the anti-inflammatory activity of PRE. Punicalagin was found throughout the skin, in particular the lower regions, indicating appendageal delivery as a significant route to the viable epidermis. Topical application of TPT and PRE had significant anti-inflammatory effects in ex vivo skin, confirming that PRE penetrates the skin and modulates COX-2 regulation in the viable epidermis. Pomegranates have potential as a novel approach in ameliorating the inflammation and pain associated with a range of skin conditions, including cold sores and herpetic stromal keratitis

In vitro permeation and biological activity of punicalagin and zinc (II) across skin and mucous membranes prone to Herpes simplex virus infection

Coadministration of pomegranate rind extract (PRE) and zinc (II) ions has recently been reported as a potential new topical treatment for Herpes simplex virus (HSV) infections. In the current work we examined the in vitro topical delivery of punicalagin (major phytochemical of PRE) and zinc from hydrogels across epithelial membranes that can become infected with HSV. Porcine epidermal, buccal and vaginal mucous membranes were excised and mounted in Franz diffusion cells and dosed with a simple hydrogel containing PRE and zinc sulphate (ZnSO4). The permeation of punicalagin and zinc were determined by HPLC and ICPMS respectively; punicalagin was also determined in the basal layers by reverse tape stripping. Receptor phases from the epidermal membrane experiment were also used to challenge HSV-1 in Vero host cells, and ex vivo porcine skin was used to probe COX-2 modulation. Punicalagin and zinc permeated each of the three test membranes, with significantly greater amounts of both delivered across the epidermal membrane. The amounts of punicalagin permeating the buccal and vaginal membranes were similar, although the amount of zinc permeating the vaginal membrane was comparatively very large – it is known that zinc interacts with vaginal mucosa. The punicalagin recovered by reverse tape stripping of the epidermal, buccal and vaginal membranes gave 0.47 ± 0.016, 0.45 ± 0.052 and 0.51 ± 0.048 nM cm− 2 respectively, and were statistically the same (p < 0.05). A 2.5 log reduction was achieved against HSV-1 using diffusion cell receptor phase, and COX-2 expression was reduced by 64% in ex vivo skin after 6 h. Overall, a hydrogel containing 1.25 mg mL− 1 PRE and 0.25 M ZnSO4 was able to topically deliver both the major bioactive compound within PRE and Zn (II) across all membranes and into the site specific region of Herpes simplex vesicular clusters, while maintaining potentiated virucidal and anti-inflammatory properties. This novel therapeutic system therefore has potential for the topical treatment of HSV infections

More than sense of place? Exploring the emotional dimension of rural tourism experiences

It is widely suggested that participation in rural tourism is underpinned by a sense of rural place or “rurality”. However, although nature and the countryside have long been recognised as a source of spiritual or emotional fulfilment, few have explored the extent to which tourism, itself often claimed to be a sacred experience, offers an emotional/spiritual dimension in the rural context. This paper addresses that literature gap. Using in-depth interviews with rural tourists in the English Lake District, it explores the extent to which, within respondents’ individual understanding of spirituality, a relationship exists between sense of place and deeper, emotional experiences and, especially, whether participation in rural tourism may induce spiritual or emotional responses. The research revealed that all respondents felt a strong attachment to the Lake District; similarly, and irrespective of their openness to spirituality, engaging in rural tourism activities resulted in highly emotive experiences for all respondents, the description/interpretation of such experiences being determined by individual “beliefs”. However, sense of place was not a prerequisite to emotional or spiritual experiences. Being in and engaging with the landscape � effectively becoming part of it � especially through physical activity is fundamental to emotional responses

A melt-focusing zone in the lithospheric mantle preserved in the Santa Elena Ophiolite, Costa Rica

The Santa Elena Ophiolite in Costa Rica is composed of a well-preserved fragment of the lithospheric mantle that formed along a paleo-spreading center. Within its exposed architecture, this ophiolite records a deep section of the melt transport system of a slow/ultra-slow spreading environment, featuring a well-developed melt-focusing system of coalescent diabase dikes that intrude the peridotite in a sub-vertical and sub-parallel arrangement. Here we present an integrated analysis of new structural data, 40Ar/39Ar geochronology, major and trace element geochemistry and radiogenic isotope data from the diabase dikes in order to elucidate the tectonic setting of the Santa Elena Ophiolite. The dikes are basaltic and tholeiitic in composition. Petrological models of fractional crystallization suggest deep pressures of crystallization of &gt;0.4GPa for most of the samples, which is in good agreement with similar calculations from slow/ultra-slow spreading ridges and require a relatively hydrated (~0.5wt.% H2O) MORB-like source composition. The diabase dikes share geochemical and isotope signatures with both slow/ultra-slow spreading ridges and back-arc basins and indicate mixing of a DMM source and an enriched mantle end-member like EMII. The 40Ar/39Ar geochronology yielded an age of ~131Ma for a previous pegmatitic gabbroic magmatic event that intruded the peridotite when it was hot and plastic and an age of ~121Ma for the diabase intrusions, constraining the cooling from near asthenospheric conditions to lithospheric mantle conditions to ~10Ma. Our findings suggest a complex interplay between oceanic basin and back-arc extension environments during the Santa Elena Ophiolite formation. We propose an alternative hypothesis for the origin of Santa Elena as an obducted fragment of an oceanic core complex (OCC)

Cell envelope proteins of Staphylococcus epidermidis grown in vivo in a peritoneal chamber implant

Staphylococcus epidermidis was grown in vivo in chambers implanted intraperitoneally in rats. The cell wall and cytoplasmic membrane protein profiles of the in vivo-grown organisms were compared with those of S. epidermidis grown in vitro in nutrient broth (NB), in iron-restricted NB, or in pooled human peritoneal dialysate (HPD). Compared with growth in broth and in common with growth in HPD, growth in vivo in chambers resulted in the repression of many S. epidermidis wall proteins, with proteins of 27, 42, 54, and 70 kDa predominating. Growth in vivo also resulted in the induction of two iron-repressible cytoplasmic membrane proteins of 32 and 36 kDa, which were also present in staphylococci grown in HPD and in iron-restricted NB. Immunoblotting experiments revealed that in sera taken 21 days after inoculation of the intraperitoneal chambers, the predominant antibody response to cell envelope proteins was directed against the 32- and 36-kDa iron-repressible membrane proteins