Volcanic Stratigraphy of Hannah Point, Livingston Island, South Shetland Islands, Antarctica

The Upper Cretaceous volcanic succession of Hannah Point is the best exposure of the Antarctic Peninsula Volcanic Group on Livingston Island. The aim of the present paper is to contribute to the characterisation of the stratigraphy and petrography of this little studied succession, and briefly discuss some aspects of the eruptive style of its volcanism. The succession is about 470 m thick and is here subdivided into five lithostratigraphic units (A to E from base to top). Unit A, approximately 120 m thick, is mainly composed of polymict clast-supported volcaniclastic breccias and also includes a dacitic lava laye r. Interstratified in the breccias of this unit, there is a thin laminated devitrified layer which shows some degree of welding. Unit B, approximately 70 m thick, is almost entirely composed of volcaniclastic breccias, and includes a volcaniclastic conglomerate layer. Breccias in this unit can be subdivided into two distinct types; polymict clast-supported breccias, and monomict matrix-supported breccias rich in juvenile components and displaying incipient welding. Unit C, about 65 m thick, is mainly composed of basaltic lavas, which are interlayered with minor volcaniclastic breccias. Unit D, approximately 65 m thick, is lithologically similar to unit B, composed of an alternation of polymict clasts upported breccias and matrix-supported breccias, and includes a volcaniclastic conglomerate layer. Unit E, about 150 m thick, is mainly formed of thick andesitic lava layers. Minor basaltic dykes and a few normal faults cut the succession, and the contact between units A and B can be interpreted both as an unconformity or a fault. The matrix-supported breccias included in the succession of Hannah Point have high contents of juvenile components and incipient welding, which suggest that part of the succession is the result of pyroclastic fragmentation and emplacement from pyroclastic flows. In contrast, the polymict clast-supported breccias suggest reworking of previous deposits and deposition from cool mass flows. The lavas indicate effusive volcanic eruptions, and the absence of features indicative of subaqueous volcanism suggests that at least these portions of the succession were emplaced in a subaerial environment

Mesozoic geology of Cape Shirreff, Livingston Island, South Shetland Islands, Antarctica

The stratigraphic succession at Cape Shirr e ff has a minimum thickness of 450 m and is mainly composed of lavas and a smaller amount of volcaniclastic breccias. Lavas are subalkaline olivine basalts and basaltic andesites which are locally well - bedded, but in most areas give a homogeneous, sometimes massive aspect to outcrops. Volcaniclastic massive breccias are found in the northern part of Cape Shirreff where they are interstratified with lavas in a few outcrops. Breccias are indurated, heterometric, grain - supported and consist of angular to subangular volcanic rock fragments, 5 to 80 cm in diameter. Petrographic evidence of magma supercooling (skeletal microlites of plagioclase, thermal - shocked phenocrysts of olivine) enables a subaqueous environment for part of the lavas to be deposited and suggests a possible hyaloclastic origin for some interstratified volcanic breccias. The whole succession is cut by subve rtical dykes (10 to 40 cm thick and a few meters to 400 m long), which show variable trends around a NW-SE maximum. These consist of commonly vesiculated basaltic and basaltic andesite porp hyritic rocks, commonly indistinguishable from the lava bodies. Lavas dip variably between 15 and 80º, more gently in the south than in the central and northern areas. Although significant variations in dipping attitude could be associated with depositional geometries, the general dipping pattern is clearly consistent with NW-SE oriented large-scale folds showing a gentle dome and basin structure. In the southern area, the NW-SE folds are not so well developed and the structure seems to be consistent with an interference of N-S and E-W oriented folds. The large scale NW-SE folds are consistent with NE-SW shortening. This shortening direction is parallel to the direction of extension deducible from dykes and, hence, folds and dykes are not consistent with the same deformational event

Active tectonic and sedimentary processes along the São Vicente Canyon (SW Iberian Margin): High-Resolution Imaging

Marine Technology Workshop (Martech05), 17-18 November 2005, Vilanova i la Geltrú, Barcelona.-- 2 pages, 1 figureThe authors are grateful for funding from MCYT Acción Especial HITS (REN2000-2150-E), European Commission EASSS-III programme (HPRI-CT99-0047), European Large Scale Facility (HPRI-CT2001-00120) and Spanish National Project IMPULS (REN2003-05996MAR)Peer Reviewe

On-ground tests of LISA PathFinder thermal diagnostics system

Thermal conditions in the LTP, the LISA Technology Package, are required to be very stable, and in such environment precision temperature measurements are also required for various diagnostics objectives. A sensitive temperature gauging system for the LTP is being developed at IEEC, which includes a set of thermistors and associated electronics. In this paper we discuss the derived requirements applying to the temperature sensing system, and address the problem of how to create in the laboratory a thermally quiet environment, suitable to perform meaningful on-ground tests of the system. The concept is a two layer spherical body, with a central aluminium core for sensor implantation surrounded by a layer of polyurethane. We construct the insulator transfer function, which relates the temperature at the core with the laboratory ambient temperature, and evaluate the losses caused by heat leakage through connecting wires. The results of the analysis indicate that, in spite of the very demanding stability conditions, a sphere of outer diameter of the order one metre is sufficient. We provide experimental evidence confirming the model predictions.Comment: 18 pages, 5 figures, LaTeX2e (compile with pdflatex), sumbitted to CQG. This paper is a significant extension of gr-qc/060109

Phase Change Materials (PCM) microcapsules with different shell compositions: Preparation, characterization and thermal stability

In this study, phase change materials (Rubitherm® RT 27) microcapsules were successfully obtained by two different methods. The main difference between them remains on the shell composition, as they are composed of different coacervates (Sterilized Gelatine/Arabic Gum for the SG/AG method and Agar-Agar/Arabic Gum for the AA/AG method). Microcapsules were thermally characterized by thermo-optical microscopy and differential scanning calorimetry. Using scanning electron microscopy, their spherical morphology (sphericity factor of 0.94-0.95) and their particle size distribution were determined, obtaining an average diameter of 12 μm for the SG/AG method and lower values for the AA/AG method, where nanocapsules were also observed (average diameter of 4.3 μm for the microcapsules and 104 nm for the nanocapsules). The thermal stability determination was carried out by Thermogravimetric analyses (TG) and the results show a high decomposition temperature, although the process takes places in four steps for the two mentioned methods. Moreover, the microcapsules obtained by the AA/AG method decompose in a more gradual way, as in the TG results a double step, instead of one, is appreciable. On the whole, the prepared microencapsulated PCM are totally capable of developing their role in thermal energy storage

First evidence of paleoearthquakes along the Carboneras Fault Zone (SE Iberian Peninsula): Los Trances site

Seismogenic faults that have not produced historical large earthquakes remain unnoticed and, thus, are dangerously left out from seismic hazard analyses. The seismogenic nature of the Carboneras Fault Zone, a left-lateral strikeslip fault in the Eastern Betic Shear Zone (southeastern Spain), has not been fully explored to date in spite of having a morphological expression equivalent to the Alhama de Murcia Fault, a seismogenic fault in the same tectonic system. This study provides the first paleoseismic evidence of the seismogenic nature of the Carboneras Fault Zone, based on the analysis of 3 trenches at Los Trances site, on the northwestern edge of the La Serrata Range. Cross cutting relationships and numerical dating, based on radiocarbon, thermoluminescence and U-series, reveal a minimum of 4 paleoearthquakes: Paleoearthquake1 (the oldest) and Paleoearthquake2 took place after 133ka, Paleoearthquake3 occurred between 83–73ka and Paleoearthquake4 happened after 42.5ka (probably after 30.8ka), resulting in a maximum possible average recurrence of 33ka. This value, based on a minimum amount of paleoearthquakes, is probably overestimated, as it does not scale well with published slip-rates derived from offset channels or GPS geodetical data. The characterization of this fault as seismogenic, implies that it should be considered in the seismic hazard analyses of the SE Iberian Peninsula

AAV-mediated expression of secreted and transmembrane αKlotho isoforms rescues relevant aging hallmarks in senescent SAMP8 mice

Senescence represents a stage in life associated with elevated incidence of morbidity and increased risk of mortality due to the accumulation of molecular alterations and tissue dysfunction, promoting a decrease in the organism's protective systems. Thus, aging presents molecular and biological hallmarks, which include chronic inflammation, epigenetic alterations, neuronal dysfunction, and worsening of physical status. In this context, we explored the AAV9-mediated expression of the two main isoforms of the aging-protective factor Klotho (KL) as a strategy to prevent these general age-related features using the senescence-accelerated mouse prone 8 (SAMP8) model. Both secreted and transmembrane KL isoforms improved cognitive performance, physical state parameters, and different molecular variables associated with aging. Epigenetic landscape was recovered for the analyzed global markers DNA methylation (5-mC), hydroxymethylation (5-hmC), and restoration occurred in the acetylation levels of H3 and H4. Gene expression of pro- and anti-inflammatory mediators in central nervous system such as TNF-α and IL-10, respectively, had improved levels, which were comparable to the senescence-accelerated-mouse resistant 1 (SAMR1) healthy control. Additionally, this improvement in neuroinflammation was supported by changes in the histological markers Iba1, GFAP, and SA β-gal. Furthermore, bone tissue structural variables, especially altered during senescence, recovered in SAMP8 mice to SAMR1 control values after treatment with both KL isoforms. This work presents evidence of the beneficial pleiotropic role of Klotho as an anti-aging therapy as well as new specific functions of the KL isoforms for the epigenetic regulation and aged bone structure alteration in an aging mouse model. Intraventricular administration of AAV vectors expressing secreted and transmembrane Klotho isoforms, rescued accelerated aging phenotype of SAMP8 mice. An improvement in cognitive and physical performance, recovery of epigenetic, inflammatory and senescence markers, as well as structural changes in long bones of these mice was detected

AAV-mediated expression of secreted and transmembrane αKlotho isoforms rescues relevant aging hallmarks in senescent SAMP8 mice

Senescence represents a stage in life associated with elevated incidence of morbidity and increased risk of mortality due to the accumulation of molecular alterations and tissue dysfunction, promoting a decrease in the organism's protective systems. Thus, aging presents molecular and biological hallmarks, which include chronic inflammation, epigenetic alterations, neuronal dysfunction, and worsening of physical status. In this context, we explored the AAV9-mediated expression of the two main isoforms of the aging-protective factor Klotho (KL) as a strategy to prevent these general age-related features using the senescence-accelerated mouse prone 8 (SAMP8) model. Both secreted and transmembrane KL isoforms improved cognitive performance, physical state parameters, and different molecular variables associated with aging. Epigenetic landscape was recovered for the analyzed global markers DNA methylation (5-mC), hydroxymethylation (5-hmC), and restoration occurred in the acetylation levels of H3 and H4. Gene expression of pro- and anti-inflammatory mediators in central nervous system such as TNF-α and IL-10, respectively, had improved levels, which were comparable to the senescence-accelerated-mouse resistant 1 (SAMR1) healthy control. Additionally, this improvement in neuroinflammation was supported by changes in the histological markers Iba1, GFAP, and SA β-gal. Furthermore, bone tissue structural variables, especially altered during senescence, recovered in SAMP8 mice to SAMR1 control values after treatment with both KL isoforms. This work presents evidence of the beneficial pleiotropic role of Klotho as an anti-aging therapy as well as new specific functions of the KL isoforms for the epigenetic regulation and aged bone structure alteration in an aging mouse model

Characterizing active faults and associated mass transport deposits in the South Iberian Margin (Alboran Sean and Gulf of Cadiz): on-fault and off-fault paleoseismic evidence

During the last years we have carried out successive high-resolution marine geological and geophysical surveys to investigate the seismic potential of the slow-moving seismogenic faults from the South Iberian Margin. Based on ,ultiscale acoustic mapping, sub-seafloor seismic imaging and dating methods we have characterized submarine fault systems with unprecedented resolution. We present primary paleoseismic evidence obtained by direct investigations of selected faults from theMediterranean Sea (i.e. Carboneras Fault, Bajo Segura Fault, Adra Fault) and the external part of the Gulf of Cadiz (i.e. Marques de Pombal Fault, Horseshoe Fault, Coral Patch Ridge Fault and SWIM lineaments). The obtained fault seismic parameters suggest that these faults are active and capable of generating large magnitude (Mw > 6) seismic events, representing an earthquake and tsunami hazard for the surrounding coastal areas. Secondary paleoseismic evidence in the SW Iberian Margin (based on landslides and turbidite deposits) yields a regional recurrence rate of large magnitude earthquake of 1800 - 2000 years

First evidence of paleoearthquakes along the Carboneras Fault Zone (SE Iberian Peninsula): Los Trances site

Seismogenic faults that have not produced historical large earthquakes remain unnoticed and, thus, are dangerously left out from seismic hazard analyses. The seismogenic nature of the Carboneras Fault Zone, a left-lateral strikeslip fault in the Eastern Betic Shear Zone (southeastern Spain), has not been fully explored to date in spite of having a morphological expression equivalent to the Alhama de Murcia Fault, a seismogenic fault in the same tectonic system. This study provides the first paleoseismic evidence of the seismogenic nature of the Carboneras Fault Zone, based on the analysis of 3 trenches at Los Trances site, on the northwestern edge of the La Serrata Range. Cross cutting relationships and numerical dating, based on radiocarbon, thermoluminescence and U-series, reveal a minimum of 4 paleoearthquakes: Paleoearthquake1 (the oldest) and Paleoearthquake2 took place after 133ka, Paleoearthquake3 occurred between 83-73ka and Paleoearthquake4 happened after 42.5ka (probably after 30.8ka), resulting in a maximum possible average recurrence of 33ka. This value, based on a minimum amount of paleoearthquakes, is probably overestimated, as it does not scale well with published slip-rates derived from offset channels or GPS geodetical data. The characterization of this fault as seismogenic, implies that it should be considered in the seismic hazard analyses of the SE Iberian Peninsula