Crustal structure and subduction erosion in the central Costa Rica subduction zone

On the Pacific margin off central Costa Rica, an anomalous lens-shaped zone is located between the overriding plate and the subducting oceanic lithosphere approximately 25 km landward of the deformation front. This feature was previously recognized in reflection seismic data when it was termed ‘megalens’. Its origin and seismic velocity structure, however, could not unambiguously be derived from earlier studies. Therefore during RV SONNE cruise SO163 in 2002, seismic wide-angle data were acquired using closely spaced ocean bottom hydrophones and seismometers along two parallel strike lines and two parallel dip lines above the ‘megalens’, intersecting on the middle slope. In this study, the P-wave velocities and structure of the subducting oceanic Cocos Plate and overriding Caribbean Plate are determined from modeling of the wide-angle seismic data of cruise SO163. In addition, coincident reflection seismic data are analyzed and incorporated into the forward modeling and tomographic inversion of the refraction data. Based on the results of the velocity modeling, synthetic seismograms are calculated for an amplitude analysis of the refraction data to determine seismic attenuation variations across the seaward extent of the margin. The margin wedge is defined by high seismic velocities (4.3-6.1 km/s) identified within a wedge-shaped body covered by a slope sediment drape. It is divided into two layers with different velocity gradients. Seismic velocities of the upper margin wedge vary from 4.0 to 4.3 km/s near the trench to 4.0-5.1 km/s close to the shoreline. The lower margin wedge is clearly constrained by decreasing velocities towards the trench and terminates beneath the middle slope at the location of the ‘megalens’. Seismic velocities of the ‘megalens’ are lower (3.8-4.3 km/s) relative to the margin wedge, implying that the ‘megalens’ represents hybrid material composed of subducted sediment and eroded fragments from the base of the upper plate. Upward-migrating overpressured fluids weaken the base of the margin wedge through hydrofracturing, V thus causing material transfer from the upper plate to the lower plate. Results from amplitude modeling confirm that the ‘megalens’ observed off central Costa Rica is bound by a low velocity zone documenting fluid drainage from the plate boundary to the upper plate. Seismic attenuation of the central Costa Rica margin wedge is determined from amplitude analysis of the wide-angle seismic data. Travel time and amplitude modeling is applied to ocean bottom hydrophones along two trench-parallel profiles, located 30 km (P21&P22) and 35 km (P18) landward of the deformation front northeast of Quepos Plateau. Tomographic inversion images a progressively thinning margin wedge from the coast to the lower slope at the trench. A 1-1.5 km thick décollement zone with seismic velocities of 3.5-4.5 km/s is sandwiched between the margin wedge basement and the subducting Cocos plate. For strike line P21, amplitude modeling indicates a Qp value of 50-150 for the upper margin wedge with velocities of 3.9-4.9 km/s. Along strike line P18, Qp values of 50-150 are determined with velocities of 4.3-5.0 km/s in the upper margin wedge, increasing to 5.1-5.4 km/s in the lower margin wedge. Quantitative amplitude decay curves support the observed upper plate Qp. In conjunction with earlier results from offshore Nicoya Peninsula, our study documents laterally landward decreasing attenuation across the margin wedge, consistent with a change in lithology from the sediment-dominated frontal prism to the igneous composition of the forearc middle prism

Krustenstruktur und Subduktionserosion der Subduktionszone vor Costa Rica

On the Pacific margin off central Costa Rica, an anomalous lens-shaped zone is located between the overriding plate and the subducting oceanic lithosphere approximately 25 km landward of the deformation front. This feature was previously recognized in reflection seismic data when it was termed ‘megalens’. Its origin and seismic velocity structure, however, could not unambiguously be derived from earlier studies. Therefore during RV SONNE cruise SO163 in 2002, seismic wide-angle data were acquired using closely spaced ocean bottom hydrophones and seismometers along two parallel strike lines and two parallel dip lines above the ‘megalens’, intersecting on the middle slope. In this study, the P-wave velocities and structure of the subducting oceanic Cocos Plate and overriding Caribbean Plate are determined from modeling of the wide-angle seismic data of cruise SO163. In addition, coincident reflection seismic data are analyzed and incorporated into the forward modeling and tomographic inversion of the refraction data. Based on the results of the velocity modeling, synthetic seismograms are calculated for an amplitude analysis of the refraction data to determine seismic attenuation variations across the seaward extent of the margin. The margin wedge is defined by high seismic velocities (4.3-6.1 km/s) identified within a wedge-shaped body covered by a slope sediment drape. It is divided into two layers with different velocity gradients. Seismic velocities of the upper margin wedge vary from 4.0 to 4.3 km/s near the trench to 4.0-5.1 km/s close to the shoreline. The lower margin wedge is clearly constrained by decreasing velocities towards the trench and terminates beneath the middle slope at the location of the ‘megalens’. Seismic velocities of the ‘megalens’ are lower (3.8-4.3 km/s) relative to the margin wedge, implying that the ‘megalens’ represents hybrid material composed of subducted sediment and eroded fragments from the base of the upper plate. Upward-migrating overpressured fluids weaken the base of the margin wedge through hydrofracturing, V thus causing material transfer from the upper plate to the lower plate. Results from amplitude modeling confirm that the ‘megalens’ observed off central Costa Rica is bound by a low velocity zone documenting fluid drainage from the plate boundary to the upper plate. Seismic attenuation of the central Costa Rica margin wedge is determined from amplitude analysis of the wide-angle seismic data. Travel time and amplitude modeling is applied to ocean bottom hydrophones along two trench-parallel profiles, located 30 km (P21&P22) and 35 km (P18) landward of the deformation front northeast of Quepos Plateau. Tomographic inversion images a progressively thinning margin wedge from the coast to the lower slope at the trench. A 1-1.5 km thick décollement zone with seismic velocities of 3.5-4.5 km/s is sandwiched between the margin wedge basement and the subducting Cocos plate. For strike line P21, amplitude modeling indicates a Qp value of 50-150 for the upper margin wedge with velocities of 3.9-4.9 km/s. Along strike line P18, Qp values of 50-150 are determined with velocities of 4.3-5.0 km/s in the upper margin wedge, increasing to 5.1-5.4 km/s in the lower margin wedge. Quantitative amplitude decay curves support the observed upper plate Qp. In conjunction with earlier results from offshore Nicoya Peninsula, our study documents laterally landward decreasing attenuation across the margin wedge, consistent with a change in lithology from the sediment-dominated frontal prism to the igneous composition of the forearc middle prism.Am pazifischen Kontinentalrand vor zentralen Costa Rica, etwa 25 km landwärts der Deformationsfront, befindet sich eine linsenförmige Struktur zwischen der abtauchenden und der überfahrenden Platte. Diese als "Megalinse" bezeichnete Struktur wurde zunächst Ende der neunziger Jahre des letzten Jahrhunderts in seismischen Reflexionsdaten identifiziert; ihr Ursprung und ihre seismische Geschwindigkeitsstruktur sind jedoch nach wie vor unklar. Im Rahmen der FS SONNE Fahrt SO163 im Jahr 2002 wurden daher vier weitwinkelseismische Kreuzungsprofile im Bereich der "Megalinse" abgeschossen. Die Geschwindigkeitsmodellierung der aufgenommenen Ozeanbodenhydrophon- und Ozeanbodenseismometerdaten ergibt, unter Einbeziehung der Reflexionsdaten, die detaillierte P-Wellen Geschwindigkeitsstruktur der abtauchenden Cocos Platte und der überfahrenden Karibischen Platte. Aufbauend auf den Ergebnissen der Geschwindigkeitsmodellierung wurden im Rahmen einer Amplitudenanlyse synthetische Seismogramme erstellt, welche die räumliche Variation der seismischen Dämpfungsparameter im seewärtigen Teil der Oberplatte dokumentieren. Der marine Bereich des Kontinenthangs weist hohe seismische Geschwindigkeiten auf (Vp=4.3- 6.1 km/s) und besteht aus einer keilförmigen Struktur, überdeckt von einer dünnen Schicht Hangsedimente. Er ist unterteilt in einen oberen und unteren Bereich mit jeweils unterschiedlichen Geschwindigkeitsgradienten. Der untere Bereich des Forearc-Keils ist gekennzeichnet durch landwärts zunehmende Geschwindigkeiten und endet mit dem Auftreten der "Megalinse". Die "Megalinse" ist eine Inversionsstruktur mit Geschwindigkeiten von 3.8-4.3 km/s, die als eine Ansammlung von subduzierten Sedimenten und erodiertem Material von der Unterkante der Oberplatte interpretiert wird. Durch Entwässerungsprozesse in den subduzierten Sedimenten freigesetzte und aufwärts migrierende Fluide, unter hohen Drücken stehend, führen zur Erosion darüberliegender Gesteinsschichten und damit zum Materialtransfer von der Ober- zur Unterplatte. Die Ergebnisse der Amplitudenmodellierung zeigen, dass die "Megalinse" von einer Niedriggeschwindigkeitsschicht umgeben ist, was auf entsprechende Entwässeerungsvorgänge entlang der Plattengrenze hindeutet. VII In dieser Arbeit wird die seismische Attenuation (Qp) des unteren Kontinentalhanges vor Costa Rica aus der Amplitudenanalyse zweier parallel zum Tiefseegraben verlaufender weitwinkelseismischer Profile abgeleitet. Für jeweils ein 30 km (P21&P22) und ein 35 km (P18) landwärts der Deformationsfront verlaufendes Profil werden Laufzeit- und Amplitudenmodellierungen vorgestellt. Die tomographischen Modelle bestätigen die sukzessive Ausdünnung der Oberplatte von der Küste zum Tiefseegraben. Die "Megalinse" wird dabei als ein 1-1.5 km mächtiger Bereich des Décollements zwischen Ober- und Unterplatte mit seismischen Geschwindigkeiten von 3.4-4.5 km/s abgebildet. Der obere Kontinenthang ist auf Profil 21 durch Geschwindigkeiten von 3.9-4.9 km/s und Qp Werte von 50-150 gekennzeichnet. Für Profil 18 ergeben sich entsprechende Geschwindigkeitswerte von 4.3-5.0 km/s und Qp Werte von 50-150 sowie Geschwindigkeiten von 5.1-5.4 km/s für den tieferen Bereich des Kontinentrands. Die ermittelten Qp-Werte auf beiden Profilen stehen im Einklang mit quantitativen Amplitudenverlaufskurven. Unter Berücksichtigung früherer Arbeiten vor der Nicoya Halbinsel bestätigen die Ergebnisse eine landwärtige Zunahme der seismischen Attenuation und damit den lithologischen Wechsel vom überwiegend sedimentären frontalen Prisma zum krustalen Bereich des mittleren Forearcs

Margin architecture and seismic attenuation in the central Costa Rican forearc

Seismic attenuation across the central Costa Rican margin wedge is determined fromamplitude analysis ofwideangle seismic data. Travel time and amplitude modeling are applied to ocean bottom hydrophones along two trench-parallel profiles, located 30 km (P21) and 35 km (P18) landward of the deformation front northeast of Quepos Plateau. Tomographic inversion images a progressively thinning margin wedge from the coast to the lower slope at the trench. A 1–1.5 km thick décollement zone with seismic velocities of 3.5–4.5 km/s is sandwiched between the marginwedge and the subducting Cocos plate. For strike line P21, amplitude modeling indicates a Qp value of 50–150 for the upper margin wedge with seismic velocities ranging from 3.9 km/s to 4.9 km/s. Along strike line P18, Qp values of 50–150 are determined with velocities of 4.3–5.0 km/s in the upper margin wedge, increasing to 5.1–5.4 km/s in the lower margin wedge. Quantitative amplitude decay curves support the observed upper plate Qp values. In conjunction with earlier results from offshore Nicoya Peninsula, our study documents landward decreasing attenuation across the margin wedge, consistent with a change in lithology from the sediment-dominated frontal prism to the igneous composition of the forearc middle pris

Facile one-pot synthesis of Pt nanoparticles/SBA-15: an active and stable material for catalytic applications

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Pt/SBA-15 with an enhanced surface area but unchanged pore diameter (compared to pure SBA-15) and a Pt average particle size of ∼9 nm shows a high and stable activity for both gas-phase CO oxidation and liquid-phase cyclooctadiene hydrogenation. No intrinsic change in the structure of the catalyst occurs after several reaction cycles, suggesting that the Pt/SBA-15 presented here is an active and stable catalyst.DFG, EXC 314, Unifying Concepts in Catalysi

Two-step synthesis of Fe2O3 and Co3O4 nanoparticles: towards a general method for synthesizing nanocrystalline metal oxides with high surface area and thermal stability

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.A simple, two-step method using activated carbon (AC) as a support/scaffold was developed to synthesize metal oxide nanocrystalline materials (NCMs). In the first step, metal nitrate precursors were deposited by wet impregnation onto the AC, then heated in argon at 350 °C to immobilize the metal oxides. In the second step, the AC was removed by calcination in air at 500 °C, to obtain the unsupported metal oxide NCMs. Characterization by N2-sorption isotherms, TGA, XPS and EXAFS reveals that the metal oxide particles are crystalline and nanometre-sized, with surface areas up to 148 m2 g−1. Moreover, the TEM images show particle sizes in the range 5–10 nm, even after calcination at 500 °C for 2 h. Their thermal stability and high surface areas, together with the nanometre-sized structures, make them promising materials for catalytic applications (e.g., CO oxidation).DFG, EXC 314, Unifying Concepts in Catalysi

Efficiency of improved RAPD and ISSR markers in assessing genetic diversity and relationships in Angelica sinensis (Oliv.) Diels varieties of China

Background: Angelica sinensis is awell-known traditional Chinesemedicinal plant.Weaimed to assess the genetic diversity and relationships in A. sinensis cultivars collected from different locations of China and also some other Angelica species. Results: We employed an improved random amplified polymorphic DNA (RAPD) technique for the amplification of DNAmaterials fromten Angelica cultivars, and the resultswere verified by inter-simple sequence repeat (ISSR) analysis. Twenty six RAPD primers were used for RAPD, and the amplified bands were found highly polymorphic (96%). Each primer amplified 8\u201314 bands with an average of 10.25. The cluster dendrogram showed that the similarity coefficients ranged from 0.41 to 0.92. The similarity coefficients were higher among different cultivars of A. sinensis, and lower among different species. Twenty ISSR primers were used for the amplification, and each primer generated 6\u201310 bands with an average of 7.2 bands per primer. The cluster dendrogram showed that the similarity coefficients ranged from 0.35 to 0.89. Conclusions: This study genetically characterized the Angelica species,whichmight have a significant contribution to the genetic and ecological conservation of this important medicinal plant. Also, this study indicates that the improved RAPD and ISSR analyses are important and potent molecular tools for the study of genetic diversity and authentication of organisms

Tripartite motif containing 28 (TRIM28) promotes breast cancer metastasis by stabilizing TWIST1 protein.

TRIM28 regulates its target genes at both transcriptional and posttranscriptional levels. Here we report that a TRIM28-TWIST1-EMT axis exists in breast cancer cells and TRIM28 promotes breast cancer metastasis by stabilizing TWIST1 and subsequently enhancing EMT. We find that TRIM28 is highly expressed in both cancer cell lines and advanced breast cancer tissues, and the levels of TRIM28 and TWIST1 are positively correlated with the aggressiveness of breast carcinomas. Overexpression and depletion of TRIM28 up- and down-regulates the protein, but not the mRNA levels of TWIST1, respectively, suggesting that TRIM28 upregulates TWIST1 post-transcriptionally. Overexpression of TRIM28 in breast cancer cell line promotes cell migration and invasion. Knockdown of TRIM28 reduces the protein level of TWIST1 with concurrent upregulation of E-cadherin and downregulation of N-cadherin and consequently inhibits cell migration and invasion. Furthermore, Immunoprecipitation and GST pull-down assays demonstrated that TRIM28 interacts with TWIST1 directly and this interaction is presumed to protect TWIST1 from degradation. Our study revealed a novel mechanism in breast cancer cells that TRIM28 enhances metastasis by stabilizing TWIST1, suggesting that targeting TRIM28 could be an efficacious strategy in breast cancer treatment

IODP Expedition 334: An Investigation of the Sedimentary Record, Fluid Flow and State of Stress on Top of the Seismogenic Zone of an Erosive Subduction Margin

The Costa Rica Seismogenesis Project (CRISP) is an experiment to understand the processes that control nucleation and seismic rupture of large earthquakes at erosional subduction zones. Integrated Ocean Drililng Program (IODP) Expedition 334 by R/V JOIDES Resolution is the first step toward deep drilling through the aseismic and seismic plate boundary at the Costa Rica subduction zone offshore the Osa Peninsula where the Cocos Ridge is subducting beneath the Caribbean plate. Drilling operations included logging while drilling (LWD) at two slope sites (Sites U1378 and U1379) and coring at three slope sites (Sites U1378–1380) and at one site on the Cocos plate (Site U1381). For the first time the lithology, stratigraphy, and age of the slope and incoming sediments as well as the petrology of the subducting Cocos Ridge have been characterized at this margin. The slope sites recorded a high sediment accumulation rate of 160–1035m m.y.-1 possibly caused by on-land uplift triggered by the subduction of the Cocos Ridge. The geochemical data as well as the in situ temperature data obtained at the slope sites suggest that fluids are transported from greater depths. The geochemical profiles at Site U1381 reflect diffusional communication of a fluid with seawater-like chemistry and the igneous basement of the Cocos plate (Solomon et al., 2011; Vannucchi et al., 2012a). The present-day in situ stress orientation determined by borehole breakouts at Site U1378 in the middle slope and Site U1379 in the upper slope shows a marked change in stress state within ~12 km along the CRISP transect; that may correspond to a change from compression (middle slope) to extension (upper slope)

IODP expedition 334: An investigation of the sedimentary record, fluid flow and state of stress on top of the seismogenic zone of an erosive subduction margin

金沢大学理工研究域地球社会基盤学

Editorial to the Special Issue “Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry”

The Special Issue on “Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry” encompasses two aims: one is to remove the pollutants produced in the downstream, and the other is to synthesize chemicals by a green route, avoiding the production of pollutants [...