A study of the temporal changes recorded by ERTS and their geological significance

The temporal changes that are recorded by ERTS were evaluated for an area around Bathurst Inlet in the North West Territories. The seasons represented by the images included: early winter, spring, early summer, summer, and fall. Numerous surface characteristics (vegetation, drainage patterns, surface texture, lineament systems and topographic relief, etc.) were used to relate the change in observable features with the different seasons. It was found that the time of year when an observation is made has a strong control over the amount and type of information that can be derived by an experienced interpreter. It was concluded that a detailed study of temporal changes is an important part of any ERTS interpretation for geology

5D Black Rings and 4D Black Holes

It has recently been shown that the M theory lift of a IIA 4D BPS Calabi-Yau black hole is a 5D BPS black hole spinning at the center of a Taub-NUT-flux geometries, and a certain linear relation between 4D and 5D BPS partition functions was accordingly proposed. In the present work we fortify and enrich this proposal by showing that the M-theory lift of the general 4D multi-black hole geometry are 5D black rings in a Taub-NUT-flux geometry.Comment: 8 pages; version 2, with additional references and explanation

IODP Expedition 338: NanTroSEIZE stage 3: NanTroSEIZE plate boundary deep riser 2

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is designed to investigate fault mechanics and seismogenesis along a subduction megathrust, with objectives that include characterizing fault slip, strain accumulation, fault and wall rock composition, fault architecture, and state variables throughout an active plate boundary system. Integrated Ocean Drilling Program (IODP) Expedition 338 was planned to extend and case riser Hole C0002F from 856 to 3600 meters below the seafloor (m b.s.f.). Riser operations extended the hole to 2005.5mb.s.f., collecting logging-while-drilling (LWD) and measurement-while-drilling, mud gas, and cuttings data. Results reveal two lithologic units within the inner wedge of the accretionary prism that are separated by a prominent fault zone at ¿ 1640mb.s.f. Due to damage to the riser during unfavorable winds and strong currents, riser operations were suspended, and Hole C0002F left for re-entry during future riser drilling operations. Contingency riserless operations included coring at the forearc basin site (C0002) and at two slope basin sites (C0021 and C0022), and LWD at one input site (C0012) and at three slope basin sites (C0018, C0021 and C0022). Cores and logs from these sites comprehensively characterize the alteration stage of the oceanic basement input to the subduction zone, the early stage of Kumano Basin evolution, gas hydrates in the forearc basin, and recent activity of the shallow megasplay fault zone system and associated submarine landslides. © Author(s) 2014.Peer Reviewe

Deformation of the Nankai Trough inner accretionary prism: The role of inherited structures

Accretionary prisms commonly grow seaward, with the strata of the inner prism consisting of older, previously accreted outer prism rocks overlain by thick fore-arc basin strata. We focus on the Nankai Trough inner accretionary prism using three-dimensional (3-D) seismic data and logging data from the Integrated Ocean Drilling Program (IODP). We update the 3-D seismic volume using well velocity data to better constrain deeper horizons. Interpretation of these horizons reveals multiple folds with axial surfaces that strike near parallel to modern outer prism thrust faults, and we interpret that these folds formed as a result of thrust faulting. Reactivation of one inner prism thrust fault continued until at least ∼0.44 Ma, after the modern fore-arc basin formed, indicating that the inner prism had continued deformation until that time. Structural restorations of these folded seismic horizons demonstrate that ∼580 m of slip occurred on this steeply dipping reactivated thrust after fore-arc basin formation. Structural interpretation and analysis of logging-while-drilling data, including borehole images, in the deep inner prism revealed intense deformation of a generally homogenous lithology characterized by bedding that dips steeply (60°–90°), intersected by faults and fractures that have a range of dips and densities. Our study of the deep Kumano Basin provides new insights into the structure of the inner prism and reveals that although the inner prism has partially preserved inherited outer prism structures, these older folds and faults are steeply rotated and cut by multiple fracture populations during subsequent deformation.Funding for this research was provided by the National Science Foundation (grant OCE-0451790) and a U.S. Science Support Program Post-Expedition Award.Peer reviewe

Shallow fault systems of thrust anticlines responding to changes in accretionary prism lithology (Nankai, SE Japan)

Three-dimensional (3D) pre-stack depth migrated seismic data are used to analyse the geometry and growth of shallow faults associated with tectonic shortening in four (4) prominent thrust anticlines off Nankai, SE Japan. The four thrust anticlines show a trenchward increase in horizontal shortening and deform the seafloor at present. They shortened the overburden strata by 7143 m in the Late Quaternary, reflecting a horizontal shortening of 32.9% in response to plate subduction. A significant number of closely spaced and segmented fault arrays is observed in their hinge regions. Vertically segmented fault arrays with local throw maxima between 5 and 14 m relate to the existence of more competent (strong) intervals, or layers. Incompetent (weak) intervals record relatively small throw values between 2 and 5 m. We show that the presence of closely spaced, segmented fault arrays at shallow stratigraphic levels can have a significant impact on local stress distribution, controlling near-seafloor strain in accretionary prisms as Nankai's. The observed mechanical layering is likely to continue at depth to control the accumulation of tectonic stress in faults posed to reactivate during seismic events

Distribution of gas hydrates on continental margins by means of a mathematical envelope: A method applied to the interpretation of 3D Seismic Data

A 3D seismic volume from the Nankai Trough accretionary wedge (SE Japan) is used to evaluate the subsurface distribution of gas hydrates as a function of structural and stratigraphic complexity, variable heat flow patterns and the presence of subsurface fluid conduits. Eleven equations were modified for depth, pressure, and temperature, modeled in 3D, and compared with the distribution of Bottom- Simulating Reflections (BSRs) offshore Nankai. The results show that the equations produce overlapping—and thus potentially consistent—predictions for the distribution of BSRs, leading us to propose the concept of a ‘‘BSR Stability Envelope’’ as a method to quantify the subsurface distribution of gas hydrates on continental margins. In addition, we show that the ratio (R) between shallow and deep BSRs of seven subenvelopes, which are defined by BSR stability equations, indicates local gas hydrate equilibrium conditions. Values of R1 the majority of BSRs are located in warmer structural traps. The method in this paper can be used to recognize any divergence between observed and theoretical depths of occurrence of BSRs on 3D or 4D (time lapse) seismic volumes. In the Nankai Trough, our results point out for equilibrium conditions in BSRs located away from the Megasplay Fault Zone and major thrust faults. This latter observation demonstrates the applicability of the method to: (a) the recognition of subsurface fluid conduits and (b) the prediction of maximum and minimum depths of occurrence of gas hydrates on continental margins, under distinct thermal and hydrologic conditions

Strain decoupling reveals variable seismogenic risk in SE Japan (Nankai Trough)

The determination of in situ stress states is vital in understanding the behavior of faults and subsequent seismogenesis of accretionary prisms. In this paper, a high quality 3D seismic volume is used to map the depth of the extensional-compressional decoupling (ECD) boundary in the accretionary prism of Nankai, with the prior knowledge that strike-slip and compressional stresses occur deeper than 1250 meters below seafloor (mbsf) in the Kumano Basin, changing to extension towards the seafloor. A total of 1108 faults from the accretionary prism are analyzed to estimate paleostresses via fault inversion and slip tendency techniques. A key result is this paper is that the ECD boundary can be used as a proxy to identify active structures on accretionary prisms as its depth depends on: a) local tectonic uplift in areas adjacent to active faults, and b) on the thickness of sediment accumulated above active thrust anticlines. The depth of the ECD boundary ranges from 0 to ∼650 mbsf, being notably shallower than in the Kumano Basin. In Nankai, frontal regions of the imbricate thrust zone, and the megasplay fault zone, reveal the shallower ECD depths and correlate with the regions where faulting is most active. As a corollary, this work confirms that estimates of stress state variability based on the analysis of 3D seismic data are vital to understand the behavior of faults and potential seismogenic regions on convergent margins. This article is protected by copyright. All rights reserved

I-Brane Inflow and Anomalous Couplings on D-Branes

We show that the anomalous couplings of $D$-brane gauge and gravitational fields to Ramond-Ramond tensor potentials can be deduced by a simple anomaly inflow argument applied to intersecting $D$-branes and use this to determine the eight-form gravitational coupling.Comment: 8 pages, harvmac, no figure