Delimiting the eastern extent of the Altyn Tagh Fault: Insights from structural analyses of seismic reflection profiles     

Yuqing Zhang  Fengqi Zhang  Xiaogan Cheng  Xiubin Lin  Hanlin Chen  Karl‐Heinz Wyrwoll  Lei Wu  Jie Chen  Bryan Krape  Yanchou Lu  Weiwei Ding  Kaixuan An  Yaguang Chen  Chunyang Li 《地学学报》2021,33(1):1-11

The Altyn Tagh Fault (ATF) serves as a key continental‐scale controlling structural element of the Tibetan Plateau. However, its eastward extent remains controversial. Here we use high‐resolution seismic reflection profiles to investigate the subsurface structures of the easternmost ATF and use these to delimit the easternmost extent of the fault. The structural analyses show an eastward geometric change from transpressional positive flower structures to compressional thrusts, with transpression‐induced shortening magnitudes decreasing eastwards from a maximum of ~5.3 km to being absent. Stratigraphic controls indicate that the deformation took place over the last ~<1.2 Ma. Our wider findings lead us to: (a) reject the suggestion that the ATF previously extended beyond the Kuantan Shan‐Hei Shan to link with the Alxa‐East Mongolia Fault; and (b) propose that the rigid block model used to describe the Tibetan Plateau crust is not consistent with the extent and structural details of the easternmost ATF.  相似文献   

Anisotropy of magnetic susceptibility studies in Tertiary ridge-parallel dykes (Iceland), Tertiary margin-normal Aishihik dykes (Yukon), and Proterozoic Kenora–Kabetogama composite dykes (Minnesota and Ontario)     

John P. Craddock  Bryan C. Kennedy  Avery L. Cook  Melissa S. Pawlisch  Stephen T. Johnston  Mike Jackson 《Tectonophysics》2008,448(1-4):115-124

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Computing the steady oceanic circulation using an optimization approach     

Eli Tziperman  William Carlisle Thacker  Kirk Bryan 《Dynamics of Atmospheres and Oceans》1992,16(5)

The traditional method for computing the steady oceanic circulation has been by stepping an oceanic model forward in time until transients are damped by friction. An alternative method, which has the potential for being more economical is to minimize the sum of the squares of the residuals of the steady model equations. A variety of algorithms might be considered for computing the minimum; attention here is focused on preconditioned conjugate-gradient descent with the gradient computed using an adjoint model. The choice of varibles, i.e. the preconditioning transformation used in the optimization process, is found to be critical to the efficiency of the method. An appropriate preconditioning transformation can be suggested by a heuristic analysis similar to that commonly used to test the stability of numerical models. The method is demonstrated within the context of the barotropic vorticity equation.  相似文献   

Hydrothermal spinel,corundum and diaspore in lower oceanic crustal troctolites from the Hess Deep Rift     

Toshio Nozaka  Romain Meyer  Robert P. Wintsch  Bryan Wathen 《Contributions to Mineralogy and Petrology》2016,171(6):53

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Dynamical theory driven observational analysis of ENSO modes in the equatorial Pacific     

Bryan C. Weare 《Climate Dynamics》2016,47(5-6):1515-1526

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A Spatial Data Infrastructure Approach for the Characterization of New Zealand's Groundwater Systems   总被引：1，自引：0，他引：1       下载免费PDF全文

Alexander Kmoch  Hermann Klug  Alistair B. H. Ritchie  Jochen Schmidt  Paul A. White 《Transactions in GIS》2016,20(4):626-641

The future information needs of stakeholders for hydrogeological and hydro‐climate data management and assessment in New Zealand may be met with an Open Geospatial Consortium (OGC) standards‐compliant publicly accessible web services framework which aims to provide integrated use of groundwater information and environmental observation data in general. The stages of the framework development described in this article are search and discovery as well as data collection and access with (meta)data services, which are developed in a community process. The concept and prototype implementation of OGC‐compliant web services for groundwater and hydro‐climate data include demonstration data services that present multiple distributed datasets of environmental observations. The results also iterate over the stakeholder community process and the refined profile of OGC services for environmental observation data sharing within the New Zealand Spatial Data Infrastructure (SDI) landscape, including datasets from the National Groundwater Monitoring Program and the New Zealand Climate Database along with datasets from affiliated regional councils at regional‐ and sub‐regional scales. With the definition of the New Zealand observation data profile we show that current state‐of‐the‐art standards do not necessarily need to be improved, but that the community has to agree upon how to use these standards in an iterative process.  相似文献   

Energy dispersive X-ray analysis of the surface of a deep-sea ferromanganese nodule     

Bryan R. Burnett  Kenneth H. Nealson 《Marine Geology》1983,53(4):313-329

In an effort to elucidate the mechanism of formation and accretion of ferromanganese nodules, transverse sections of undisturbed botryoid surfaces of nodules from the abyssal central North Pacific were examined by X-ray analyses both by multiple replicate sample transects and mapping. Surface concentrations of Mn and Fe were found of the size and shape of microorganisms. Abundant microorganism-like objects covering the surface and the apparent absence of Si (i.e. no sediment) with the Mn and Fe concentrations suggests microorganisms may be involved either in the selective accretion or removal of these metals. If metal accretion was simply physicochemical, one would expect a more or less even distribution of Mn and Fe on the botryoid surfaces.The replicate X-ray sample transects showed that Mn and Fe have a distribution corresponding to botryoid zonation. Areas of high Mn X-ray intensity were found associated with the cap and equatorial zones of the botryoid. Most of the valley zone of the botryoid show a more or less even Mn distribution and an increase in Fe X-ray intensity. At the base of the botryoid both metals apparently precipitously decrease.  相似文献   

LOCHNESS--a new multi-net midwater sampler     

Dunn  J.; Mitchell  R. B.; Urquhart  G. G.; Ritchie  B. J. 《ICES Journal of Marine Science》1993,50(2):203-212

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Model Simulations of Carbon Sequestration in the Northwest Pacific by Direct Injection     

Katsumi?MatsumotoEmail author  Bryan?K.?Mignone 《Journal of Oceanography》2005,61(4):747-760

The direct disposal of CO₂ into the ocean interior represents a possible means to help mitigate rising levels of atmospheric CO₂. Here, we use three different versions of an ocean general circulation model (OGCM) to simulate the direct injection of liquid CO₂ near Tokyo. Our results confirm that direct injection can sequester large amounts of CO₂ from the atmosphere when disposal is made at sufficient depth (80–100% of the carbon injected at 3000 m remains in the ocean after 500 years) but show that the calculated efficiency is rather sensitive to the choice of physical model. Moreover, we show, for the first time in an OGCM and under a reasonable set of economic assumptions, that sequestration effectiveness is quite high for even shallow injections. However, the severe acidification that accompanies injection and the impossibility of effectively monitoring injected plumes argue against the large-scale viability of this technology. Our coarse-grid models show that injection at the rate of 0.1 Pg-C/yr lowers pH near the site of injection by as much as 0.7–1.0 pH-unit. Such pH anomalies would be much larger in more finely gridded models (and in reality) and have potential to severely harm deep-sea organisms. We also show that, after several hundred years, one would effectively need to survey the entire ocean in order to accurately verify the inventory of injected carbon. These results suggest that while retention may be sufficient to justify disposal costs, other practical problems will limit or at best delay widespread deployment of this technology.  相似文献   

Chandra smells a RRAT     

Bryan M. Gaensler  Maura McLaughlin  Stephen Reynolds  Kazik Borkowski  Nanda Rea  Andrea Possenti  Gianluca Israel  Marta Burgay  Fernando Camilo  Shami Chatterjee  Michael Kramer  Andrew Lyne  Ingrid Stairs 《Astrophysics and Space Science》2007,308(1-4):95-99

“Rotating RAdio Transients” (RRATs) are a newly discovered astronomical phenomenon, characterised by occasional brief radio bursts, with average intervals between bursts ranging from minutes to hours. The burst spacings allow identification of periodicities, which fall in the range 0.4 to 7 seconds. The RRATs thus seem to be rotating neutron stars, albeit with properties very different from the rest of the population. We here present the serendipitous detection with the Chandra X-ray Observatory of a bright point-like X-ray source coincident with one of the RRATs. We discuss the temporal and spectral properties of this X-ray emission, consider counterparts in other wavebands, and interpret these results in the context of possible explanations for the RRAT population. B.M.G. acknowledges the support of NASA through LTSA grant NAG5-13023 and of an Alfred P. Sloan Fellowship.  相似文献