Intensity of Magnetization of Subaerial and Submarine Basalts and its Possible Change with Time     

Michel Prévot  Sherman Grommé 《Geophysical Journal International》1975,40(2):207-224

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Informed selection of future climates     

Channing Arndt  Charles Fant  Sherman Robinson  Kenneth Strzepek 《Climatic change》2015,131(1):21-33

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Sea-level and reef accretion history of Marine Oxygen Isotope Stage 7 and late Stage 5 based on age and facies of submerged late Pleistocene reefs,Oahu, Hawaii     

Clark E. Sherman  Charles H. Fletcher  Ken H. Rubin  Kathleen R. Simmons  Walter H. Adey 《Quaternary Research》2014

In situ Pleistocene reefs form a gently sloping nearshore terrace around the island of Oahu. TIMS Th–U ages of in situ corals indicate that most of the terrace is composed of reefal limestones correlating to Marine Oxygen Isotope Stage 7 (MIS 7, ~ 190–245 ka). The position of the in situ MIS 7 reef complex indicates that it formed during periods when local sea level was ~ 9 to 20 m below present sea level. Its extensiveness and geomorphic prominence as well as a paucity of emergent in situ MIS 7 reef-framework deposits on Oahu suggest that much of MIS 7 was characterized by regional sea levels below present. Later accretion along the seaward front of the terrace occurred during the latter part of MIS 5 (i.e., MIS 5a–5d, ~ 76–113 ka). The position of the late MIS 5 reefal limestones is consistent with formation during a period when local sea level was below present. The extensiveness of the submerged Pleistocene reefs around Oahu compared to the relative dearth of Holocene accretion is due to the fact that Pleistocene reefs had both more time and more accommodation space available for accretion than their Holocene counterparts.  相似文献   

An object-based conceptual framework and computational method for representing and analyzing coastal morphological changes     

Hongxing Liu  Lei Wang  Douglas Sherman  Yige Gao  Qiusheng Wu 《International journal of geographical information science》2013,27(7):1015-1041

This article presents an object-based conceptual framework and numerical algorithms for representing and analyzing coastal morphological and volumetric changes based on repeat airborne light detection and ranging (LiDAR) surveys. This method identifies and delineates individual zones of erosion and deposition as discrete objects. The explicit object representation of erosion and deposition zones is consistent with the perception and cognition of human analysts and geomorphologists. The extracted objects provide ontological and epistemological foundation to localize, represent, and interpret erosion and deposition patches for better coastal resource management and erosion control. The discrete objects are much better information carriers than the grid cells in the field-based representation of source data. A set of spatial and volumetric attributes are derived to characterize and quantify location, area, shape, orientation, depth, volume, and other properties of erosion and deposition objects. Compared with the conventional cell-by-cell differencing approaches, our object-based method gives a concise and high-level representation of information and knowledge about coastal morphological dynamics. The derived attributes enable the discrimination of true morphological changes from artifacts caused by data noise and processing errors. Furthermore, the concise object representation of erosion and deposition zones facilitates overlay analysis in conjunction with other GIS data layers for understanding the causes and impacts of morphological and volumetric changes. We have implemented a software tool for our object-based morphological analysis, which will be freely available for the public. An example is used to demonstrate the utility and effectiveness of this new method.  相似文献   

Geodynamic evolution of a forearc rift in the southernmost Mariana Arc     

Julia M. Ribeiro  Robert J. Stern  Fernando Martinez  Osamu Ishizuka  Susan G. Merle  Katherine Kelley  Elizabeth Y. Anthony  Minghua Ren  Yasuhiko Ohara  Mark Reagan  Guillaume Girard  Sherman Bloomer 《Island Arc》2013,22(4):453-476

The southernmost Mariana forearc stretched to accommodate opening of the Mariana Trough backarc basin in late Neogene time, erupting basalts at 3.7–2.7 Ma that are now exposed in the Southeast Mariana Forearc Rift (SEMFR). Today, SEMFR is a broad zone of extension that formed on hydrated, forearc lithosphere and overlies the shallow subducting slab (slab depth ≤ 30–50 km). It comprises NW–SE trending subparallel deeps, 3–16 km wide, that can be traced ≥ ∼30 km from the trench almost to the backarc spreading center, the Malaguana‐Gadao Ridge (MGR). While forearcs are usually underlain by serpentinized harzburgites too cold to melt, SEMFR crust is mostly composed of Pliocene, low‐K basaltic to basaltic andesite lavas that are compositionally similar to arc lavas and backarc basin (BAB) lavas, and thus defines a forearc region that recently witnessed abundant igneous activity in the form of seafloor spreading. SEMFR igneous rocks have low Na₈, Ti₈, and Fe₈, consistent with extensive melting, at ∼23 ± 6.6 km depth and 1239 ± 40°C, by adiabatic decompression of depleted asthenospheric mantle metasomatized by slab‐derived fluids. Stretching of pre‐existing forearc lithosphere allowed BAB‐like mantle to flow along the SEMFR and melt, forming new oceanic crust. Melts interacted with pre‐existing forearc lithosphere during ascent. The SEMFR is no longer magmatically active and post‐magmatic tectonic activity dominates the rift.  相似文献   

Public participation in China’s green communities: Mobilizing memories and structuring incentives     

Alana Boland  Jiangang Zhu 《Geoforum》2012,43(1):147-157

In recent years, there has been heightened interest in creating more environmentally sustainable forms of urban development in China. Central in these greening initiatives has been increased attention on promoting public participation in community-based environmental activities. Focusing on China’s green community initiatives, we examine the production and effects of participation in a state-led development program. Our analysis considers how incentives for program organizers and participants are structured by broader political and economic imperatives facing Chinese cities. We also consider what influence China’s history of neighborhood-based mobilization campaigns had on the meanings and methods of participation in green communities. To understand how urban development processes and memories of mobilization influence participation at the local level, we present two examples of the community greening process from the city of Guangzhou, comparing policy outcomes between a new and older neighborhood. This article seeks to demonstrate that the participatory processes associated with such an urban environmental initiative cannot be adequately understood without reference to earlier participatory practices and broader policy priorities guiding development in Chinese cities.  相似文献   

The Oligocene Lund Tuff, Great Basin, USA: a very large volume monotonous intermediate     

Larissa L. Maughan  Eric H. Christiansen  Myron G. Best  C. Sherman Gromm  Alan L. Deino  David G. Tingey 《Journal of Volcanology and Geothermal Research》2002,113(1-2)

Unusual monotonous intermediate ignimbrites consist of phenocryst-rich dacite that occurs as very large volume (>1000 km³) deposits that lack systematic compositional zonation, comagmatic rhyolite precursors, and underlying plinian beds. They are distinct from countless, usually smaller volume, zoned rhyolite–dacite–andesite deposits that are conventionally believed to have erupted from magma chambers in which thermal and compositional gradients were established because of sidewall crystallization and associated convective fractionation. Despite their great volume, or because of it, monotonous intermediates have received little attention. Documentation of the stratigraphy, composition, and geologic setting of the Lund Tuff – one of four monotonous intermediate tuffs in the middle-Tertiary Great Basin ignimbrite province – provides insight into its unusual origin and, by implication, the origin of other similar monotonous intermediates.The Lund Tuff is a single cooling unit with normal magnetic polarity whose volume likely exceeded 3000 km³. It was emplaced 29.02±0.04 Ma in and around the coeval White Rock caldera which has an unextended north–south diameter of about 50 km. The tuff is monotonous in that its phenocryst assemblage is virtually uniform throughout the deposit: plagioclase>quartz≈hornblende>biotite>Fe–Ti oxides≈sanidine>titanite, zircon, and apatite. However, ratios of phenocrysts vary by as much as an order of magnitude in a manner consistent with progressive crystallization in the pre-eruption chamber. A significant range in whole-rock chemical composition (e.g., 63–71 wt% SiO₂) is poorly correlated with phenocryst abundance.These compositional attributes cannot have been caused wholly by winnowing of glass from phenocrysts during eruption, as has been suggested for the monotonous intermediate Fish Canyon Tuff. Pumice fragments are also crystal-rich, and chemically and mineralogically indistinguishable from bulk tuff. We postulate that convective mixing in a sill-like magma chamber precluded development of a zoned chamber with a rhyolitic top or of a zoned pyroclastic deposit. Chemical variations in the Lund Tuff are consistent with equilibrium crystallization of a parental dacitic magma followed by eruptive mixing of compositionally diverse crystals and high-silica rhyolite vitroclasts during evacuation and emplacement. This model contrasts with the more systematic withdrawal from a bottle-shaped chamber in which sidewall crystallization creates a marked vertical compositional gradient and a substantial volume of capping-evolved rhyolite magma. Eruption at exceptionally high discharge rates precluded development of an underlying plinian deposit.The generation of the monotonous intermediate Lund magma and others like it in the middle Tertiary of the western USA reflects an unusually high flux of mantle-derived mafic magma into unusually thick and warm crust above a subducting slab of oceanic lithosphere.  相似文献   

Topographic mapping of the Moon     

Sherman S. C. Wu 《Earth, Moon, and Planets》1985,32(2):165-172

Contour maps of the Mooon have been compiled by photogrammetric methods that use stereoscopic combinations of all available metric photographs from the Apollo 15, 16, and 17 missions. The maps utilize the same format as the existing NASA shaded-relief Lunar Planning Charts (LOC-1, -2, -3, and -4), which have a scale of 1:2 750 000. The map contour interval is 500m. A control net derived from Apollo photographs by Doyle and others was used for the compilation. Contour lines and elevations are referred to the new topographic datum of the Moon, which is defined in terms of spherical harmonics from the lunar gravity field. Compilation of all four LOC charts was completed on analytical plotters from 566 stereo models of Apollo metric photographs that cover approximately 20% of the Moon. This is the first step toward compiling a global topographic map of the Moon at a scale of 1:5 000 000.  相似文献   

Electronic and vibrational transitions in minerals: Applications of density functional theory     

D. M. Sherman 《Physics and Chemistry of Minerals》1996,23(4-5):214-214

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Space geodesy in geodynamic studies: Recent movements in the Zeya-Bureya Basin     

A. I. Miroshnichenko  A. P. Sorokin  V. A. San’kov  A. V. Lukhnev  S. V. Ashurkov  A. T. Sorokina  N. I. Panfilov  M. A. Serov  S. I. Sherman 《Russian Journal of Pacific Geology》2008,2(1):64-71

The Amur-Zeya geodynamic test ground was set up in 2000 to study recent intracontinental crustal deformations. The velocity field calculations for the period of 2000 to 2003 describe three movements scales. The general level is characterized by the vectors of IGS sites in the eastern part of Asia, the BLAG (Blagoveshchensk) site included. The southeast movement of the IRKT (Irkutsk) site of the stable Siberian Platform is indicative of deformations in the northeastern part of the Amur Plate. Measurement data on the regional near-latitudinal profile Blagoveshchensk-Sutara, which crosses the Nizhnyaya Zeya Basin, demonstrate a southwestward displacement of the Badzhal-Bureya-Lesser Khingan block relative to the North China block. The dynamic effect of the convergent boundary between the Amur and Okhotsk Sea plates is assumed to extend inland also involving the Zeya-Bureya Basin area. The measurements on the local geodynamic test site relate the deformations of buildings and constructions in the Settlement of Konstantinovka to the mobility of basement faults in the southern part of the Nizhnyaya Zeya Basin. Aseismic deformations are determined by slow horizontal tectonic movements in the junction zone of NNE-trending structures of the latter basin and near-latitudinal faults of the Khailar-Xunhei Belt.  相似文献