Analytical Solutions Involving Shock Waves for Testing Debris Avalanche Numerical Models

Analytical solutions to debris avalanche problems involving shock waves are derived. The debris avalanche problems are described in two different coordinate systems, namely, the standard Cartesian and topography-linked coordinate systems. The analytical solutions can then be used to test debris avalanche numerical models. In this article, finite volume methods are applied as the numerical models. We compare the performance of the finite volume method with reconstruction of the conserved quantities based on stage, height, and velocity to that of the conserved quantities based on stage, height, and momentum for solving the debris avalanche problems involving shock waves. The numerical solutions agree with the analytical solution. In addition, both reconstructions lead to similar numerical results. This article is an extension of the work of Mangeney et al. (Pure Appl Geophys 157(6–8):1081–1096, 2000).     

Microbially induced formation of ooid-like coated grains in the Late Cretaceous methane-seep deposits of the Nakagawa area, Hokkaido, northern Japan

Abstract   Ooid-like coated grains are found in the Late Cretaceous methane-seep deposits in the Nakagawa area, Hokkaido, Japan. The coated grains were examined using macro- and microscopic observations, electron-probe microanalysis, and biomarker analysis. They are round- to oval-shaped, with nuclei consisting of fractured sediment and micritic envelopes. The fractures probably occurred as a result of increasing hydrostatic pressure when the sediment was still unconsolidated or weakly consolidated. Biomarker analysis revealed that two types of molecules, crocetane and PMI, are predominant in the hydrocarbon fraction with highly negative carbon isotopic composition as low as −122‰ ( vs Vienna Peedee Belemnite). These data suggest that the coated grains were formed under the influence of anaerobic oxidation of methane, near the sediment/seawater interface. The presence of such grains indicates that methane-containing pore water reached the sea floor at that time.     

The Jewish colonization of the Nablus region —perspectives and continuing developments

While the mounting Jewish colonization of the Occupied Territories, especially the Nablus region, is considered against the backcloth of notions on Eretz Yisrael, the Land of Israel, the settlement-development must also be viewed as suburbanization outwards from Israeli metropolitan space and penetration into the essentially peripheral, dominantly rural Palestinian domain of the West Bank. Recent relaxitions in Soviet emigration controls and tighter US immigration policies towards Soviet Jewish emigrants are realizing a quite dramatic increase in the number of Soviet Jews immigrating into both Israel and the Occupied Territories. In turn, this will herald increasing and deeper competitions over land. Various assistance programmes and initiatives for the Jewish settlements within the West Bank are outlined with a consideration of Ariel, The Capital of Samaria, providing a specific case study. The continuing attempts to broaden the economic bases of the colonial settlements are also considered. Problems are set to continue. The contentious nature of the subject is to be emphasized.     

The centrality of Islam: Space,form and process

This paper considers the centralizing and unifying tendencies of Islamic space paying particular and direct attention to the nature and reality of the pilgrimage to Mecca, theHajj. For the human geographer both theHajj and the other pillars-foundations of Islamic belief provide a constancy and spatially reinforcing dynamic to facilitate at least a partial comprehension of the properties of a specific and large cultural region; the community of Islam. It is to be stressed that any singular concern with theHajj that fails to see it as a part or rite within a wider functioning Islam will do a disservice both to the pilgrimage itself and present an unacceptable view of Islam. The recent growth of theHajj is considered as part of the continuity and indeed mounting ebullience and vitality of Islam. Continuing population growths and developments in transport technologies that present increasing opportunities to a widening number of Muslims are outlined and the various transport modes utilized byHajjees are considered.     

Hydrothermal uranium deposits containing molybdenum and fluorite in the Marysvale volcanic field, west-central Utah

Uranium deposits containing molybdenum and fluorite occur in the Central Mining Area, near Marysvale, Utah, and formed in an epithermal vein system that is part of a volcanic/hypabyssal complex. They represent a known, but uncommon, type of deposit; relative to other commonly described volcanic-related uranium deposits, they are young, well-exposed and well-documented. Hydrothermal uranium-bearing quartz and fluorite veins are exposed over a 300 m vertical range in the mines. Molybdenum, as jordisite (amorphous MoS₂), together with fluorite and pyrite, increase with depth, and uranium decreases with depth. The veins cut 23-Ma quartz monzonite, 20-Ma granite, and 19-Ma rhyolite ash-flow tuff. The veins formed at 19-18 Ma in a 1 km² area, above a cupola of a composite, recurrent, magma chamber at least 24 × 5 km across that fed a sequence of 21- to 14-Ma hypabyssal granitic stocks, rhyolite lava flows, ash-flow tuffs, and volcanic domes. Formation of the Central Mining Area began when the intrusion of a rhyolite stock, and related molybdenite-bearing, uranium-rich, glassy rhyolite dikes, lifted the fractured roof above the stock. A breccia pipe formed and relieved magmatic pressures, and as blocks of the fractured roof began to settle back in place, flat-lying, concave-downward, “pull-apart” fractures were formed. Uranium-bearing, quartz and fluorite veins were deposited by a shallow hydrothermal system in the disarticulated carapace. The veins, which filled open spaces along the high-angle fault zones and flat-lying fractures, were deposited within 115 m of the ground surface above the concealed rhyolite stock. Hydrothermal fluids with temperatures near 200 °C, ¹⁸O_H2O∼−1.5, D_H2O∼−130, log f O₂ about −47 to −50, and pH about 6 to 7, permeated the fractured rocks; these fluids were rich in fluorine, molybdenum, potassium, and hydrogen sulfide, and contained uranium as fluoride complexes. The hydrothermal fluids reacted with the wallrock resulting in precipitation of uranium minerals. At the deepest exposed levels, wallrocks were altered to sericite; and uraninite, coffinite, jordisite, fluorite, molybdenite, quartz, and pyrite were deposited in the veins. The fluids were progressively oxidized and cooled at higher levels in the system by boiling and degassing; iron-bearing minerals in wall rocks were oxidized to hematite, and quartz, fluorite, minor siderite, and uraninite were deposited in the veins. Near the ground surface, the fluids were acidified by condensation of volatiles and oxidation of hydrogen sulfide in near-surface, steam-heated, ground waters; wall rocks were altered to kaolinite, and quartz, fluorite, and uraninite were deposited in veins. Secondary uranium minerals, hematite, and gypsum formed during supergene alteration later in the Cenozoic when the upper part of the mineralized system was exposed by erosion. Received: 23 June 1997 / Accepted: 15 October 1997     

A Review of “Qualitative GIS: A Mixed Methods Approach”

Books Reviewed:

Browning, Frank A Queer Geography: Journeys Toward a Sexual Self

Fellows, Will Farm Boys: Lives of Gay Men from the Rural Midwest

Rubenstein, James M. The Cultural Landscape: An Introduction to Human Geography. 6th ed

Knox, Paul L. and Marston, Sallie A. Human Geography: Places and Regions in Global Context

Kuby, Michael; Harner, John, and Gover, Patricia Human Geography in Action