Dredging through the remains.     

B Morton 《Marine pollution bulletin》2001,42(5):333-334

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Heat extraction from hot,dry, crustal rock     

Morton C. Smith 《Pure and Applied Geophysics》1978,117(1-2):290-296

Natural heat stored in the earth's interior represents an essentially inexhaustible energy supply which, at usefully high temperatures, is accessible at practical drilling depths from almost anywhere on the earth's land surface. The problems of extracting and using this heat are those of engineering and economics, and can be expected to vary with the local geology and value of thermal energy. The first major experimental system designed to investigate these problems in one common type of geologic environment has recently been completed in the crystalline rock underlying the Jemez Plateau of northern New Mexico. It consists principally of two boreholes connected at a depth of about 2.7 km by a system of hydraulic fractures produced in granitic rock at a temperature of approximately 185°C. Cool water injected through one hole is heated as it flows through the fractures, and is recovered through the second hole as pressurized, superheated water. In a surface heat-exchange system now being completed, this heat will be extracted and the cool water reinjected to maintain a continuous, closed, pressurized-water energy-extraction loop.  相似文献   

Long-term change in eelgrass distribution at Bahía San Quintín,Baja California,Mexico, using satellite imagery     

David?H.?WardEmail author  Alexandra?Morton  T.?Lee?Tibbitts  David?C.?Douglas  Eduardo?Carrera-González 《Estuaries and Coasts》2003,26(6):1529-1539

Seagrasses are critically important components of many marine coastal and estuarine ecosystems, but are declining worldwide. Spatial change in distribution of eelgrass,Zostera marina L., was assessed at Bahía San Quintín, Baja California, Mexico, using a map to map comparison of data interpreted from a 1987 Satellite Pour l'Observation de la Terre multispectral satellite image and a 2000 Landsat Enhanced Thematic Mapping image. Eelgrass comprised 49% and 43% of the areal extent of the bay in 1987 and 2000, respectively. Spatial extent of eelgrass was 13% less (−321 ha) in 2000 than in 1987 with most losses occurring in subtidal areas. Over the 13-yr study period, there was a 34% loss of submerged eelgrass (−457 ha) and a 13% (+136 ha) gain of intertidal eelgrass. Within the two types of intertidal eelgrass, the patchy cover class (<85% cover) expanded (+250 ha) and continuous cover class (≥85% cover) declined (−114 ha). Most eelgrass losses were likely the result of sediment loading and turbidity caused by a single flooding event in winter of 1992–1993. Recent large-scale agricultural development of adjacent uplands may have exacerbated the effects of the flood. Oyster farming was not associated with any detectable losses in eelgrass spatial extent, despite the increase in number of oyster racks from 57 to 484 over the study period.  相似文献   

The sediment and hydrographic characteristics of three horseshoe crab nursery beaches in hong kong     

Helen M.C. Chiu  Brian Morton 《中国海洋大学学报(英文版)》2003,2(1):35-43

1　Introduction　Thelifecycleofhorseshoecrabsislengthywhencom paredtoothermarinearthropodssuchasbluecrabsandshrimpspecies (Sekiguchietal.,1988) .Thetwospecies,TachypleustridentatusandCarcinoscorpiusrotundicauda,knowntooccurinHongKongrequire ,respectively ,betweenthirteentofourteenandtentoelevenyearstomaturebeforedepartingtheirnurserybeachesfordeeperwaters (ChiuandMorton ,1999a ;Sekiguchietal.,1988) .Thelivingenvironmentofthenurserybeacheswheretheeggsarelaidandincu bated ,andfromwhichtheyoun…  相似文献   

Hydrothermal environments during the genesis of silver deposits in the Northwest Territories of Canada: Evidence from fluid inclusions     

A. Changkakoti  R. D. Morton  J. Gray 《Mineralium Deposita》1986,21(1):63-69

The Ag-Ni-Co-Bi-As-U veins in the Northwest Territories of Canada are hosted by volcano-sedimentary and intrusive rocks of the Great Bear Batholithic Complex. Fluid inclusion data from the gangue minerals of the veins suggest a wide range in salinity and temperature for the hydrothermal fluids. The salinities of the fluids range from about 15 to 35 wt.% NaCl equivalent. The homogenization temperatures range from 150° to 250°C for stage I fluids; 220° to 480°C for stage II fluids; 250° to 350°C for stage III fluids; 150° to 250°C for stage IV fluids and 90° to 250°C for stage V fluids. The coexistence of liquid-rich and vapour-rich inclusions in stages II and III minerals suggest that the hydrothermal fluids were boiling or effervescing. The coexistence of saturated and unsaturated inclusions in stages II and III minerals may be due to effervescence of a less saline fluid, whilst for stages IV and V it may be due to mixing of a highly saline fluid with a less saline fluid, or due to alternation of hydrostatic and lithostatic pressures at the time of trapping of the inclusions.  相似文献   

Coastal geoindicators of environmental change in the humid tropics     

R. Morton 《Environmental Geology》2002,42(7):711-724

The primary geoindicators appropriate for monitoring environmental changes in the humid tropics are transitory surface water levels, shoreline position, wetlands distribution, coral reefs, landforms, and sediment sequence and composition. Lateral zonations and temporal successions of vegetation also can be used as geoindicators of riverine and shoreline changes. All of these coastal geoindicators are sensitive to regional tectonic processes and anthropogenic alterations and they typically reflect significant changes in coastal conditions such as fluvial processes, coastal energy, water quality, relative sea level, and sediment supply. Where humid tropical coasts coincide with active tectonic margins, indicators of seismic activity are critical to understanding coastal changes associated with co-seismic subsidence or uplift, tsunamis, and liquefaction of coastal sediments. Coastal landforms and sedimentary deposits that record late Quaternary environmental changes include perched fluvial and marine terraces, delta-plain morphologies, crevasse-splay deposits, peats and other paleosols, beach ridges, mud capes, and mud volcanoes. Although these features and deposits typically reflect environmental changes spanning more than 100 years, they are relevant to modern processes, management of coastal lands and resources, and prediction of future conditions. In some regions of the humid tropics, large coastal areas are unaffected by hurricanes or typhoons. Nevertheless, these tropical coasts are vulnerable to other non-storm processes, such as El Niño events, tsunamis, and monsoons that increase water levels, and cause widespread flooding and beach erosion. The environmental and political significance of coastal geoindicators increases when they are integrated and applied to issues of human safety and health such as hazards mapping, risk assessment, and dispersion of contaminated sediments. However, to be relevant, those socio-environmental applications demand accurate predictions of future trends and rates of change.  相似文献   

Assessing representation error in point-based coverage modeling   总被引：2，自引：1，他引：2  

Alan T. Murray  Morton E. O'Kelly 《Journal of Geographical Systems》2002,4(2):171-191

 Accurately representing geographic space in a digital environment continues to confound and challenge researchers. Carrying out spatial analysis in a setting where geographic representation is subject to change poses problems to be addressed. In this paper we examine spatial representation in the context of coverage-based location modeling. A geographic region can be represented in a variety of ways. We present an evaluation of spatial representation in the location of facilities that provide coverage oriented services. The analysis shows that the modeling results are sensitive to how spatial demand for service is represented in a digital environment. We develop an approach for evaluating representational appropriateness. This research contributes to spatial analysis integrated in geographic information system environment. Received: 10 January 2001 / Accepted: 8 April 2002  相似文献   

Late Quaternary stratigraphy of the northern Rockall trough and Faeroe-Shetland channel,northeast Atlantic Ocean     

Martyn S. Stoker  Rex Harland  Andrew C. Morton  Douglas K. Graham 《第四纪科学杂志》1989,4(3):211-222

A late Quaternary deep-water stratigraphic framework has been established for the deep-water areas (>450m) of the northern Rockall Trough and Faeroe-Shetland Channel. Four stratigraphic units (1–4) are identified; these are primarily biostratigraphic units based on dinoflagellate cyst evidence. Unit 1 represents the late Weichselian glacial (pre-13 000 yr BP); unit 2 the Late Glacial Interstadial (11 000-13 000 yr BP); unit 3 is of Younger Dryas age (10 000-11 000 yr BP); and unit 4 represents the Holocene interglacial (post-10 000 yr BP). This stratigraphy is supported by the discovery of the mixed Vedde Ash (10 600 yr BP) and North Atlantic Ash zone 1, and the Saksunarvatn Ash (9000–9100 yr BP), concentrated in units 3 and 4 respectively. The sedimentology indicates that the oceanographic regime underwent a major change between the glacial and interglacial stages. This is marked by the onset of strong bottom current activity, allied to the restoration of overflow of the Norwegian Sea Deep Water into the North Atlantic, towards the end of the Younger Dryas Stadial. Despite intense bioturbation and bottom-current reworking the basic stratigraphic framework is maintained. Recognition of two volcanic ash markers enables correlation with established onshore and offshore sequences of marine and non-marine environments.  相似文献   

South China Sea   总被引：8，自引：0，他引：8  

Morton B  Blackmore G 《Marine pollution bulletin》2001,42(12):1236-1263

The South China Sea is poorly understood in terms of its marine biota, ecology and the human impacts upon it. What is known is most often contained in reports and workshop and conference documents that are not available to the wider scientific community. The South China Sea has an area of some 3.3 million km² and depths range from the shallowest coastal fringe to 5377 m in the Manila Trench. It is also studded with numerous islets, atolls and reefs many of which are just awash at low tide. It is largely confined within the Tropic of Cancer and, therefore, experiences a monsoonal climate being influenced by the Southwest Monsoon in summer and the Northeast Monsoon in winter. The South China Sea is a marginal sea and, therefore, largely surrounded by land. Countries that have a major influence on and claims to the sea include China, Malaysia, the Philippines and Vietnam, although Thailand, Indonesia and Taiwan have some too. The coastal fringes of the South China Sea are home to about 270 million people that have had some of the fastest developing and most vibrant economies on the globe. Consequently, anthropogenic impacts, such as over-exploitation of resources and pollution, are anticipated to be huge although, in reality, relatively little is known about them. The Indo-West Pacific biogeographic province, at the centre of which the South China Sea lies, is probably the world's most diverse shallow-water marine area. Of three major nearshore habitat types, i.e., coral reefs, mangroves and seagrasses, 45 mangrove species out of a global total of 51, most of the currently recognised 70 coral genera and 20 of 50 known seagrass species have been recorded from the South China Sea. The island groups of the South China Sea are all disputed and sovereignty is claimed over them by a number of countries. Conflicts have in recent decades arisen over them because of perceived national rights. It is perhaps because of this that so little research has been undertaken on the South China Sea. What data are available, however, and if Hong Kong is used, as it is herein, as an indicator of what the perturbations of other regional cities upon the South China Sea are like, then it is impacted grossly and an ecological disaster has probably already, but unknowingly, happened.  相似文献   

Origin of Carboniferous sandstones fringing the northern margin of the Wales‐Brabant Massif: insights from detrital zircon ages     

Andrew Morton  Colin Waters  Mark Fanning  Ian Chisholm  Matt Brettle 《Geological Journal》2015,50(5):553-574

A study of detrital zircon age populations in Namurian–Westphalian (Carboniferous) sandstones in the southern Central Pennine Basin of the UK has revealed considerable complexity in their provenance history. The Pendleian–Marsdenian Morridge Formation, which is known to have been derived from the Wales‐Brabant Massif to the south on the basis of palaeocurrent and petrographic information, is dominated by zircons ultimately derived from the Caledonian belt to the north. These zircons were recycled from sandstones of northern origin that had been previously deposited over the massif during Middle to Late Devonian times. The Morridge Formation also includes Late Neoproterozoic zircons of local Wales‐Brabant Massif origin. The south lobe of the Yeadonian Rough Rock has been previously interpreted as having a complex provenance including sediment of northern origin interbedded with sediment ascribed to a Wales‐Brabant Massif source. However, the zircon spectrum lacks a Late Neoproterozoic component that would have been diagnostic of input from the Wales‐Brabant Massif, and the provenance history of the Rough Rock south lobe therefore remains enigmatic. The Langsettian Ludgbridge Conglomerate is dominated by Late Neoproterozoic zircons of Wales‐Brabant Massif origin, but even in this evidently proximal deposit, the provenance is complex since the main zircon group (ca. 640 Ma) cannot be matched with known local Neoproterozoic basement sources. The data either indicate the presence of hitherto‐unknown magmatic rocks of this age adjacent to the South Staffordshire coalfield or indicate that the zircons were recycled from sediment with a more distal origin. Finally, the Duckmantian Top Hard Rock contains zircons that can be reconciled with a source in the Irish Caledonides, consistent with the palaeocurrent evidence, supplemented by zircons derived from the Wales‐Brabant Massif, possibly including the Monian Composite Terrane of Anglesey. The study reinforces the important message that failure to recognize the presence of recycled zircon could lead to erroneous reconstructions of sediment provenance and transport history. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献