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Selected AbstractsGeoarchaeology of the Boca Negra Wash Area, Albuquerque Basin, New Mexico, USAGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 8 2006Vance T. Holliday Dozens of Paleoindian sites, including the Boca Negra Wash (BNW) Folsom site (LA 124474), are scattered across a basalt plateau (the West Mesa) on the western side of the Albuquerque Basin, and adjacent uplands. The BNW site, like many others in the area, is located near a small (,60 × 90 m) playa basin that formed in a depression on the basalt surface and was subsequently covered by an eolian sand sheet (Unit 1) dated by OSL to ,23,000 yr B.P. Most of the basin fill is ,2 m of playa mud (Units 2 and 3) dating ,13,970 14C yr B.P. (17,160,16,140 cal yr B.P.) at the sand,mud interface to ,2810 14C yr B.P. (,2960,2860 cal yr B.P.) at the top. C/N ratios suggest that the BNW playa basin probably held water more often during the Folsom occupation; stable carbon isotope values indicate C3 vegetation was more common as well, but C4 grasses became dominant in the Holocene. Cores extracted from four playa basins nearby revealed a similar stratigraphy and geochronology, documenting presence of wetlands on playa floors during the Paleoindian occupation of the area. © 2006 Wiley Periodicals, Inc. [source] Thickness of the lithosphere east of the Dead Sea TransformGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2006Ayman Mohsen SUMMARY We use the S receiver function method to study the lithosphere at the Dead Sea Transform (DST). A temporary network of 22 seismic broad-band stations was operated on both sides of the DST from 2000 to 2001 as part of the DESERT project. We also used data from six additional permanent broad-band seismic stations at the DST and in the surrounding area, that is, in Turkey, Saudi Arabia, Egypt and Cyprus. Clear S -to- P converted phases from the crust,mantle boundary (Moho) and a deeper discontinuity, which we interpret as lithosphere,asthenosphere boundary (LAB) have been observed. The Moho depth (30,38 km) obtained from S receiver functions agrees well with the results from P receiver functions and other geophysical data. We observe thinning of the lithosphere on the eastern side of the DST from 80 km in the north of the Dead Sea to about 65 km at the Gulf of Aqaba. On the western side of the DST, the few data indicate a thin LAB of about 65 km. For comparison, we found a 90-km-thick lithosphere in eastern Turkey and a 160-km-thick lithosphere under the Arabian shield, respectively. These observations support previous suggestions, based on xenolith data, heat flow observations, regional uplift history and geodynamic modelling, that the lithosphere around DST has been significantly thinned in the Late Cenozoic, likely following rifting and spreading of the Red Sea. [source] Cross-cutting moraines reveal evidence for North Atlantic influence on glaciers in the tropical Andes,JOURNAL OF QUATERNARY SCIENCE, Issue 3 2010Jacqueline A. Smith Abstract Surface exposure dating of boulders on an exceptionally well-preserved sequence of moraines in the Peruvian Andes reveals the most detailed record of glaciation heretofore recognised in the region. The high degree of moraine preservation resulted from dramatic changes in the flow path of piedmont palaeoglaciers at the southern end of the Cordillera Blanca (10° 00, S, 77° 16, W), which, in turn, generated a series of cross-cutting moraines. Sixty 10Be surface exposure ages indicate at least four episodes of palaeoglacier stabilisation (>65, ca. 65, ca. 32 and ca. 18,15,ka) and several minor advances or stillstands on the western side of the Nevado Jeulla Rajo massif. The absence of ages close to the global Last Glacial Maximum (ca. 21,ka) suggests that if an advance culminated at that time any resulting moraines were subsequently overridden. The timing of expanded ice cover in the central Peruvian Andes correlates broadly with the timing of massive iceberg discharge (Heinrich) events in the North Atlantic Ocean, suggesting a possible causal connection between southward migration of the Intertropical Convergence Zone during Heinrich events and a resultant increase in precipitation in the tropical Andes. Copyright © 2010 John Wiley & Sons, Ltd. [source] Oyster Crassostrea virginica Spat Settlement as it Relates to the Restoration of Fish River Reef in Mobile Bay, AlabamaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2000Imad G. Saoud Spat collectors at the reefs were replaced every 2 wk and spat-set estimated as number of oysters per meter square per day. Water quality data at Fish River Reef was monitored using remote sensors. Spat-set data revealed significant variation between the four sites and between the 2 yr. Spat settlement was 5 to 10 times greater at the other three reefs than at Fish River Reef. Dates and intensity of oyster settlement at Fish River Reef were different from dates and intensity of oyster settlement at Shell Bank Reef, both on the eastern side of the bay. However, settlement was similar between Cedar Point Reef and White House Reef, both on the western side of the bay. Spat set appears to occur 3 wk after a rapid decline in water temperature, provided adequate oxygen concentrations are present at the time of settlement. Data collected suggest that intensity of settlement at Fish River Reef is considerably less than at other reefs in this study but could be adequate to reestablish the reef, if cultch and environmental conditions are suitable. The data also suggest that the source of larval oysters at Fish River Reef is different from the source of larval oysters at the other sites tested in the present study. [source] The influence of synoptic-mesoscale winds and sea surface temperature distribution on fog formation near the Korean western peninsulaMETEOROLOGICAL APPLICATIONS, Issue 4 2006Hyo Choi Abstract When high pressure is located near the Korean peninsula, a diffluent wind regime generally occurs over the Yellow Sea. At night or early morning, diffluent westerly winds occur on the western side of the Korean peninsula near Inchon city and encounter a combined land breeze and katabatic easterly offshore wind, resulting in conditions ranging from calm to a moderate westerly wind near the coast. Nocturnal radiational cooling of the land surface and the moisture laden westerly winds can cause air near the coast to become saturated, resulting in coastal advection fog. During the day, on the other hand, the synoptic-scale westerly wind is reinforced by a westerly sea breeze and is further reinforced by a westerly valley wind directed upslope towards the mountain top. Even if the resulting intensified onshore wind could transport a large amount of moisture from the sea over the land, it would be very difficult for fog to form because the daytime heat flux from the ground would develop the convective boundary layer inland from Inchon city sufficiently to reduce significantly the moisture content of the air. Therefore, fog does not generally form in situ over the inland coastal basin. When an area of cold sea water (10°C average) exists approximately 25,50 km offshore and the sea surface temperature increases towards the coast, air parcels over the cool sea surface are cooled sufficiently to saturation, resulting in the formation of advection sea fog. However, at the coast, nocturnal cooling of the ground further cools the advected moist air driven by the westerly wind and causes coastal advection fog to form. Copyright © 2006 John Wiley & Sons, Ltd. [source] PATTERNS OF EVOLUTION AND EXTINCTION IN THE LAST HARPETID TRILOBITES DURING THE LATE DEVONIAN (FRASNIAN)PALAEONTOLOGY, Issue 1 2009KENNETH J. McNAMARA Abstract:, Late Devonian (Frasnian) harpetid trilobites have hitherto only been described from the western side of the Protethys Ocean, in what is now Europe and North Africa, as well as from Gondwana-derived northwestern Kazakhstan (Mugodjar). However, late Frasnian strata in the Canning Basin, Western Australia, that were deposited on the eastern side of this ocean, contain a rich harpetid fauna. Described herein are two new harpetids: Eskoharpes gen. nov. and Globoharpes gen. nov., within which are placed six species: E. palanasus sp. nov., E. wandjina sp. nov., E. boltoni sp. nov., E. guthae sp. nov., G. teicherti sp. nov. and G. friendi sp. nov. The ontogenetic development of E. palanasus, E. wandjina and G. teicherti are described, including the first unequivocal harpetid protaspis. Globoharpes exhibits evidence of sexual dimorphism in the development of a pronounced preglabellar boss in some specimens. This structure is thought to have functioned as a brood pouch. Such structures have previously only been described in Cambrian and Ordovician trilobites, and never before in harpetids. It is suggested that the characteristic harpetid fringe functioned as a secondary respiratory structure. The Eskoharpes lineage shows evolutionary trends that mirror changes seen in ontogenetic development of the youngest species, suggesting the operation of peramorphic processes. This is the first record of heterochrony in harpetids and the first documented example of peramorphosis in Devonian trilobites. These harpetids demonstrate a stepped pattern of extinction during the late Frasnian, probably related to the effects of the two Kellwasser biocrises that have been well documented in European Frasnian sections. Highly vaulted species of Eskoharpes and the strongly vaulted Globoharpes became extinct at the Lower Kellwasser Event. The flatter species of Eskoharpes became extinct at the base of the Upper Kellwasser Event shortly prior to the Frasnian/Famennian boundary. The extinction of these harpetids, along with contemporaneous forms from Europe, which are also discussed herein, marks the end of the trilobite order Harpetida worldwide. [source] Climatic and geomorphic factors affecting contemporary (1950,2004) activity of retrogressive thaw slumps on the Aklavik Plateau, Richardson Mountains, NWT, CanadaPERMAFROST AND PERIGLACIAL PROCESSES, Issue 1 2010Denis Lacelle Abstract The climatic and geomorphic factors affecting retrogressive thaw slump initiation and activity on the Aklavik Plateau (Richardson Mountains, NWT) were examined using historical air photographs over a 54-year period (1950 to 2004). In this region, thaw slumps include a near-vertical headwall, a floor of low gradient (2,10°) and a steeply sloping evacuation channel (15,25°) that connects the floor of the thaw slumps to Willow River located 60,150,m below. All thaw slumps on the Aklavik Plateau are located within the glacial limit of the Laurentide Ice Sheet and the majority developed on the western side of the valley on gently sloping terrain. Aerial photographic analysis showed an increase in thaw slump initiation from 0.35 new thaw slump yr,1 over the 1954,71 period to 0.68 new thaw slump yr,1 over the 1985,2004 period. This increase follows the pattern of the 10-year running mean summer air temperature record over the 1950,2004 period. However, the total number of active mature thaw slumps on the Aklavik Plateau decreased from a maximum of 46 in 1950 to a minimum of 24 observed in 2004, which follows, to a certain extent, the 10-year running average of rainfall. Both these trends may relate to the influence of climate on the erosional processes that are thought to initiate thaw slumps and keep them active in regions of highlands. Copyright © 2009 John Wiley & Sons, Ltd. and Her Majesty the Queen in right of Canada. [source] Carbonatitic Volcanic Genesis of Hetaoqing Fe-Cu Deposit in Central Yunnan, ChinaRESOURCE GEOLOGY, Issue 4 2003Yongbei Zhang Abstract. The Kunyang rift on western margin of Yangtze Platform is a continental rift, and also a rare Precambrian Fe-Cu mineralization zone in China. The Wuding-Lufeng mineralization area in the middle section of the rift is an important part of the zone, and an elliptic-shaped volcanic collapsed basin, controlled by a ring fracture system with carbonatitic volcanic rocks mainly occurring along the northwestern edge of the basin. The Hetaoqing Fe-Cu ore deposit at the western side of the basin is hosted in carbonatitic volcanic rocks and pyroclastic sedimentary rocks. The original ore bodies occur as layers, bands and lenses conformable to the host carbonatitic rocks. The ores usually appear as massive, impregnated and granular in carbonatitic rocks, and as brecciform and sandy in pyroclastic sedimentary rocks. Ore-forming minerals are magnetite, hematite, chalcopy-rite, bornite, pyrite, carrollite, molybdenite, cobaltite and skinnerite, and secondary minerals limonite, chalcocite, azurite, malachite and tenorite. Gangue minerals are calcite, dolomite, ankerite, common hornblende, arfvedsonite, augite, aegirine-augite, albite, phlogopite, biotite, chlorite and apatite. Evidences of mineral chemistry, trace elements and isotopic ratios of ores, as well as geological features, suggest that the original ores are igneous in origin. Chemical features of magnetites in the deposit belong to carbonatite type, and are similar to those from the Bayan Obo carbonatites. The ores are rich in iron, titanium, rare earth elements, niobium, tantalum, gold, silver, phosphor and sulfur. These features indicate that the Fe-Cu deposit associated with volcanic activity in the Wuding-Lufeng basin is alkali-carbonatite volcanic type. [source] Baroclinic development within zonally-varying flowsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 626 2007David M. Schultz Abstract Previous idealized-modelling studies have shown the importance of across-jet barotropic shear to the resulting evolution of cyclones, anticyclones, surface-based fronts, and upper-level fronts. Meanwhile, many observational studies of cyclones have shown the importance of along-jet variations in the horizontal wind speed (i.e. confluence and diffluence). This study investigates the importance of these along-jet (zonal, for zonally-oriented jets) variations in the horizontal wind speed to the resulting structures and evolutions of baroclinic waves, using idealized models of growing baroclinic waves. An idealized primitive-equation channel model is configured with growing baroclinic perturbations embedded within confluent and diffluent background flows. When the baroclinic perturbations are placed in background confluence, the lower-tropospheric frontal structure and evolution initially resemble the Shapiro,Keyser cyclone model, with a zonally-oriented cyclone, strong warm front, and bent-back warm front. Later, as the baroclinic wave is amplified in the stronger downstream baroclinicity, the warm sector of the cyclone narrows, becoming more reminiscent of the Norwegian cyclone model. The upper-level frontal structure develops with a southwest,northeast orientation, and becomes strongest at the base of the trough, where geostrophic cold advection is occurring. In contrast, when the baroclinic perturbations are placed in background diffluence, the lower-tropospheric frontal structure and evolution resemble the Norwegian cyclone model, with a meridionally-oriented cyclone, strong cold front, and occluded front. The upper-level frontal structure is initially oriented northwest,southeast on the western side of the trough, before becoming zonally oriented. Weak geostrophic temperature advection occurs along its length. These results are compared to those from previous observational and idealized-modelling studies. Copyright © 2007 Royal Meteorological Society [source] Ground-penetrating radar and magnetic survey to the west of Al-Zayyan Temple, Kharga Oasis, Al-Wadi Al-Jadeed (New Valley), EgyptARCHAEOLOGICAL PROSPECTION, Issue 2 2002Dr. Hiroyuki Kamei Abstract Al-Zayyan Temple or Qasr Al-Zayyan might be regarded as one in a chain of several fortresses that the Romans built to secure the salver's trade caravan route between Asyut and Sudan, known as Darb Al-Arbain. Al-Zayyan temple lies about 25 km south of Al-Kharga city, the capital of the New Valley, and deviates to the east of Al-Kharga-Paris main road some 2 km along the Al-Zayyan-Aarif minor road. The background information about the temple is very scarce, and even what is known is neither clear nor accurate. Some indications have ascribed it to Amenebis and that it was restored during the reign of Emperor Antoninus (AD 138,161). An integrated ground-penetrating radar (GPR)survey using the SIR 2000 Geophysical Survey Systems, Inc. (GSSI) together with magnetic survey using FM36 (GeoScan) and the three component fluxgate gradiometer TRM-70D (Tokin) have been applied to the western side of the temple. The results show relatively large-scale buried structures in a direction intersecting that of the present temple at about 45°. Some particular features within the structure have been speculatively ascribed on the basis of comprehending their signatures in the GPR sections. The magnetic results have improved the identification of some objects revealed by the GPR and provided ideas about some of the other features. Copyright © 2002 John Wiley & Sons, Ltd. [source] Global distribution of the European species of the lichen genus Melanelia Essl.JOURNAL OF BIOGEOGRAPHY, Issue 7 2005Volker Otte Abstract Aim, The global distribution of the European species of Melanelia Essl. (Lichenes: Parmeliaceae) was investigated in order to understand their distribution patterns against the background of ecogeographical and historical factors. Location, The location of the study is global, with a local emphasis on Europe. Methods, Geographical distribution and ecology of the species were investigated on the basis of herbarium studies and data from the literature as well as field observations. Distribution maps were created with ArcView GIS. The distribution patterns are expressed as three-dimensional ,areal formulas', regarding zonal distribution, altitudinal range and oceanicity, using a previously described method. The observed distribution patterns are discussed on the basis of their analogies with vascular plants and with respect to the ecogeographical vs. historical factors reflected by them. Results, With the exception of one species that is endemic to Europe, all species studied occur in both northern continents. A number of species have tropical-alpine outposts, and two species occur also in extratropical zones of the southern hemisphere. Arctic and boreal distributions are circumpolar, while in the southern holarctic zones an affinity to the western sides of both northern continents is frequent. Main conclusions, The distribution patterns appear to be mainly determined by contemporary ecogeographical factors. Most species probably have largely filled their potential distribution, at least within the Holarctic. Thus, the geographical origin and dispersal history of a species cannot reliably be reconstructed; they can be dissimilar in different species with similar distributions. [source] Complementary integrated geophysical investigation around Al-Zayyan temple, Kharga oasis, Al-Wadi Al-Jadeed (New Valley), EgyptARCHAEOLOGICAL PROSPECTION, Issue 3 2005M. A. Atya Abstract Qasr Al-Zayyan or Al-Zayyan temple in Al-Kharga oasis is documented as a node in the fortress chain that was built by the Romans to secure Darb Al-Arbain; the slaver's trade caravan route between Asyuit and Sudan. The historical and archaeological background of the temple is very scarce; it has been ascribed to Amenebis and was restored during the reign of Emperor Antoninus AD 138,161. In March 2001, an integrated ground-penetrating radar (GPR) and magnetic survey to the west of the temple showed the possibility of an existing structural complex intersecting the present temple at about 45°. It was interpreted as a multigate structure or a tomb complex. In March 2002, the relative topographic elevations were measured and the surface archaeological features were marked on a map. Also a complementary integrated geophysical survey including electromagnetic, geomagnetic and GPR was conducted along northern and western extensions of, and partially covering, the formerly prospected structure in the survey of 2001. It was designed to verify the structure, to define its extent on both the northern and western sides, and to decide about a possible excavation. The results verified the formerly prospected structure of 2001; some of its particular features have been detected. The structure therefore has been mapped over the surveyed area at the northern and western parts of the 2001 structure and it might extend wider than the surveyed area. The former proposition of a multigate structure becomes stronger because of its general appearance, and the idea of a tomb complex still exists owing to the presence of some depressions thought to be graves. Copyright © 2005 John Wiley & Sons, Ltd. [source] |