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111.
R. Abdullah U. Shaanan K. Lynn G. Rosenbaum 《Australian Journal of Earth Sciences》2020,67(2):153-173
AbstractCambrian deformation associated with the Delamerian Orogeny is most evident in the Delamerian Orogen (southwestern Tasmanides) but has also been documented in the Thomson Orogen (northern Tasmanides). The tectonic evolution of the Thomson Orogen in the context of the Delamerian Orogeny is poorly understood. In particular, tectonostratigraphic relationships between the different parts of the Thomson Orogen (Anakie Inlier, Nebine Ridge, and southern Thomson Orogen) are still unclear. New detrital zircon data from the Nebine Ridge revealed an age spectrum that is consistent with published geochronological data from the Anakie Inlier. These results, in conjunction with petrographic observations and the interpretation of geophysical data, suggest that along the eastern part of the Thomson Orogen, the?~?NNE-trending Nebine Ridge represents the southward continuation of the?~?N–S-trending Anakie Inlier. New detrital zircon geochronological data are also presented for metasedimentary rocks from both sides of the Thomson–Lachlan boundary. The results constrain the maximum age of deposition (Ordovician–Devonian), and show that both sides of the Thomson–Lachlan boundary received detritus from a similar provenance. This might suggest that the Thomson–Lachlan boundary did not play a major role as a crustal-scale boundary prior to the Devonian. We speculate that transpressional deformation along this?~?E–W boundary, during the Early Devonian, was responsible for disrupting the original belt that connected the Delamerian Orogen (Koonenberry Belt) with the eastern Thomson Orogen (Nebine Ridge and Anakie Inlier).
- Highlights
The Nebine Ridge is the southward continuation of the Anakie Inlier.
The Anakie Inlier and Nebine Ridge represent a northern segment of the Cambrian Delamerian–Thomson Belt.
~E–W-trending crustal-scale structures at the southern Thomson Orogen were active during Devonian.
112.
113.
The low-redshift IGM probes the last ten billion years of metal enrichment from galactic feedback processes. We present preliminary results from a survey of intergalactic metal-line absorption systems in archival HST STIS, GHRS, and FUSE spectra of ≈50 z?2 UV-bright objects. We summarize the detailed analysis of one sightline (PKS1302–102, z QSO =0.2784) with which we set the methodology for the larger survey. We use simple CLOUDY models to constrain the ionizing mechanism(s) and metallicities for the metal-line systems. For about 15 sightlines, including PKS1302–102, we have a complementary galaxy survey, and we look for correlations between galaxies and absorption systems in order to understand the large-scale distribution of the metal-enriched IGM. 相似文献
114.
This study used “factor separation” to quantify the sensitivity of simulated present and future surface temperatures and precipitation to alternative regional climate model physics components. The method enables a quantitative isolation of the effects of using each physical component as well as the combined effect of two or more components. Simulation results are presented from eight versions of the Mesoscale Modeling System Version 5 (MM5), one-way nested within one version of the Goddard Institute for Space Studies Atmosphere-Ocean Global Climate Model (GISS AOGCM). The MM5 simulations were made at 108 km grid spacing over the continental United States for five summers in the 1990s and 2050s. Results show that the choice of cumulus convection parameterization is the most important “factor” in the simulation of contemporary surface summer temperatures and precipitation over both the western and eastern USA. The choice of boundary layer scheme and radiation package also increases the range of model simulation results. Moreover, the alternative configurations give quite different results for surface temperature and precipitation in the 2050s. For example, simulated 2050s surface temperatures by the scheme with the coolest 1990s surface temperatures are comparable to 1990s temperatures produced by other schemes. The study analyzes the spatial distribution of 1990s to 2050s projected changes in the surface temperature for the eight MM5 versions. The predicted surface temperature change at a given grid point, averaged over all eight model configurations, is generally about twice the standard deviation of the eight predicted changes, indicating relative consensus among the different model projections. Factor separation analysis indicates that the choice of cumulus parameterization is the most important modeling factor amongst the three tested contributing to the computed 1990s to 2050s surface temperature change, although enhanced warming over many areas is also attributable to synergistic effects of changing all three model components. Simulated ensemble mean precipitation changes, however, are very small and generally smaller than the inter-model standard deviations. The MM5 versions therefore offer little consensus regarding 1990s to 2050s changes in precipitation rates. 相似文献
115.
Ronald E. Stewart Daniel Betancourt James B. Davies Deborah Harford Yaheli Klein Robert Lannigan Linda Mortsch Erin O’Connell Kathy Tang Paul H. Whitfield 《Natural Hazards》2017,87(2):791-815
Using studies of places where heat waves are common, projected changes in heat waves in Metro Vancouver are assessed from a multi-disciplinary perspective with respect to the potential impacts of the physical change on the people and infrastructure with the intention of being better prepared for future events. Trends in maximum temperature parameters for Metro Vancouver for the past 75 years are generally not statistically significant; however, projections for 2041–2060 and 2081–2100 suggest that the region will experience such events more frequently in the future due to climate change. While Metro Vancouver, British Columbia (BC) generally does not typically experience heat waves it was strongly affected by a major heat event in July 2009, with temperature records being broken at Vancouver (≥31 °C) on the coast and at Abbotsford (≥36 °C) 65-km inland. A lack of sea breeze during this event meant that there was no cooling effect, and land surface temperatures over the downtown area approached 40 °C and excess deaths occurred. Many victims were either in the 65–74 age category, the vulnerable poor, or people with mental health issues. Because these events are rare, many buildings lack air-conditioning, and residents of Metro Vancouver under-anticipate their vulnerability. The costs of health-related impacts outweighed those related to higher electricity usage. 相似文献
116.
Restoration of Florida’s Everglades requires scientifically supportable hydrologic targets. This study establishes a restoration
baseline by developing a method to simulate hydrologic and salinity conditions prior to anthropogenic changes. The method
couples paleoecologic data on long-term historic ecosystem conditions with statistical models derived from observed meteorologic
and hydrologic data that provide seasonal and annual variation. Results indicate that pre-drainage freshwater levels and hydroperiods
in major sloughs of the Everglades were about 0.15 m higher and two to four times greater, respectively, on average compared
to today’s values. Pre-drainage freshwater delivered to the wetlands and estuaries is estimated to be 2.5 to four times greater
than the modern-day flow, and the largest deficit is during the dry season. In Florida Bay, salinity has increased between
5.3 and 20.1 with the largest differences in the areas near freshwater outflow points. These results suggest that additional
freshwater flows to the Everglades are needed for restoration of the freshwater marshes of the Everglades and estuarine environment
of Florida Bay, particularly near the end of the dry season. 相似文献
117.
Preliminary investigation of some large landslides triggered by the 2008 Wenchuan earthquake, Sichuan Province, China 总被引:14,自引:5,他引:9
Fawu Wang Qiangong Cheng Lynn Highland Masakatsu Miyajima Huabin Wang Changgen Yan 《Landslides》2009,6(1):47-54
The M
s 8.0 Wenchuan earthquake or “Great Sichuan Earthquake” occurred at 14:28 p.m. local time on 12 May 2008 in Sichuan Province, China. Damage by earthquake-induced landslides was an important part of the
total earthquake damage. This report presents preliminary observations on the Hongyan Resort slide located southwest of the
main epicenter, shallow mountain surface failures in Xuankou village of Yingxiu Town, the Jiufengchun slide near Longmenshan
Town, the Hongsong Hydro-power Station slide near Hongbai Town, the Xiaojiaqiao slide in Chaping Town, two landslides in Beichuan
County-town which destroyed a large part of the town, and the Donghekou and Shibangou slides in Qingchuan County which formed
the second biggest landslide lake formed in this earthquake. The influences of seismic, topographic, geologic, and hydro-geologic
conditions are discussed. 相似文献
118.
119.
The reprojection of image data causes the loss or duplication of original pixel values. This research investigated the feasibility of using the sinusoidal projection for global image database construction. Specifically, reprojection accuracies were tested with geographic latitude and longitude coordinates, and the Hammer‐Aitoff, Eckert IV, Mollweide, and sinusoidal projections. Reprojections between these five global projections and the Universal Transverse Mercator (UTM) projection and referencing system were performed using fifty‐four sample datasets. A statistical analysis of categorical accuracy, a measure describing the omission of pixel values during reprojection, was conducted. Geographic coordinates and the sinusoidal projection both showed very high accuracy rates (100.0 percent and 99.5 percent respectively) when sample datasets were reprojected from UTM. The geographic coordinates, however, showed very low accuracy (65.3 percent) when sample datasets were reprojected to the UTM projection, while the sinusoidal projection showed the highest accuracy (98.4 percent). The results strongly suggest that the sinusoidal projection is very accurate and efficient for building global image databases. 相似文献
120.
The composition of the Earth's atmosphere is thought to have been highly modified by surface microbiotas and modulated around quantities of gases optimized for growth of these microbiotas. Three diagrams are presented: The first shows a probable order of appearance of major metabolic pathways in microbes that interact with sediment and atmosphere. It is based on evolutionary considerations and was devised independently of the fossil record. The second diagram shows the qualitative emissions and removals of atmospheric gases by obligately anaerobic organisms; it approximates those processes thought to have dominated the Earth's atmosphere in Archean times. The third diagrams gaseous emissions and removals by the major groups of organisms, including oxygen-releasing and utilizing forms. Biological gas exchange processes thought to have dominated the atmosphere since the Proterozoic are thus represented. 相似文献