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51.
提出了冰雷达数据处理的流程,详细论述了冰雷达数据处理中常规修正的关键技术：静态校正、增益控制、带通滤波以及偏移处理等。以中国第24次南极科学考察（CHINARE 24）所获取的Dome A 地区30 km×30 km范围冰雷达原始数据处理作为实例,提取得到了该区域冰盖内部等时层埋深以及冰盖的冰厚数据。通过插值展现了冰盖等时层以及冰岩界面的三维空间形态。结合该区域ICESat冰盖表面高程数据,构建出了Dome A地区涵盖冰盖表面、冰盖等时层以及冰岩界面形态特征的三维模型。 相似文献
52.
Located on the centre of ice drainage range, the highest Dome Argus （Dome A） of East Antarctic Ice Sheet （EAIS）, could be represented as an ideal site for deep ice cores drilling containing oldest paleo-climate records. To select a suitable drilling site for deep ice core, it needs gather all information pertaining to the local meteorology, ice sheet landforms, ice thickness, subgla- cial topography of bed rocks, ice velocity, internal structures of ice sheet, etc. Based on the International Partnerships in Ice Core Sciences （IPICS）, we present recent achievement of glaciological research and its perspective at Dome A in this paper. We system- atically discussed the merits and possible ventures of potential drilling sites around Dome A. Among all the candidates, we find that the Chinese Antarctic Kunlun Station is the best site for and assess further the possibility to obtain a replicate core for carrying out the first deep ice core drilling campaign. We emphasize studying dynamics and evolution of climate change. 相似文献
53.
54.
Thermal models for Barrovian metamorphism driven by doubling the thickness of the radiogenic crust typically meet difficulty in accounting for the observed peak metamorphic temperature conditions. This difficulty suggests that there is an additional component in the thermal budget of many collisional orogens. Theoretical and geological considerations suggest that viscous heating is a cumulative process that may explain the heat deficit in collision orogens. The results of 2D numerical modelling of continental collision involving subduction of the lithospheric mantle demonstrate that geologically plausible stresses and strain rates may result in orogen‐scale viscous heat production of 0.1 to >1 μW m?3, which is comparable to or even exceeds bulk radiogenic heat production within the crust. Thermally induced buoyancy is responsible for crustal upwelling in large domes with metamorphic temperatures up to 200 °C higher than regional background temperatures. Heat is mostly generated within the uppermost mantle, because of large stresses in the highly viscous rocks deforming there. This thermal energy may be transferred to the overlying crust either in the form of enhanced heat flow, or through magmatism that brings heat into the crust advectively. The amplitude of orogenic heating varies with time, with both the amplitude and time‐span depending strongly on the coupling between heat production, viscosity and collision strain rate. It is argued that geologically relevant figures are applicable to metamorphic domes such as the Lepontine Dome in the Central Alps. We conclude that deformation‐generated viscous dissipation is an important heat source during collisional orogeny and that high metamorphic temperatures as in Barrovian type metamorphism are inherent to deforming crustal regions. 相似文献
55.
The Mont-de-l’Aigle deposit is located in the northern part of Dome Lemieux, in the Connecticut Valley-Gaspé Synclinorium, Gaspé Peninsula, Québec. The Dome Lemieux is a subcircular antiform of Siluro–Devonian sedimentary rocks that is cut by numerous mafic and felsic sills and dikes of Silurian to Late Devonian age. Plutonism occurred in a continental within-plate extensional setting typical of orogenic collapse. The Cu−Fe (± Au) mineralization of Mont-de-l’Aigle occurs in veins, stockworks, and breccias. Mineralization is located near or within N−S and NW−SE faults cutting sedimentary rocks. IOCG mineralization postdates intrusions, skarns, hornfels, and epithermal mineralization typical of the southern part of the Dome Lemieux. The paragenetic sequence comprises: (1) pervasive sodic, potassic, chlorite, and silica alteration, (2) hematite, quartz, pyrite, magnetite, and chalcopyrite veins, stockworks and breccias and, (3) dolomite ± hematite veins and veinlets cutting the earlier mineralization. Intrusions display proximal sodic and potassic alteration, whereas sedimentary rocks have proximal decalcification, silicification, and potassic alteration. Both intrusive and sedimentary rocks are affected by a pervasive distal chlorite (± silica) alteration. The sulfur isotope composition of pyrite and chalcopyrite (δ34S=−1.5 to 4.8‰) suggests that sulfur was derived mainly from igneous rocks. Fluid δ18O (−0.4 to 2.65‰) indicates meteoric or seawater that reacted with the country rocks. Mixing of hot magmatic fluids with a cooler fluid, perhaps meteoric or seawater is suggested for mineral deposition and alteration of the Mont-de-l’Aigle deposit. The mineralogy, alteration, and sulfur isotope composition of the Mont-de-l’Aigle deposit compare well with IOCG deposits worldwide, making the Mont-de-l’Aigle deposit a rare example of Paleozoic IOCG mineralization, formed at shallow depth, within a low metamorphic grade sedimentary rock sequence. 相似文献
56.
位于北喜马拉雅穹隆带东段的然巴构造穹隆外围发育环形韧性剪切带,带内岩石经韧性剪切形成各类糜棱状岩石。石英为带内变形岩中最为常见的造岩矿物,在不同的温度、应变速率下产生不同的显微构造,其中动态重结晶最为常见。重结晶新晶颗粒边界普遍具有锯齿状或港湾状结构,是应变和变形环境的天然记录。新晶粒分维几何统计分析表明:带内动态重结晶石英颗粒边界形态具有自相似性(1≤D≤2),表现出分形特征,分维数值为1.14～1.19,变形温度大约500℃。同构造变质环境属中——高绿片岩相;初步估算古应变速率可能低于10-9.5S-1;根据重结晶粒径估算变形古应力6.2～58.8MPa。 相似文献
57.
概述了GLAS高度计的在轨性能，分析了其数据产品的精度。利用高精度的ICESat卫星测高数据，以及第21次中国南极科学考察内陆冰盖考察GPS的实测资料，验证了此次考察中南极内陆冰盖Dome A最高点可能区域选取的正确性，并分析了Dome A最高点位置测定的准确性。 相似文献
58.
藏南康马拆离断层的构造特征及其活动时代 总被引：1，自引：0，他引：1
藏南康马穹窿是北喜马拉雅片麻岩穹窿的经典代表,穹窿内发育上、下两条拆离断层并将穹窿分为三个构造层,其中上拆离断层分隔了上构造层未变质/轻微变质的特提斯喜马拉雅沉积岩系和中构造层的石榴石二云母片岩,而下拆离断层,即康马拆离断层,分隔了中构造层的石榴石二云母片岩和下构造层的片麻状二云母花岗岩。受康马拆离断层的影响,其上下两盘靠近拆离断层面处的岩石遭受强烈的韧性变形改造,形成了糜棱岩化石榴石二云母片岩和花岗质糜棱岩,宏观构造解析以及构造岩的显微构造分析表明,康马拆离断层经历了上盘向北的伸展拆离。本次研究采用40Ar/39Ar定年方法,选择拆离断层带内糜棱岩化石榴石二云母片岩中同变形新生白云母进行年代学测定,结果显示白云母40Ar/39Ar坪年龄为13.23±0.15 Ma,结合宏微观岩石矿物学分析,认为其代表了向北伸展拆离的变形时间,即康马拆离断层的活动时代,该时代与康马穹窿南部的藏南拆离系的活动时代一致,从年代学上暗示二者可能为同一条拆离断层,是在不同区域的出露,但该结论仍然需要更多地质、地球物理等方面的证据来证实。 相似文献
59.
A super El Ni?o event occurred in the equatorial Pacific during 2015-2016,accompanied by considerable regional eco-hydro-climatic variations within the Mindanao Dome(MD)upwelling system in the tropical western Pacific.Using timeseries of various oceanic data from 2013 to 2017,the variability of eco-hydro-climatic conditions response to the 2015/2016 super El Ni?o in the upper 300 m of the MD region are analyzed in this paper.Results showed that during the 2015/2016 super El Ni?o event,the upwelling in the MD region was greatly enhanced compared to those before and after this El Ni?o event.Upwelling Rossby waves and the massive loss of surface water in the western Pacific were suggested to be the main reasons for this enhanced upwelling.De-creased precipitation caused by changes in large-scale air-sea interaction led to the increased surface salinities.Changes in the struc-tures of the thermohaline and nutrient distribution in deep waters contributed to the increased surface chlorophyll a,suggesting a po-sitive effect of El Ni?o on surface carbon storage in the MD region.Based on the above analysis,the synopsis mechanism illustrating the eco-hydro-climatic changing processes over the MD upwelling system responding to the El Ni?o event was proposed.It high-lights the prospect for the role played by El Ni?o in local eco-hydro-climatic effects,which has further profound implications for understanding the influence of the global climate changes on the ocean carbon cycle. 相似文献
60.
High-accuracy topographical information extraction based on fusion of ASTER stereo-data and ICESat/GLAS data in Antarctica 总被引：1，自引：0，他引：1
In order to better support Antarctic inland ice sheet expedition from Zhongshan Station to Dome A, the topographic data are
necessary. At present, although the entire Antarctic DEM provided by RAMP (Radarsat Antarctic Mapping Project) was estimated
at the highest horizontal (spatial) resolution of about 200 m, the real horizontal resolution of the DEM varies from place
to place depending on the density and scale of the original source data. For ice shelves and the inland ice sheet, the horizontal
resolution is about 5 km; the vertical accuracy is estimated to be ±50 m in interior East Antarctic ice sheet and away from
the mountain ranges. Therefore, more accurate topographic data are unavailable in Antarctica. In order to meet the requirements
of high-accuracy topographic information for further researches, this paper mainly addresses a fusion study of ASTER stereo
pairs and ICESat/GLAS altimetry data for extraction of high-accuracy DEM in East Antarctica, based on the high horizontal
resolution (15 m) of ASTER and vertical accuracy (13.8 cm) of ICESat/GLAS. First, some altimetry data were selected as vertical
control points to reduce errors of image correlation matching during the extraction of ASTER-based DEM. Second, ice sheet
altimetry data derived from ICESat were used to generate DEM ranging from 75° to 81°S because existing ASTER data do not cover
this area and high density of the coverage of ICESat altimetry data. Finally, the DEM in coverage of the expedition route
was produced. The analysis of result reveals that the DEM accuracy is improved significantly. The absolute vertical accuracy
of DEM is higher than 15 m in some cases and higher than 30 m for all the areas along the expedition route except from the
009-001 scene; the interior accuracy is higher than 15 m and higher than 7 m in some cases. It can meet the requirements of
topographic map at 1:50000 scale, which is an economic and advantageous method to produce the topographic products.
Supported by National Natural Science Foundation (Grant No. 40606002), Surveying and Mapping in Chinese Antarctic Expedition
Area (Grant No. 1469990711109-1), National Key Technology R & D Program (Grant No. 2006BAD18B01), and GLA12 dataset of ICESat/GLAS
in National Snow and Ice Data Center (NSIDC) 相似文献