The ocean tide can cause the redistribution of the seawater mass, resulting in earth＇s surface deforma- tion, namely ocean tidal loading （OTL）. OTL vertical displacement may reach several centimeters, especially in...The ocean tide can cause the redistribution of the seawater mass, resulting in earth＇s surface deforma- tion, namely ocean tidal loading （OTL）. OTL vertical displacement may reach several centimeters, especially in coastal areas, so its effect in the field of high precision geodesy must be considered. This study concentrates on the influences of OTL on InSAR deformation measurements. We improve the osu.chinasea.2010 regional model and then compare the improved regional model with other regional models. It turns out that the improved regional model can achieve higher precision. Then we use it to replace the offshore part of the global model to generate the present model. We find that the displacement observed by the present model is 2-3 mm larger than that of other models on some sites. Finally, the present model is used to correct the deformation observed by InSAR of Shanghai and Los Angeles. A comparison between the displacements of IGS station with the corrected data shows that the OTL correction can improve the accuracy of InSAR deformation results by about 20%.展开更多
The Assosa region of western Ethiopia hosts newly discovered and potentially highly economic graphite-bearing schist units. Due to its unique physical and chemical properties, graphite is quickly becoming an increasin...The Assosa region of western Ethiopia hosts newly discovered and potentially highly economic graphite-bearing schist units. Due to its unique physical and chemical properties, graphite is quickly becoming an increasingly important economic resource. Graphite occurs over much of the area, and is hosted predominantly by quartz-graphitic schist, quartz-feldspar-mica schist and quartzite. The quartz-graphitic schist covers an area of 37 km2, forming steep valleys and ridges across a 190 km long belt. Graphite is texturally-variable within and across units. Crystal habit varies from highly crystalline to irregular flakes. Flake sizes range from amorphous and crystalline small flake to coarse large flake （〉 150 p.m）, with beneficiation of- 70% and yield potential of 〉 95% （froth flotation methods）. The license area is already a well-known gold-hosting area, and potentially economic gold deposits occur within the graphite-bearing units. Overall, the site shows excellent geochemical indicators, field observations and historical accounts of high gold content. It is suggested that textural variations may be the product of （1） early in-situ formation during （early- to late-Proterozoic） prograde metamorphism and （2） later vein-type mineralization during retrograde metamorphism. The discovery of graphite in western Ethiopia is the first documented and preliminary studies suggest a high economic potential for the deposits.展开更多
基金supported by the National Natural Science Foundation of China(41404013,U1531128)
文摘The ocean tide can cause the redistribution of the seawater mass, resulting in earth＇s surface deforma- tion, namely ocean tidal loading （OTL）. OTL vertical displacement may reach several centimeters, especially in coastal areas, so its effect in the field of high precision geodesy must be considered. This study concentrates on the influences of OTL on InSAR deformation measurements. We improve the osu.chinasea.2010 regional model and then compare the improved regional model with other regional models. It turns out that the improved regional model can achieve higher precision. Then we use it to replace the offshore part of the global model to generate the present model. We find that the displacement observed by the present model is 2-3 mm larger than that of other models on some sites. Finally, the present model is used to correct the deformation observed by InSAR of Shanghai and Los Angeles. A comparison between the displacements of IGS station with the corrected data shows that the OTL correction can improve the accuracy of InSAR deformation results by about 20%.
文摘The Assosa region of western Ethiopia hosts newly discovered and potentially highly economic graphite-bearing schist units. Due to its unique physical and chemical properties, graphite is quickly becoming an increasingly important economic resource. Graphite occurs over much of the area, and is hosted predominantly by quartz-graphitic schist, quartz-feldspar-mica schist and quartzite. The quartz-graphitic schist covers an area of 37 km2, forming steep valleys and ridges across a 190 km long belt. Graphite is texturally-variable within and across units. Crystal habit varies from highly crystalline to irregular flakes. Flake sizes range from amorphous and crystalline small flake to coarse large flake （〉 150 p.m）, with beneficiation of- 70% and yield potential of 〉 95% （froth flotation methods）. The license area is already a well-known gold-hosting area, and potentially economic gold deposits occur within the graphite-bearing units. Overall, the site shows excellent geochemical indicators, field observations and historical accounts of high gold content. It is suggested that textural variations may be the product of （1） early in-situ formation during （early- to late-Proterozoic） prograde metamorphism and （2） later vein-type mineralization during retrograde metamorphism. The discovery of graphite in western Ethiopia is the first documented and preliminary studies suggest a high economic potential for the deposits.
