The Ancestral South Sandwich Arc (ASSA) has a short life-span of c.20 m.y. (Early Oligocene to Middle-Upper Miocene) before slab retreat and subsequent ‘resurrection’ as the active South Sandwich Island Arc (SSIA). The ASSA is, however, significant because it straddled the eastern margin of the Drake Passage Gateway where it formed a potential barrier to deep ocean water and mantle flow from the Pacific to Atlantic. The ASSA may be divided into three parts, from north to south: the Central Scotia Sea (CSS), the Discovery segment, and the Jane segment. Published age data coupled with new geochemical data (major elements, trace elements, Hf-Nd-Sr-Pb isotopes) from the three ASSA segments place constraints on models for the evolution of the arc and hence gateway development. The CSS segment has two known periods of activity. The older, Oligocene, period produced basic-acid, mostly calc-alkaline rocks, best explained in terms of subduction initiation volcanism of Andean-type (no slab rollback). The younger, Middle-Late Miocene period produced basic-acid, high-K calc-alkaline rocks (lavas and pyroclastic rocks with abundant volcanigenic sediments) which, despite being erupted on oceanic crust, have continental arc characteristics best explained in terms of a large, hot subduction flux most typical of a syn- or post-collision arc setting. Early-Middle Miocene volcanism in the Discovery and Jane arc segments is geochemically quite different, being typically tholeiitic and compositionally similar to many lavas from the active South Sandwich island arc front. There is indirect evidence for Western Pacific-type (slab rollback) subduction initiation in the southern part of the ASSA and for the back-arc basins (the Jane and Scan Basins) to have been active at the time of arc volcanism. Models for the death of the ASSA in the south following a series of ridge-trench collisions, are not positively supported by any geochemical evidence of hot subduction, but cessation of subduction by approach of progressively more buoyant oceanic lithosphere is consistent with both geochemistry and geodynamics. In terms of deep ocean water flow the early stages of spreading at the East Scotia Ridge (starting at 17-15 Ma) may have been important in breaking up the ASSA barrier while the subsequent establishment of a STEP (Subduction-Transform Edge Propagator) fault east of the South Georgia microcontinent (< 11 Ma) led to formation of the South Georgia Passage used by the Antarctic Circumpolar Current today. In terms of mantle flow, the subduction zone and arc root likely acted as a barrier to mantle flow in the CSS arc segment such that the ASSA itself became the Pacific-South Atlantic mantle domain boundary. This was not the case in the Discovery and Jane arc segments, however, because northwards flow of South Atlantic mantle behind the southern part of the ASSA gave an Atlantic provenance to the whole southern ASSA.
to resettle is to solve the problem of "one water can’t afford people" the most direct and effective way, in accordance with the province’s economic and social development law, in accordance with the long-term need for ecological protection, meet the urgent desire of the people live and work in peace. In April 8th, the reporter learned from the provincial poverty alleviation and Development Bureau, according to the "Qinghai province" in 13th Five-Year "to resettle plan" (hereinafter referred to as the "plan"), "13th Five-Year" period, the province’s relocation task is completed 200 thousand impoverished population, accounted for 38.5% of the population out of poverty.
crack one side of the soil and water can not feed a person problem
provincial Party committee and government attach great importance to the work of poverty alleviation and relocation, and take this work as a fundamental measure to solve the problem of "one side is difficult to feed one side". The causes of poverty are diverse, our province to take measures to promote poverty alleviation of poverty, easily relocated is one of the important measures. Why do you want to relocate? The main reasons are as follows: first, because one side of the soil and water can not feed a person, easy to move the village in the mountains, deep ditch, poor natural conditions, poor land, traffic information blocking place. Two years, the Party committee and the government invested a lot of financial resources, the local people also want a lot of ways to pay a hard effort, but still can not change the face of poverty there. Practical experience tells us that the relocation is easy to solve the one side of the soil and water can not feed a person, the most direct and effective way.
who wants to move?
relocated more than 50 thousand, 200 thousand
according to the "plan", "13th Five-Year" period, our province to resettle work adhere to government led, voluntary participation of the masses, according to local conditions, the implementation of the classification, urban and rural areas, comprehensive development, integration of resources, and vigorously promote the construction of the principle of force. To live in the "one water can’t afford people" local participatory poverty implementation to be relocated, with centralized resettlement, to improve the supporting infrastructure and public service as the focus, to support the follow-up industry as the foundation, and strive to move out, live firmly, something to do, to get rich. To ensure that the removal of the object as soon as possible out of poverty, and strive to ease the relocation of the village to build a new socialist countryside, new pastoral areas.
from 2016 to 2019, the province will be in 8 cities (prefectures), 38 counties (cities, districts), 279 townships (towns), the implementation of the village of poverty alleviation projects in the village, the relocation of 52480 households, the 200067 people in the city, the people’s Republic of China, the city of poverty and poverty alleviation projects, the implementation of the project to help the poor, the relocation of 1234 people. Xining, Haidong city two relocation of 23750 households, 94890 people, accounted for 45.3% of the total size of the province’s relocation and 47.4% in six states; relocation of 28730 households, 105177 people, accounted for the province’s total relocation scale of 54.7% and 52.6%.
want to move?
moved out of the hope of moving out of a happy life
through easy to move to move ideas, move, move the spirit of struggle, confidence and hope to move gratitude;