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.
cleaning is a matter of countless people hate, and in the power of science and technology, there are more and more sweeping robot brand come out, so that people’s home life has brought greater convenience. Home Furnishing life cleaning believe that many people are more hate, so some people love to use some smart appliances at home, so that they can comfortably use sweeping robot is the most common, the sweeping robot which brand is good? We understand the ten major brands of sweeping robots, which can make a better choice.
sweeping robot ten brands list NO.1:iRobot
Hunan of high-tech smart division where the limited supply of equipment, ten sweeping robot brand, founded in 1990, the global leader in household robot, pioneered the world’s first domestic cleaning robot, a listed company, the world’s most innovative magazine new invention award, the red dot design award, to enter the world of robot Hall of fame, science and Technology Innovation Award Chinese home appliances Expo Yipu lan.
mainstream models: iRobot 65056708 good partner portfolio, etc.
sweeping robot ten brand list: Ecovacs ECOVACS
robot technology (Suzhou) Co. Ltd., sweeping robot ten brands, key national Torch Plan high-tech enterprises in Jiangsu Province, well-known trademarks, brand-name products in Jiangsu Province, high-tech enterprises in Jiangsu Province, the national demonstration enterprise transformation upgrade of processing trade, Jiangsu Province outstanding innovative enterprises.
from the popular Ding Ding, to the recent explosion of blossoming, and a new upgrade every s.
sweeping robot ten brands list NO.3:Proscenic
Taiwan Pu Sonny grams of Polytron Technologies Inc, ten big brands focus on Intelligent sweeping robot, the field of clean development and production, intelligent sweeping machine industry well-known brands, to create market leading technology industry association, Taiwan permanent council members of the robot design standard for unit, Taiwan won the excellent prize.
sweeping robot ten brands list NO.4: FOMART
Beijing lierpu Electrical Appliance Co., Ltd., FOMART, sweeping robot ten brands, well-known (famous) cleaner brand, founded in 1999 in Sweden, the world’s leading brands of smart household cleaning market, Chinese intelligent vacuum cleaner (robot) leader, one of the first domestic intelligent sweeping machine enterprise.