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.
With the rapid development of
network media, the network journalism has shown a strong vitality, and it will inevitably put forward a new requirement for the quality of network news practitioners. Network news media practitioners of the occupation quality determines the quality of the network media to provide information, determines the quality of the information network in China, from a national perspective, is key to our success in the international competition in the Information Sovereignty! Therefore, strengthen the network news media practitioners of occupation quality training. To improve the quality of occupation, the netizen is a good thing for the state information sovereignty is a good thing! It is urgent to strengthen the network news media practitioners of the occupation literacy
network news communication should be "high energy reporter", namely "has not only profound knowledge of Humanities and Social Sciences, and familiar with news gathering and editing business, modern journalism talents but also acquire modern communication skills". The quality of all-round network news practitioners should include profound theoretical foundation, consummate professional skills, good moral cultivation and advanced communication concepts.
network news "soft underbelly"
is, first of all, false news. In recent years, false news has emerged, such as false news, "women’s volleyball girl, 20 years Olympic champion, dream of failure to round", "Bill Gates assassination", "Millennium mummy unearthed after pregnancy" and so on. According to statistics, most of them are reprinted by network news, the popularity of the Internet, the increase of the media category, greatly accelerated the speed of the spread of various information, expanding the people’s vision of the news. At the same time, the deliberately fabricated "false curiosity" news is flooded with various media and flooded every corner of the network.
followed by low severity. Most commercial websites tend to have a tendency to kitsch, and there are a lot of vulgar, violent and pornographic information in the web. They change news into "sex", "smell", "Star", and "smell". Such news is spreading and even spreading in many websites, especially in culture, entertainment, news and sports.
three is bad advertising, advertising, news, more. For example, some illegal medical advertisements; containing fraudulent information, get rich quick erotic voice advertising, some special false promises of real estate advertising and the use of so-called soft advertising news package and so on, these ads greatly harm the interests of the audience.
network editors do?
news network fraud almost form a "occupation", the personnel structure, a part-time writer, scattered in all walks of life; two is a freelance writer, they have no work unit, the occupation is. Especially the latter, what genre they have written on the line, as long as you can make money. Fabrications of false news freak, because this part of the hands. For some social writers, making up false news is no longer an occasional one, but a "professional" operation and a means of livelihood.
false news today, just like a runaway horse, if not timely tame, will be endless troubles. As our web site >