Plate tectonics and planetary convection

1976 ◽  
Vol 13 (2) ◽  
pp. 331-340 ◽  
Author(s):  
E. R. Kanasewich

A series of azimuthal–equidistant map projections, centered on each of the plates of lithosphere, is used to demonstrate the high degree of ordering and symmetry in the major plates. The Pacific and African plates are approximately circular with a radius of 60°. The entire pattern is dominated by these two major plates, exactly antipodal to one another in the form of a dipole. Between the two 'circular' plates is a ring of elliptical plates with irregular boundaries but a organized geometric interrelationship. The average major and minor axes of the 'elliptical' plates, measured at the center of the earth, are 62° ± 6 °and 30° ± 5°, and the major axes are oriented at angles of 56° ± 3 °to lines joining the center of the African plate. The centers of the 'elliptical' plates are arranged within 6° ± 3 °of a great circle path through the North pole. This organized distribution of the major plates is most likely the result of convection currents involving the entire mantle, from the lithosphere to the core. To a first approximation, the convective pattern may be modelled by a superposition of third order spherical harmonics, P03, P13, and P23 in a pattern that regressed from a first spherical harmonic, −P01.

Author(s):  
Stephen Crump ◽  
Kylie Twyford ◽  
Theresa Koroivulaono

Remote and rural education is a resonating issue worldwide, given the new and emerging capabilities of digitization to reduce barriers of distance, time, and space, particularly for Oceania. Issues based on achieving equitable educational access and participation that ameliorates the disadvantages for many students in remote and rural locations of Australasia and the Pacific, compared to those in urban classrooms, are pertinent. Nonetheless, students in remote and rural locations also show great resilience and have built up a trove of informal knowledge from the demands of daily life requiring a high degree of independence and maturity. This is evident in the distance education School of the Air in Australia, the University of the South Pacific, and the Marshall Islands College in the North Pacific. These sites provide insights into strength-based reform strategies intended to improve rural and remote education and training and, consequently, work and life choices.


Author(s):  
А. А. Sidorov ◽  
A. V. Volkov ◽  
А. L. Galyamov

The article discusses the actual aspects of the metallogeny of the Pacific volcanic belts (PVB), which are a complexes of volcanogenic-plutogenic formations associated with the development of the marginal lithosphere and has an expressive specificity of ore formation. It is shown that over time the notions of metallogenic homogeneity of PVB have received a new justification from the position of global plate tectonics. Metallogenic significance of Ag/Au relationships in ore deposits of the PVB is shown. The correlation between porphyry-epithermal and the VMS ore-forming systems, regenerated and rejuvenated epithermal deposits is discussed. Global metallogenic homogeneity of the Pacific ore belt suggests a wide development of analogues of American volcanogenic deposits in its Asian half, including in the North-East of Russia. The main part of the internal zone of the Okhotsko-Chukchi marginal volcanic belt the Udo-Murgal island-arc belt, as well as the Uyandino-Yasachensky and Oloysky volcanic belts, are similar in geological structure not only to the Japanese green tuffs province, but also to other Pacific volcanic zones of the island-arc type and, therefore, within their limits, there is a high probability of revealing the entire variety of deposits of the VMS ore-formation series.


1997 ◽  
Vol 14 (2) ◽  
pp. 172-187
Author(s):  
Arif Sultan

Within a short span of time a number of economic blocs have emergedon the world horizon. In this race, all countriedeveloped, developingand underdeveloped-are included. Members of the North America FreeTrade Agreement (NAITA) and the European Economic Community(EEC) are primarily of the developed countries, while the EconomicCooperation Organization (ECO) and the Association of South EastAsian Nations (ASEAN) are of the developing and underdevelopedAsian countries.The developed countries are scrambling to create hegemonies throughthe General Agreement on Tariff and Trade (GATT). In these circumstances,economic cooperation among Muslim countries should be onthe top of their agenda.Muslim countries today constitute about one-third of the membershipof the United Nations. There are around 56 independentMuslim states with a population of around 800 million coveringabout 20 percent of the land area of the world. Stretchingbetween Atlantic and the Pacific Oceans, the Muslim Worldstraddles from North Africa to Indonesia, in two major Islamicblocs, they are concentrated in the heart of Africa to Indonesia,in two major blocs, they are concentrated in the heart of Africaand Asia and a smaller group in South and Southeast Asia.'GATT is a multilateral agreement on tariffs and trade establishing thecode of rules, regulations, and modalities regulating and operating internationaltrade. It also serves as a forum for discussions and negotiations ...


2018 ◽  
Vol 76 (3) ◽  
pp. 626-638 ◽  
Author(s):  
J Anthony Koslow ◽  
Pete Davison ◽  
Erica Ferrer ◽  
S Patricia A Jiménez Rosenberg ◽  
Gerardo Aceves-Medina ◽  
...  

Abstract Declining oxygen concentrations in the deep ocean, particularly in areas with pronounced oxygen minimum zones (OMZs), are a growing global concern related to global climate change. Its potential impacts on marine life remain poorly understood. A previous study suggested that the abundance of a diverse suite of mesopelagic fishes off southern California was closely linked to trends in midwater oxygen concentration. This study expands the spatial and temporal scale of that analysis to examine how mesopelagic fishes are responding to declining oxygen levels in the California Current (CC) off central, southern, and Baja California. Several warm-water mesopelagic species, apparently adapted to the shallower, more intense OMZ off Baja California, are shown to be increasing despite declining midwater oxygen concentrations and becoming increasingly dominant, initially off Baja California and subsequently in the CC region to the north. Their increased abundance is associated with warming near-surface ocean temperature, the warm phase of the Pacific Decadal oscillation and Multivariate El Niño-Southern Oscillation Index, and the increased flux of Pacific Equatorial Water into the southern CC.


1977 ◽  
Vol 8 (1) ◽  
pp. 128-148 ◽  
Author(s):  
Sylvia J. Hallam

Following several discussions in recent numbers of Quaternary Research on the peopling of the Americas, this paper suggests that movements into the New World should be viewed in the wider context of subsistence, technology, and movement around the western littorals of the Pacific, resulting in the colonization not of one but of two new continents by men out of Asia. Specific points which have been raised by these recent papers are reviewed in the light of Australian, Wallacian, and East Asian data.(1) The earliness of watercraft is evidenced by chronology of the human diaspora through Wallacia and Greater Australia.(2) The simplistic nomenclature of chopper-flake traditions masks considerable complexity and technological potential, revealed in detailed Antipodean studies.(3) These traditions also have great potential for adapting to differing ecological zones, evidenced within Greater Australia; and for technological and economic innovation there, through Southeast Asia, and to Japan and the north Asian littoral.(4) The history of discovery and the nature of the evidence from Australia cannot validly be used to controvert early dates in the Americas.(5) Demographic data from Australia suggest that total commitment to a rapid-spread “bowwave” model for the peopling of new continents may be unwise.


2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Ming-Xiang Mei ◽  
Muhammad Riaz ◽  
Zhen-Wu Zhang ◽  
Qing-Fen Meng ◽  
Yuan Hu

AbstractAs a type of non-laminated microbial carbonates, dendrolites are dominated by isolated dendritic clusters of calcimicrobes and are distinct from stromatolites and thrombolites. The dendrolites in the upper part of the Miaolingian Zhangxia Formation at Anjiazhuang section in Feicheng city of Shandong Province, China, provide an excellent example for further understanding of both growth pattern and forming mechanism of dendrolites. These dendrolites are featured by sedimentary fabrics and composition of calcified microbes as follows. (1) The strata of massive limestones, composed of dendrolites with thickness of more than one hundred meters, intergrade with thick-bedded to massive leiolites, formimg the upper part of a third-order depositional sequence that constitutes a forced regressive systems tract. (2) A centimeter-sized bush-like fabric (shrub) typically produced by calcified microbes is similar to the mesoclot in thrombolites but distinctive from clotted fabrics of thrombolites. This bush-like fabric is actually constituted by diversified calcified microbes like the modern shrub as a result of gliding mobility of filamentous cyanobacteria. Such forms traditionally include: the Epiphyton group (which actually has uncertain biological affinity), the Hedstroemia group which closely resembles modern rivulariacean cyanobacteria, and the possible calcified cyanobacteria of the Lithocodium–Bacinella group. (3) Significantly, dense micrite of leiolite is associated with sponge fossils and burrows, and is covered by microstromatolite. The Lithocodium–Bacinella group is a controversial group of interpreted calcified cyanobacteria in the Cambrian that has also been widely observed and described in the Mesozoic. Therefore, dendrolites with symbiosis of leiolites in the studied section provide an extraordinary example for further understanding of growing style of bush-like fabrics (shrubs) of the dendrolites dominated by cyanobacterial mats. Furthermore, the present research provides some useful thinking approaches for better understanding of the history of the Early Paleozoic skeletal reefs and the microbe–metazoan transitions of the Cambrian.


2021 ◽  
Vol 13 (5) ◽  
pp. 1013
Author(s):  
Kuo-Wei Yen ◽  
Chia-Hsiang Chen

Remote sensing (RS) technology, which can facilitate the sustainable management and development of fisheries, is easily accessible and exhibits high performance. It only requires the collection of sufficient information, establishment of databases and input of human and capital resources for analysis. However, many countries are unable to effectively ensure the sustainable development of marine fisheries due to technological limitations. The main challenge is the gap in the conditions for sustainable development between developed and developing countries. Therefore, this study applied the Web of Science database and geographic information systems to analyze the gaps in fisheries science in various countries over the past 10 years. Most studies have been conducted in the offshore marine areas of the northeastern United States of America. In addition, all research hotspots were located in the Northern Hemisphere, indicating a lack of relevant studies from the Southern Hemisphere. This study also found that research hotspots of satellite RS applications in fisheries were mainly conducted in (1) the northeastern sea area in the United States, (2) the high seas area of the North Atlantic Ocean, (3) the surrounding sea areas of France, Spain and Portugal, (4) the surrounding areas of the Indian Ocean and (5) the East China Sea, Yellow Sea and Bohai Bay sea areas to the north of Taiwan. A comparison of publications examining the three major oceans indicated that the Atlantic Ocean was the most extensively studied in terms of RS applications in fisheries, followed by the Indian Ocean, while the Pacific Ocean was less studied than the aforementioned two regions. In addition, all research hotspots were located in the Northern Hemisphere, indicating a lack of relevant studies from the Southern Hemisphere. The Atlantic Ocean and the Indian Ocean have been the subjects of many local in-depth studies; in the Pacific Ocean, the coastal areas have been abundantly investigated, while offshore local areas have only been sporadically addressed. Collaboration and partnership constitute an efficient approach for transferring skills and technology across countries. For the achievement of the sustainable development goals (SDGs) by 2030, research networks can be expanded to mitigate the research gaps and improve the sustainability of marine fisheries resources.


2021 ◽  
Vol 33 (2) ◽  
pp. 382-411
Author(s):  
Chris Madsen

Henry Eccles, in classic studies on logistics, describes the dynamics of strategic procurement in the supply chain stretching from home countries to military theatres of operations. Naval authorities and industrialists concerned with Japanese aggression before and after Pearl Harbor looked towards developing shipbuilding capacity on North America’s Pacific Coast. The region turned into a volume producer of merchant vessels, warships and auxiliaries destined for service in the Pacific and Indian Oceans. Shipbuilding involved four broad categories of companies in the United States and Canada that enabled the tremendous production effort.


2021 ◽  
Vol 13 (1) ◽  
pp. 215-218
Author(s):  
Federica Veronese ◽  
Francesca Graziola ◽  
Pamela Farinelli ◽  
Elisa Zavattaro ◽  
Vanessa Tarantino ◽  
...  

We describe a case of cutaneous Larva Migrans in an 8-year-old Caucasian girl. The lesion appeared ten days after a bath in the river in a valley in the north-east of Piedmont. The patient was successfully treated with Albendazole 400 mg daily for 5 days. Autochthonous cases are rare, particularly in northern Italy. Probably the high temperatures and the high degree of humidity favored by the climate changes to which Europe is subjected are favorable to the development of larvae. The diagnosis of cutaneous Larva Migrans should, therefore, be considered also in individuals who have not traveled in geographic areas at risk for the climate.


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