984 resultados para Pacific Coast (North America)


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Analyses of the isotopic composition of Pb in (1) western Pacific Ocean sediments [Jurassic(?) to Pleistocene in age, including clays and biogenic oozes], (2) Pacific Ocean basaltic rocks, (3) Mariana frontal arc volcanic rocks (Eocene to Miocene), and (4) Mariana active arc volcanic rocks [Pliocene (?) to Holocene] indicate that Pacific Ocean sediments could not have been a significant component of the source material for the Mariana arc volcanic rocks. Calculations involving the average concentrations and isotopic compositions of Pb in oceanic sediments, sea-floor basaltic rocks, and the Mariana arc volcanic rocks suggest that the sediment component must have been less than 1 percent of this source material. The Pb isotopic compositions of the Mariana arc volcanic rocks lie, within experimental error, along the trend of available Pacific Ocean basalt analyses in versus 207Pb/204Pb versus 206Pb/204Pb and 208Pb/204Pb versus 206Pb/204Pb diagrams. Isotopic analyses of Pb in Pacific Ocean sediments do not lie along this trend; they have higher 207Pb/204Pb and 208Pb/204Pb values for comparable 206Pb/204Pb ratios. Clayey sediments generally have higher 208Pb/204Pb and 207Pb/204Pb ratios than biogenic oozes regardless of the age of the sediment. Comparison of combined Sr and Pb isotopic analyses for (1) mantle-derived materials erupted through oceanic crust, (2) altered ocean-floor basaltic rocks, and (3) volcanic rocks from oceanic island arcs suggests that the Mariana arc volcanic rocks were derived, at least in part, from altered Pacific lithosphere subducted beneath the Mariana arc. Unaltered basalts from the Mariana inter-arc basin (Mariana Trough) have Pb and Sr isotopic compositions that are very similar to those reported for some Hawaiian volcanic rocks but distinct from Mariana active and frontal arc compositions. These observations, in addition to existing major-and trace-element data, support a mantle origin for the interarc basin volcanic rocks. Dacites dredged from the Mariana remnant arc (South Honshu Ridge) have Pb isotopic compositions that are within experimental error of the active-arc analyses, consistent with a genetic relation.

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Sediments from the Cretaceous/Tertiary (K/T) boundary at Deep Sea Drilling Project Site 596 record accumulation of pelagic clays at about lat 45°S,in the center of the ancestral South Pacific. The K/T boundary in this region is characterized by oxidized, thoroughly bioturbated sediments containing large amounts of Ir and relict high-pressure and high-temperature mineral phases. The net Ir fluence (320 ng/cm**2) is among the largest on Earth, and the number of shocked quartz grains >30 µm in size (~1800/cm**2) exceeds that in all localities outside of North America.

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This paper gives a global summary of the number of constitutions and the number of articles in each constitution for many representative countries around the world. Several works have already been written comparing different legal systems and different constitutional traditions around the world; the purpose of this paper is just to compare the numbers of constitutions and articles in the diverse regions of the world, namely: North America, Latin America, Europe, Oceania, Middle East, Asia and Africa. Around the world, on average, Latin America has had the most convoluted constitutional history. The Dominican Republic has had a total of 32 constitutions, the largest number of constitutions of any country, since its independence in 1844. Three other countries have also had 20 or more constitutions throughout their history, all of them in Latin America: Venezuela (26), Haiti (24) and Ecuador (20). On the other hand, there are economies and societies that do not even have codified constitutions, like the United Kingdom in Europe, Hong Kong in Asia and New Zealand in Oceania. The United States has had only one constitution, even if it has been amended several times. There are also the special cases of Israel and Saudi Arabia, both in the Middle East, that do not have official written constitutions for historical and religious reasons. Comparative constitutional numbers and history help explain several things about the stability of political systems, but not necessarily about their quality.

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This study maps out the degree of services trade liberalization by the APEC members toward achieving a Free Trade Area of the Asia-Pacific (FTAAP) and makes some comparative analyses. The study finds that the commitment level differs greatly between sensitive and less sensitive sectors, and that the commitment level under the ASEAN Framework Agreement (AFAS) package 8 is the highest among the four FTAs studied. It also finds that there are cross-country and sector-wide similarities in the pattern of service sector commitment under and across each of the FTAs; this implies that the shared domestic sensitivities can be overcome by an APEC-wide economic cooperation scheme for enhancing competitiveness (through, e.g., the Trans-Pacific Strategic Economic Partnership Agreement or TPP).

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One of the most important policy questions relating to the future impact of the Trans-Pacific Partnership on the global and regional economy is whether other countries in the region, particularly China, will join the partnership. While several commentators have made some observations regarding the future prospects of TPP expansion, little scholarly analysis has been conducted. To go beyond the speculation of a certain country's accession to TPP, we first attempt to generalize the issue before moving on to a specific question. We conduct a comparative analysis of a large number of regional trade agreements for a better understanding of the parameters of RTAs that are critical for membership expansion. This general framework enables us to conduct a systematic examination of specific membership expansion cases, such as China's membership in TPP. The paper also proposes a necessary "accession practice" that truly facilitates new members' participation.

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There are few previous references to fossil crustaceans for the Neogene marine layers of the Canary Islands (Spain). The Mio-Pliocene marine sedimentary layers in the eastern islands (Gran Canaria, Fuerteventura and Lanzarote) were previously characterised by the presence of numerous fossil fauna, mainly anthozoans and molluscs, which correspond to an equatorial-typepalaeoclimate, warmer than the present climate. This Mio-Pliocene transition dated between 9.3 and 4.1 Ma. In this paper, 12 fossil crustacean taxa are identified and classified, including decapods and barnacles: Balanus concavus Bronn, 1831, Balanus spongicola Brown, 1827, Balanus perforatus Bruguière, 1789, Chenolobia testudinaria Linnè, 1767, Tetraclita cf. rubescens Darwin, 1854, Callianassa matsoni Rathbun, 1935, Callianassa sp., Upogebia sp, Eriphia aff. verrucosa (Forskal, 1775) , Maja sp., Scylla michelini Milne-Edwards, 1861 and Ocypode sp. Some of these taxa mean new references for the Atlantic islands and the North African Atlantic and definitely enlarge the palaeographic distribution of Neogene crustaceans beyond the Mediterranean region, extending it to the North Atlantic. Particularly significant are the presence of Tetraclita cf. rubescens ,this being the first reported fossil occurrence of this barnacle outside the North America Pacific coasts, and Chenolobia testudinaria , indicating for the first time the existence of marine turtles in these islands during the Neogene. These results are coherent with previous research hypothesising the existence of a flow of surface water between the Pacific and Atlantic in the Mio-Pliocene transition (Central American Seaway, CAS) which explains the arrival of organisms, in larval stage, from Central America to the Canary Islands

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A densely sampled, diverse new fauna from the uppermost Cedar Mountain Formation, Utah, indicates that the basic pattern of faunal composition for the Late Cretaceous of North America was already established by the Albian-Cenomanian boundary. Multiple, concordant 40Ar/39Ar determinations from a volcanic ash associated with the fauna have an average age of 98.39 ± 0.07 million years. The fauna of the Cedar Mountain Formation records the first global appearance of hadrosaurid dinosaurs, advanced lizard (e.g., Helodermatidae), and mammal (e.g., Marsupialia) groups, and the first North American appearance of other taxa such as tyrannosaurids, pachycephalosaurs, and snakes. Although the origin of many groups is unclear, combined biostratigraphic and phylogenetic evidence suggests an Old World, specifically Asian, origin for some of the taxa, an hypothesis that is consistent with existing evidence from tectonics and marine invertebrates. Large-bodied herbivores are mainly represented by low-level browsers, ornithopod dinosaurs, whose radiations have been hypothesized to be related to the initial diversification of angiosperm plants. Diversity at the largest body sizes (>106 g) is low, in contrast to both preceding and succeeding faunas; sauropods, which underwent demise in the Northern hemisphere coincident with the radiation of angiosperms, apparently went temporarily unreplaced by other megaherbivores. Morphologic and taxonomic diversity among small, omnivorous mammals, multituberculates, is also low. A later apparent increase in diversity occurred during the Campanian, coincident with the appearance of major fruit types among angiosperms, suggesting the possibility of adaptive response to new resources.

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Long-distance population dispersal leaves its characteristic signature in genomes, namely, reduced diversity and increased linkage between genetic markers. This signature enables historical patterns of range expansion to be traced. Herein, we use microsatellite loci from the human pathogen Coccidioides immitis to show that genetic diversity in this fungus is geographically partitioned throughout North America. In contrast, analyses of South American C. immitis show that this population is genetically depauperate and was founded from a single North American population centered in Texas. Variances of allele distributions show that South American C. immitis have undergone rapid population growth, consistent with an epidemic increase in postcolonization population size. Herein, we estimate the introduction into South America to have occurred within the last 9,000–140,000 years. This range increase parallels that of Homo sapiens. Because of known associations between Amerindians and this fungus, we suggest that the colonization of South America by C. immitis represents a relatively recent and rapid codispersal of a host and its pathogen.