Palaeoclimate, sedimentation and continental accretion

1981 ◽  
Vol 301 (1461) ◽  
pp. 253-264 ◽  
Keyword(s):  
South America ◽  
Subduction Zones ◽  
Heated Surface ◽  
Climatic Zones ◽  
Run Off ◽  
Tectonic Erosion ◽  
Opposite Process ◽  
North And South ◽  
Trench Sediments ◽  
Continental Accretion

Climate has a pervasive effect on sedimentation today, and the same climatic patterns are reflected in the distribution of lithofacies through the Palaeozoic, as the continents migrate beneath the climatic zones. The low-latitude hot wet zone is represented by thick elastics, coals and carbonates and is best developed along east coasts where prevailing winds bring moisture and heated surface waters toward the continent. The desert zones occur on the west sides of continents centred at 20° north and south, and these dry belts are represented in the geological record by evaporites. Tillites, thick elastics and coals occur in the temperate rainy belts, especially on the windward, west sides of continents above 40° latitude. Continental accretion occurs where subduction zones coincide with rainy zones, such that the products of erosion are transported to the trench, and thus thrust back, extending the margin of the continent. The opposite process of ‘tectonic erosion’, wherein the descending oceanic slab continually ‘rasps’ away the margin of the continental crust, may occur in areas where rainfall and surface run-off is insufficient to provide trench sediments. This process has been operating adjacent to the Atacama Desert in South America during the past 200 Ma. To judge by the eastward migration of the calc-alkaline intrusive foci, about 250 km of the margin of South America have been transported down the subduction zone during this period.

Seismic imaging evidence that forearc underplating built the accretionary rock record of coastal North and South America

2019 ◽  
Vol 158 (1) ◽  
pp. 104-117 ◽  
Author(s):  
David W. Scholl
Keyword(s):  
South America ◽  
Subduction Zones ◽  
Seismic Imaging ◽  
Southern Chile ◽  
Late Palaeozoic ◽  
Aleutian Arc ◽  
Seaward Edge ◽  
Metamorphic Facies ◽  
North And South America ◽  
North And South

AbstractThe submerged forearcs of Pacific subduction zones of North and South America are underlain by a coastally exposed basement of late Palaeozoic to early Tertiary age. Basement is either an igneous massif of an accreted intra-oceanic arc or oceanic plateau (e.g. Cascadia(?), Colombia), an in situ formed arc massif (e.g. Aleutian Arc) or an exhumed accretionary complex of low and high P/T metamorphic facies of late Palaeozoic (e.g. southern Chile, Patagonia) and Mesozoic age (e.g. Alaska). Seismic studies at Pacific forearcs image frontal prisms of trench sediment accreted to the seaward edge of forearc basement. Frontal prisms tend to be narrow (10–40 km), weakly consolidated and volumetrically small (∼35–40 km3/km of trench). In contrast, deep seismic imaging of submerged forearcs commonly reveals large volumes (∼2000 km3/km of trench) of underplated material accreted at subsurface depths of ∼10–30 km to the base of forearc basement. Underplates have been imaged below the southern Chile, Ecuador–Colombia, north Cascade, Alaska, and possibly the eastern Aleutian forearcs. Deep underplates have also been observed below the Japan and New Zealand forearcs. Seismic imaging of northern and eastern Pacific forearcs supports the conclusion drawn from field and laboratory studies that exposed low and high P/T accretionary complexes accumulated in the subsurface at depths of 10–30 km. It seems significant that imaged underplated bodies are characteristic of modern well-sedimented subduction zones. It also seems likely that large Pacific-rim underplates store a significant fraction of sediment subducted in Cenozoic time.

IV.—The Geological Development, Descent and Distribution of the Mammalia

1893 ◽  
Vol 10 (9) ◽  
pp. 401-412 ◽  
Author(s):  
Karl A. von Zittel
Keyword(s):  
South America ◽  
The Past ◽  
Limited Experience ◽  
The World ◽  
Relationship Of ◽  
North And South America ◽  
The Relationship ◽  
North And South ◽  
Animal World

In a spirited treatise on the ‘Origin of our Animal World’ Prof. L. Rütimeyer, in the year 1867, described the geological development and distribution of the mammalia, and the relationship of the different faunas of the past with each other and with that now existing. Although, since the appearance of that masterly sketch the palæontological material has been, at least, doubled through new discoveries in Europe and more especially in North and South America, this unexpected increase has in most instances only served as a confirmation of the views which Rutimeyer advanced on more limited experience. At present, Africa forms the only great gap in our knowledge of the fossil mammalia; all the remaining parts of the world can show materials more or less abundantly, from which the course followed by the mammalia in their geological development can be traced with approximate certainty.

Transatlantic Radicalism

2021 ◽  
Keyword(s):  
South America ◽  
Atlantic Ocean ◽  
Case Studies ◽  
Individual Case ◽  
History Of ◽  
Late Nineteenth ◽  
Organizational Ties ◽  
North And South America ◽  
North And South ◽  
Political Radicalism

The Atlantic Ocean not only connected North and South America with Europe through trade but also provided the means for an exchange of knowledge and ideas, including political radicalism. Socialists and anarchists would use this “radical ocean” to escape state prosecution in their home countries and establish radical milieus abroad. However, this was often a rather unorganized development and therefore the connections that existed were quite diverse. The movement of individuals led to the establishment of organizational ties and the import and exchange of political publications between Europe and the Americas. The main aim of this book is to show how the transatlantic networks of political radicalism evolved with regard to socialist and anarchist milieus and in particular to look at the actors within the relevant processes—topics that have so far been neglected in the major histories of transnational political radicalism of the late nineteenth and early twentieth centuries. Individual case studies are examined within a wider context to show how networks were actually created, how they functioned and their impact on the broader history of the radical Atlantic.

scholarly journals Modelling tree ring cellulose <i>δ</i><sup>18</sup>O variations in two temperature-sensitive tree species from North and South America

2017 ◽  
Vol 13 (11) ◽  
pp. 1515-1526 ◽  
Author(s):  
Aliénor Lavergne ◽  
Fabio Gennaretti ◽  
Camille Risi ◽  
Valérie Daux ◽  
Etienne Boucher ◽  
...  
Keyword(s):  
South America ◽  
Isotopic Fractionation ◽  
Circulation Model ◽  
Effect Of Temperature ◽  
Temperature Sensitive ◽  
Nothofagus Pumilio ◽  
Climate Signal ◽  
North And South America ◽  
North And South ◽  
Two Temperature

Abstract. Oxygen isotopes in tree rings (δ18OTR) are widely used to reconstruct past climates. However, the complexity of climatic and biological processes controlling isotopic fractionation is not yet fully understood. Here, we use the MAIDENiso model to decipher the variability in δ18OTR of two temperature-sensitive species of relevant palaeoclimatological interest (Picea mariana and Nothofagus pumilio) and growing at cold high latitudes in North and South America. In this first modelling study on δ18OTR values in both northeastern Canada (53.86° N) and western Argentina (41.10° S), we specifically aim at (1) evaluating the predictive skill of MAIDENiso to simulate δ18OTR values, (2) identifying the physical processes controlling δ18OTR by mechanistic modelling and (3) defining the origin of the temperature signal recorded in the two species. Although the linear regression models used here to predict daily δ18O of precipitation (δ18OP) may need to be improved in the future, the resulting daily δ18OP values adequately reproduce observed (from weather stations) and simulated (by global circulation model) δ18OP series. The δ18OTR values of the two species are correctly simulated using the δ18OP estimation as MAIDENiso input, although some offset in mean δ18OTR levels is observed for the South American site. For both species, the variability in δ18OTR series is primarily linked to the effect of temperature on isotopic enrichment of the leaf water. We show that MAIDENiso is a powerful tool for investigating isotopic fractionation processes but that the lack of a denser isotope-enabled monitoring network recording oxygen fractionation in the soil–vegetation–atmosphere compartments limits our capacity to decipher the processes at play. This study proves that the eco-physiological modelling of δ18OTR values is necessary to interpret the recorded climate signal more reliably.

scholarly journals Specific Formation of the Bermuda and Dragon Triangles as a Result of a Change in the Axis of the Earth’s Rotation

2020 ◽  
pp. 19-25
Keyword(s):  
South America ◽  
Southeast Asia ◽  
Earth’S Rotation ◽  
Earth's Rotation ◽  
Axis Of Rotation ◽  
The Earth ◽  
Rotation Of The Earth ◽  
North And South America ◽  
North And South

The Bermuda Triangle is located in the area of the archipelago between North and South America and the Dragon Triangle is located in the area of the archipelago in Southeast Asia. There is a great resemblance between these two triangular areas; both were formed following special geological and tectonic conditions. It is herein proposed that their creation stems from the change in location of the axis of rotation of the earth and, accordingly, the change in the location of the equator.

scholarly journals Review of the Species of New World Erythroneurini (Hemiptera: Cicadellidae: Typhlocybinae)

2008 ◽  
Vol 38 (1-6) ◽  
pp. 129-175
Author(s):  
Christopher H. Dietrich ◽  
Dmitry A. Dmitriev
Keyword(s):  
Phylogenetic Analysis ◽  
New Species ◽  
South America ◽  
New World ◽  
Morphological Characters ◽  
Amazon Region ◽  
New Synonyms ◽  
Branch Support ◽  
North And South America ◽  
North And South

The 35 previously described species (including 4 junior synonyms) of the New World erythroneurine leafhopper genus Zyginama are reviewed and descriptions are provided for 43 new species, 2 from U.S.A., 26 from Mexico, 1 from Panama, and 14 from the Amazon region of South America. The following new synonyms are recognized: Z. aucta (McAtee) equals Erythroneura bilocularis Van Duzee, syn. n., and E. inclita Beamer, syn. n.; Z. nicholi (Beamer) equals E. canyonensis Beamer, syn. n., and E. ales Beamer, syn. n. Separate keys are provided for identification of males from North and South America, all known species are illustrated, and data on their distributions are summarized. Phylogenetic analysis of 40 morphological characters of the 71 species for which males are known yielded a reasonably well resolved estimate of relationships among the included species, but branch support was low overall.

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