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Although this report includes the results of a 6-month reconnaissance investigation of the geology and mineral resources of Paraguay, it is essentially a compilation and interpretation of existing published and unpublished information on the subject. The rocks can be divided into five major classes, depending on age and mode of origin.
All major Appalachian tectonostratographic zones in Gaspesie, Quebec and New Brunswick (i.e. Humber, Dunnage, Gander, and Avalon) are intruded by Paleozoic granites. Granite petrological and geochemical data assist in evaluating the economic potential of the plutons and provide insight into the crustal and tectonic evolution of the orogen. Based on Na2O and Al index values (generally >3.2 wt.% and <1.1 respectively) and high-field strength element contents, most of the granites are 1-types; some have "А-type affinities". Granite chemical and isotopic characteristics distinguish three contrasting groups of granites: Humber-Dunnage, Gander, and Avalon. Positive eNd values for Humber, Dunnage, and Avalon granites indicate melting of predominately juvenile sources. Negative e Nd and elevated 201РЫШРЬ and 518 values for Gander granites are consistent with reworking of older (1.1-1.8 Ga) crust containing a significant supracrustal component. Neodymium isotopic data effectively rules out Grenville basement as a source for Humber-Dunnage granites. Gander zone is apparently the autochthonous surface expression of a distinct lower crustal block. Contrasting e Nd signatures from Avalon and Gander granites indicates that Gander and Avalon zones are underlain by different crustal blocks, i.e. Precambrian Avalon basement is not a suitable protolith for Gander granites.<...>
Рассматриваются общие и региональные вопросы стратиграфии, палеонтологии, литологии, палеогеографии докембрия и фанерозоя различных областей Восточно-Европейской и Сибирской древних платформ, Урало-Монгольского, Тихоокеанского и Средиземноморского геосинклинальноскладчатых поясов.
The British sector of the Caledonide-Appalachian fold belt, which bridges the Iapetus plate closure zone, has a range of plutonic, volcanic and volcaniclastic lithologies with characteristic space-time variations. The map of Caledonian igneous rocks in the British Isles (Plate 1) is compiled from many sources, some of which predate the use of methods of classification which are based largely on chemical data. In such cases, whilst extensive re-mapping continues, the compilers have had to resort to the collection and analysis of representative samples from the areas in question, the collection sites being based on existing maps. Thus, whilst the references to the mapped areas indicate specific publications, the chemical data on which the coding is based are commonly derived from compilations such as Stillman & Williams (1979) and Stillman & Francis (1979) for volcanic rocks and Sutherland & Pankhurst (1982), Le Bas (1982), Hall (1972) and Brown et al. (1981) for plutonic rocks.
Preface E.C. Leitch and E. Scheibner Stratotectonic Terranes of the Eastern Australian Tasmanides E.C. Leitch and E. Scheibner A Critique of Paleomagnetic Results From Australian Paleozoic Fold Belts and Displaced Terranes P. W. Schmidt and B. J. J. Embleton Terranes of the Wonominta Block, Far Western New South Wales E. C. Leitch, B. D. Webby, K. J. Mills, and P. Kolbe 31 Early Palaeozoic Back-Arc Deformation in the Lachlan Fold Belt, Southeastern Australia: Implications for Terrane Translations in Eastern Gondwanaland Christopher L. Fergusson Terranes of the Tumut District, Southeastern New South Wales, Australia H. Basden, B. J. Franklin, B. Marshall, and A. E. Waltho The Eastern Lachlan Fold Belt of Southeast Australia: A Possible Late Ordovician to Early Devonian Sinistral Strike Slip Regime G. H. Packham
Franke, W., Haak, V., Oncken, O. & Tanner, D. Orogenic processes: quantification and modelling in the Variscan Belt McKerrow, W. S. & van Staal, C, R. The Palaeozoic time scale reviewed McKerrow, W. S., MacNiocaill, C., Ahlberg, P. E., Clayton, G., Cleal, C. J. & Eagar, R. M. C. The Late Palaeozoic relations between Gondwana and Laurussia Tait, J., Schatz, M., Bachtadse, V. & Soffel, H. Palaeomagnetism and Palaeozoic palaeogeography of Gondwana and European terranes Franke, W. The mid-European segment of the Variscides: tectonostratigraphic units, terrane boundaries and plate tectonic evolution Franke, W. & Zelazniewicz, A. The eastern termination of the Variscides: terrane correlation and kinematic evolution Belka, Z., Ahrendt, FI., Franke, W. & Wemmer, K. The Baltica-Gondwana suture in central Europe: evidence from K-Ar ages of detrital muscovites and biogeographical data Finger. F., Hanzl, P., Pin, C., von Quadt, A. & Steyrer. FI. P. The Brunovistulian: Avalonian Precambrian sequence at the eastern end of the Central European Variscides? Hegner, E. & Kroner. A. Review of Nd isotopic data and xenocrystic and detrital zircon ages from the pre-Variscan basement in the eastern Bohemian Massif: speculations on palinspastic reconstructions
Editors’ Preface —J. Duncan Keppie, J. Brendan Murphy, F. Ortega-Gutierrez, and W. G. Ernst Middle American Terranes Terranes of Mexico Revisited: A 1.3 Billion Year Odyssey —J. Duncan Keppie Oaxaquia Terrane Sedimentary Origin of Calcareous Intrusions in the ~1 Ga Oaxacan Complex, Southern Mexico: Tectonic Implications —J. Dostal, J. D. Keppie, H. Macdonald, and F. Ortega-Gutierrez Geochronology and Geochemistry of the ~917 Ma, Calc-alkaline Etla Granitoid Pluton (Oaxaca, Southern Mexico): Evidence of Post-Grenvillian Subduction along the Northern Margin of Amazonia —C. Ortega-Obregon, J. D. Keppie, L. A. Solari, F. Ortega-Gutierrez, J. Dostal, R. Lopez, A. Ortega-Rivera, and J. W. K. Lee
Foreword Raymond A. Price Preface J. W. H. Monger and Jean Francheteau Chilean vs. Mariana Type Subduction Zones With Remarks on Arc Volcanism and Collision Tectonics Seiya Uyeda Effects of Collisions at Trenches on Oceanic Ridges and Passive Margins Zvi Ben-Avraham and Amos Nur Reconstructions, Plate Interactions, and Trajectories of Oceanic and Continental Plates in the Pacific Basin David C. Engebretson, Allan Cox, and Michel Debiche Pacific and Kula/Eurasia Relative Motions During the Last 130 Ma and Their Bearing on Orogenesis in Northeast Asia L. P. Zonenshain, M. V. Kononov, and L. A. Savostin
This volume was stimulated by a Pardee Symposium titled “Evolution of the Early Atmosphere, Hydrosphere, and Biosphere: Constraints from Ore Deposits,” which we convened in 2002 at the national meeting of the Geological Society of America. The history of Earth’s early atmosphere, hydrosphere, and biosphere, from Hadean through Archean and into Proterozoic time, is one of the enduring puzzles in the geological sciences. When did the oceans appear, and did they remain liquid throughout Earth’s history? What was the composition of the early atmosphere, and how did it affect climate? How did the atmosphere and ocean compositions change through time, and why? When, where, and how did life emerge on Earth? When did cyanobacteria, sulfate reducers, methanogens, and eukarya appear, and how did they affect their geologic environments? How did changes in the atmosphere, hydrosphere, and biosphere affect the lithosphere, and vice versa?
The geology of Cuba has been a challenge to geologists because of features such as the presence of well-preserved Jurassic ammonites, the rich Tertiary foraminiferal faunas (including remarkable Paleogene orbitoids), the gigantic Upper Cretaceous rudistids, the spectacular limestone Mogotes of Pinar del Rio, the extensive outcrops of ultrabasic igneous rocks, the chromite and manganese deposits, and the extraordinary structural complexity. In addition to these features, the numerous petroleum seeps, many of them coming out of basic igneous rock, have attracted much attention.
