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INDEX Africa Antarctica, separation, 918 Bottom water, 937 Agulhas Plateau, 949 Boundaries, criteria used to locate, 678 Albian foraminifera assemblages, 750 Boundary, biostratigraphic, 677 Albian-Cenomanian foraminifera, 747 foraminifera, Amphipyndax enesseffi Zone, 774 Miocene/Pliocene, 678 Amsterdam-St. Paul volcanic complex, 924 Oligocene/Miocene, 678 Angiosperms, 816 Pleistocene/Holocene, 680 Angular unconformity, 283, 288 Pliocene/Miocene, 687 Antarctic Bottom Water, 918 Pliocene/Quaternary, 679 Antarctica, separation of Africa, 918 Quaternary/Pliocene, 677, 687 Argon, nonradiogenic, 514 Brachiopod, 167 Argon analyses, 513 Broken Ridge, 8, 9, 233, 243, 281, 288, 359, 370, 418, Artostrobiom urna Zone, 772, 774, 775 925, 950 Aseismic ridges, 571, 910 Broken Ridge-Naturaliste Plateau, 7 Australian continental margin, 419 Bryozoans, 166, 167 Australian plate, 233 Calcareous nannoplankton, Site 251, 84 Authigenic garnet, 80, 85, 593, 594, 915 Calcispheres, 335, 747 Basalt, 80, 161, 162, 238, 301, 329, 331, 336, 466 Campanian-lower Eocene unconformity, 619 classification of tholeiites, 480 Carbon emmission spectrography, 541 criteria for recognizing altered, 472 Carbon-carbonate analysis, 16 crystallization differentiation, 481 Carbonate compensation depth, 140, 306, 336, 419, 950 electrical resistivity of, 505 Carlsberg Ridge, Central Indian Ridge, spreading on, grain-size range, 533 913 hematite in, 533 Celadonite,471 normative compositions, 477 Cenozoic species, nannoplankton, 619 ocean ridge, 484 Central Indian Basin, 418 olivine, 28, 235, 299, 329, 478 Ceratolithus tricorniculatus Zone, 623 petrography of, 466 Chemical analysis, authigenic, garnet, 594 phase chemistry, 484 Chemical analysis of pyroclastics, 560 plagioclase feldspars in, 485 Chemistry of basalts, 472 porphyritic, 471 Chert, 745 pyroxenes in, 484 Circumpolar current, 7, 9, 135, 140, 359, 929 rare-earth elements in, 569 Classification of pyroclastics, 553 sill, 466 tholeiites, 480 Site 250, 487, 914 Climatic shifts, 613 Site 251, 489, 915 Conglomerates, 237 Site 253, 489 Coniacian/Santonian foraminifera, 750 Site 254, 489 Coniacian/Santonian boundary, 750 Site 256, 489 Contamination, foraminifera, 677 Site 257, 466, 489 Corals, 167 thermal conductivity, 454 Cretaceous, nannoplankton, 669 thermally unstable state of, 529 Paleogene, nannoplankton, 669, 670 trace elements in, 483 sedimentation, 938 xenoliths, 470 systematics, foraminifera, 751 Basalt flows, graded, 470 Cretaceous magnetic lineations, 951 Basalt-sediment contact, 467 Cretaceous zonation, Radiolaria, 773 Basaltic flows, 418 Cretaceous/Tertiary boundary, 32 Basaltic terrain, 244 Crinoids, 166, 167, 745 Basis for age determination, Crozet Basin, 135, 140, 418, 913, 915 foraminifera, 13 Crustal ages, 9, 34 nannoplankton, 13 Wharton Basin sites, 930 Beach gravels, 929 Crystallization differentiation, basalt, 481 Bengal Fan, 919 Crystallization fractionation, 489 Biogenic ooze, 235 Current, Bottom, 23, 34, 140, 914 Bottom current, 23, 140, 914 Darling Fault Zone, 947 Bottom current circulation, 34, 918 Datum levels, 677 1123 Davie Ridge, 949 Site 255, 287, 690 Deccan traps, 949 Site 256, 304, 695 Detrital clay, 299, 329 Site 257, 335, 695 Detrital sediments, 914 Site 258, 368, 695 Deuteric oxidation, 533 Turonian, 750 Diamantina Fracture Zone, 359, 925 upper Pliocene, 679 Diamictites, 237, 244, 553 Zone N21, 84, 687 Diatoms, 671 Zone N20, 84 Dictyomitra veneta Zone, 772, 773, 774, 775 Zone N19, 84 Differentiation of magma, 489 Zone N16-N18, 681 Direct-reading spectrography, 541 Zone N4-N8, 33, 681 Discoaster asymmetricus Zone, 623 Zone P21, 166 barbadiensis Zone, 670 Zone P18, 166 druggi Zone, 623 Framboidal pyrite, 603, 604 exilis Zone, 623, 625 Garnet, authigenic, 80, 85, 593, 594 quinqueramus Zone, 623 Gartnerago obliquus Zone, 626, 635, 672 saipanemsis Subzone, 167, 670 Gastropods, 241 tani nodifer, 167 Geochemical measurements, Disconformities, 34, 914 Site 250, 29 Dissolution effects, 85 Site 251, 81 Dissolution facies, 7, 9, 930, 932, 934 Site 252, 138 Dissolved organic carbon, 615 Site 253, 163 Distribution of sediments, Indian Ocean, 7 Site 254, 239 Dolomite, 28 Site 255, 285 Drag folding, 922 Site 256, 303 Drake passage, 950 Site 257, 332 Drilling mud usage, 573 Site 258, 365 Ebridians, 671 Geochemistry, 542 Echinoids, 167 Geochemistry, rare-earth element concentrations in Eiffelithus turriseiffeli Zone, 306, 625, 633 pyroclastics, 563 Electrical resistivity of basalt, 505 Geochemistry of pyroclastics, 560 Endiopsode field, 484 Geochemistry of basalt, 567, 569 Environment of deposition, 617 Geochemistry of sediments, 542, 547 Fauna, shallow-water, 168 Geophysical measurements, 417 Fish debris, stratigraphic results, 910 Geothermal measurements, 451 system of descriptors, 827 sediment temperatures, 456 Fission track method, 515 Site 251, 456 Foraminifera, Site 253, 456 Albian-Cenomanian, 747, 750 Site 254, 458 basis for age determination, 13 Site 256, 460 Coniacian-Santonian, 750 Site 257, 461 contamination, 677 Gephyrocapsa oceanica Zone, 623 Cretaceous, systematics, 751 Gingin chalk, 626, 633, 636, 751 early Miocene, 678 Glass, fresh, 470 Globigerinatheka semiinvoluta Zone, 167 Globigerinatheka semiinvoluta Zone, 167 larger, 167 Gondwanaland, 7, 9, 281, 295, 327, 359, 910, 918, 929, lower Pliocene, 678 945 method of preparation, 675 Graded basalt flows, 470 middle Miocene, 678 Grain-size analyses, 15 middle Miocene/upper Miocene Boundary, 678 Grain-size range, basalt, 533 middle Pliocene, 679 Gypsum, 605 Miocene/Pliocene boundary, 241, 678 Harmonic mean thermal conductivity, 454 Oligocene marker species, 678 Hematite in basalt, 533 Pleistocene/Holocene, boundary, 687 as an alteration product of basalt, 507 Pliocene/Quaternary, boundary, 679 Hiatus, Quaternary, 680 Late Cretaceous, 932 Quaternary/Pliocene boundary, 241, 687 Oligocene, 935 Site 250, 32, 680 formation in the deep sea, model for, 937 Site 251, 83, 681 in the Eastern Indian Ocean, 933 Site 252, 687 High-temperature oxidation, 529 Site 253, 166, 687 Holocene/Pleistocene boundary, 695 Site 254, 241, 690 Hydrogarnets, 597 1124 Indian Ocean, 910 Microscopic pyrite, 603 distribution of sediments, 7 Micula staurophora Zone, 626, 635 formation of, 910 Mid-latitudinal Neogene sequence, 83 oldest sediment, 7 Mid-Ocean Ridge, 7 sediment thickness distribution, 910 Middle Eocene sedimentation, 939 southwestern, 911 Middle Miocene foraminifera, 678 Indian Ocean Ridge, southeast branch, 417 Middle Miocene/upper Miocene boundary, fora- Indian plate, 233 minifera, 678 Indonesia, 947 Middle Pliocene, foraminifera, 679 Indus Cone, 950 Miocene, subdivision of the, 678 Inoceramus, 287, 745, 750, 751 Miocene/Oligocene boundary, 690 Intrabasalt hiatus, 930 Miocene/Pliocene boundary, foraminifera, 241, 678 Invertebrate fossils, 167 Molluscs, 166, 242 Investigator Fracture Zone, 932 Mozambique Basin, 21, 33, 466, 913, 914, 918 Iron postdepositional migration of, 563 Mozambique Plateau, 417 Iron-rich tholeiitic basalt, 570 Mudstone, 235 Isotope fractionation, 615 Nannoplankton, Kamptnerius magnificus Zone, 626, 635 basis for age determination, 13 Kerguelen Plateau, 281, 925, 950 Cenozoic species, 619 Lanthanium and samarium enrichment factors, 549 Cretaceous, 669 Lapilli, 161, 553 Mesozoic species, 620 Larger foraminifera, 167 Paleoenvironment, 670 Late Cretaceous hiatus, 932, 933 Paleogene, 669 Late Pliocene and Quaternary, paleoclimate, 743 preservation of, 622 Limestone, 745 Site 250, 33, 626, 669 Lithiophorite, 299 Site 251, 628, 669 Lithologic nomenclature, 14 Site 252, 628, 670 Lithology, 26, 78, 137 Site 253, 167, 628, 670 Lithology, site 253, 157 Site 254, 242, 632, 671 Site 254, 235 Site 255, 288, 632 Site 255, 283 Site 256, 306, 633, 671 Site 256, 299 Site 257, 634, 671 Site 257, 329 Site 258, 369, 635, 672 Site 258, 363 solution of, 670 Lithraphidites alatus Zone, 625, 635 taxonomy, 636 Lower Miocene/middle Miocene boundary, Nannoplankton zonation, foraminifera, 678 Ceratolithus tricorniculatus Zone, 623 Lower Pliocene foraminifera, 678 Discoaster asymmetricus Zone, 623 Lysocline, 34, 85, 305, 306 Discoaster barbadiensis Zone, 670 M sequence of magnetic anomalies, 932 Discoaster druggi Zone, 623 Macrofossil debris, 237 Discoaster exilis Zone, 623, 625 Macrofossils, 244 Discoaster quinqueramus Zone, 623 Madagascar Basin, 417 Discoaster saipanensis Subzone, 167, 670 Maghemite, 533 Discoaster tani nodifer Zone, 167 Magma, differentiation of, 489 Eiffellithus turriseiffeli Zone, 306, 625, 633 Magnetic anomalies, 520, 919 Gartnerago obliquum Zone, 626, 635, 672 Magnetic lineations, 945 Gephyrocapsa oceanica Zone, 623 Magnetic measurements, correlation of resistivity with Kamptnerius magnificus Zone, 626, 635 petrology, 507 Lithraphidites alatus Zone, 625, 635 Magnetic susceptibility, 517 Marthasterites furcatus Zone, 626, 635, 672 Major elements, 542 Mesozoic, 625 Manganese, postdepositional migration of, 563 Micula staurophora Zone, 335, 626, 635 Mantle plume, 549, 571 Prediscosphaera cretacea Zone, 625, 634, 672 Marker species foraminifera, Oligocene, 678 Reticulofenestra hillae Subzone, 670 Marthasterites furcatus Zone, 626, 635, 672 Reticulofenestra pseudoumbilica Zone, 623 Median destructive field, 519 Rhabdosphaera inflata Subzone, 671 Mesozoic species, nannoplankton, 620, 625 Sphenolithus heteromorphus Zone, 623 Method of preparation, foraminifera, 675 Triquetrorhabdulus carinatus Zone, 623 Methods, X-ray mineralogy, 573 Natal Basin, 417 Methods of resistivity measurements in basalt, 505 Natural remanent magnetization, 519 Methods
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    Large igneous provinces and silicic large 1888 2013 igneous provinces: Progress in our understanding CELEBRATING ADVANCES IN GEOSCIENCE over the last 25 years Invited Review Scott E. Bryan1,† and Luca Ferrari2,3,† 1School of Earth, Environmental and Biological Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, 4001, Australia 2Centro de Geociencias, Universidad Nacional Autonoma de Mexico, Boulevard Juriquilla 3001, Querétaro, 76230, Mexico 3Instituto de Geología, Universidad Nacional Autonoma de Mexico, Circuito Investigacion Cientifi ca, Ciudad Universitaria, Mexico City, 04510, Mexico ABSTRACT margins, where, in the latter setting, large ig- ities, and are characterized by igneous pulse(s) neous province magmatism can be dominated of short duration (1–5 m.y.), during which a Large igneous provinces are exceptional by silicic products. (3) Mineral and energy re- large proportion (>75%) of the total igneous intraplate igneous events throughout Earth’s sources, with major platinum group elements volume was emplaced (Bryan and Ernst, 2008). history. Their signifi cance and potential (PGEs) and precious metal resources, are Continental fl ood basalt provinces, such as the global impact are related to the total volume hosted in these provinces, as well as magma- Deccan Traps, Siberian Traps, and Columbia of magma intruded and released during these tism impacting on the hydro carbon potential River fl ood basalt province, are some of the best geologically brief events (peak eruptions are of volcanic basins and rifted margins through recognized examples of continental large igne- often within 1–5 m.y. in duration) where mil- enhancing source-rock maturation, providing ous provinces (Fig. 1). While continental fl ood lions to tens of millions of cubic kilometers fl uid migration pathways, and initiating trap basalt provinces had been widely recognized of magma are produced.

  • Crustal Structure of the Southern Margin of the African Plate: Results

    Originally published as: Stankiewicz, J., Parsiegla, N., Ryberg, T., Gohl, K, Weckmann, U., Trumbull, R., Weber, M. (2008): Crustal Structure of the Southern Margin of the African Continent: Results from Geophysical Experiments. - Journal of Geophysical Research, 113, B10313 DOI: 10.1029/2008JB005612. 1 Crustal Structure of the Southern Margin of the African 2 Continent: Results from Geophysical Experiments. 3 4 J. Stankiewicz, N. Parsiegla, T. Ryberg, K. Gohl, U. Weckmann, R. Trumbull & M. Weber. 5 6 Abstract 7 A number of geophysical onshore and offshore experiments were carried out along a profile across the 8 southern margin of the African Plate in the framework of the Inkaba yeAfrica project. Refraction 9 seismic experiments show that Moho depth decreases rapidly from over 40 km inland to around 30 km 10 at the present coast, before gently thinning out towards the Agulhas-Falkland Fracture Zone, which 11 marks the transition zone between continental and oceanic crust. In the region of the abruptly 12 decreasing Moho depth, in the vicinity of the boundary between the Namaqua-Natal Mobile Belt and 13 the Cape Fold Belt, lower crustal P-wave velocities up to 7.4 km/s are observed. This is interpreted as 14 metabasic lithologies of Precambrian age in the Namaqua-Natal Mobile Belt, or mafic intrusions added 15 to the base of the crust by younger magmatism. The velocity model for the upper crust has excellent 16 resolution, and is consistent with the known geological record. A joint interpretation of the velocity 17 model with an electrical conductivity model, obtained from magnetotelluric studies, makes it possible 18 to correlate a high velocity anomaly north of the centre of the Beattie Magnetic Anomaly with a highly 19 resistive body.
  • The Agulhas Plateau: Structure and Evolution of a Large Igneous Province

    The Agulhas Plateau: Structure and Evolution of a Large Igneous Province

    Geophys. J. Int. (2008) 174, 336–350 doi: 10.1111/j.1365-246X.2008.03808.x The Agulhas Plateau: structure and evolution of a Large Igneous Province N. Parsiegla, K. Gohl and G. Uenzelmann-Neben Alfred Wegener Institute for Polar and Marine Research, PO Box 12161, 27515 Bremerhaven, Germany. E-mail: [email protected] Accepted 2008 March 28. Received 2008 March 13; in original form 2008 January 5 SUMMARY Large Igneous Provinces (LIP) are of great interest due to their role in crustal generation, magmatic processes and environmental impact. The Agulhas Plateau in the southwest Indian Ocean off South Africa has played a controversial role in this discussion due to unclear evidence for its continental or oceanic crustal affinity. With new geophysical data from seismic refraction and reflection profiling, we are able to present improved evidence for its crustal structure and composition. The velocity–depth model reveals a mean crustal thickness of 20 km with a maximum of 24 km, where three major units can be identified in the crust. In our seismic reflection records, evidence for volcanic flows on the Agulhas Plateau can be observed. The middle crust is thickened by magmatic intrusions. The up to 10 km thick lower crustal body is characterized by high seismic velocities of 7.0–7.6 km s−1. The velocity–depth distribution suggests that the plateau consists of overthickened oceanic crust similar to other oceanic LIPs such as the Ontong-Java Plateau or the northern Kerguelen Plateau. The total volume of the Agulhas Plateau was estimated to be 4 × 106 km3 of which about 10 per cent consists of extruded igneous material.