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Elsa Jullien Francis Grousset Bruno Malaiz Josette Duprat Maria Fernanda Sanchez-Goni Frdrique Eynaud Karine Charlier Ralph Schneider Aloys Bory Viviane Bout Jose Abel Flores 《Quaternary Research》2007,68(3):379-386
It has been proposed that tropical events could have participated in the triggering of the classic, high-latitude, iceberg-discharge Heinrich events (HE). We explore low-latitude Heinrich events equivalents at high resolution, in a piston core recovered from the tropical north-western African margin. They are characterized by an increase of total dust, lacustrine diatoms and fibrous lacustrine clay minerals. Thus, low-latitude events clearly reflect severe aridity events that occurred over Africa at the Saharan latitudes, probably induced by southward shifts of the Inter Tropical Convergence Zone. At a first approximation, it seems that there is more likely synchronicity between the high-latitude Heinrich Events (HEs) and low-latitude events (LLE), rather than asynchronous behaviours. 相似文献
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《Geoarchaeology》2004,19(6):613-613
The original article to which this Erratum refers was published in Geoarchaeology 19(3), 2004, 185–218. Due to an oversight, authorship of the paper by Bassett, K.N., Gordon, H.W., Nobes, D.C., & Jacomb, C. (2004), “Gardening at the edge: Documenting the limits of tropical Polynesian kumara horticulture in southern New Zealand” (Geoarchaeology 19, No. 3, pp. 185–218), was assigned incorrectly. The correct authorship is Hamish W. Gordon, Kari N. Bassett, David C. Nobes, and Chris Jacomb. The authors apologize for this error. 相似文献
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To obtain the desired answer in support of a popular, previous cooling model for the sea floor, Wei and Sandwell provide a construct that is contrary to the simple physics governing subsidence of cooling oceanic crust and is also fraught with mathematical errors. Seven of their eight equations are either misused or incorrect or both. Errors made by Wei and Sandwell include not conserving rock-mass, incorrect differentiation, dividing by zero, moving variable parameters freely in and out of integrals, and neglecting variations in density that embody the essence of the phenomenon being modeled. We demonstrate all the above, show that their construct is closely related to the half-space cooling model, and that the linear, not volumetric thermal expansivity should have been used. 相似文献
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Ilmenite is one of the common kimberlitic indicator minerals recovered during diamond exploration, and its distinction from non-kimberlitic rock types is important. This is particularly true for regions where these minerals are present in relatively low abundance, and they are the dominant kimberlitic indicator mineral recovered. Difficulty in visually differentiating kimberlitic from non-kimberlitic ilmenite in exploration concentrates is also an issue, and distinguishing kimberlitic ilmenite from those derive from other similar rocks, such as ultramafic lamprophyres, is practically impossible. Ilmenite is also the indicator mineral whose compositional variety has the most potential to resolve provenance issues related to mineral dispersions with contributions from multiple kimberlite sources.
Various published data sets from selected kimberlitic (including kimberlites, lamproites, and various ultramafic lamprophyres) and non-kimberlitic rock types have been compiled and evaluated in terms of their major element compositions. Compositional fields and bounding reference lines for ilmenites derived from kimberlites (sensu stricto), ultramafic lamprophyres, and other non-kimberlitic rock types have been defined primarily on MgO–TiO2 graphs as well as MgO–Cr2O3 relationships. 相似文献
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M. Cemal Gncüoglu 《Journal of Asian Earth Sciences》2009,34(6):796-797
A continent-oceanic island arc collision model was proposed as a new geodynamic scenario for the evolution of the Cretaceous Central Anatolian granitoids in the Central Anatolian crystalline complex (CACC) by Boztug et al. (2007b) [Boztug, D., Tichomirowa, M., Bombach, K., 2007b. 207Pb–206Pb single-zircon evaporation ages of some granitoid rocks reveal continent-oceanic island arc collision during the Cretaceous geodynamic evolution of the central Anatolian crust, Turkey. Journal of Asian Earth Sciences 31, 71–86]. The key aspects of this model include an intra-oceanic subduction in the Neotethyan Izmir-Ankara Ocean, formation of an island arc and its subsequent collision with the northern margin of the Tauride–Anatolide Platform. The identical scenario was initially proposed by Göncüoglu et al. (1992) [Göncüoglu, M.C., Erler, A., Toprak, V., Yalınız, K., Olgun, E., Rojay, B., 1992. Geology of the western Central Anatolian Massif, Part II: Central Areas. TPAO Report No: 3155, 76 p] . Moreover, the weighted mean values of the reported 207Pb–206Pb single-zircon evaporation ages by Boztug et al. (2007b) [Boztug, D., Tichomirowa, M., Bombach, K., 2007b. 207Pb–206Pb single-zircon evaporation ages of some granitoid rocks reveal continent-oceanic island arc collision during the Cretaceous geodynamic evolution of the central Anatolian crust: Turkey. Journal of Asian Earth Sciences 31, 71–86] from A-type granitoids in the CACC seem to be miscalculated and contrast with the field data. 相似文献
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