summaryThe mass of the Phanerozoic sediments is about 2.1 x 1018 metric tons, and between a quarter and one-third of it is distributed on the present continental margins and deep sea floor. The survival rate (surviving mass per unit time of deposition) seems to decrease exponentially with advancing age back to the Carboniferous, beyond which the tail of the distribution holds up and is somewhat irregular. The distribution for the past 300 Ma can be expressed by the equation log s = 10.01 - 0.24t, where s is the survival rate in metric tons per year and t is in units of 100 Ma. For a constant sediment mass with constant probability of destruction, this corresponds to a mean sedimentation rate since Devonian time of 101(} metric tons per year and a half-life for the post-Devonian mass of about 130 Ma. The overall distribution, however, is the sum of the distributions for three major realms, cratonic, marginal and pelagic, each with its own characteristic pattern. The last two account for most of the exponential-looking trend in the later Phanerozoic, but it is not clear (nor, in the case of the pelagic sediments, likely) that they are themselves exponential in character.The surviving masses (per unit time) of the Phanerozoic Systems tend to decrease with advancing age. This trend was revealed by a series of global volumetric estimates for the Devonian through Jurassic Systems (Ronov 1959) and extrapolations to the rest of the Phanerozoic based on a rough correlation between the volumes of the Systems surveyed and their maximum known thicknesses (Gregor 1967). Ronov and his colleagues have lately published (Ronov et al. 1980) complete volumetric estimates for those parts of the Phanerozoic Systems that underlie the global land surface. These estimates (after subtraction of the volcanic component and conversion from volume to mass) are summarized here in Table 3, Column 4. To them, in order to obtain the complete Phanerozoic mass-age distribution, must be added the sediments of the continental margins and deep sea. For convenience of study, the submarine realm can be divided into: 1. 'Passive' continental margins as defined by the US National Academy of Sciences (1979) and by Sclater et al. (1980). Examples are the margins bordering the Atlantic and Arctic Oceans and the Indian Ocean as far east as the Andaman Sea; 2. Marginal basins (Sclater et al. 1980) separated from ocean ridges by tectonic barriers (trenches, arcs, continental crust). They include such regions as the Caribbean and Mediterranean Seas and the marginal basins of the western Pacific; 3. The deep sea floor. The areal distribution of these submarine sedimentary environments, as determined by Sclater et al. (1980) is, in millions of km2: passive margins, 52.2; marginal basins, 26.9; deep sea floor, 281.7.
ZusammenfassungDie mesozoischen Laven und kleineren Intrusionen innerhalb der Schuppen yon Westsizilien besitzen folgende Charakteristika: 1. Die Laven innerhalb der triassischen Mufara-Formation im Norden sind zerbrochen zu Fragmenten, die unabh/ingig voneinander innerhalb der umgebenden inkompetenten Schichten rotiert wurden. Dieses ist fiir die magmatischen Gesteine der inneren (n6rdli-cheren) Oberschiebungseinheiten typisch. AbstractThe Mesozoic lavas and minor intrusions in the thrust sheets of western Sicily have the following characteristics: I. The lavas in the Triassic Mufara Formation in the north were broken into fragments which rotated independently within the incompetent strata that enclose them. This behavior is characteristic of igneous rocks found within the more internal (northerly) thrust units. 2. The Jurassic lavas in the more external (southerly) units have consistent directions which agree with those of the Ammonitico Rosso limestones in the same zone and lie about 30 ~ clockwise from those of coeval autochthonous formations in Tunisia. SCHULr presumed Cretaceous directions from Custonaci on the north coast (similar to those found in the Cretaceous Scaglia Rossa at Terrasini to the east by CHANNEL et al., 1980) are rotated still more (140 ~ with respect to those of the autochthonous Iblean platform of SE Sicily. These differences are believed to reflect rotation of the thrust R6sum6Leg laves et leg instrusions mineures m6sozoiques pr6sentes dang leg roches charri6es de la Sicile occidentale montrent leg caract6ristiques suivantes:1. Leg laves intercal6es dang la Formation de Mufara d'gtge triasique ont 6t6 morcel6es en fragments qui ont subi des rotations ind~pendantes dang leg marnes incomp6tentes qui leg enrobent. Ce comportement est typique des roches ign6es qui se trouvent dang les unit~s charri~es de la zone plus interne (septentrionale).2. Leg laves jurassiques des unit~s plus externes (m~ridionales) poss~dent des directions d'aimantation qui accordenz avec celles des calcaires de l'ammonitico rosso de la m~me zone externe qui d~vi~es d'environ 30 ~ vers la droite par rapport aux roches de m~me f~ge de la Tunisie. Leg directions, dites cr~tac~es de Schult, de la r6gion de Custonaci sur la c6te septentrionale (qui concordent bien avec celles trouv6es par CHANNELL et al. (1980) & Terrasini) diff+rent encore plus, avec une rotation de 140 ~ par rapport fi la plateforme autochtone d'Iblei (Sicile) SE). Ces diffOrences sont interpr6t6es comme refl6tant la rotation des nappes charri6es au cours du transport tectonique durant le Cenozo~que, la zone interne ayant subi une rotation plus intense.3. Toutes les roches ign+es sont fortement altOr6es; en gOn6ral on ne peut pas identifier les minOraux originels. L'abondance relative de certains des 616ments non-mobiles (Ti, Sr, Y) suggOrent une origine intracratonique. KpaTuoe eo~ep~aHneMe3030~crne naabi ~ He60abLuae !4HTpy3!4!4 BHyTp!4 qeLuyfi 3arIa~Ho~ C!4tlHYlH!4 xapaKxepH3yK)TC~ cJIe~yl~3ttt!4Mrl Oco6eHHOCT~MH:1. 5IaBbt BHyTpH rpriaccoaoi~ d...
ZusammenfassungDie Aufsammlung und Untersuchung plio-pleistoz~iner und oberkretazischer Basalte in SE-Sizilien ergab die folgende palaomagnetische Information:Pol-Position dp dm
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