Geochemistry of basement carbonates from ODP Site 801 in the western Pacific Ocean

Many studies argue, based partly on Pb isotopic evidence, that recycled, subducted slabs reside in the mantle source of ocean island basalts (OIB) (Hofmann and White, 1982, doi:10.1016/0012-821X(82)90161-3; Weaver, 1991 doi:10.1016/0012-821X(91)90217-6; Lassiter, and Hauri, 1998, doi:10.1016/S0012-821X(98)00240-4). Such models, however, have remained largely untested against actual subduction zone inputs, due to the scarcity of comprehensive measurements of both radioactive parents (Th and U) and radiogenic daughter (Pb) in altered oceanic crust (AOC). Here, we discuss new, comprehensive measurements of U, Th, and Pb concentrations in the oldest AOC, ODP Site 801, and consider the effect of subducting this crust on the long-term Pb isotope evolution of the mantle. The upper 500 m of AOC at Site 801 shows >4-fold enrichment in U over pristine glass during seafloor alteration, but no net change to Pb or Th. Without subduction zone processing, ancient AOC would evolve to low 208Pb/206Pb compositions unobserved in the modern mantle (Hart and Staudigel, 1989 [Isotopic characterization and identification of recycled components, in: Crust/Mantle Recycling at Convergence Zones, Eds. S.R. Hart, L. Gqlen, NATO ASI Series. Series C: Mathematical and Physical Sciences 258, pp. 15-28, D. Reidel Publishing Company, Dordrecht-Boston, 1989]). Subduction, however, drives U-Th-Pb fractionation as AOC dehydrates in the earth's interior. Pacific arcs define mixing trends requiring 8-fold enrichment in Pb over U in AOC-derived fluid. A mass balance across the Mariana subduction zone shows that 44-75% of Pb but <10% of U is lost from AOC to the arc, and a further 10-23% of Pb and 19-40% of U is lost to the back-arc. Pb is lost shallow and U deep from subducted AOC, which may be a consequence of the stability of phases binding these elements during seafloor alteration: U in carbonate and Pb in sulfides. The upper end of these recycling estimates, which reflect maximum arc and back-arc growth rates, remove enough Pb and U from the slab to enable it to evolve rapidly (<<0.5 Ga) to sources suitable to explain the 208Pb/206Pb isotopic array of OIB, although these conditions fail to simultaneously satisfy the 207Pb/206Pb system. Lower growth rates would require additional U loss (29%) at depths beyond the zones of arc and back-arc magmagenesis, which would decrease upper mantle kappa (232Th/238U) over time, consistent with one solution to the "kappa conundrum" (Elliott et al., 1999, doi:10.1016/S0012-821X(99)00077-1). The net effects of alteration (doubling of l [238U/204Pb]) and subduction (doubling of omega [232Th/204Pb]) are sufficient to create the Pb isotopic signatures of oceanic basalts.

Chemical composition of a manganese nodule from the Pacific Ocean

By means of spectrographic analysis 96 samples of marine sediments were analyzed quantitatively for V, Ti, Zr, Co, Ni, Sc, Cr, and La, and semi-quantitatively for Ba and Sr. Ca has been estimated by visual comparison of spectrographic plates, and several Fe values have also been determined in the same way. Geographically 40 of these samples are from the Pacific Ocean basin, one of which is a manganese nodule, 21 from the Gulf of Mexico, 11 from Atchafalaya Bay, 8 from American Devonian to Miocene sedimentary rocks, 4 from the Mississippi Delta, 3 from the San Diego trough, 3 from off Grand Isle, 3 from Lake Pontchartrain, from Bay Rambour, 1 from Laguna Madre off the Texas coast, and 1 from the Guadalupe River, Texas. The afore-mentioned elements were sought using PdCl2 as an internal standard, after the method developed by Ahrens (1950) and his co-workers. Samples were run in duplicate, and standard deviations varied from 5 to 14 percent. Working curves, from which final values were obtained, were constructed with the use of standard granite, G1, and the standard diabase, W1, as standards. See Fairbairn and others (1951). An experiment was carried out to determine the effect of matrix change, involving CaCO3, on the spectral line intensities of the quantitatively analyzed elements. The distribution of each of the elements is discussed separately, and particular emphasis is given to oceanic "red clay", in which many elements are enriched. A general discussion is given to mineralogy of the sediments, cation exchange in its bearing on this thesis, and a brief recount of the two hypotheses of origin of oceanic "red clay". An application of the findings of this thesis to aid in the choice of the more likely hypothesis is made.

Alta velocidad ferroviaria en California(USA): cuarta parte (IV) Fresno-Sacramento (Roseville) = High speed railway in California (USA): fourth part (IV) Fresno-Sacramento (Roseville)

Implantación de la Red de Alta velocidad Ferroviaria en California. Tramo Fresno-Sacramento. El presente articúlo es la cuarta parte de la serie "Alta Velocidad Ferroviaria en California (CHSRS)". Recoge la Alternativa "Stockton Arch", que el Proyecto FARWEST presenta a la prevista por la Authority (CHSRA), para la Línea HSR Fresno-Sacramento, en programación y en trazado. Éste discurre, desde la gran Terminal de Fresno (implantada en las afueras al suroeste de la ciudad) por el segmento sur del "mar interior" (que en el Terciario Superior ocupaba el actual Valle Central), hasta Stockton, y por el segmento norte, hasta Sacramento. El Paet de Ripperdan (~ pK 40) queda conectado por carretera con el PAET de Oroloma de la Línea HSR Fresno-San Francisco (Golden Gate Alternative). La última parte del trazado de la Línea HSR Fresno-Sacramento (Stockton Arch Alternative), coincide en alineación y rasante con la Línea HSR San Francisco-Sacramento (Crossing Bay Alternative) a la altura de Roseville, donde se emplaza la gran terminal norte de la red de California, desde la que se unirá ésta con la de Nevada, por Reno. This article forras the fourth part of the series entitled "High Speed Railway in California (CHSRS)". It addresses the "Stockton Arch" alternative, which the FARWESTProjectpresents in scheduling and in alignment as to that provided for by the Authority (CHSRA) for the Fresno-Sacramento HSR Line. The latter runs from the grand Fresno Terminal (located in the outskirts to the southwest ofthe city) through the south segment ofthe "inland sea" (which oceupied the current Central Valley in the Upper Tertiary) to Stockton and through the north segment to Sacramento. The Ripperdan TSAP (post ofpassing and stabling trains), — kilometer point 40, conneets with the Oroloma TSAP ofthe Fresno-San Francisco HSR Line (Golden Gate Alternative) by road. The last part of the Fresno-Sacramento HSR Line alignment (Stockton Arch Alternative), coincides in alignment and grade with the San Francisco-Sacramento HSR Line (Crossing Bay Alternative) at Roseville, where the great north terminal ofthe California network is located, from which the latter will be linked with Nevada s network through Reno.

Argument of Charles F. Choate, esq., in behalf of the Northern (N.H.) railroad, against the consolidation of the Boston & Lowell and Fitchburg railroads, before the railway committee of the Massachusetts legislature, February 26, 1873.

Mode of access: Internet.

Birds of the southwest Pacific, a field guide to the birds of the area between Samoa, New Caledonia, and Micronesia,

Mode of access: Internet.

Knapsack and rifle; or, Life in the grand army. War as seen from the ranks, pen pictures and sketches, personal reminiscenes and narratives, and a complete chronology of the war,

Dedication signed: Robert W. Patrick.

The Canadian railway act 1903 : (annotated) /

90694DLA.

Ocean harvest; the story of commercial fishing in Pacific coast waters.

Mode of access: Internet.

Hawaiian and Pacific foods; a cook book of culinary customs and recipes adapted for the American hostess,

"References": p. 271-275.

Standard tee rail construction for steam rail road and industrial railway track and switch work.

"Catalogue no. 21."

Raveneau de Lussan, buccaneer of the Spanish Main and early French filibuster of the Pacific;

Mode of access: Internet.

Vikings of the Pacific; the adventures of the explorers who came from the West, eastward; Bering, the Dane; the outlaw hunters of Russia; Benyowsky, the Polish pirate; Cook and Vancouver, the English navigators; Gray of Boston, the discoverer of the Columbia; Drake, Ledyard, and other soldiers of fortune on the west coast of America.

"The contents of this volume appeared serially in Leslie's monthly, Outing, and Harper's magazine." - Foreword.

Pacific charter; our destiny in Asia.

"First edition."

In the arbitration proceedings between the employes of Indianapolis traction and terminal company by and through their committee and Indianapolis traction and terminal company before the Public service commission of Indiana, acting as a voluntary board of arbitration ...

Argument of W.H. Latta, counsel for the respondent, testimony, etc.

Letters from leading engineers and naval architects as to the practicability of constructing and operating a ship railway.

Mode of access: Internet.