140 research outputs found
Petrological relationships among lavas, dikes, and gabbros from Integrated Ocean Drilling Program Hole 1256D: Insight into the magma plumbing system beneath the East Pacific Rise
No full textA continuous section from extrusive lavas, through sheeted dikes, and uppermost gabbros recovered from Integrated Ocean Drilling Program Hole 1256D provides important information regarding magma plumbing systems beneath superfast spreading ridges. Petrological examination demonstrates that a model of fractional crystallization from a magma of composition similar to one of the more primitive gabbros in a shallow (?50–100 MPa) melt lens reasonably explains mineral and whole rock compositions of many lavas and dikes. Elevated concentrations of trace elements in some rocks appear to have resulted from mixing between primitive magma and highly evolved magma. About half of the dike samples have more evolved Fe-rich compositions than the extrusive lava samples. Magma densities of the Fe-rich dikes are a little higher (?30 kg/m3) than those of lavas, suggesting that these dike magmas would not reach the surface. Mineralogical investigations reveal that both lavas and dikes contain oscillatory zoned plagioclase xenocrysts, implying magma mixing caused by successive episodes of fractionation and magma replenishment in the melt lens. The plagioclase xenocrysts contain high-Anorthite sections [An: 100 × Ca/(Ca+Na) in mole percent] whose compositions are not in equilibrium with host liquids. The high-An sections were likely crystallized when primitive magmas with high CaO/Na2O were injected in the melt lens. Since the oscillatory zoned plagioclase generally forms crystal clots, they were probably accumulated in a mush zone. The petrographical examination favors a model suggesting that injection of primitive magma into the melt lens broke the mush zone and pushed out the oscillatory zoned plagioclase
Letter from John I. Ingle, D.D.D, University of Southern California, School of Dentistry, to Janet Kuromi and family; Letter from George J. Inagaki to Mrs. Kuromi, January 28, 1970
No full textLetter from John I. Ingle to Janet Kuromi and family stating that a gift from Ronald James Wong to the Alumni Memorial Fund for the School of Dentistry at the University of Southern California has been made in Yoke Kuromi's name. Attached to the back is a handwritten sympathy letter from George J. Inagaki to Mrs. Kuromi.This collection contains two photograph albums and material related to Hitoshi "Yoke" Kuromi and Corrine Nobuko Nishimura Kuromi. Subjects in the collection include the Kuromi family, the Gila River incarceration camp, and hot rods, and classic cars
Boron and chlorine contents of upper oceanic crust: basement samples from IODP Hole 1256D
No full textBoron, Cl, Ti, K, Sm, and Gd concentrations of oceanic crust samples were determined by prompt gamma neutron activation analysis. The samples include 63 basalts and 5 gabbros obtained at various depths (369–1503 m below seafloor) from Hole 1256D during Ocean Drilling Program Leg 206 and Integrated Ocean Drilling Program Expedition 309 and 312. The results show stepwise downhole variations, B content and B/K decrease, and Cl content and Cl/K increase with increasing depth. High B content (>1.5 ppm) in shallower rocks (extrusive lavas) is probably achieved by low-temperature seawater alteration, and high Cl contents (up to 1400 ppm) in the deeper rocks (plutonic section) would show result of high-temperature hydrothermal alteration. Average B and Cl values for the upper oceanic crust in Hole 1256D are 1.5 ppm and 334 ppm, respectively
Relationship between the early Kerguelen plume and continental flood basalts of the paleo-Eastern Gondwanan margins
No full textCretaceous basalts recovered during Ocean Drilling Program Leg 183 at Site 1137 on the Kerguelen Plateau show remarkable geochemical similarities to Cretaceous continental tholeiites located on the continental margins of eastern India (Rajmahal Traps) and southwestern Australia (Bunbury basalt). Major and trace element and Sr-Nd-Pb isotopic compositions of the Site 1137 basalts are consistent with assimilation of Gondwanan continental crust (from 5 to 7%) by Kerguelen plume-derived magmas. In light of the requirement for crustal contamination of the Kerguelen Plateau basalts, we re-examine the early tectonic environment of the initial Kerguelen plume head. Although a causal role of the Kerguelen plume in the breakup of Eastern Gondwana cannot be ascertained, we demonstrate the need for the presence of the Kerguelen plume early during continental rifting. Activity resulting from interactions by the newly formed Indian and Australian continental margins and the Kerguelen plume may have resulted in stranded fragments of continental crust, isolated at shallow levels in the Indian Ocean lithosphere
Depleted mantle wedge and sediment fingerprint in unusual basalts from the Manihiki Plateau, central Pacific Ocean
No full textNumerous large igneous provinces formed in the Pacific Ocean during Early Cretaceous time, but their origins and relations are poorly understood. We present new geochronological and geochemical data on rocks from the Manihiki Plateau and compare these results to those for other Cretaceous Pacific plateaus. A dredged Manihiki basalt gives an 40Ar-39Ar age of 117.9 ± 3.5 Ma (2?), essentially contemporaneous with the Ontong Java Plateau 2500 km to the west, and the possibly related Hikurangi Plateau 3000 km to the south. Drilled Manihiki lavas are tholeiitic with incompatible trace element abundances similar to those of Ontong Java basalts. These lavas may result from high degrees of partial melting during the main eruptive phase of plateau formation. There are two categories of dredged lavas from the Danger Islands Troughs, which bisect the plateau. The first is alkalic lavas having strong enrichments in light rare earth and large-ion lithophile elements; these lavas may represent late-stage activity, as one sample yields an 40Ar-39Ar age of 99.5 ± 0.7 Ma. The second category consists of tholeiitic basalts with U-shaped incompatible element patterns and unusually low abundances of several elements; these basalts record a mantle component not previously observed in Manihiki, Ontong Java, or Hikurangi lavas. Their trace element characteristics may result from extensive melting of depleted mantle wedge material mixed with small amounts of volcaniclastic sediment. We are unaware of comparable basalts elsewhere
Tributaries: Spring 2010
No full textTributaries is a “collection of artwork. [The pages are filled with] poetry, prose and visual art accumulated from the pens, keyboards and brushes of our local and extended family of artists.” –Patrick Tisdel, Editor-in-Chief (2010). This issue contains the following works of poetry: Pawpaw's Rough Mechanic's Hands by Elsbeth Wofford-Tyler; The Boss-man Took It Away by Robert Frazier; White Picket Fence by Geoffrey Craig; The Station Just West of Northport by Robert Collet Tricaro; If You Ever Wish to Grow by Jose Trejo; Escape by Stephanie Harrell; Nature's Script by Robert Collet Tricaro; The Barn by Stephanie Harrell; Screening Prayers by Robert Collet Tricaro; Modern-Day Granddaughter by Stephanie Harrell; I Go Back to Oklahoma 1974 by Lizzy Gregory; Memory Long Gone by Lauren Harmon; Today Is Not My Day by Rabiul Hasan; Untitiled Haiku by Jerred Jesse; Literature Past by Rebecca Lowery; The Cost of First Dates by Patrick Tisdel; Head to Toe by Cindy Kirkland; Death Pulls Me South by Marsha Mathews; Honeybee by Regis Crowder; Constellations of Blueberries by Elsbeth Wofford-Tyler; All In by Corey Taylor; and I Should Tell You But I Would Not by Rabiul Hasan. It contains the following short stories: Lost in Reality by Lauren Harmon; Clouds by Ashlee Swilling; Frayed by Meredith Edwards; Something Blue by Nancy Mason; and His Ring by Stephanie Harrell. The following visual art works are included: The Fence by Samantha Willis; La Push by Aric Brown; Dedication by Kristen Ray Johnson; The Rejected Bride by Alex Ingle; Granny's Pain by Alex Ingle; Untitled by Jeremy Marchmon; Pure Love by Rigoberto Delgado; Wintertime by Tina Phillips; Sam Elliott by Rigoberto Delgado; Awareness by Rigoberto Delgado; Light off the Train by Samantha Willis
Book Review: An Uneasy Story.
No full textAn Uneasy Story. The Nationalising of South African Mission Hospitals 1960 - 1976. A Personal Account. By Dr Ronald Ingle. Foreword by Professor Dons Kritzinger. Pp. xiii+189. Published by the author. 2010. ISBN 978-0-620-47820-5. Illustrated. R230 (including postage). For overseas order options, contact the author. To order, e-mail Dr Ingle ([email protected]) or tel +27 (0)31 716-8237
(Table 1) Major and trace element concentrations of basaltic rocks from ODP Hole 183-1137A
No full text(Table 1) Major and trace element concentrations of basaltic rocks from ODP Hole 183-1137
Municipal commonage in South Africa: A public good going bad?
No full textThis article deals with the ‘Cinderella' of urban spaces – municipal commonage. The author argues that commonage is a valuable natural heritage resource. However, municipalities face pitfalls in giving expression to central policymakers' dictates regarding land redistribution. A warning is issued that by trying to turn the clock back to commonage policies more suited to a bygone era, municipalities run the risk of forfeiting both the income their commonage has the potential to generate and the very asset itself. The author contends that, until government can offer municipalities a coherent, viable model for commonage management, it would be folly to abandon the system of renting out commonage to the highest bidders. Africa Insight Vol. 36 (2) June 2006: 46-5
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