Geochemical processes. Water and sediment environments.: A. Lerman. Wiley—Interscience,New York,N.Y., 1979, 481 pp.     

Gerald M. Friedman 《Sedimentary Geology》1980,27(4):316-317

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Centennial of the U.S. geological survey     

Irving A. Breger 《Organic Geochemistry》1979,1(3):185

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Paleomagnetic results from Permian rocks of the northern Saharan craton and motions of the Moroccan Meseta and Pangea     

P. Morel  E. Irving  L. Daly  A. Moussine-Pouchkine 《Earth and Planetary Science Letters》1981,55(1):65-74

The characteristic magnetization of redbed samples from the upper part of the Série d'Abadla (probably Early Permian 31°N, 2.7°W) has a mean direction derived from 13 sites of D=129°, I=11°, k=59, α₉₅=6° and a corresponding south paleopole at 29°S, 60°E, A₉₅=5°. All directions have reversed polarity. The paleolatitude of the northern fringe of the Saharan craton was 6°±3°S, which is in excellent agreement with that for the Moroccan Meseta. Therefore, in all probability, there has been no paleolatitudinal displacement greater than about 500 km of the Moroccan Meseta relative to Africa since Permian time. Comparison of results from sedimentary rocks shows no evidence for relative rotation of the Moroccan Meseta since Permian time. Small apparent rotations are indicated by evidence from massive trachyandesite lavas from Morocco, but we argue that these could have arisen from the incomplete averaging of secular variation and uncertainties in estimates of paleohorizontal, rather than from true tectonic rotations. The combined latest Carboniferous/Early Permian paleopole for the Saharan craton and the Meseta differs form the path of apparent polar wandering for North America when the continents are assembled in Wegener's Pangea (Pangea A, in which northwest Africa is opposite North America). It is in reasonable agreement when the continents are assembled in the Pangea B configuration (northwest Africa opposite Europe).  相似文献   

Modern deposition of manganese along the Dead Sea shore     

R.A. Garber  A. Nishri  A. Nissenbaum  G.M. Friedman 《Sedimentary Geology》1981,30(4):267-274

Manganese-rich encrustations along the modern shoreline of the Dead Sea are of three kinds: (a) Black laminae, ranging in thickness from 0.1 mm to 4 mm, alternating with aragonite layers which form continous hard crusts on pebbles and boulders (b) Thin black laminae in laminated muds found in very shallow waters. (c) Thin black laminae, alternating with aragonite and gypsum, surrounding partially submerged tree trunks.

No identifiable X-ray diffraction pattern was obtained in the black layers. SEM studies revealed discrete, shapeless manganese-rich aggregates embedded in an aragonitic matrix. The black laminae consist of approximately 75% aragonite, 15% insoluble residue (mostly quartz), and about 10% manganese-rich fraction. Chemical analyses of the isolated manganese-rich fraction gave up to 50% manganese, and less than 1% iron.

Profiles of dissolved manganese in interstitial water show a two-fold enrichment of manganese as compared with the overlying water, with a particularly high concentration (18 mg/l) at the sediment—water interface. This is interpreted to be due to release of manganese from solid phases in the reduced sediments, and upward migration of dissolved manganese in interstitial water, and oxidation to insoluble tetravalent manganese at the interface with the oxygen-containing water.

The manganese-rich crusts were formed below the water table and were deposited no later than 350 years and possibly sooner.  相似文献   

Carbonate deformation mechanisms in the world's deepest wells (~ 9 km)     

Gerald M. Friedman  S. Anne Reeckmann  Barry Borak 《Tectonophysics》1981,74(3-4)

Carbonate rocks penetrated to a depth of 9.07 km in the Anadarko Basin of south-western Oklahoma, show a number of deformation features induced solely by the increased pressures and temperatures of deep burial. The rocks are at temperatures around 210° C and an overburden pressure of about 2.5 kb.Large calcite crystals in the limestones show extensive twin development accompanied by bending or multiple displacement along twin lamellae. Inferred granulation or cataclastic textures are shown by large calcite crystals which are now bordered by small anhedral calcite grains, a product of mechanical breakage. Pressure-solution features are common and aggrading recrystallization has led to an increase in average crystal size with depth.Limestones at these depths are tight compared to dolostones in the same basin at slightly shallower depths. These dolostones still retain in excess of 20% porosity at 8.08 km.  相似文献   

The Magnetism of Some Permian Rocks from New South Wales   总被引：6，自引：0，他引：6  

E. Irving  L. G. Parry 《Geophysical Journal International》1963,7(4):395-411

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The Palaeomagnetism of the Bloomsburg Red Beds and its Possible Application to the Tectonic History of the Appalachians     

E. Irving  N. D. Opdyke 《Geophysical Journal International》1965,9(2-3):153-167

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Potassium Doppler-resonance lidar for the study of the mesosphere and lower thermosphere at the Arecibo Observatory     

Jonathan S. Friedman  Craig A. Tepley  Shikha Raizada  Qihou H. Zhou  Jonas Hedin  Rubn Delgado 《Journal of Atmospheric and Solar》2003,65(16-18):1411-1424

We have developed a lidar to study the temperature structure of the nighttime mesopause region over the Arecibo Observatory (18.35°N, 66.75°W) by measuring the lineshape of the fluorescence spectrum of atomic potassium that is deposited in the mesosphere and lower thermosphere (MLT) by meteors. To demonstrate how the potassium lidar can enhance MLT studies at Arecibo, we show recent results for: (1) comparisons with airglow temperature measurements; (2) simultaneous operations with stratospheric and mesospheric temperature profiling by Rayleigh lidar; (3) simultaneous observations of K, Ca⁺, and E-region electron density profiles; and (4) occurrences of sporadic K layers, and relationships to sporadic E layers.  相似文献   

Effects of sediment slurry enrichment on salt marsh rehabilitation: Plant and soil responses over seven years     

Matthew G. Slocum  Irving A. Mendelssohn  Nathan L. Kuhn 《Estuaries and Coasts》2005,28(4):519-528

In deltaic marshes, mineral sediment promotes positive elevation change and counters subsidence and sea level rise. In many such marshes sediment deficits result in wetland loss. One new way to address sediment deficiency is to supply marshes with sediments in a slurry that deposits the sediment in a thin layer over a large area. The long-term effects of this strategy are poorly understood. In a rapidly submerging,Spartina alterniflora salt marsh, we tested how different amounts of sediment ameliorated the effects of sea level rise and subsidence over 7 yr (1992–1998). Sediment slurry enrichment likely affected plants and soils by two mechanisms. It increased elevation and soil bulk density, leading to increased plant vigor and soil condition. These effects were long lasting, such that by 1998 areas receiving moderate amounts of sediment (5–12 cm relative elevation) had better plant vigor and soil condition compared to areas not receiving sediment (55% cover versus 20%; bulk densities of 0.4–1.0 g cm⁻³ versus 0.2 g cm⁻³; 0 mM hydrogen sulfide versus > 1.0 mM). The sediment slurry also had high nutrient content, which resulted in a pulse of growth, especially in areas receiving the most sediment (areas > 12 cm relative elevation initially had >90% cover and canopy heights >1.6 m). This nutrient-induced growth spurt was short lived and faded after 3 yr, at which point the long lasting effects of increased elevation probably became the dominant factor promoting plant vigor and soil condition. Moderate levels of sediment generated the most beneficial and long lasting effects to the vegetation and soils. This degree of sediment slurry addition countered the effects of subsidence and sea level rise, but not so much as to surpass the intertidal position to whichS. alterniflora is best adapted.  相似文献   

Trace element abundances in megacrysts and their host basalts: Constraints on partition coefficients and megacryst genesis   总被引：1，自引：0，他引：1  

Anthony J. Irving  Fred A. Frey 《Geochimica et cosmochimica acta》1984,48(6):1201-1221

In an effort to obtain information about mineral/melt trace element partitioning during the high pressure petrogenesis of basic rocks, we determined rare earth and other trace element abundances in megacrysts of clinopyroxene, orthopyroxene, amphibole, mica, anorthoclase, apatite and zircon, and in their host basalts. In general, the ranges of mineral/melt partition coefficients established from experimental partitioning studies and phenocryst/matrix measurements overlap with the ranges of megacryst/host abundance ratios. Our data for Hf, Sc, Ta and Th partitioning represent some of the only estimates available. Consideration of phase equilibria, major element partitioning and isotopic ratios indicate that most of the pyroxene and amphibole megacrysts may have been in equilibrium with their host magmas at high pressures (mostly 10–25 kb). In contrast, it is unlikely that mica, anorthoclase, apatite and zircon megacrysts formed in equilibrium with their host basalts; instead, we conclude that they were precipitated from more evolved magmas and have been mixed into their present host magmas. Consequently, the trace element abundance ratios for megacryst/host should not be interpreted as partition coefficients, but only as guides for understanding trace element partitioning during high pressure petrogenesis. With this caveat, we conclude that the megacryst/ host trace element abundance data indicate that mineral/melt partition coefficients in basaltic systems during high pressure fractionation are not drastically different from partition coefficients valid for low pressure fractionation.  相似文献