Indirect Methods for Estimation of Catchment Precipitation     

D. N. Brash  D. L. Murray 《New Zealand geographer》1980,36(2):57-67

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Planetary exploration: The condon lectures: Carl Sagan. Oregon State System of Higher Education,Eugene, Oregon, 1970. 76 pp. Price $2.00     

Bruce C. Murray 《Icarus》1971

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Quartz and polymineral luminescence dating of Japanese loess over the last 0.6 Ma: Comparison with an independent chronology     

Takuya Watanuki  Andrew S. Murray  Sumiko Tsukamoto 《Earth and Planetary Science Letters》2005,240(3-4):774-789

There are only a few luminescence dating studies of loess sediments in Japan, but interleaved with these deposits are many well-described tephras of known age based on ¹⁴C and fission track analysis; these independent age controls provide an opportunity to test the reliability of loess luminescence ages. This study provides such a comparison at two sites in central Honshu, the largest island in the Japanese archipelago. Samples were collected from sequences of interleaved volcanic tephra and loess deposited on a Middle Pleistocene river terrace in the Niigata Prefecture and on an Early to Middle Pleistocene dissected fluvial surface at in the Tochigi Prefecture, Honshu. Equivalent doses (D_e) were estimated from fine grains (4–11 μm) using both polymineral IR-OSL and (post-IR) blue-OSL, and quartz blue-OSL. The blue-stimulated luminescence signals could be represented by up to three exponentially decaying components; only the most light sensitive of these components was used in the final D_e estimation. Almost all the estimates of D_e from polymineral IR-OSL are smaller than those from polymineral (post-IR) blue-OSL and quartz blue-OSL, whereas the latter two are in good agreement. The blue-light stimulated luminescence ages using the most light sensitive component are shown to be in good agreement with the independent control, up to 500 ka. Although the IR-OSL signals underestimate the known age, a simple laboratory fading test is found empirically to correct for this underestimation. We conclude that the most rapidly blue-stimulated luminescence signals from quartz extracted from our loess samples give reliable ages, and that future loess dating studies should concentrate on these signals.  相似文献   

Geology and geochemistry of jasperoids from the Gold Bar district, Nevada     

Ozcan Yigit  Albert H. Hofstra  Murray W. Hitzman  Eric P. Nelson 《Mineralium Deposita》2006,41(6):527-547

Gold Bar is one of several Carlin-type gold mining districts located in the Battle Mountain–Eureka trend, Nevada. It is composed of one main deposit, Gold Bar; five satellite deposits; and four resources that contain 1.6 Moz (50 t) of gold. All of the deposits and resources occur at the intersection of north-northwest- and northeast-trending high-angle faults in slope facies limestones of the Devonian Nevada Group exposed in windows through Ordovician basin facies siliciclastic rocks of the Roberts Mountains allochthon. Igneous intrusions and magnetic anomalies are notably absent. The Gold Bar district contains a variety of discordant and stratabound jasperoid bodies, especially along the Wall Fault zone, that were mapped and studied in some detail to identify the attributes of those most closely associated with gold ore and to constrain genetic models. Four types of jasperoids, J₀, J₁, J₂, and J₃, were distinguished on the basis of their geologic and structural settings and appearance. Field relations suggest that J₀ formed during an early event. Petrographic observations, geochemistry, and δ¹⁸O values of quartz suggest it was overprinted by the hydrothermal event that produced ore-related J₁, J₂, and J₃ jasperoids and associated gold deposits. The greater amount of siliciclastic detritus present in J₀ jasperoids caused them to have higher δ¹⁸O values than J_1,2,3 jasperoids hosted in underlying limestones. Ore-related jasperoids are composed of main-ore-stage replacements and late-ore-stage open-space filling quartz with variable geochemistry and an enormous range of δ¹⁸O values (24.5 and −3.7‰). Jasperoids hosted in limestones with the most anomalous Au, Ag, Hg, ±(As, Sb, Tl) concentrations and the highest δ¹⁸O values are associated with the largest deposits. The 28‰ range of jasperoid δ¹⁸O values is best explained by mixing between an ¹⁸O-enriched fluid and an ¹⁸O-depleted fluid. The positive correlation between the sizes of gold deposits and the δ¹⁸O composition of jasperoids indicates that gold was introduced by the ¹⁸O-enriched fluid. The lowest calculated δ¹⁸O value for water in equilibrium with late-ore-stage quartz at 200°C (−15‰) and the measured δD value of fluid inclusion water extracted from late-ore-stage orpiment and realgar (−116‰) indicate that the ¹⁸O-depleted fluid was composed of relatively unexchanged meteoric water. The source of the ¹⁸O-enriched ore fluid is not constrained. The δ³⁴S values of late-ore-stage realgar, orpiment, and stibnite (5.7–15.5‰) and barite (31.5–40.9‰) suggest that H₂S and sulfate were derived from sedimentary sources. Likewise, the δ¹³C and δ¹⁸O values of late-stage calcite (−4.8 to 1.5‰ and 11.5 to 17.4‰, respectively) suggest that CO₂ was derived from marine limestones. Based on these data and the apparent absence of any Eocene intrusions in the district, Gold Bar may be the product of a nonmagmatic hydrothermal system.  相似文献   

Marine scavenging: Trace metal adsorption by interfacial sediment from MANOP Site H     

Laurie S. Balistrieri  James W. Murray 《Geochimica et cosmochimica acta》1984,48(5):921-929

The adsorption of thirteen trace metals from seawater was studied on interfacial sediment from MANOP site H. The adsorption data indicate a long (~20 day) equilibration time for most metals, an increase in adsorption with an increase in pH and particle concentration, a dependence of adsorption on total metal concentration at high adsorption densities, and a lack of correlation between metal binding ability and metal hydrolysis in solution.Apparent equilibrium binding constants normalized to the total number of available sites on the solid were determined for metal binding with the interfacial sediment. The binding constants indicate that the affinity sequence for metal interactions with the interfacial sediment is: Pb > Fe > Sn ? Co≈ Mn > Cu > Be > Sc ? Zn > Ni > Cd ? Ba > Cs at pH 7.82 in seawater.A comparison of the binding constants for suspended particles, interfacial sediment, and surface sediment indicate that the composition of particles influences the binding ability of the particles. Biogenic particles tend to bind most metals more strongly than lithogenic or authigenic particles.Based on limited data, there is a strong positive correlation between the measured binding constants and the observed partitioning of metals between sediment and seawater.  相似文献   

A model for coupled sulfate reduction and methane oxidation in the sediments of Saanich Inlet   总被引：2，自引：0，他引：2  

A.H. Devol  J.J. Anderson  K. Kuivila  J.W. Murray 《Geochimica et cosmochimica acta》1984,48(5):993-1004

A methane-sulfate coupled reaction diffusion model has been developed to describe the inverse relationship commonly observed between methane and sulfate concentrations in the pore waters of anoxic marine sediments. The sediment column was divided into two zones; an upper zone where diagenetic reaction rates are limited by the concentration of oxidizable organic matter and a lower zone in which reaction rates are limited by the concentration of oxidizing agent—sulfate. For each zone differential equations describing the distribution of methane and sulfate were derived. The boundary conditions used to solve these equations resulted in a set of four coupled equations. When fit to data from Saanich Inlet (B.C., Canada) and Skan Bay (Alaska) the model not only reproduces the observed methane and sulfate pore water concentration profiles but also accurately predicts the methane oxidation and sulfate reduction rates. Maximum methane oxidation rates occur at the transition boundary from the upper to the lower layer. In Saanich Inlet sediments from 23 to 40% of the downward sulfate flux is consumed in methane oxidation while in Skan Bay this value is only about 12%.  相似文献   

Metallogeny and tectonic development of the Tasman Fold Belt System in Queensland     

C.G. Murray 《Ore Geology Reviews》1986,1(2-4)

The northern part of the Tasman Fold Belt System in Queensland comprises three segments, the Thomson, Hodgkinson- Broken River, and New England Fold Belts. The evolution of each fold belt can be traced through pre-cratonic (orogenic), transitional, and cratonic stages. The different timing of these stages within each fold belt indicates differing tectonic histories, although connecting links can be recognised between them from Late Devonian time onward. In general, orogenesis became younger from west to east towards the present continental margin. The most recent folding, confined to the New England Fold Belt, was of Early to mid-Cretaceous age. It is considered that this eastward migration of orogenic activity may reflect progressive continental accretion, although the total amount of accretion since the inception of the Tasman Fold Belt System in Cambrian time is uncertain.The Thomson Fold Belt is largely concealed beneath late Palaeozoic and Mesozoic intracratonic basin sediments. In addition, the age of the more highly deformed and metamorphosed rocks exposed in the northeast is unknown, being either Precambrian or early Palaeozoic. Therefore, the tectonic evolution of this fold belt must remain very speculative. In its early stages (Precambrian or early Palaeozoic), the Thomson Fold Belt was probably a rifted continental margin adjacent to the Early to Middle Proterozoic craton to the west and north. The presence of calc-alkaline volcanics of Late Cambrian Early Ordovician and Early-Middle Devonian age suggests that the fold belt evolved to a convergent Pacific-type continental margin. The tectonic setting of the pre-cratonic (orogenic) stage of the Hodgkinson—Broken River Fold Belt is also uncertain. Most of this fold belt consists of strongly deformed, flysch-type sediments of Silurian-Devonian age. Forearc, back-arc and rifted margin settings have all been proposed for these deposits. The transitional stage of the Hodgkinson—Broken River Fold Belt was characterised by eruption of extensive silicic continental volcanics, mainly ignimbrites, and intrusion of comagmatic granitoids in Late Carboniferous Early Permian time. An Andean-type continental margin model, with calc-alkaline volcanics erupted above a west-dipping subduction zone, has been suggested for this period. The tectonic history of the New England Fold Belt is believed to be relatively well understood. It was the site of extensive and repeated eruption of calc-alkaline volcanics from Late Silurian to Early Cretaceous time. The oldest rocks may have formed in a volcanic island arc. From the Late Devonian, the fold belt was a convergent continental margin above a west-dipping subduction zone. For Late Devonian- Early Carboniferous time, parallel belts representing continental margin volcanic arc, forearc basin, and subduction complex can be recognised.A great variety of mineral deposits, ranging in age from Late Cambrian-Early Ordovician and possibly even Precambrian to Early Cretaceous, is present in the exposed rocks of the Tasman Fold Belt System in Queensland. Volcanogenic massive sulphides and slate belt-type gold-bearing quartz veins are the most important deposits formed in the pre-cratonic (orogenic) stage of all three fold belts. The voicanogenic massive sulphides include classic Kuroko-type orebodies associated with silicic volcanics, such as those at Thalanga (Late Cambrian-Early Ordovician. Thomson Fold Belt) and at Mount Chalmers (Early Permian New England Fold Belt), and Kieslager or Besshi-type deposits related to submarine mafic volcanics, such as Peak Downs (Precambrian or early Palaeozoic, Thomson Fold Belt) and Dianne. OK and Mount Molloy (Silurian—Devonian, Hodgkinson Broken River Fold Belt). The major gold—copper orebody at Mount Morgan (Middle Devonian, New England Fold Belt), is considered to be of volcanic or subvolcanic origin, but is not a typical volcanogenic massive sulphide.The most numerous ore deposits are associated with calc-alkaline volcanics and granitoid intrusives of the transitional tectonic stage of the three fold belts, particularly the Late Carboniferous Early Perman of the Hodgkinson—Broken River Fold Belt and the Late Permian—Middle Triassic of the southeast Queensland part of the New England Fold Belt. In general, these deposits are small but rich. They include tin, tungsten, molybdenum and bismuth in granites and adjacent metasediments, base metals in contact meta somatic skarns, gold in volcanic breccia pipes, gold-bearing quartz veins within granitoid intrusives and in volcanic contact rocks, and low-grade disseminated porphyry-type copper and molybdenum deposits. The porphyry-type deposits occur in distinct belts related to intrusives of different ages: Devonian (Thomson Fold Belt), Late Carboniferous—Early Permian (Hodgkinson—Broken River Fold Belt). Late Permian Middle Triassic (southeast Queensland part of the New England Fold Belt), and Early Cretaceous (northern New England Fold Belt). All are too low grade to be of economic importance at present.Tertiary deep weathering events were responsible for the formation of lateritic nickel deposits on ultramafics and surficial manganese concentrations from disseminated mineralisation in cherts and jaspers.  相似文献   

The adsorption of Cu,Pb, Zn,and Cd on goethite from major ion seawater     

L.S. Balistrieri  J.W. Murray 《Geochimica et cosmochimica acta》1982,46(7):1253-1265

The adsorption of Cu, Pb, Zn, and Cd on goethite (αFeOOH) from NaNO₃ solutions and from major ion seawater was compared to assess the effect of the major ions of seawater (Na, Mg, Ca, K, Cl, and SO₄) on the adsorption behavior of the metals. Magnesium and sulphate are the principal seawater ions which enhance or inhibit adsorption relative to the inert system. Their effect, as determined from the site-binding model of Davis et al. (1978), was a combination of changing the electrostatic conditions at the interface and decreasing the available binding sites.The basic differences between the experimental system of major ion seawater and natural seawater were examined. It was concluded that: 1) although the experimental metal concentrations in major ion seawater were higher than those found in natural seawater, estimates of the binding energy of Cu, Zn, and Cd with αFeOOH for natural seawater concentrations could be made from the data, 2) Cu, Pb, Zn, and Cd showed little or no competition for surface sites on goethite, and 3) the presence of carbonate, phosphate, and silicate had little or no effect on the adsorption of Zn and Cd on goethite.  相似文献   

Aerobic respiration in pelagic marine sediments     

Varis Grundmanis  James W Murray 《Geochimica et cosmochimica acta》1982,46(6):1101-1120

Analyses for dissolved oxygen, nitrate and total CO₂ in the interstitial water have been combined with solid phase sediment analyses of carbon and nitrogen to calculate the rates of reaction and stoichiometry of decomposing organic matter in central Equatorial Pacific pelagic sediments. The diagenesis is dominated by aerobic respiration and nitrification.Organic carbon and total nitrogen decrease exponentially with depth in both red clay and carbonate ooze sediments. In addition, there is a correlation between surface organic carbon and total nitrogen with distance from the equator. Fixed NH₄ is relatively constant with depth and constitutes 12 to 64% of the total nitrogen. The remainder is considered to be organic nitrogen.The $\text{C}\text{N}$ ratio of the decomposing organic matter was obtained using three approaches. Using the correlations of organic carbon with total nitrogen or organic nitrogen the molar ratios varied from 3.4 to 18.1. The average of all stations was 12.6 using total nitrogen and 13.7 using organic nitrogen. The Redfield ratio is 6.6. Approaches using interstitial water chemistry gave lower ratios. The average value using correlations between dissolved oxygen and nitrate was 8.1. The same approach using total CO₂ and nitrate gave an average of 9.1. Due to difficulties in unambiguously interpreting the solid phase data we favor the ratios obtained from the pore water analyses.The rate of organic matter decomposition can be obtained from model calculations using the dissolved oxygen and solid organic carbon data. Most gradients occur in the upper 10 to 20 cm of the sediments. Assuming that bioturbation is more important than sedimentation we have calculated first order rate constants. The average values using organic carbon and dissolved oxygen was 3.9 kyr^? and 4.2 kyr^? respectively using a biological mixing coefficient of 100 cm² kyr^?1. These rate constants decrease in direct proportions to the mixing coefficient.  相似文献   

Sedimentary indicators of water movement in the western approaches to the English Channel     

J.W. Murray  J.W. Weston  S. Sturrock 《Continental Shelf Research》1983,1(4):339-352

The continental shelf to the southwest of the British Isles is an area of intense tidal current activity. Although most of the sediment is coarse, it still contains a small proportion of fine (<63 μm) material, consisting mainly of biogenic debris. Coccoliths in particular are both common and widespread and they are found in the adjacent slope sediments. The results presented here show that coccolithophorid diversity is high in the deeper parts of Whittard Canyon, the abyssal plain, and on a small area of shelf. Diversity decreases away from the ocean towards the land. Coccoliths and coccospheres have also been recorded from surface water samples. Apart from the landward movement of oceanic water shown by the coccolithophorids, movement of material on the bottom from shelf to slope is shown by the distribution of benthic diatom frustules and mollusc shell chips cut by clionid sponges. Thus, a study of the fine sediment reveals details of sediment transport and water movement.  相似文献