scholarly journals Global atmospheric oxygen variations recorded by Th/U systematics of igneous rocks

2019 ◽  
Vol 116 (38) ◽  
pp. 18854-18859 ◽  
Author(s):  
He Liu ◽  
Robert E. Zartman ◽  
Trevor R. Ireland ◽  
Wei-dong Sun
Keyword(s):  
Oceanic Crust ◽  
Sea Water ◽  
Atmospheric Oxygen ◽  
Sharp Decrease ◽  
Temporal Variations ◽  
Global Scale ◽  
Significant Rise ◽  
Water Soluble ◽  
Igneous Rocks ◽  
Major Step

Atmospheric oxygen has evolved from negligible levels in the Archean to the current level of about 21% through 2 major step rises: The Great Oxidation Event (GOE) in the early Proterozoic and the Neoproterozoic Oxygenation Event (NOE) during the late Proterozoic. However, most previous methods for constraining the time of atmospheric oxygenation have relied on evidence from sedimentary rocks. Here, we investigate the temporal variations of the Th/U of arc igneous rocks since 3.0 billion y ago (Ga) and show that 2 major Th/U decreases are recorded at ca. 2.35 Ga and ca. 0.75 Ga, coincident with the beginning of the GOE and NOE. The decoupling of U from Th is predominantly caused by the significant rise of atmospheric oxygen. Under an increasingly oxidized atmosphere condition, more uranium in the surface environment became oxidized from the water-insoluble U4+ to the water-soluble U6+ valance and incorporated in the sea water and altered oceanic crust. Eventually, the subduction of this altered oceanic crust produced the low-Th/U signature of arc igneous rocks. Therefore, the sharp decrease of Th/U in global arc igneous rocks may provide strong evidence for the rise of atmospheric oxygen. We suggest that the secular Th/U evolution of arc igneous rocks could be an effective geochemical indicator recording the global-scale atmospheric oxygen variation.

Specifics of the Caledonian Collision in the Ol’khon Region (Lake Baikal, Russia)

2021 ◽  
Vol 62 (4) ◽  
pp. 389-400
Author(s):  
V.A. Makrygina
Keyword(s):  
Subduction Zone ◽  
Oceanic Crust ◽  
Lake Baikal ◽  
Siberian Craton ◽  
Island Arc ◽  
Geophysical Data ◽  
Igneous Rocks ◽  
Fold Belt ◽  
Adjacent Part

Abstract —Analysis of geochemical, geochronological, and new geophysical data on metasedimentary and igneous rocks of the Ol’khon region has made it possible to substantiate: (1) the absence of products of the Caledonian suprasubduction magmatism from the adjacent part of the Siberian craton and (2) the presence of a product of this magmatism in the Anga–Talanchan island arc, namely, the Krestovsky massif with gabbro-diorite to granite phases. This suggests subduction of the Paleoasian oceanic crust under the island arc before the collision. The geophysical data showed a steep sinking of the Siberian craton margin. This sinking and the supposed contrary movement and rotation of the Siberian craton prevented the appearance of a subduction zone beneath the craton during the collision but caused the wide development of fault plates in the fold belt at the late collision stage. The residue of oceanic crust slab was pressed out along the fault planes near the surface and formed a row of gabbro-pyroxenite massifs of the Birkhin Complex in the fold belt, where syncollisional granitic melts (Sharanur Complex) formed at the same time. The interaction of two contrasting melts gave rise to the Tazheran and Budun alkaline syenite massifs and alkaline metasomatites of the Birkhin and Ulanganta gabbroid massifs.

Low temperature fluid alteration of oceanic layer 2 basalts, DSDP Leg 37

1977 ◽  
Vol 14 (4) ◽  
pp. 911-926 ◽  
Author(s):  
A. J. Andrews
Keyword(s):  
Low Temperature ◽  
Chemical Nature ◽  
Sea Water ◽  
Significant Rise ◽  
Secondary Phases ◽  
Acoustic Basement ◽  
Layer 2 ◽  
Fluid Alteration ◽  
Fluid Interaction ◽  
Mineralogical Evidence

Penetration of cold seawater into layer 2 of the oceanic crust occurs to at least 600 m, the maximum depth drilled below the sediment-acoustic basement boundary during Leg 37 of the DSDP. The main alteration phases are Mg-saponite, Fe-K rich celadonite, phillipsite, calcite, and hematite. The only exception to this occurs in the form of intensely hydrothermally altered gabbro breccias from an intrusive complex at site 334. There is no mineralogical evidence to suggest an increase in metamorphic grade with depth; however, a variation in mineralogy and alteration intensity, occurs as a function of structure, permeability, and the chemical nature of rock-fluid interaction. On this basis three types of alteration are defined as follows: (A) fracture focussed, oxidative; (B) palagonitic; and (C) non-oxidative, pervasive.Electron microprobe analyses reveal that alteration of fresh glass to palagonite involves the addition of H2O, an increase in total Fe, K2O, TiO2, and possibly SiO2, and the loss of CaO, MgO, Na2O, and MnO.Detailed examination of the mineralogy and chemistry of oxidative alteration suggests that during low temperature sea water–basalt interaction, basalt experiences a net gain in CaO, total Fe and K2O, while SiO2 and MgO appear to have been locally remobilized. These trends are generally consistent with the distribution of secondary phases. The distributions of Mn, Cu, Ni, Zn, Co, and Sr do not appear to have been significantly affected during this process.It is apparent that seawater must have experienced significant Eh lowering during this interaction; however, the occurrence of hematite–magnetite and absence of sulphide in this particular environment requires that seawater was either highly depleted in total sulfur or experienced a significant rise in pH.

scholarly journals Multi-species inversion of CH<sub>4</sub>, CO and H<sub>2</sub> emissions from surface measurements

2009 ◽  
Vol 9 (14) ◽  
pp. 5281-5297 ◽  
Author(s):  
I. Pison ◽  
P. Bousquet ◽  
F. Chevallier ◽  
S. Szopa ◽  
D. Hauglustaine
Keyword(s):  
Transport Model ◽  
Regional Scale ◽  
Surface Concentration ◽  
Temporal Variations ◽  
Global Scale ◽  
Chemical Transport Model ◽  
Methyl Chloroform ◽  
Emission Fluxes ◽  
Surface Measurements ◽  
One Year

Abstract. In order to study the spatial and temporal variations of the emissions of greenhouse gases and of their precursors, we developed a data assimilation system and applied it to infer emissions of CH4, CO and H2 for one year. It is based on an atmospheric chemical transport model and on a simplified scheme for the oxidation chain of hydrocarbons, including methane, formaldehyde, carbon monoxide and molecular hydrogen together with methyl chloroform. The methodology is exposed and a first attempt at evaluating the inverted fluxes is made. Inversions of the emission fluxes of CO, CH4 and H2 and concentrations of HCHO and OH were performed for the year 2004, using surface concentration measurements of CO, CH4, H2 and CH3CCl3 as constraints. Independent data from ship and aircraft measurements and satellite retrievals are used to evaluate the results. The total emitted mass of CO is 30% higher after the inversion, due to increased fluxes by up to 35% in the Northern Hemisphere. The spatial distribution of emissions of CH4 is modified by a decrease of fluxes in boreal areas up to 60%. The comparison between mono- and multi-species inversions shows that the results are close at a global scale but may significantly differ at a regional scale because of the interactions between the various tracers during the inversion.

scholarly journals The mechanism of ciliary movement.—IV. The relation of ciliary activity to oxygen consumption

1924 ◽  
Vol 96 (673) ◽  
pp. 95-114 ◽  
Keyword(s):  
Sea Water ◽  
Atmospheric Oxygen ◽  
Pure Oxygen ◽  
Active Movement ◽  
Ciliary Activity ◽  
Partial Recovery ◽  
Ciliary Movement ◽  
Hydrogen Recovery ◽  
Typical Experiment ◽  
Time Required

Engelmann (5) showed that the cells of the ciliated epithelium of the frog’s œsophagus remain active for as much as two hours after the tissue is exposed to an atmosphere of hydrogen. From this he concluded that the cells contained a considerable store of intramolecular oxygen, on which they could draw in the total absence of atmospheric oxygen. This experiment is, however, not conclusive. In the case of the cilia on the gills of Mytilus edulis , the absolute time required for cessation of movement in hydrogen depends very largely on the amount of water in contact with the tissue. Oxygen dissolved in an undisturbed drop of water is only slowly removed by a current of hydrogen; in a large drop of water there is, therefore, more oxygen available for the use of the tissue than is the case when the experiment is performed with tissue simply moistened with water. If a piece of gill, kept moist but not immersed in sea-water, is placed on a coverslip in an Engelmann gas chamber and exposed to an atmosphere of hydrogen, active movement persists for 30 to 45 minutes; the speed of the beat gradually falls, and after 60 to 75 minutes all movement ceases. If air be admitted when the movement has begun to slow down partial recovery takes place at once, and is soon complete. If, however, the cilia have become almost inactive in hydrogen, recovery in air is much slower, and may not be complete for about half an hour. In pure oxygen recovery is much more rapid. In order to determine to what extent the prolonged activity of the cells in an atmosphere of hydrogen is due to free oxygen in the water or tissue, the experiments were repeated with hæmoglobin in sea-water. A solution of hæmoglobin was used of such a strength as would enable a film of liquid in contact with the tissue to give a well-marked spectrum with a Zeiss microspectroscope. The following table gives the details of a typical experiment.

Revised stratigraphy of the Mesozoic rocks of southern Cyprus

1980 ◽  
Vol 117 (6) ◽  
pp. 547-563 ◽  
Author(s):  
R. E. Swarbrick ◽  
A. H. F. Robertson
Keyword(s):  
Oceanic Crust ◽  
Continental Margin ◽  
Late Cretaceous ◽  
Sedimentary Cover ◽  
Igneous Rocks ◽  
Late Triassic ◽  
Metamorphic Rocks ◽  
Southern Cyprus

SummaryRecent resurgence of interest in the Mesozoic rocks of SW and southern Cyprus necessitates redefinition of the Mesozoic sedimentary and igneous rocks in line with modern stratigraphical convention. Two fundamentally different rocks associations are present, the Troodos Complex, not redefined, a portion of late Cretaceous oceanic crust, and the Mamonia Complex, the tectonically dismembered remnants of a Mesozoic continental margin. Based on earlier work, the Mamonia Complex is divided into two groups, each subdivided into a number of subsidiary formations and members. The Ayios Photios Group is wholly sedimentary, and records the evolution of a late Triassic to Cretaceous inactive continental margin. The Dhiarizos Group represents Triassic alkalic volcanism and sedimentation adjacent to a continental margin. Several other formations not included in the two groups comprise sedimentary mélange and metamorphic rocks. The Troodos Complex possesses an in situ late Cretaceous sedimentary cover which includes two formations of ferromanganiferous pelagic sediments, radiolarites and volcaniclastic sandstones. The overlying Cainozoic calcareous units are not redefined here.

Recycling of Paleo-oceanic crust: Geochemical evidence from Early Paleozoic mafic igneous rocks in the Tongbai orogen, Central China

Lithos ◽  
2019 ◽  
Vol 328-329 ◽  
pp. 312-327 ◽  
Author(s):  
Fei Zheng ◽  
Li-Qun Dai ◽  
Zi-Fu Zhao ◽  
Yong-Fei Zheng ◽  
Zheng Xu
Keyword(s):  
Oceanic Crust ◽  
Igneous Rocks ◽  
Central China ◽  
Early Paleozoic ◽  
Geochemical Evidence

Germination behaviour in beach spinifex (Spinifex hirsutus Labill.)

1972 ◽  
Vol 20 (3) ◽  
pp. 241 ◽  
Author(s):  
RL Harty ◽  
TJ McDonald
Keyword(s):  
Sea Water ◽  
Field Capacity ◽  
Water Soluble ◽  
Lettuce Seed ◽  
Tetrazolium Chloride ◽  
Chemical Inhibitors ◽  
Eastern Australia ◽  
Pot Trials ◽  
Germination Behaviour ◽  
Germination Experiments

This paper deals with threshing and seed germination studies on hand-harvested beach spinifex (Spinifex hirsutus Labill.). This work was carried out as part of a detailed study of the autecology of beach spinifex, an important pioneer sand stabilizer on beaches and dunes along the coast of eastern Australia. Hammer-milling was suitable for threshing out caryopses from beach spinifex inflorescences, but in the process the caryopses were excessively damaged. A barley de-awning machine produced spikelets (caryopses enclosed in lemma, palea, and glumes plus the base of the associated spine) which were free flowing and therefore suitable for mechanical planting. Laboratory germination experiments disclosed that the caryopses were negatively photoblastic when germinated alone, or enclosed within the spikelet. Alternating thermoperiods (10-25, 15-25, 20-25 ; 10-35, 15-35, 20-35�C) were generally superior to constant thermoperiods (25, 30, 35") in the induction of germination. The germination of caryopses from inflorescences harvested 2 months previously agreed with an estimate of viability made by using tetrazolium chloride. This indicated that beach spinifex seed has no pronounced after-ripening requirements. The rate of germination of caryopses and their germinative capacity were markedly increased when the caryopses were removed from the spikelets. It is likely that germination in the spikelet is inhibited by a slow rate of gaseous exchange between the embryo and the atmosphere. A sensitivity to anaerobic conditions was demonstrated by soaking spikelets for varying periods up to 48 hr in distilled and sea water. Such treatments led to a decrease in germination. Pot trials showed that in waterlogged sand, no appreciable germination occurred below 3.75 cm. In sand held at field capacity, some germination occurred down to the maximum depth tried (8.75 cm), but the best germination was from 2.5 to 3 .75 cm. Soaking spikelets in distilled water for 48 hr and testing the leachate on germinating lettuce seed failed to disclose the presence of water-soluble chemical inhibitors in the spikelets.

scholarly journals Problems of water supply of the population and application of the method of electrolysis-structural activation for partial solution

2018 ◽  
Vol 193 ◽  
pp. 02019
Author(s):  
Ludmila Prikhodko ◽  
Galina Bryukhanova ◽  
Ekaterina Beljakova
Keyword(s):  
Water Supply ◽  
Reverse Osmosis ◽  
Arid Regions ◽  
Sea Water ◽  
Partial Solution ◽  
Global Scale ◽  
Membrane Technology ◽  
Saline Groundwater ◽  
Desalinated Water

We analyzed the problems of water supply for the population of global scale and regional importance. A method for the electrolysis-structural activation of water oriented on the use of initial fresh rainwater or desalinated membrane technology of sea water in a mix with biologically purified household sewage waters. This method can be used on sea vessels, in arid regions of the planet, and in areas with saline groundwater. Activation of water is achieved by mixing biologically purified wastewater obtained by technology that ensures the quality of purified water at the level of requirements for release in a fishery pond and desalinated water (rainwater) or obtained by reverse osmosis in a ratio of their volumes not more than 10:1

scholarly journals On the function of chlorocruorin

1940 ◽  
Vol 129 (855) ◽  
pp. 137-153 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Oxygen Consumption ◽  
Dissolved Oxygen ◽  
Sea Water ◽  
Oxygen Carrier ◽  
Significant Rise ◽  
Oxygen Concentrations

1.The oxygen consumption of Sabella decreases soon after the concentration of dissolved oxygen in the sea water falls below the value corresponding to air saturation both at 10 and 17° C. Above air saturation at 17° C there is no significant rise in oxygen consumption. 2. The oxygen consumption of Sabella whose chlorocruorin has been converted to carboxychlorocruorin is lower than that of normal worms. This is the case at air saturation of the water and at oxygen concentrations below air saturation both at 10 and 17° C. 3. The fall in oxygen consumption of the animals after treatment with carbon monoxide is not due to an action of the latter on cell enzymes. 4. It follows that chlorocruorin functions as an oxygen carrier in Sabella at all temperatures and oxygen pressures to which the animals are subjected in nature.

Recognition and Prevention of Distillate Fuel Emulsions

2006 ◽  
Author(s):  
T. D. Newbound ◽  
A. N. Al-Nasser ◽  
M. P. Sang ◽  
W. J. Carrigan
Keyword(s):  
Gas Turbine ◽  
Microbial Activity ◽  
Red Sea ◽  
Diesel Fuel ◽  
Sodium Sulfate ◽  
Sea Water ◽  
Hydrocarbon Fuel ◽  
Liquid Hydrocarbon ◽  
Water Soluble ◽  
High Concentrations

This paper describes a case study involving chronic plugging of 5μm particulate filters in a gas turbine diesel fuel system in a Red Sea refinery. Rapid plugging of the filters was caused by water-in-diesel emulsions generated in diesel fuel supply tanks. Sludge with a wax-like appearance recovered from the 5 μm filters was, in fact, found to be composed of up to 50 percent water with no significant wax content. X-ray studies of the filter catch solids revealed a variety of iron oxide phases, sodium chloride, and high concentrations of sodium sulfate. Microbial cultures inoculated from storage tank ‘rag’ layers yielded moderate to high counts of general aerobic bacteria (GAB), moderate fungal cultures (yeast and molds) and low sulfate reducing bacteria (SRB). Elemental analysis of water in supply tanks where microbial activity was highest revealed ion concentrations similar to those found in Red Sea water. Sulfur isotope ratios in sulfate from filter catches suggest that much of the sulfate was derived from microbial metathesis of sulfur-bearing hydrocarbons. Frequent contamination of on-shore liquid hydrocarbon fuel tanks with sea water can cause corrosion and create a favorable environment for bacterial growth. Surfactant byproducts of microbial activity are capable of stabilizing emulsions, suspending water soluble salts such as sodium sulfate, and metals such as lead and copper. Copper is well known to promote gum formation, while all of these contaminants are potentially corrosive to gas turbine hot gas path components.

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