Treatise on Geochemistry
Papers 180
1 page of 18 pages (180 results)
Subducted crust refertilizes the subarc mantle wedge as well as the deep convecting mantle. In the subarc region, mass transfer occurs mainly through fluids, melts, or supercritical liquids. Experiments show that devolatilization reactions may occur at almost any depth in the chemically complex subducting lithosphere. Extreme temperature gradients across the slab lithosphere, the subduction channel, and the mantle hanging wall promote diachronous fluid production. Fluids are dominated by H2O, an...
89 CitationsSource
#1Y.-H. Li (UH: University of Hawaii)H-Index: 1
#2J.E. Schoonmaker (UH: University of Hawaii)H-Index: 1
In this chapter, a review of the composition of marine sediments is presented, first addressing pelagic sediments in general, and then considering several specific types of sediments, each dominated by hydrogenous components. In each section, a review of the mineralogy of sediments is followed by an examination of their geochemistry using enrichment factors and factor analysis.
110 CitationsSource
#1A. Bekker (UM: University of Manitoba)H-Index: 4
#2Noah J. PlanavskyH-Index: 40
Last.Kurt O. KonhauserH-Index: 50
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Iron formations are economically significant, iron- and silica-rich sedimentary rocks that are restricted to Precambrian successions. There are no known modern or Phanerozoic analogues for these deposits that are comparable in terms of areal extent and thickness. Although many aspects of iron formation origin remain debatable, it is generally accepted that secular changes in the style of deposition are genetically linked to plate tectonic processes, mantle plume events, and evolution of Earth's ...
64 CitationsSource
#1W.B.N. Berry (University of California, Berkeley)
Sedimentary rocks are commonly organized into discrete strata. The strata are composed of materials, diverse particles of inorganic and/or organic origin, that reflect aspects of the environmental conditions under which they got accumulated. Sequences of sedimentary rock layers were observed and studied initially in cliffs, man-made exposures, and sites where the vegetation was not thick enough to obscure the rock layers. It was in mines, however, that sequences of strata came to be examined clo...
#1W.R. Martin (WHOI: Woods Hole Oceanographic Institution)H-Index: 1
#2F.L. Sayles (WHOI: Woods Hole Oceanographic Institution)H-Index: 1
The biogenic component of the rain of particles to the sea floor, consisting of organic matter, calcium carbonate, and biogenic silica, is efficiently recycled at the surface of marine sediments. The reactions these materials undergo affect the Earth's surface geochemical cycles on both short and long timescales. Further, they alter the composition of the particulate flux, so that their effects must be considered in the interpretation of the sedimentary record. The reactions of biogenic material...
24 CitationsSource
#1Jean Jouzel (CNRS: Centre national de la recherche scientifique)H-Index: 2
This chapter is an update of the review previously published. The focus is twofold: the first part dealing with theoretical aspects related with the physics and the modeling of water isotopes in the atmosphere is followed by a detailed presentation of the climatic information that can be extracted from these isotopes measured along deep ice cores drilled in Greenland and Antarctica. Here, the author reviews the considerable amount of research conducted in these complementary topics over the last...
23 CitationsSource
#1J.S. Levine (LaRC: Langley Research Center)H-Index: 1
Biomass burning is both a process of geochemical cycling of gases and particulates from the biosphere to the atmosphere and a process of global change. Biomass burning or vegetation burning is the burning of living and dead vegetation and includes human-initiated burning and natural lightning-induced burning. The bulk of the world's biomass burning occurs in the tropics − in the tropical forests of South America and Southeast Asia and in the savannas of Africa and South America. The majority of ...
5 CitationsSource
The composition of the primitive mantle derived here shows that Earth was assembled from material that shows many of the same chemical fractionation processes as chondritic meteorites. These processes occurred at the initial stage of the solar system formation, under conditions thought to be present in the solar nebula. But the stable isotope record excludes chondritic meteorites as the ‘building blocks’ of Earth. Meteorites formed in local environments separated from that part of the inner sola...
706 CitationsSource
#1Teofilo A. Abrajano (RPI: Rensselaer Polytechnic Institute)H-Index: 30
#2Beizhan Yan (RPI: Rensselaer Polytechnic Institute)H-Index: 23
Last.V. O'Malley (RPI: Rensselaer Polytechnic Institute)H-Index: 1
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Geochemistry is ultimately the study of sources, movement, and fate of chemicals in the geosphere at various spatial and temporal scales. Environmental organic geochemistry focuses such studies on organic compounds of toxicological and ecological concern. This field emphasizes not only those compounds with potential toxicological properties, but also the geological systems accessible to the biological receptors of those hazards. Hence, the examples presented in this chapter focus on hydrocarbons...
34 CitationsSource
#1Eugene C. Perry (NIU: Northern Illinois University)H-Index: 1
Cherts, specifically Precambrian cherts, are fine-grained rocks consisting dominantly or entirely of SiO2 in the form of microcrystalline quartz, subordinate megaquartz, and (rarely) chalcedonic quartz. Cherts may be chemical precipitates, or they may be replacements of preexisting carbonates, volcanoclastic sediments, or igneous and metamorphic rocks. The silica cycle in the Precambrian was dominated by inorganic processes, because siliceous microorganisms, which control the silica concentratio...
46 CitationsSource
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Environmental chemistry
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Mantle (geology)