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  • Geologic map  (2)
  • 129-801A; 16-162; 20-196; 34-319; 35-323; 5-39; 8-74; 91-596; 92-597; 9-77B; AGE; Antarctic Ocean/PLAIN; Calculated; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Elevation of event; Event label; Glomar Challenger; Inductively coupled plasma - mass spectrometry (ICP-MS); Joides Resolution; Latitude of event; Leg129; Leg16; Leg20; Leg34; Leg35; Leg5; Leg8; Leg9; Leg91; Leg92; Longitude of event; North Pacific/ABYSSAL FLOOR; North Pacific/CONT RISE; North Pacific/HILL; North Pacific Ocean; Ocean Drilling Program; ODP; Osmium; Osmium-187/Osmium-186, error; Osmium-187/Osmium-186 ratio; Osmium-187/Osmium-188, error; Osmium-187/Osmium-188 ratio; Rhenium; Rhenium-187/Osmium-186 ratio; Sample code/label; Sample comment; South Pacific; South Pacific/BASIN; Thermal Ionization Mass Spectrometry (TIMS)  (1)
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  • 1
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    Unknown
    Os and Re concentrations and Os isotope ratios for DSDP and ODP metalliferous sediments from the Pacific Ocean (Table 1) (1995)
    PANGAEA
    In:  Supplement to: Peucker-Ehrenbrink, Bernhard; Ravizza, Gregory E; Hofmann, Albrecht W (1995): The marine 187Os/186Os record of the past 80 million years. Earth and Planetary Science Letters, 130(1-4), 155-167, https://doi.org/10.1016/0012-821X(95)00003-U
    Details
    Publication Date: 2024-06-26
    Description: We report new 187Os/186Os data and Re and Os concentrations in metalliferous sediments from the Pacific to construct a composite Os isotope seawater evolution curve over the past 80 m.y. Analyses of four samples of upper Cretaceous age yield 187Os/186Os values of between 3 and 6.5 and 187Re/186Os values below 55. Mass balance calculations indicate that the pronounced minimum of about 2 in the Os isotope ratio of seawater at the K-T boundary probably reflects the enormous input of cosmogenic material into the oceans by the K-T impactor(s). Following a rapid recovery to 187Os/186Os of 3.5 at 63 Ma, data for the early and middle part of the Cenozoic show an increase in 187Os/186Os to about 6 at 15 Ma. Variations in the isotopic composition of leachable Os from slowly accumulating metalliferous sediments show large fluctuations over short time spans. In contrast, analyses of rapidly accumulating metalliferous carbonates do not exhibit the large oscillations observed in the pelagic clay leach data. These results together with sediment leaching experiments indicate that dissolution of non-hydrogenous Os can occur during the hydrogen peroxide leach and demonstrate that Os data from pelagic clay leachates do not always reflect the Os isotopic composition of seawater. New data for the late Cenozoic further substantiate the rapid increase in the 187Os/186Os of seawater during the past 15 Ma. We interpret the correlation between the marine Sr and Os isotope records during this time period as evidence that weathering within the drainage basin of the Ganges-Brahmaputra river system is responsible for driving seawater Sr and Os toward more radiogenic isotopic compositions. The positive correlation between 87Sr/86Sr and U concentration, the covariation of U and Re concentrations, and the high dissolved Re, U and Sr concentrations found in the Ganges-Brahmaputra river waters supports this interpretation. Accelerating uplift of many orogens worldwide over the past 15 Ma, especially during the last 5 Ma, could have contributed to the rapid increase in 187Os/186Os from 6 to 8.5 over the past 15 Ma. Prior to 15 Ma the marine Sr and Os record are not tightly coupled. The heterogeneous distribution of different lithologies within eroding terrains may play an important role in decoupling the supplies of radiogenic Os and Sr to the oceans and account for the periods of decoupling of the marine Sr and Os isotope records.
    Keywords: 129-801A; 16-162; 20-196; 34-319; 35-323; 5-39; 8-74; 91-596; 92-597; 9-77B; AGE; Antarctic Ocean/PLAIN; Calculated; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Elevation of event; Event label; Glomar Challenger; Inductively coupled plasma - mass spectrometry (ICP-MS); Joides Resolution; Latitude of event; Leg129; Leg16; Leg20; Leg34; Leg35; Leg5; Leg8; Leg9; Leg91; Leg92; Longitude of event; North Pacific/ABYSSAL FLOOR; North Pacific/CONT RISE; North Pacific/HILL; North Pacific Ocean; Ocean Drilling Program; ODP; Osmium; Osmium-187/Osmium-186, error; Osmium-187/Osmium-186 ratio; Osmium-187/Osmium-188, error; Osmium-187/Osmium-188 ratio; Rhenium; Rhenium-187/Osmium-186 ratio; Sample code/label; Sample comment; South Pacific; South Pacific/BASIN; Thermal Ionization Mass Spectrometry (TIMS)
    Type: Dataset
    Format: text/tab-separated-values, 321 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 2
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    Unknown
    Quantitative bedrock geology of the continents and large-scale drainage regions (2007)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q06009, doi:10.1029/2006GC001544.
    Description: We quantitatively analyze the area-age distribution of sedimentary, extrusive volcanic, and endogenous (plutonic and/or metamorphic) bedrock on the basis of data from the most recent digital Geological Map of the World at a scale of 1:25,000,000. The spatial resolution of the digital bedrock data averages 13,905 km2 per polygon. Comparison of certain regions of the world, previously analyzed at higher spatial resolution, with the low-resolution world data reveals general consistency in the areal exposure of major rock types as well as a minor systematic bias toward older average bedrock ages in the global data set. Application of the global bedrock data to 19 large-scale drainage regions and three large, internally drained regions reveals considerable regional variability of Earth's bedrock geology that is consistent with the dominant geotectonic setting of the respective drainage region.
    Description: B.P.E. acknowledges financial support from the United States National Science Foundation (NSF-EAR- 0125873) and from the Woods Hole Oceanographic Institution.
    Keywords: Geologic map ; World ; Age ; Bedrock ; Sediment ; Volcanic rock
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Location Call Number Limitation Availability
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    PAPER (OA)
  • 3
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    Unknown
    Quantitative bedrock geology of Brazil (2007)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q05014, doi:10.1029/2006GC001505.
    Description: We quantitatively analyze the area-age distribution of sedimentary, igneous, metamorphic, and ultramafic bedrock on the basis of data from the digital geologic map of Brazil, published as a GIS map by the Brazilian Geological Survey. Bedrock units exclusively encompassing sedimentary rocks, igneous rocks, or metamorphic rocks cover 40.4%, 31.5%, and 17.7%, respectively, of the total bedrock area. These numbers have to be considered minimum estimates of the areal abundance of sedimentary, igneous, and metamorphic bedrock because polygons defined by mixed lithologies cover ~8.5–9.5% of the total bedrock area. These mixed units are sedimentary rocks with igneous and/or metamorphic contributions (1.4%), metamorphic rocks with sedimentary contributions (1.2%), metamorphic rocks with igneous contributions (1.5%), igneous rocks with sedimentary and/or metamorphic contributions (4.4%), and ultramafic units with sedimentary, igneous, and/or metamorphic contributions (~1–2%). The average ages of major lithologic units, weighted according to bedrock area, are as follows: sedimentary rocks (average stratigraphic age of 248 ± 5 [1σ] Myr; median stratigraphic age of 87.5 Myr), igneous rocks (1153 ± 13 [1σ] Myr), metamorphic rocks (1678 ± 30 [1σ] Myr), and ultramafic rocks (~1227 ± 25 [1σ] Myr). The average bedrock age of Brazil is 946 ± 7 [1σ] Myr. The range in lithologic composition and age structure of the various bedrock units reflects the complex tectonic makeup of Brazil that ranges from Neogene sedimentary cover in the Amazon Basin to Precambrian cratons (Guyana and Brazilian shields) and Transamazonian greenstone belts. The average spatial resolution of the data is 232 km2 polygon−1 and is sufficient to perform area-age analyses of individual river drainage basins larger than ~5,000 km2.
    Description: B.P.E. acknowledges financial support from the U.S. National Science Foundation (NSF-EAR-0125873) and the Woods Hole Oceanographic Institution.
    Keywords: Geologic map ; Brazil ; Age ; Bedrock ; Sediment
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Location Call Number Limitation Availability
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    PAPER (OA)
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