A high-resolution 187Os/88Os record for the late Maastrichtian

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Author(s): Robinson, Nichole
Source: 128p. Institution: University of Hawaii at Manoa, Honolulu, HI, United States
Note: In English. Includes appendices. 134 refs. Master's thesis
Summary: The marine osmium (Os) isotope record can potentially act as an independent proxy indicator of major volcanic activity, marked by decreases in seawater 187Os/188Os to more mantle-like values. A composite late Maastrichtian (66 to 68.5 Ma) marine Os record, based on bulk sediment samples from the Southern Ocean (Ocean Drilling Program (ODP) Site 690), the Tropical Pacific Ocean (Deep Sea Drilling Project (DSDP) Site 577), the South Atlantic (DSDP Site 525) and the paleo-Tethys Ocean, provides robust evidence of a 20% decline in seawater 187Os/188Os over a period of about 200 ka early in magnetochron C29r, ending approximately 200 ka before the Cretaceous-Paleogene (K-Pg) boundary (Robinson et al., 2009). This shift in 187Os/188Os is interpreted as a chemostratigraphic marker of Deccan volcanism, and is temporally separate from the Os isotope excursion associated with the Chicxulub impact at the K-Pg boundary. Improved geochronologic data constraining the eruptive history of the Deccan (Renne et al., 2015; Schoene et al., 2015), as well as Os isotope records coinciding with other episodes of large igneous province (LIP) eruption (Duvivier et al., 2015; Bottini et al., 2012; Kuroda et al., 2010), provide a new and larger context for understanding the response of the marine Os record to LIP emplacement. Comparison of Os isotope records coinciding with other LIP events to the Deccan/K-Pg record reveal important differences in the structure and duration of shifts in the Os isotope record, and precludes a single interpretation of all LIP-associated Os isotope excursions.
Year of Publication: 2016
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Cenozoic; Chemostratigraphy; Chicxulub Crater; Cretaceous; DSDP Site 525; DSDP Site 577; Deccan Traps; Deep Sea Drilling Project; Eruptions; IPOD; Isotope ratios; Isotopes; K-T boundary; Large igneous provinces; Leg 113; Leg 74; Leg 86; Lower Paleocene; Maestrichtian; Mantle; Maud Rise; Mesozoic; Metals; North Pacific; Northwest Pacific; ODP Site 690; Ocean Drilling Program; Os-188/Os-187; Osmium; Pacific Ocean; Paleocene; Paleogene; Platinum group; Sea water; Shatsky Rise; South Atlantic; Southern Ocean; Stable isotopes; Stratigraphic boundary; Tertiary; Tethys; Upper Cretaceous; Volcanism; Walvis Ridge; Weddell Sea; West Pacific
Coordinates: S650938 S650937 E0011218 E0011218
S290415 S290414 E0025908 E0025907
N322628 N322632 E1574324 E1574323
Record ID: 2017022539
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