Fine-scale shipboard resolution among mafic igneous rock sequences recovered during ocean drilling; quantitative pXRF determination of key elements on rock surfaces and powders during IODP Expedition 352

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doi: 10.1130/abs/2016AM-286069
Author(s): Ryan, Jeffrey G.; Li, Yibing; Li Hongyan; Heaton, D. E.; Reagan, Mark K.; Shervais, John W.; Pearce, Julian A.; Petronotis, Katerina; Chapman, Timothy; Godard, Marguerite; Kirchenbaur, Maria; Nelson, Wendy R.; Prytulak, Julie; Shimizu, Kenji; Whattam, Scott A.
Author Affiliation(s): Primary:
University of South Florida, School of Geosciences, Tampa, FL, United States
Chinese Academy of Sciences, Guangzhou Institute of Geochemistry, China
Oregon State University, United States
University of Iowa, United States
Utah State University, United States
Cardiff University, United Kingdom
International Ocean Discovery Program, United States
University of Sydney, Australia
Université de Montpellier, France
Universität Köln, Germany
Towson University, United States
Imperial College London, United Kingdom
Japan Agency for Marine Earth-Science and Technology, Japan
Korea University, South Korea
Volume Title: Geological Society of America, 2016 annual meeting & exposition
Source: Abstracts with Programs - Geological Society of America, 48(7); Geological Society of America, 2016 annual meeting & exposition, Denver, CO, Sept. 25-28, 2016. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: While handheld energy dispersive X-ray spectrometers (pXRF) are designed and generally used for qualitative survey applications on land, we employed a handheld pXRF instrument to conduct rapid, quantitative elemental measurements on recovered mafic rock samples onboard the JOIDES Resolution over the eight weeks of the International Ocean Discovery Program (IODP) Expedition 352 to the Izu-Bonin forearc. Working curves were developed via pXRF measurements of a suite of geologic standard reference materials and characterized lavas compositionally similar to our drilling targets (basalts and boninites), which permitted accurate quantitative measurements for a range of major and trace elements on both sample powders and rock surfaces, with good agreement between pXRF and shipboard ICP-OES data (and subsequently with post-cruise XRF determinations) for most elements. pXRF performance on the ship was found to be optimal for elements between Z=19 and Z=40, yielding reproducible data for K, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Rb, Sr, and Zr on both powdered samples and rock surfaces. Some 2000 pXRF determinations were made on igneous materials recovered during >1600 m of basement drilling on the Expedition. While XRF and pXRF instrumentation have been sporadically employed on previous research cruises, IODP Expedition 352 is the first time the instrument has been used to establish a detailed, high-density chemostratigraphy of rock core surface measurements, allowing the recognition and resolution of chemically distinct eruptive units in near real-time, as well as larger-scale trends in compositional change potentially related to changes in mantle sources during subduction initiation magmatism. The rapid identification of geochemical trends vastly improved our selection of samples for shipboard and shore-based analysis, facilitated drilling decisions on the ship, and has permitted a more comprehensive interpretation of Expedition results.
Year of Publication: 2016
Research Program: IODP2 International Ocean Discovery Program
Key Words: 07 Marine Geology and Oceanography; Cores; Expedition 352; International Ocean Discovery Program; Marine sediments; North Pacific; Northwest Pacific; Pacific Ocean; Sediments; West Pacific
Coordinates: N282425 N282705 E1424600 E1423600
Record ID: 2017022839
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States