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Noble gas evidence for the presence of recycled material in magma sources of the Shatsky Rise

Takeshi Hanyu, Kenji Shimizu and Takashi Sano
Noble gas evidence for the presence of recycled material in magma sources of the Shatsky Rise (in The origin, evolution, and environmental impact of oceanic large igneous provinces, Clive R. Neal (editor), William W. Sager (editor), Takashi Sano (editor) and Elisabetta Erba (editor))
Special Paper - Geological Society of America (February 2015) 511: 57-67

Abstract

The Shatsky Rise is an oceanic plateau consisting of three main massifs that were constructed in the Pacific Ocean by intense volcanism during the Late Jurassic to Early Cretaceous. In order to explore the sources of this oceanic plateau, we present noble gas compositions from fresh quenched glasses cored by ocean drilling at Integrated Ocean Drilling Program Site U1347 on the Tamu Massif and Site U1350 on the Ori Massif. The studied glasses are normal-type basalts, the most abundant of four types of basalts defined by trace element compositions. Possible disturbances of noble gas compositions by posteruption radiogenic ingrowth in aged glasses are assessed by extraction of gases from glass vesicles by stepwise crushing. The (super 3) He/ (super 4) He ratios in glasses from Site U1347 are lower than atmospheric (super 3) He/ (super 4) He, presumably owing to magma degassing coupled with radiogenic ingrowth of (super 4) He. In contrast, glasses from Site U1350 exhibit a limited range of (super 3) He/ (super 4) He (5.5-5.9 Ra). Uniform (super 3) He/ (super 4) He cannot be achieved if gases in glass vesicles have been affected by secondary contamination or posteruption radiogenic ingrowth. Therefore, the uniform (super 3) He/ (super 4) He in the normal-type basalts from Site U1350 is ascribed to their source characteristics. Relatively low (super 3) He/ (super 4) He among oceanic basalts suggests the involvement of recycled slab material in the source of the normal-type basalts. However, the depleted radiogenic isotope signatures are inconsistent with recycled slab being a distinct melting component. Instead, we propose that the normal-type basalts of the Shatsky Rise were sourced from a domain where subducted fertile material is dispersed in the mantle.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 511
Title: Noble gas evidence for the presence of recycled material in magma sources of the Shatsky Rise
Title: The origin, evolution, and environmental impact of oceanic large igneous provinces
Author(s): Hanyu, TakeshiShimizu, KenjiSano, Takashi
Author(s): Neal, Clive R.editor
Author(s): Sager, William W.editor
Author(s): Sano, Takashieditor
Author(s): Erba, Elisabettaeditor
Affiliation: Japan Agency for Marine-Earth Science and Technology, Department of Solid Earth Geochemistry, Yokosuka, Japan
Pages: 57-67
Published: 20150212
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 68
Accession Number: 2015-032350
Categories: Isotope geochemistryIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, geol. sketch map
N32°30'29" - N32°30'29", E159°14'05" - E159°14'05"
N36°04'29" - N36°04'29", E159°17'04" - E159°17'04"
Secondary Affiliation: National Museum of Nature and Science, JPN, Japan
Source Note: Online First
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201515
Program Name: IODPIntegrated Ocean Drilling Program
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