Data report; Lithologic diversity, mineral composition, and temperature and redox conditions in ODP/IODP Hole 1256D; a study of sand and gravels recovered during IODP Expedition 335

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doi: 10.2204/iodp.proc.335.203.2016
Author(s): Abily, Bénédicte; Python, Marie
Integrated Ocean Drilling Program, Expedition 335 Scientists, College Station, TX
Author Affiliation(s): Primary:
Macquarie University, Department of Earth and Planetary Sciences, Sydney, N.S.W., Australia
Université Montpellier II, France
Integrated Ocean Drilling Program, United States
Lamont-Doherty Earth Observatory, United States
Japan Agency for Marine-Earth Science and Technology, Japan
Université Toulouse III, France
Niigata University, Japan
University of Michigan, United States
University of Tsukuba, Japan
University of Adelaide, Australia
Texas Tech University, United States
Woods Hole Oceanographic Institution, United States
Southern Illinois University-Carbondale, United States
Nancy-Université, France
Seoul National University, South Korea
University of Hanover, Germany
Cardiff University, United Kingdom
University of Plymouth, United Kingdom
Yamagata University, Japan
Kanazawa University, Japan
Hokkaido University, Japan
National Geophysical Research Institute, India
Université Pierre et Marie Curie, France
University of California-Santa Barbara, United States
Volume Title: Proceedings of the Integrated Ocean Drilling Program; superfast spreading rate crust 4; Expedition 335 of the riserless drilling platform, Puntarenas, Costa Rica, to Balboa, Panama; Site 1256, 13 April-3 June 2011
Volume Author(s): Teagle, Damon; Ildefonse, Benoît; Blum, Peter; Guérin, Gilles; Zakharova, Natalia; Abe, Natsue; Abily, Bénédicte; Adachi, Yoshiko; Alt, Jeffrey C.; Anma, Ryo; Baines, Graham; Deans, Jeremy; Dick, Henry J. B.; Endo, Daisuke; Ferre, Eric C.; France, Lydéric; Godard, Marguerite M.; Harris, Michelle; Kim, Yoon-Mi; Koepke, Juergen H.; Kurz, Mark D.; Lissenberg, C. Johan; Miyashita, Sumio; Morris, Antony; Oizumi, Ryo; Payot, Betchaida D.; Python, Marie; Roy, Parijat; Till, Jessica L.; Tominaga, Masako; Wilson, Douglas S.
Source: Proceedings of the Integrated Ocean Drilling Program; superfast spreading rate crust 4; Expedition 335 of the riserless drilling platform, Puntarenas, Costa Rica, to Balboa, Panama; Site 1256, 13 April-3 June 2011, Damon Teagle, Benoît Ildefonse, Peter Blum, Gilles Guérin, Natalia Zakharova, Natsue Abe, Bénédicte Abily, Yoshiko Adachi, Jeffrey C. Alt, Ryo Anma, Graham Baines, Jeremy Deans, Henry J. B. Dick, Daisuke Endo, Eric C. Ferre, Lydéric France, Marguerite M. Godard, Michelle Harris, Yoon-Mi Kim, Juergen H. Koepke, Mark D. Kurz, C. Johan Lissenberg, Sumio Miyashita, Antony Morris, Ryo Oizumi, Betchaida D. Payot, Marie Python, Parijat Roy, Jessica L. Till, Masako Tominaga and Douglas S. Wilson; Integrated Ocean Drilling Program, Expedition 335 Scientists, College Station, TX. Proceedings of the Integrated Ocean Drilling Program, Vol.335, 21p. Publisher: International Ocean Discovery Program, Washington, DC, United States. ISSN: 1930-1014 CODEN: IDSDA6
Note: In English. 25 refs.; illus., incl. 2 tables
Summary: This data report presents an uncommon study of fine drill cuttings (sand and gravels) recovered from hole maintenance operations in Ocean Drilling Program/Integrated Ocean Drilling Program (IODP) Hole 1256D (East Pacific Rise) during Expedition 335. Drill cuttings represent an integrated sampling of the entire hole and offer the opportunity to study the petrological characteristics of the various lithologies making up the upper oceanic crust. We selected the fine-grained fraction of cuttings coming from 12 pipe deployments (runs) and conducted microscopic observations (mineralogy and texture), image processing, electron microprobe analyses (∼4400 analyses), and oxythermobarometry calculations on 16-25 grain-mount thin sections. This study shows that drill cuttings sample all of the lithologies in the hole (glass, aphyric and phyric basalts, dolerite, gabbro, diorite, gabbronorite, albitite, and three kinds of granoblastic basalt) but overrepresent non- or poorly recovered materials like albitites and granoblastic basalts. Drill cuttings are thus a good alternative to study these "rare" lithologies. Based on the composition of the main minerals and the oxythermobarometry calculations, two major lithologic groups were defined in the cuttings: a basaltic lavas-dolerites group and a gabbroic lithologies-granoblastic basalts group. Basaltic lavas (glass and basalts) and dolerites are characterized by Mg-augites rich in Al2O3, Cr2O3, and TiO2; MgO-rich plagioclases with a mean composition of An60-70; and titanomagnetites. Their Fe-Ti oxides (magnetite and ilmenite) indicate relatively reducing conditions (ΔNNO=-1.26 to -0.80), and clinopyroxenes in dolerites give a mean equilibrium temperature of 1017°C. Gabbroic lithologies and granoblastic basalts are characterized by Ca-rich clinopyroxenes (augites and diopsides) depleted in Al2O3, Cr2O3, and TiO2; MgO-poor plagioclases with a mean composition of An50-60; and Ti-poor magnetites. Oxybarometers give oxidizing (ΔNNO=-0.08 to +0.58) to very oxidizing (ΔNNO=+1.97 to +2.38) conditions for these lithologies, and their pyroxenes indicate high (909°C-985°C) to relatively high (783°C-888°C) mean temperatures according to the thermometer considered. Albitites show equivalent mineral compositions and temperature and redox conditions to gabbroic lithologies and granoblastic basalts. They are, however, characterized by albitic plagioclases (An0-20) and usually display slightly lower temperatures (780°C) and higher ΔNNO values (+2.66). One grain of gabbro Run14EXJB-T-G15) strongly differs from the other gabbroic grains (∼40 grains) in terms of clinopyroxene composition, temperature, and oxidation state. This gabbro has thus probably suffered from peculiar processes compared to the other gabbroic lithologies.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 05 Petrology, Igneous and Metamorphic; Albitite; Basalts; Boreholes; Crust; Cuttings; Diabase; East Pacific; Eh; Equatorial Pacific; Expedition 335; Gabbronorite; Gabbros; Geologic barometry; Geologic thermometry; Glasses; Guatemala Basin; Igneous rocks; Integrated Ocean Drilling Program; Mineral composition; North Pacific; Northeast Pacific; ODP Site 1256; Ocean Drilling Program; Oceanic crust; Pacific Ocean; Plutonic rocks; Syenites; Temperature; Thin sections; Upper crust; Volcanic rocks
Coordinates: N064400 N064400 W0915600 W0915600
Record ID: 2016025846
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