IODP Expedition 324; ocean drilling at Shatsky Rise gives clues about oceanic plateau formation

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doi: 10.2204/iodp.sd.12.03.2011
Author(s): Sager, William W.; Sano, Takashi; Geldmacher, Jorg; Almeev, R.; Ando, A.; Carvallo, C.; Delacour, A.; Evans, H. A.; Greene, A. R.; Harris, A. C.; Herrmann, S.; Heydolph, K.; Hirano, N.; Idrissi, N.; Ishikawa, A.; Iturrino, G.; Kang, M. H.; Koppers, A. A. P.; Li, S.; Littler, K.; Mahoney, J. J.; Matsubara, N.; Miyoshi, M.; Murphy, D. T.; Natland, J. H.; Ooga, M.; Prytulak, J.; Shimizu, K.; Tominaga, M.; Ucho, Y.; Widdowson, M.; Woodard, S. C.
Integrated Ocean Drilling Program, Expedition 324 Scientists, College Station, TX
Author Affiliation(s): Primary:
Texas A&M University, Department of Oceanography, College Station, TX, United States
Other:
National Museum of Nature and Science, Japan
Volume Title: Scientific Drilling
Source: Scientific Drilling, Vol.12, p.24-31. Publisher: Integrated Ocean Drilling Program Management International, Sapporo; Washington, DC, International. ISSN: 1816-8957
Note: In English. 29 refs.; illus., incl. sketch map
Summary: Integrated Ocean Drilling Program (IODP) Expedition 324 cored Shatsky Rise at five sites (U1346-U1350) to study processes of oceanic plateau formation and evolution. Site penetrations ranged from 191.8 m to 324.1 m with coring of 52.6 m to 172.7 m into igneous basement at four of the sites. Average recovery in basement was 38.7%-67.4%. Cored igneous sections consist mainly of variably evolved tholeiitic basalts emplaced as pillows or massive flows. Massive flows are thickest and make up the largest percentage of section on the largest and oldest volcano, late Jurassic age Tamu Massif; thus, it may have formed at high effusion rates. Such massive flows are characteristic of flood basalts, and similar flows were cored at Ontong Java Plateau. Indeed, the similarity of igneous sections at Site U1347 with that cored on Ontong Java Plateau implies similar volcanic styles for these two plateaus. On younger, smaller Shatsky Rise volcanoes, pillow flows are common and massive flows thinner and fewer, which might mean volcanism waned with time. Cored sediments from summit sites contain fossils and structures implying shallow water depths or emergence at the time of eruption and normal subsidence since. Summit sites also show pervasive alteration that could be due to high fluid fluxes. A thick section of volcaniclastics cored on Tamu Massif suggests that shallow, explosive submarine volcanism played a significant role in the geologic development of the plateau summit. Expedition 324 results imply that Shatsky Rise began with massive eruptions forming a huge volcano and that subsequent eruptions waned in intensity, forming volcanoes that are large, but which did not erupt with unusually high effusion rates. Similarities of cored sections on Tamu Massif with those of Ontong Java Plateau indicate that these oceanic plateaus formed in similar fashion.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 05 Petrology, Igneous and Metamorphic; Alteration; Basalts; Boreholes; Cenozoic; Cores; Cretaceous; Expedition 324; Genesis; IODP Site U1346; IODP Site U1347; IODP Site U1348; IODP Site U1349; IODP Site U1350; Igneous rocks; Integrated Ocean Drilling Program; Large igneous provinces; Lava; Mesozoic; North Pacific; Northwest Pacific; Pacific Ocean; Pillow lava; Plateaus; Sedimentary rocks; Sediments; Shatsky Rise; Volcanic rocks; Volcanism; West Pacific
Coordinates: N323000 N380100 E1623900 E1582700
Record ID: 2012014164
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