Towards a paleolatitude record from the Louisville seamount trail

Author(s): Gee, J. S.; Pressling, N.; Hoshi, H.; Yamazaki, T.
Integrated Ocean Drilling Program, Expedition 330 Scientists, College Station, TX
Author Affiliation(s): Primary:
Scripps Institution of Oceanography, La Jolla, CA, United States
Other:
University of Southampton, United Kingdom
Aichi University of Education, Japan
Geological Survey of Japan, Japan
Texas A&M University, United States
Volume Title: AGU 2011 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2011; American Geophysical Union 2011 fall meeting, San Francisco, CA, Dec. 5-9, 2011. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The 4300 km long Louisville Seamount trail is the South Pacific counterpart of the much better studied Hawaii-Emperor chain. Both chains are thought to reflect motion of the Pacific plate over persistent mantle melting anomalies although the stationarity of these hotspots, and thus their suitability as a reference frame for Pacific plate motions, remains uncertain. Drilling at the Emperor Seamounts documented an ∼15° southward shift of the Hawaiian hotspot between about 80 and 50 Ma. IODP Expedition 330 provided the first drillcore samples from the Louisville chain, with a primary goal of documenting the paleolatitudes of seamounts with ages comparable to those drilled in the Hawaii-Emperor chain. Six sites were drilled on five Louisville guyots. The recovered materials include sediments, submarine lava flows/pillows, less abundant subaerial flows and a substantial proportion of volcaniclastic and hyaloclastite material. Sites U1374 and U1373 on Rigil Guyot (28.6°S, ∼73 Ma) penetrated 522m and 66m, respectively, and yielded about thirty cooling units including both normal and reversed polarity flows. Approximately 20 normal polarity cooling units were recovered from the 233m cored interval at Site U1372 on Canopus Guyot (26.5°, ∼76 Ma). Site U1376 on Burton Guyot (32.2°, ∼64 Ma) penetrated 182m, with 11 reversed polarity flows. A total of 17 reversed polarity cooling units were sampled at Hadar Guyot (38.2°S, ∼50 Ma) despite more limited penetration. Characteristic remanent magnetization directions were determined for more than 22,000 two-cm intervals on the archive half cores. The most reliable of these data were used to calculate average directions for individual core pieces that compare well with results from stepwise demagnetization of nearly 500 discrete samples. Because of the abundance of (mostly submarine) volcaniclastic material recovered, estimating the paleolatitude for the Louisville guyots is less straightforward than for the sites on the Hawaii-Emperor chain, where a sequence of discrete (primarily subaerial) lava flows was recovered. Although sedimentary and some volcanic breccias have scattered inclinations as might be expected from redeposition after cooling, many volcaniclastic units have consistent inclinations that are similar to those of intercalated lava flows. The consistent inclinations in these cases may represent either a chemical remanence acquired after deposition or possibly a partial thermal remanent magnetization acquired during the latest stages of cooling if the particles were still hot (e.g. where larger clasts have lobate, chilled margins) after final emplacement. Documenting the origin and timing of the remanence acquisition in these units will play a critical role in estimating the paleolatitude and its uncertainty.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; Basalts; Burton Guyot; Canopus Guyot; East Pacific; Emperor Seamounts; Expedition 330; Flood basalts; Hadar Guyot; Hawaiian Plume; Hot spots; IODP Site U1372; IODP Site U1373; IODP Site U1374; IODP Site U1376; Igneous rocks; Integrated Ocean Drilling Program; Large igneous provinces; Lava; Lava flows; Louisville Ridge; Magnetization; Mantle; Mantle plumes; North Pacific; Northwest Pacific; Ocean floors; Pacific Ocean; Paleolatitude; Paleomagnetism; Pillow lava; Plate tectonics; Remanent magnetization; Rigil Guyot; Seamounts; South Pacific; Southeast Pacific; Volcanic rocks; West Pacific
Coordinates: S262936 S262936 W1744345 W1744345
S283353 S283353 W1731651 W1731651
S283545 S283545 W1732250 W1732250
S321303 S321303 W1715250 W1715250
Record ID: 2014087597
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