Igneous evolution of Hess Rise; petrologic evidence from DSDP Leg 62

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doi: 10.1029/JB086iB07p06311
Author(s): Windom, Kenneth E.; Seifert, Karl E.; Vallier, Tracy L.
Author Affiliation(s): Primary:
Iowa State Univ., Dep. Earth Sci., Ames, IA, United States
Other:
U. S. Geol. Surv., United States
Volume Title: Journal of Geophysical Research
Source: Journal of Geophysical Research, 86(B7), p.6311-6322. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0148-0227
Note: In English. 50 refs.; illus. incl. 2 anals., 2 tables, sketch map
Summary: Igneous rock was recovered at three sites on Hess Rise, north-central Pacific Ocean, during Deep Sea Drilling Project leg 62: tholeiitic basalt at site 464 (northern Hess Rise), trachyte at site 465, and rounded clasts of alkalic basalt at site 466 (both on southern Hess Rise). The depths at which the igneous rocks from sites 464 and 465 were recovered correspond to strong acoustic reflectors, whereas the clasts from site 466 were recovered from within calcareous sediment. Although all the rocks are moderately to highly altered, petrographic and chemical studies, especially rare earth element determinations, provide data on the nature of these rocks. Data from these studies, combined with geophysical models of the evolution of the Pacific plate during the Mesozoic, allow an interpretation of the formation of Hess Rise involving building of a volcanic platform by eruption of tholeiitic mid-oceanic ridge basalt caused by the breakup of a R-R-R-type triple junction during the middle Cretaceous. This period of platform building was accompanied by edifice building along the south edge of Hess Rise involving alkalic basalt and its differentiation products associated with a leaky transform fault. This interpretation agrees with proposed models for the origin of the tholeiitic parts of other oceanic plateaus but requires a different mechanism--namely, volcanism associated with leaky transform faults--to account for the alkalic rocks.
Year of Publication: 1981
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 05 Petrology, Igneous and Metamorphic; Alkali basalts; Basalts; Cores; Cretaceous; DSDP Site 464; DSDP Site 465; DSDP Site 466; Data; Deep Sea Drilling Project; Genesis; Geochemistry; Hess Rise; IPOD; Igneous rocks; Leg 62; Mesozoic; Middle Cretaceous; North Pacific; Northwest Pacific; Pacific Ocean; Petrology; Plate tectonics; Sea-floor spreading; Seamounts; Tectonophysics; Tholeiitic basalt; Trachytes; Triple junctions; Volcanic rocks; Volcanism; West Pacific
Coordinates: N334900 N395100 E1791500 E1735300
Record ID: 1982005905
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