Continental rocks from Indian Ocean floor; significance of the continental rocks distributed in oceans

Author(s): Yano, T.; Vasiliev, B. I.; Choi, D. R.; Miyagi, S.; Gavrilov, A. A.; Adachi, H.
Author Affiliation(s): Primary:
Tottori University, Department Regional Environment, Tottori, Japan
Russian Academy of Sciences, Pacific Oceanological Institute, Russian Federation
Raax Australia, Australia
Tokyo Metropolitan Kitazono Senior High School, Japan
Tokyo University of Agriculture, Japan
Volume Title: Chikyu Kagaku Earth Science
Source: Chikyu Kagaku = Earth Science, 65(5), p.199-215. Publisher: Chigaku Dantai Kenkyu-kai, Tokyo, Japan. ISSN: 0366-6611 CODEN: CKKAA8
Note: In Japanese with English summary. 108 refs.; illus., incl. 1 table, sketch maps
Summary: This paper reviews the continental rocks known in the Indian Ocean floor and together with those in the Atlantic and Pacific, clarifies their implications to ocean genesis. Continental rocks distributed at 34 localities in the Indian Ocean are classified into three types: Type A (continental rocks found at continental margin under the ocean floor level; 11 localities), Type B (continental-crustal rocks collected from mid-oceanic ridges and ocean basins; 14) and Type C (rocks with geochemical signatures of continental lithosphere, collected from mid-oceanic ridges and ocean basins; 9). In the Atlantic, Indian and Pacific ocean-floors, ancient continental rocks are known at totally 86 localities. Among them the Type A rocks are of continental fragment, having been submerged and turned to constituents of the ocean-floors. The Type B rocks manifest the presence of continental rocks in mid-oceanic ridges and ocean basins. The Type C suggests the existence of continental rocks under mid-oceanic ridges and ocean basins, as well as the partial melting of the continental rocks due to local heating or nearby magmatic activity. The occurrence of the rocks of the latter two types conflicts to the hypothesis of ocean floor spreading, requiring some additional mechanism. It also provides substantial evidences to the hypotheses of oceanization and micro-expansion. Furthermore, the presence of two gigantic ring-structures, i.e., the Dupal anomaly belt and the circum Pacific mobile belt indicates the vast-scaled thermo-chemical heterogeneity and low fluidity of the Earth's mantle. The occurrence of Types B and C rocks presents the key to elucidate the ocean genesis under the circumstances of more heterogeneous and viscous mantle than generally believed.
Year of Publication: 2011
Research Program: ODP Ocean Drilling Program
Key Words: 05 Petrology, Igneous and Metamorphic; Alkaline earth metals; Chemical composition; Circum-Pacific region; Continental crust; Continental lithosphere; Continental margin; Crust; Dupal anomaly; Geochemistry; Heterogeneity; Igneous rocks; Indian Ocean; Isotope ratios; Isotopes; Kerguelen Plateau; Leg 183; Lithosphere; Magmatism; Mantle; Metals; Mid-ocean ridges; Mobile belts; Nd-144/Nd-143; Neodymium; ODP Site 1137; Ocean Drilling Program; Ocean basins; Ocean floors; Pacific region; Partial melting; Plate tectonics; Rare earths; Ring structures; Sea-floor spreading; Sr-87/Sr-86; Stable isotopes; Strontium; Viscosity; Volcanism
Coordinates: S565000 S565000 E0680536 E0680536
Record ID: 2015053052
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