Source characteristics of the basement rocks from the Sulu and Celebes basins (western Pacific); chemical and isotopic evidence

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doi: 10.1007/s004100050148
Author(s): Spadea, P.; D'Antonio, M.; Thirlwall, M. F.
Author Affiliation(s): Primary:
Universita di Udine, Udine, Italy
Universita di Naples, Italy
University of London, United Kingdom
Volume Title: Contributions to Mineralogy and Petrology
Source: Contributions to Mineralogy and Petrology, 123(2), p.159-176. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999 CODEN: CMPEAP
Note: In English. 70 refs.; illus., incl. 3 tables, geol. sketch map
Summary: New Sr- Nd- and Pb-isotopic and trace element data are presented on basalts from the Sulu and Celebes basins, and the submerged Cagayan Ridge arc (W Pacific), recently sampled during Ocean Drilling Program Leg 124. Drilling has shown that the Sulu Basin developed ∼ 18 m.y. ago as a backarc basin, associated with the now submerged Cagayan Ridge arc, whereas the Celebes Basin was generated ∼ 43 m.y. ago, contemporaneous with a general plate reorganisation in the W Pacific, subsequently developing as an open ocean receiving pelagic sediments until the middle Miocene. In both basins, a late middle Miocene collision phase and the onsets of volcanic activity on adjacent arcs in the late Miocene are recorded. Covariations between 87Sr/86Sr and 143Nd/144Nd show that the seafloor basalts from both the Sulu and Celebes basins are isotopically similar to depleted Indian MORB, and distinct from E Pacific Rise MORB, defining a single negative correlation. The Cagayan arc volcanics are different, in that they have distinctly lower εV>Nd(T) for a given εV>Sr(T) compared to Sulu and Celebes basalts. In the Pb comparative diagrams, the Sulu and Cagayan rocks all plot distinctly above the N Hemisphere Reference Line. They define a single trend of radiogenic Pb enrichment from Celebes through Sulu to Cagayan Ridge, within the Indian Ocean MORB data field. The data suggest that the overall chemical and isotopic features of the Sulu, Cagayan and Celebes rocks may be explained by partial melting of a depleted asthenospheric N-MORB-type ('normal') mantle source with isotopic characteristics similar to those of the Indian Ocean MORB source. This asthenospheric source was slightly heterogeneous, giving rise to the Sr-Nd differences between the Celebes and Sulu basalts and the Cagayan Ridge volcanics. In addition, a probably slab-derived component enrichment in LILE and LREE is required to generate the elemental characteristics and low εV>Nd(T) of the Cagayan Ridge island arc tholeiitic and calc-alkaline lavas, and to contribute to a small extent in the backarc basalts of the Sulu Sea. The results of this study confirm and extend the widespread Indian Ocean MORB signature in the W Pacific region.
Year of Publication: 1996
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 05 Petrology, Igneous and Metamorphic; Alkaline earth metals; Basalts; Basins; Cagayan Ridge Arc; Celebes Sea; Cenozoic; Chemical composition; Igneous rocks; Indian Ocean; Indonesian Seas; Isotopes; Lead; Leg 124; Metals; Mid-ocean ridge basalts; Miocene; Nd-144/Nd-143; Neodymium; Neogene; North Pacific; Northwest Pacific; Ocean Drilling Program; Pacific Ocean; Pb-206/Pb-204; Pb-207/Pb-204; Pb-208/Pb-204; Plate collision; Plate tectonics; Radioactive isotopes; Rare earths; Sr-87/Sr-86; Stable isotopes; Strontium; Sulu Sea; Tertiary; Trace elements; Volcanic rocks; West Pacific
Coordinates: N050000 N100000 E1250000 E1200000
Record ID: 1996073356
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom