Sr, Nd, and Pb isotopic compositions of Hainan basalts (south China): Implications for a subcontinental lithosphere Dupal source

Journal Article · Sat Jun 01 00:00:00 EDT 1991 · Geology; (USA)

OSTI ID:5541716

Tu, Kan; Flower, M F.J.; Zhang, Ming ^[1]; Carlson, R W ^[2]; Xie, Guanghong ^[3]

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1. Univ. of Illinois, Chicago (USA)
2. Carnegie Institution of Washington, DC (USA)
3. Academia Sinica, Guangzhou (China)

Sr, Nd, and Pb isotopic ratios were determined for postspreading basalts from Hainan Island, erupted in a quasi-oceanic pull-apart trough at the northern edge of the South China Basin. The basalts comprise quartz tholeiite, olivine tholeiite, alkali basalt, and basinite and show oceanic island basalt (OIB)-type trace element distributions relatively enriched in Nb, Ta, and Th. Despite normal OIB-like Sr and Nd isotopic compositions, Hainan lavas have unexpectedly high {sup 208}Pb/{sup 204}Pb and {sup 207}Pb/{sup 204}Pb ratios, resembling those of Southern Hemisphere Dupal OIB and some alkalic arc basalts. The authors propose that the Hainan source comprises a lower lithospheric region of accreted asthenospheric melt (isotopically resembling Central Indian Ridge-type basalt) overprinted by radiogenic melts of subducted sediment. In the absence of a mantle plume, decompression melting of subcontinental lithospheric mantle may result from lithosphere stretching, as a regional response to the Indo-Eurasian collision.

• OSTI ID: 5541716
• Journal Information: Geology; (USA), Journal Name: Geology; (USA) Vol. 19:6; ISSN GLGYB; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ACTINIDES
ALKALI METALS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ALPHA DECAY RADIOISOTOPES
ASIA
BARIUM
BASALT
CERIUM
CHINA
DEFORMATION
EARTH MANTLE
ELEMENTS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
HAFNIUM
HEAVY NUCLEI
HOURS LIVING RADIOISOTOPES
IGNEOUS ROCKS
ISLANDS
ISOMERIC TRANSITION ISOTOPES
ISOTOPE RATIO
ISOTOPES
LAVA
LEAD 204
LEAD 207
LEAD 208
LEAD ISOTOPES
MELTING
METALS
MILLISEC LIVING RADIOISOTOPES
MINERALOGY
NEODYMIUM
NEODYMIUM ISOTOPES
NONMETALS
NUCLEI
PHASE TRANSFORMATIONS
PHOSPHORUS
PLATE TECTONICS
POTASSIUM
RADIOISOTOPES
RARE EARTHS
ROCKS
RUBIDIUM
SAMARIUM
SECONDS LIVING RADIOISOTOPES
SEDIMENTARY BASINS
SEDIMENTS
SOURCE ROCKS
STABLE ISOTOPES
STRONTIUM
STRONTIUM ISOTOPES
SUBDUCTION ZONES
TANTALUM
TECTONICS
THORIUM
TITANIUM
TRACE AMOUNTS
TRANSITION ELEMENTS
VOLCANIC ROCKS
YEARS LIVING RADIOISOTOPES
YTTERBIUM
YTTRIUM
ZIRCONIUM