Isotope and trace element systematics in a spinel-lherzolite-bearing suite of basanitic volcanic rocks from San Luis Potosi, Mexico

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:6643130

Pier, J E.G.

Lherzolite-bearing basanitic magmas of Quaternary age have erupted to form maars, lava/cinder cones and lava flows in two volcanic fields (Ventura and Santo Domingo) in the central Mexican state of San Luis Potosi. The systematics of the radiogenic isotopes of Sr, Nd, and Pb and the relationship between these parameters and elemental compositions are used to investigate the petrogenesis of the volcanic rocks and the nature of their mantle sources. Sr and Nd isotopic data are presented for 19 basanitic rocks, 5 kaersutites, and 6 lherzolitic xenoliths; Pb data presented for the same 19 volcanic rocks and 4 of the 5 kaersutites. The isotopic compositions for all of these samples fall within the mantle range defined by MORBs and OIBs. The basanites generally plot within the OIB field on isotopic diagrams; most of the kaersutites are displaced to slightly more-depleted (i.e. MORB-like) values than the volcanic samples and the xenoliths, with one exception, are significantly more-depleted than either of these sample-types. As crustal contamination is considered unlikely for most of the volcanic samples, these trends are thought to arise from mixing multiple mantle components. The absence of similar isotopic elemental relationships for Epsilon Nd and the lack of correlation between {sup 206}Pb/{sup 204}Pb and the other Pb isotopes require a mixture of at least three mantle reservoirs: a depleted reservoir analogous to that of the MORBs, a St. Helena-type component, and a third component, which primarily affects Sr and {sup 208}Pb/{sup 204}Pb composition. This third component carries relatively radiogenic Sr and {sup 208}Pb/{sup 204}Pb and appears to be correlated with the degree of melting.

• Research Organization: Washington Univ., St. Louis, MO (USA)
• OSTI ID: 6643130
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
MEXICO
VOLCANIC REGIONS
GEOCHEMISTRY
VOLCANIC ROCKS
CHEMICAL ANALYSIS
CORRELATIONS
EARTH CRUST
GEOLOGIC HISTORY
ISOTOPE RATIO
LAVA
LEAD 204
LEAD 208
LEAD ISOTOPES
LITHOLOGY
MAGMA
MIXING
NEODYMIUM ISOTOPES
ORIGIN
QUATERNARY PERIOD
STRONTIUM ISOTOPES
SUBDUCTION ZONES
TRACE AMOUNTS
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
CENOZOIC ERA
CHEMISTRY
DEVELOPING COUNTRIES
EVEN-EVEN NUCLEI
GEOLOGIC AGES
HEAVY NUCLEI
HOURS LIVING RADIOISOTOPES
IGNEOUS ROCKS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LATIN AMERICA
NORTH AMERICA
NUCLEI
RADIOISOTOPES
ROCKS
STABLE ISOTOPES
YEARS LIVING RADIOISOTOPES
580000* - Geosciences