Petrology and geochemistry of the Late Cenozoic volcanic rocks of the Dominican Republic

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5984307

Vespucci, P D

Late Cenozoic rocks of Hispaniola are subdivided into two petrographically and geochemically contrasting series, a calc-alkaline series (CA-series), and a mafic alkaline series (MA-series). The CA-series are basalts, basaltic andesites, trachyandesites, and dacites occurring in several eruptive centers in the southern part of the Cordillera Central of the Dominican Republic. MA-series basalts are alkali-olivine basalts and limburgitic basalts occurring in the San Juan Valley of the Dominican republic and in the Cul de Sac of south central Haiti. Olivine, clinopyroxene, amphibole, mica, feldspar, and titanomagnetite were analyzed for major element chemical composition. MA-series basalts are slightly to moderately silica undersaturated, have high TiO2 (>1.5%) and MgO (>5.0%) and moderately high total alkalis (>2.0%). MA-series basalts are enriched in K, Rb, Sr, Ba, U, Th and LREEs with Ba/La ratios around 0.98. REE patterns are fractionated (chrondrite normalized La/Yb ratios around 62, and La/Sm ratios around 6). HFS elements Zr, Hf, Nb, and Ta are high resembling intraplate basalts. 86SR/87SR ratios are high (0.7060-0.7070) with low Rb/Sr ratios (0.03 to 0.15). Basalts, basaltic andesites, trachyandesites, and dacites of the CA-series show low MgO (<5.0%) and TiO2(<2.0%), and moderately high total alkali contents (2 to 7%). Enrichment is seen in K Rb, Sr, Ba, Th, U, and LREEs with Ba/La ratios as high as 5.6 REE patterns are fractionated to a lesser degree compared to the MA-series (chondrite normalized La/Yb around 23, and La/Sm ratios less than 5). HFS elements are lower resembling typical island arc volcanic rocks. CA-series have 87Sr/86Sr ratios (.7043-.7053), with low Rb/Sr ratios as in the MA-series.

• Research Organization: George Washington Univ., Washington, DC (USA)
• OSTI ID: 5984307
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580300* -- Mineralogy
Petrology
&amp; Rock Mechanics-- (-1989)
580400 -- Geochemistry-- (-1989)
ACTINIDES
ALKALI METALS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
BARIUM
BASALT
BETA DECAY RADIOISOTOPES
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMISTRY
CRYSTALLIZATION
DEVELOPING COUNTRIES
DOMINICAN REPUBLIC
EARTH MANTLE
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
ENRICHMENT
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOCHEMISTRY
GEOLOGIC HISTORY
GEOLOGIC MODELS
GEOLOGY
GREATER ANTILLES
HISPANIOLA
HOURS LIVING RADIOISOTOPES
IGNEOUS ROCKS
INTERMEDIATE MASS NUCLEI
ISLANDS
ISOMERIC TRANSITION ISOTOPES
ISOTOPE RATIO
ISOTOPES
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
METALS
METAMORPHISM
MINERALOGY
MINERALS
NUCLEI
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PETROLOGY
PHASE TRANSFORMATIONS
POTASSIUM
RADIOISOTOPES
RARE EARTHS
ROCKS
RUBIDIUM
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SOURCE ROCKS
STABLE ISOTOPES
STRONTIUM
STRONTIUM 86
STRONTIUM 87
STRONTIUM ISOTOPES
THORIUM
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRACE AMOUNTS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
URANIUM
VARIATIONS
VOLCANIC ROCKS
WEST INDIES
ZIRCONIUM