Conclusions
1) Early Mesozoic tholeiite from the subsurface of Florida plots as a trend from the low-TiO2 quartznormative (LTQ) through the high-Fe203 quartz-normative (HFQ) magma types of Weigand and Ragland (1970) and is more differentiated than the average eastern North America diabase suite. 2) Seventy to 75 percent accumulation of a fractionation assemblage containing plagioclase (46 percent), pyroxene (45 percent), olivine (7 percent) and Fe-Ti oxides (1.5 to 2 percent) accounts for the differentiation patterns observed in the Florida quartz-normative magma. Petrographic analysis confirms this model in that phenocrysts of plagioclase, clinopyroxene and iddingsite (after olivine?) are observed either in this study or in previous investigations.
3) Major element data suggest that the Florida, Georgia, Liberia and northeastern United States incompatible element depleted (lED Puffer and Philpotts, 1988) tholeiite may have had the same parental magma or different parental magmas of the same composition. Ti-Zr ratios possibly indicate that the Surinam, Morocco, Georgia and northeastern United States incompatible element enriched (lEE Puffer and Philpotts, 1988) quartz-normative tholeiites had different source compositions than the Florida and lED tholeiites. Also, the lED and Florida tholeiite may have been derived from the same parental and source compositions.
4) MgO-TiO2 systematics indicate that the Florida, Georgia and lED tholeiites are co-genetic. The same relationship may exist between the lEE and Morocco tholeiites. 5) Available data suggest that there is no apparent systematic geochemical variation in the Florida tholeiite with respect to geography.
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