Abstract

The Higganum dike of Connecticut is one of the earliest basaltic dikes of the Central Atlantic Magmatic province and is geochemically representative of the widespread low-Ti basaltic lavas (~1 wt % TiO2) that make up the majority of the province in North America. Liquid compositions calculated from Cr-rich clinopyroxene cores from the Higganum dike are significantly more primitive than the bulk rock with average Mg# s of 0.63 compared to the Higganum dike which has Mg #'s ~ 0.55. However, the negative Nb and positive Pb anomalies that are seen in trace element patterns of the low-Ti group are also found in the liquids calculated from the Cr-rich clinopyroxene cores. Ca-rich plagioclase cores that probably come up from depth with the Cr-rich clinopyroxenes were found to be more radiogenic than bulk Earth with 87Sr/86Sri ratios ranging from 0.7057 to 0.7064. We conclude that this enriched isotopic signature and the trace element signatures of primitive liquids calculated from clinopyroxene are inherited from the source. This source is identified as a subduction-enriched metasomatized lithospheric mantle. High-Ti magmas (~2-5 wt % TiO2) that are limited to a small geographic area of the Central Atlantic Magmatic Province were found to be unrelated to the low-Ti magmas. These two groups probably originated from different degrees of partial melting of different sources and follow distinctive differentiation paths.

Degree

MS

College and Department

Physical and Mathematical Sciences; Geological Sciences

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2009-11-17

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd3212

Keywords

Central Atlantic Magmatic Province, Higganum Dike, LA-ICPMS, Magma Source

Language

English

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