HR: 1330h
AN: V13B-11    [Abstracts]
TI: Volcanic Chemostratigraphy on the Outcrop Using Field-Portable X-Ray Fluorescence: An Example from the Basaltic Flows of Hewitt's Cove, MA.
AU: * Wall, A M
EM: awall@wellesley.edu
AF: Wellesley College, 106 Central St., Wellesley, MA 02481 United States
AU: Brabander, D J
EM: dbraband@wellesley.edu
AF: Wellesley College, 106 Central St., Wellesley, MA 02481 United States
AB: The area of Hewitt's Cove, Hingham, Massachusetts structurally represents the southern extent of the Boston Basin, and as such, provides the opportunity to identify and recognize basin-wide events. While the stratigraphy of the Boston Basin has been developed since the advent of U-Pb geochronology and formal stratigraphic facies descriptions (Socci and Smith, 2001), the stratigraphy of the Hewitt's Cove area has not been thoroughly addressed since the work of William O. Crosby in 1894 (Billings, 1976, Bailey and Bland, 2001). Hewitt's Cove consists of an andesitic basaltic flow, approximately 150 m thick, overlain by siltstone and conglomeratic sequences. Field-Portable X-Ray Fluorescence (FP-XRF) was used on fresh and weathered surfaces on the outcrop and in hand samples, and these analyses were compared with conventional laboratory XRF analyses. The in situ field-based analyses produced a reproducible chemostratigraphy that is consistent with subsequent laboratory-based analyses. These data suggest that the series of andesitic basalt flows at Hewitt's Cove are the result of compositionally different magmatic pulses. Additional analyses must be completed to determine the extent of these pulses and the extent of variation in this area before further conclusions can be made. This study particularly demonstrates the utility of using FP-XRF in igneous geologic applications.
DE: 3640 Igneous petrology
DE: 3670 Minor and trace element composition
DE: 3694 Instruments and techniques
DE: 8439 Physics and chemistry of magma bodies
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2005 Joint Assembly