|Northeastern Section - 36th Annual Meeting (March 12-14, 2001)|
|Paper No. 15-0|
|Presentation Time: 8:30 AM-12:00 PM|
WHOLE-ROCK GEOCHEMICAL ANALYSIS OF THE STRAITS SCHIST, WESTERN CONNECTICUT
ROBERTS, Todd M. and DIETSCH, Craig, Geology Department, Univ of Cincinnati, 500 Geology/Physics, Cincinnati, OH 45221-0013, firstname.lastname@example.org|
The whole-rock geochemistry of high-grade Silurian-Devonian metasediments of the Connecticut Valley Zone of western CT and MA have been analyzed using XRF spectrometry. Analyzed rocks include The Straits Schist (DSt), its basal member (Stb), and its upper Southington Mountain member (DSts) (Table 1). Immobile Th and Ti, and high field strength elements (U, Y, Nb, and Zr) were used to evaluate protoliths. The bottom of the sequence is composed of shallow water carbonates finely interbedded with sandstone. The Straits is chemically similar to pelitic and psammitic shales and was deposited as a sandy shale fining upward into an Al-rich shale. The upper part of the sequence, DSts, is a graphite-rich schist with high U levels, characteristic of deep-water black shales. Based on field relations and chemical discrimination diagrams, this sequence of rocks is conformable and is interpreted as arc-derived sediments deposited in the distal extension of a subsiding basin.