SEARCHING FOR THE SUTURE: APPLYING GEOCHEMICAL TECHNIQUES TO UNRAVEL THE NATURE OF CAMERON’S LINE IN CENTRAL PARK, NYC
Here, we applied a combination of petrographic analysis, geothermobarometry, and phase equilibria modeling to 4 samples from Central Park and northern Manhattan. MAT-2017-01 is from the Manhattan formation and is a gt-sil-bt-ms schist. There are three generations of sil: 1) early fibrolite after ms, 2) peritectic sil formed via ms melting at peak conditions, and 3) post-anatectic sil. Combined with phase equilibria modeling, these textures suggest a clockwise P–T path with peak conditions around 5–6.5 kbar and 700–750 ˚C. Sample East-79 is a ms-bt-plg-qtz-grt schist from the Hartland formation. Preliminary phase equilibria modeling suggests peak conditions of ~600-700 °C and ~7.5-10 kbar. Traditional geothermobarometry for both samples retrieved inconsistent results, and potential reasons for this discrepancy will be explored. IWP-01 is a leucocratic grt-ms-bt schist from the Manhattan formation while MOR-NYC-04 is a grt-bt-ms schist from the Hartland formation. Results for thermodynamic modelling of both samples will be reported.
The preliminary results indicate a metamorphic break of at least ~2 kbar between the units. Coupled with the structural data, this suggests that Cameron’s line is a syn- to post-metamorphic thrust fault. Additionally, our study provides a concrete example of the utility of urban geology as a tool for tectonic study to the >140,000 students who study Earth Science in NYS, and >42 million people who visit Central Park each year.