资源环境科技发展态势分析平台

Teleseismic receiver functions were calculated to image the Moho geometry in the northern Appalachian Mountains in order to explore crustal thickness variations and possible linkages with tectonic units. Waveforms from 1995 to 2016 were analyzed for a total of similar to 200 broadband seismic stations, yielding a well-distributed data set with high lateral resolution. Consistent P-to-S phases converted at the Moho can be clearly observed. The Moho depth increases from the coastal plain northwestward to the Appalachian Plateau, with a sharp east-west gradient in southern New England. A distinct subrectangular downward deflection of the Moho is imaged in northern New Hampshire and western Maine. There is a spatial correlation observed between Moho depth variations and the NE-SW trending Appalachian orogenic strike. Variations of crustal thickness along and across the orogenic strike provide insights into the formation and modification of the crust during and after the major Appalachian orogenic events.

Plain Language Summary The Wilson tectonic cycle is one of the most fundamental processes leading to growth and modification of continental crust on Earth. Eastern North America provides a complete record of the eastward growth of the continent and has been used as a type section and model of plate tectonics for decades. Although the surface boundaries between former continental fragments are increasingly well known, a question persists about the timing and processes involved with the growth and stabilization of the continental crust. In this study, we provide high-resolution crustal thickness variations in New York and New England, in order to identify the boundaries between tectonic units within the crust. The abundance of broadband seismic stations has significantly increased in the last few years, including the EarthScope Transportable Array and many long-running stations. The crust thickness demonstrates a much sharper east-west gradient in southern New England than in northern New England. A distinct subrectangular downward deflection of the crust is imaged in northern New Hampshire and western Maine. Variations of the crustal thickness along and across the orogenic strike provide insights into the formation and modification of the crust during and after the major Appalachian orogenic events.