Reflections Under the Scottish Highlands (RUSH II): A Broadband Investigation of the Extent and Origin of Upper Mantle Reflectors in Scotland

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James H. KnappEAR-0074002Upper mantle reflections beneath the northwestern British Isles are some of the best-known and most-studied examples of fine-scale heterogeneity within the mantle. First observed on BIRPS marine deep seismic reflection profiles, these reflectors have subsequently been imaged and correlated on additional reflection and refraction profiles in the offshore area of northern and western Scotland, but have not been reliably traced beneath the mainland, although analysis of existing wide-angle reflection data suggest these reflectors do project beneath mainland Scotland. The present study will address both the scientific potential of broadband imaging of fine-scale upper mantle structure as well as the tectonic significance of major mantle reflectors beneath the British Isles. The project will support a 2-year deployment of a 25-station broadband seismic network in Scotland to perform the following tasks. 1) Correlate the seismic signature of upper mantle reflectors on passive- and active-source records. 2) Determine the regional extent of mantle reflectors beneath the Scottish mainland. 3) Examine the geometric relationship of upper mantle reflectors with lithosphere-scale structures of Paleozoic age. 4) Estimate the physical properties, including anisotropy, of these reflectors and their surrounding lithospheric mantle. 5) Test the hypothesis that upper mantle structure is largely Cenozoic in age. This effort will leverage NSF funds with existing support from the British NERC to the University of Bristol for phase I of the RUSH experiment.