Details

Autor(en) / Beteiligte

• Snyder, David B
• Meissner, Rolf
• Brown, Larry
• Franke, Wolfgang
• Seifert, Friedrich
• Dürbaum, Hans‐Jürgen
• Fuchs, Karl

Titel

Reflections from a Relic Moho in Scotland?

Ist Teil von

• Continental Lithosphere: Deep Seismic Reflections, 1991, p.307-313

Ort / Verlag

Washington, D. C: American Geophysical Union

Erscheinungsjahr

1991

Quelle

Wiley Online Library All Obooks

Beschreibungen/Notizen

• Prominent reflectors are observed at about 30 and 50 km depths throughout much of northern Scotland. The deeper reflector results from impedance contrasts here attributed to metasomatic intrusions: high‐pressure, relatively low‐density minerals such as phlogopite or kyanite in a local zone that has survived due to a decreased geothermal gradient following the Caledonian orogen. This metasomatism may be localized by a shear zone, a delamination scar or by a former base to the crust. The position of the Moho is here assumed to be controlled largely by isostatic forces driven by heat. Garnet formation in the gabbroic, deep lower crust of Caledonian Scotland produced eclogitic metamorphic rocks with seismic velocities of 8 kms −1 . These rocks are part of the Scottish lithosphere between 28 and 50 km depths that today forms the seismic uppermost mantle, capped by the Moho at 28–30 km. The relic metasomatic zone at 50 km depth marks the former Caledonian Moho, the boundary between the gabbroic/eclogitic mid‐lithosphere and the peridotitic uppermost mantle lithosphere in this alternative model.