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http://hdl.handle.net/2122/3541
Authors: | Macera, P.* Gasperini, D.* Piromallo, C.* Blichert-Toft, J.* Bosch, D.* Del Moro, A.* Martin, S.* |
Title: | Geodynamic implications of deep mantle upwelling in the source of Tertiary volcanics from the Veneto region (South-Eastern Alps) | Journal: | Journal of Geodynamics | Series/Report no.: | /36 (2003) | Publisher: | Elsevier | Issue Date: | 2003 | DOI: | 10.1016/j.jog.2003.08.004 | Keywords: | trace-element isotopic composition alkali basalts central-Europe slab break-off plume |
Subject Classification: | 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics | Abstract: | Major and trace element and Sr–Nd–Hf–Pb isotopic data for the most primitive Tertiary lavas from the Veneto region (South-Eastern Alps, Italy) show the typical features of HIMU hotspot volcanism, variably diluted by a depleted asthenospheric mantle component (87Sr/86Sri=0.70306–0.70378; "Ndi=+3.9 to +6.8; "Hfi=+6.4 to +8.1, 206Pb/204Pbi=18.786–19.574). P-wave seismic tomography of the mantle below the Veneto region shows the presence of low-velocity anomalies at depth, which is consistent with possible upwellings of plume material. Between the depths of 100–250 km the velocity anomalies are approximately 2–2.5% slower than average, implying a temperature excess of about 220–280 K, in agreement with estimates for other mantle plumes in the world. In this context, the Veneto volcanics may represent the shallow expression of a mantle upflow. The presence of a HIMU-DM component in a collision environment has significant geodynamic implications. Slab detachment and ensuing rise of deep mantle material into the lithospheric gap is proposed to be a viable mechanism of hotspot magmatism in a subduction zone setting. |
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