Publication Date:
2019-10-17
Description:
Since the first discovery of ultrahigh pressure (UHP) rocks 30 years ago in the Western Alps, the
mechanisms for exhumation of (U)HP terranes worldwide are still debated. In the western Mediterranean,
the presently accepted model of synconvergent exhumation (e.g., the channel-flow model) is in conflict
with parts of the geologic record. We synthesize regional geologic data and present alternative exhumation
mechanisms that consider the role of divergence within subduction zones. These mechanisms, i.e., (i) the
motion of the upper plate away from the trench and (ii) the rollback of the lower plate, are discussed in
detail with particular reference to the Cenozoic Adria-Europe plate boundary, and along three different
transects (Western Alps, Calabria-Sardinia, and Corsica-Northern Apennines). In the Western Alps, (U)HP
rocks were exhumed from the greatest depth at the rear of the accretionary wedge during motion of the
upper plate away from the trench. Exhumation was extremely fast, and associated with very low geothermal
gradients. In Calabria, HP rocks were exhumed from shallower depths and at lower rates during rollback of
the Adriatic plate, with repeated exhumation pulses progressively younging toward the foreland. Both
mechanisms were active to create boundary divergence along the Corsica-Northern Apennines transect,
where European southeastward subduction was progressively replaced along strike by Adriatic northwestward
subduction. The tectonic scenario depicted for the Western Alps trench during Eocene exhumation of
(U)HP rocks correlates well with present-day eastern Papua New Guinea, which is presented as a modern
analog of the Paleogene Adria-Europe plate boundary.
Description:
Published
Description:
1786–1824
Description:
1T. Struttura della Terra
Description:
JCR Journal
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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