T44 From the Guajira Desert to the Apennines, and from the Sardinia/Corsica Microplate to the Killer Asteroid: Honoring the Career of Walter Alvarez on the Occasion of His 80th Birthday

Sunday, 10 October 2021
1:30 PM - 5:30 PM
Portland Ballroom 256 (Hybrid Room)

THIN-SKINNED VERSUS THICK-SKINNED TECTONICS IN THE UMBRIA-MARCHE FOLD-AND-THRUST BELT: CONTRAST OR COEXISTENCE?

Paper number: T44-11
Program: Technical Sessions
Time: 4:00 PM – 4:15 PM

Authors

Abstract

The structural style at depth of the Umbria-Marche fold-and-thrust belt, that occupies the outer province of the Northern Apennines of peninsular Italy, has long been debated and interpreted in terms of thin-skinned or thick-skinned deformation models, respectively. Thin-skinned models predict that the Mesozoic-Tertiary sedimentary cover was detached along Upper Triassic evaporites and translated northeastwards along stepped thrust faults above a relatively undeformed basement. On the other hand, thick-skinned models predict the direct involvement of conspicuous basement slices within thrust-related folds. A description of selected examples in the southeastern part of the Umbria-Marche belt reveals that some compressional structures are indeed thin-skinned, their style being controlled by rheological properties of a mechanically heterogeneous stratigraphy containing multiple décollements, whereas other structures are genuinely thick-skinned, their style being dominated by the reverse-reactivation of pre-orogenic normal faults deeply rooted within the basement. Therefore, the contrast of thin- vs. thick-skinned structural styles, an issue that has generated a long-lasting debate, is only apparent, since both styles are documented to co-exist and to have concurred in controlling the final compressional geometry of the fold-and-thrust belt.

Geological Society of America Abstracts with Programs. Vol. 53, No. 6

doi: 10.1130/abs/2021AM-367587

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