HR: 1340h
AN: T53B-0498    [Abstracts]
TI: Topographic Signature of a Subduction and Collision Zone: Uplift Pattern from Marine Terraces and Delta Sequences along the Calabrian Ridge, South Italy (CAT SCAN Project)
AU: * Commins, D C
EM: dcommins@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964 United States
AU: Seeber, L
EM: nano@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964 United States
AU: Dewez, T
EM: t.dewez@brgm.fr
AF: BRGM, Natural Risk Dept., 3 Av. C. Guillemin, Orleans, 45060 France
AU: Stark, C
EM: stark@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964 United States
AU: Steckler, M
EM: steckler@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964 United States
AB: Ancient coastlines, in the form of abrasion platforms or coastal deposits, provide markers in the landscape that can be correlated and dated to determine patterns and rates of uplift. We present new data on an excellently exposed flight of Pleistocene coastlines to constrain patterns of uplift associated with rollback subduction and arc-continent collision in the Calabrian arc and the southern Apennines. While many aspects of this type orogen of Mediterranean tectonics are coming into focus, major issues are still unresolved. A more complete and detailed resolution of vertical tectonics is expected to discern between competing hypotheses: for instance, whether or not subduction is still ongoing. We present results from a preliminary database of marine terraces mapped on a regional scale with an SRTM-3arcsec DEM and field observations. Supplementary to the geometric correlation of terraces, we are currently processing samples for cosmogenic isotope analysis to determine age relationships. Four prominent, seaward dipping terrace levels were identified on the west coast at heights of 100m, 170m, 400m and 700m, which we call T1, T2, T3 and T4 respectively. The upper terrace levels (T2, T3 and T4) comprise both bedrock-carved platforms and fossiliferous coastal deposits, with rounded paleocliff edges that form clear scarps in the DEM. The lower terrace level (T1) consists of shallow marine deposits with fossiliferous horizons containing in-situ coral. The geographic distribution of the T4 terrace level is particularly extensive, forming a continuous ridge along the backbone of Calabria, in the footwall of a major N-S trending extensional fault bounding the M\'{e}sima Valley. Similar terraces with well-defined sea-cliffs and thick accumulations of shallow marine deposits were identified on the eastern flank of Calabria. We believe this is the first documentation of terraces at this level on the east coast, and is a particularly interesting find, as it suggests that the earliest uplift affected both sides of Calabria. In the M\'{e}sima Valley, fossiliferous shallow marine sediments, with abundant oysters, dip at 10$\deg$E, which we interpret as hangingwall tilt toward the eastern-bounding fault of the M\'{e}sima Valley. These results demonstrate that ancient marine shorelines provide a reliable datum for calibration of (1) regional vertical motion since the formation of the earliest-formed terrace, and (2) local tectonic deformation following terrace formation.
DE: 8107 Continental neotectonics
DE: 1824 Geomorphology (1625)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting