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)

APENNINE UPLIFT HISTORY AND DEVELOPMENT OF TRANSVERSE DRAINAGES FROM LONGITUDINAL PROFILE INVERSION

Paper number: T44-8
Program: Technical Sessions
Time: 3:15 PM – 3:30 PM

Authors

Abstract

Exhibiting numerous examples of steep-walled gorges carved transverse to structure through hard rock, the Apennines have inspired research on the development of transverse drainages summarized in a seminal paper by Walter Alvarez in 1999. We evaluate competing models of transverse drainage development, as well as the underlying dynamic and tectonic processes responsible for Apennine topography, by assembling the rate of base level fall (τ-U) and associated channel χ-z data of ten catchments draining the Apennine pro-wedge using a channel stream power-based linear inverse approach. The model employs the simplifying assumption of uniform uplift and erosion at the catchment scale, but accounts for variable rock erodibility as the first-order determinant of regional, mean channel steepness. Accordingly, local deviations in channel steepness are represented in the model as transient, upstream-propagating waves of base level fall originating at the catchment mouth. Modeled timing, rate, and unsteadiness of these base level falls are broadly consistent with geologic data indicating that the Apennines emerged impulsively at ~2.5 Ma at rates ranging from ~0.2-0.3 mm/yr in the north and central to rates of ~0.7 mm/yr in the south. Segmented χ-z plots suggest that the uplift may not be uniform at the catchment scale, and/or area-growing drainage integration or area-diminishing drainage captures have occurred in the past 3 Ma. Model results support syn-deformation, foreland-propagating superposition for transverse drainage development in the northern and north-central Apennines where an intact Adriatic slab remains. In contrast further south where a slab window separates the Adriatic slab from the base of the Apennine wedge, dynamic uplift prevails and the transverse drainages have developed in response to regional superposition and integration of catchments through spillover and headwater capture processes. The rates of rock uplift modeled in this study, when integrated for surfaces or stratigraphic deposits that have experienced minimal erosion since their formation, results in cumulative uplift ranging from ~900 m to ~1800 m for the central and southern Apennines respectively, both consistent with recent, independent estimates of surface uplift from paleo-elevation studies.

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

doi: 10.1130/abs/2021AM-367305

© Copyright 2021 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.