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| Titel |
Progressive-arc- vs. strike-slip-related rotations in curved orogenic belts: a case study from the Northern Apennines (Italy). |
| VerfasserIn |
Antonio Turtù, Sara Satolli, Rosanna Maniscalco, Fernando Calamita, Fabio Speranza |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075966
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| Zusammenfassung |
| A detailed paleomagnetic study has been performed in the southern sector of the
Olevano-Antrodoco-Sibillini (OAS) thrust front (i. e. the southern limb of the Northern
Apennines, Italy). The oroclinal/progressive-arc vs. non rotational nature of the
OAS thrust is still a matter of debate, as it has been interpreted in the literature as
dextral strike-slip fault, dextral transpressive fault, or as a frontal to oblique ramp
complex.
We document the paleomagnetism of 52 sites from Jurassic to Eocene pelagic limestones
and Messinian siliciclastic turbidites from both the OAS hanging wall and footwall. In the
hanging wall, sampling was designed to follow two transects perpendicular to two thrust
segments oriented roughly NE-SW and NNW-SSE. Paleomagnetic data have been integrated
with biostratigraphical and structural data, in order to understand both the rotational nature of
the OAS arc and the kinematics of the thrust front. All samples were paleomagnetically
investigated by a 2G DC-SQUID cryogenic magnetometer at the INGV of Rome. Thermal
cleaning was used throughout.
A characteristic component of magnetization was successfully isolated in 39 (over 52)
sites. The tilt-corrected directions were compared to the coeval directions expected
for the Adriatic-African foreland, in order to calculate rotations due to Apennine
orogenesis.
On the basis of cluster analysis and tectonic constrains, we document a peculiar pattern of
tectonic rotations along the OAS thrust with four rotational domains: 1. a strongly
rotated clockwise (CW) domain (54.78Ë ±5.46Ë ) in the hanging wall, close to the
NE-SW-trending segment of the thrust; 2. a less CW-rotated domain in the hanging wall
(15.1Ë ±5.8Ë ) that includes both the NNW-SSE oriented thrust segment and sites far
from the thrust; 3. a uniform counterclockwise (CCW) rotation (-30.79Ë ±4.73Ë )
in the footwall; 4. an approximately null rotation (-5.2Ë ±3.8Ë ) in the external
footwall.
The strong CW domain in the hanging wall, found in the NE-SW-oriented thrust segment
and strictly localized within 1 km far from the thrust front, suggests the presence of a dextral
strike-slip component linked to a lateral ramp development. The slight but significant
clockwise rotational domain observed in the remaining sites from the hanging wall is in
agreement with previous data from the literature, and indicate that the NNW-SSE-oriented
thrust segment is a frontal ramp.
Our data confirm the progressive nature of the Northern Apennines arc. Its
curved shape has been strongly influenced by the architecture of the Mesozoic Adria
paleomargin, accentuated by tectonic rotations, and locally complicated by transpressive
structures. This study indicate that a detailed paleomagnetic sampling is fundamental to
discriminate between progressive-arc- and strike-slip-related rotations in major arcs. |
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