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Interactions between low-angle normal faults and plutonism in the upper crust; insights from the island of Elba, Italy

Steven A. F. Smith, R. E. Holdsworth and C. Collettini
Interactions between low-angle normal faults and plutonism in the upper crust; insights from the island of Elba, Italy
Geological Society of America Bulletin (January 2011) 123 (1-2): 329-346

Abstract

The late Miocene to early Pliocene Zuccale low-angle normal fault on the Island of Elba, Italy, was one of the principal structures active during extensional collapse of the Apennine fold-and-thrust belt. We investigate the relationships among the Zuccale fault, subsidiary footwall fault networks, and igneous bodies that were intruded into the immediate footwall of the Zuccale fault. Both brittle and ductile kinematic indicators found in association with fault zones and igneous bodies yield a consistent WNW-ESE extension direction, suggesting that faulting and intrusion overlapped in time. Structure contour analysis indicates that the Zuccale fault has a regional domal morphology. The dimensions and spatial location of the dome correlate with the likely subsurface position of the Porto Azzurro pluton, originally intruded at approximately 6 km depth. We propose that doming of the Zuccale fault may have been related in part to emplacement of the Porto Azzurro pluton as a tabular intrusion, involving some component of vertical inflation and roof uplift. The immediate footwall of the Zuccale fault is everywhere crosscut by a complex, linked network of high- and low-angle extensional faults with observed displacements of <10 m. Mutual crosscutting relationships suggest that low- and high-angle faults were active broadly contemporaneously. The final geometry of the footwall fault networks is adequately explained by their position with respect to the regional domal structure, and they suggest that certain sections of the Zuccale fault were back-rotated--during doming--out of an orientation capable of accommodating continued regional extension.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 123
Serial Issue: 1-2
Title: Interactions between low-angle normal faults and plutonism in the upper crust; insights from the island of Elba, Italy
Affiliation: University of Durham, Department of Earth Sciences, Durham, United Kingdom
Pages: 329-346
Published: 201101
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 110
Accession Number: 2011-012652
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2010159
Illustration Description: illus. incl. geol. sketch maps
N42°40'00" - N42°45'00", E10°00'00" - E10°25'00"
Secondary Affiliation: Universita di Perugia, ITA, Italy
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201108
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