Show simple item record

dc.contributor.advisorSeedorff, Ericen_US
dc.contributor.authorNickerson, Phillip Anson*
dc.creatorNickerson, Phillip Ansonen_US
dc.date.accessioned2012-09-10T18:31:56Z
dc.date.available2012-09-10T18:31:56Z
dc.date.issued2012
dc.identifier.urihttp://hdl.handle.net/10150/242354
dc.description.abstractIn the Basin and Range province of southwestern North America, Oligocene and Miocene normal faults are superimposed upon the Late Cretaceous-early Tertiary magmatic arc. This study examines tilted fault blocks containing dismembered pieces of porphyry systems, including pieces below and peripheral to ore bodies, that are exposed at the modern surface. Features in the magmatic-hydrothermal porphyry systems are used to place constraints on the style of extension in Arizona, and reconstructions of extension are used to examine the deep and peripheral portions of porphyry systems to provide a more complete understanding of porphyry systems as a whole. The Eagle Pass, Tea Cup, and Sheep Mountain porphyry systems of Arizona are examined in this study. In all the study areas, previous interpretations of the style of extension involved strongly listric normal faults. However, similar amounts of tilting observed in hanging wall and footwall rocks, as well as structure contour maps of fault planes, require that down dip curvature on faults was minimal (<1°/km. Instead, extension is shown here to have occurred as sets of nearly planar, "domino-style" normal faults were superimposed upon one another, including in the Pinaleño metamorphic core complex. Reconstructions of Tertiary extension reveal that sodic (-calcic) alteration is occurs 2-4 km peripheral to, and greisen alteration is found structurally below and overlapping with, potassic alteration. In addition, a preliminary reconstruction of extension across the Laramide magmatic arc reveals that the geometry, as revealed by known porphyry systems, is of similar scale to that of other magmatic arcs. These results help further the debate surrounding competing models of continental extension, and combine with previous work to provide a more complete understanding of the geometries of Arizona porphyry systems at the district and arc scale.
dc.language.isoenen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.subjectNormal Faulten_US
dc.subjectPalinspastic Reconstructionen_US
dc.subjectPorphyry Copperen_US
dc.subjectGeosciencesen_US
dc.subjectLaramide Magmatic Arcen_US
dc.subjectMetamorphic Core Complexen_US
dc.titlePost-Mineral Normal Faulting in Arizona Porphyry Systemsen_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.contributor.committeememberBarton, Marken_US
dc.contributor.committeememberDavis, Georgeen_US
dc.contributor.committeememberReiners, Peteren_US
dc.contributor.committeememberFerguson, Charlesen_US
dc.contributor.committeememberSeedorff, Ericen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.namePh.D.en_US
refterms.dateFOA2018-09-03T23:41:43Z
html.description.abstractIn the Basin and Range province of southwestern North America, Oligocene and Miocene normal faults are superimposed upon the Late Cretaceous-early Tertiary magmatic arc. This study examines tilted fault blocks containing dismembered pieces of porphyry systems, including pieces below and peripheral to ore bodies, that are exposed at the modern surface. Features in the magmatic-hydrothermal porphyry systems are used to place constraints on the style of extension in Arizona, and reconstructions of extension are used to examine the deep and peripheral portions of porphyry systems to provide a more complete understanding of porphyry systems as a whole. The Eagle Pass, Tea Cup, and Sheep Mountain porphyry systems of Arizona are examined in this study. In all the study areas, previous interpretations of the style of extension involved strongly listric normal faults. However, similar amounts of tilting observed in hanging wall and footwall rocks, as well as structure contour maps of fault planes, require that down dip curvature on faults was minimal (<1°/km. Instead, extension is shown here to have occurred as sets of nearly planar, "domino-style" normal faults were superimposed upon one another, including in the Pinaleño metamorphic core complex. Reconstructions of Tertiary extension reveal that sodic (-calcic) alteration is occurs 2-4 km peripheral to, and greisen alteration is found structurally below and overlapping with, potassic alteration. In addition, a preliminary reconstruction of extension across the Laramide magmatic arc reveals that the geometry, as revealed by known porphyry systems, is of similar scale to that of other magmatic arcs. These results help further the debate surrounding competing models of continental extension, and combine with previous work to provide a more complete understanding of the geometries of Arizona porphyry systems at the district and arc scale.


Files in this item

Thumbnail
Name:
azu_etd_12311_sip1_m.pdf
Size:
11.65Mb
Format:
PDF

This item appears in the following Collection(s)

Show simple item record