Persistent Link:
http://hdl.handle.net/10150/185077
Title:
Tectonostratigraphic history of the southern Foothills terrane.
Author:
Newton, Maury Claiborne, III.
Issue Date:
1990
Publisher:
The University of Arizona.
Rights:
Copyright © 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.
Abstract:
As a tool in discriminating basic rocks from different tectonic settings, a type of diagram was developed that employs three ratios of trace elements. The diagram separates basic rocks formed in mid-ocean ridge, intra-plate, and volcanic arc settings. It can be used to differentiate basalts from marginal basin, forearc, and arc rift zone settings. A second application of this type of diagram, employing major elements, distinguishes tholeiitic, calcalkaline, and boninitic series volcanic rocks. The southern part of the Foothills terrane, western Sierra Nevada, California, is composed chiefly of Jurassic-Triassic(?) metavolcanic and metasedimentary rocks of lower greenschist grade. Major tectonism affecting the terrane, associated with the Late Jurassic-Early Cretaceous Nevadan orogeny, was sinistral transpression with shearing along the Bear Mountains and Melones fault zones. The line of slip in high shear strain regions is approximated by the modal stretching lineation, which is at a rake of approximately 45° SE to the general shear zone orientation, suggesting sub-equal components of strike slip and dip slip. The sense of shear from kinematic indicators is consistently east side to the northwest. The terrane hosts three types of syngenetic massive sulfide deposits: Cyprus-type Cu deposits, Kuroko-type Zn-Cu-Pb deposits, and Besshi-type Cu-Zn deposits. The Cyprus-type deposits lie at the top of a Triassic(?) tholeiitic - basalt sequence in the lower Penon Blanco Formation. The deposits are part of an ophiolitic sequence that appears to have formed in an open-ocean spreading center environment. Felsic lava facies host the Kuroko-type deposits at the top of the Middle to Late Jurassic upper Gopher Ridge Formation, a dominantly bimodal sequence of meta-rhyolitic lavas and tuffs and meta-basaltic lavas. The tectonic setting appears to have been an arc-rift zone that formed during the transition from arc volcanism forming the lower Gopher Ridge Formation to younger basinal sedimentation forming the Mariposa Formation. The Besshi-type deposits are sediment-hosted in the Late Jurassic Mariposa Formation. They appear to have formed in the median part of a long linear basin between rifted arc segments. The inferred tectonic setting of the sulfide deposits was an early back-arc or interarc basin, which may have been related to transtensional tectonics.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Geology, Structural -- Sierra Nevada (Calif. and Nev.)
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Titley, Spencer R.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleTectonostratigraphic history of the southern Foothills terrane.en_US
dc.creatorNewton, Maury Claiborne, III.en_US
dc.contributor.authorNewton, Maury Claiborne, III.en_US
dc.date.issued1990en_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.description.abstractAs a tool in discriminating basic rocks from different tectonic settings, a type of diagram was developed that employs three ratios of trace elements. The diagram separates basic rocks formed in mid-ocean ridge, intra-plate, and volcanic arc settings. It can be used to differentiate basalts from marginal basin, forearc, and arc rift zone settings. A second application of this type of diagram, employing major elements, distinguishes tholeiitic, calcalkaline, and boninitic series volcanic rocks. The southern part of the Foothills terrane, western Sierra Nevada, California, is composed chiefly of Jurassic-Triassic(?) metavolcanic and metasedimentary rocks of lower greenschist grade. Major tectonism affecting the terrane, associated with the Late Jurassic-Early Cretaceous Nevadan orogeny, was sinistral transpression with shearing along the Bear Mountains and Melones fault zones. The line of slip in high shear strain regions is approximated by the modal stretching lineation, which is at a rake of approximately 45° SE to the general shear zone orientation, suggesting sub-equal components of strike slip and dip slip. The sense of shear from kinematic indicators is consistently east side to the northwest. The terrane hosts three types of syngenetic massive sulfide deposits: Cyprus-type Cu deposits, Kuroko-type Zn-Cu-Pb deposits, and Besshi-type Cu-Zn deposits. The Cyprus-type deposits lie at the top of a Triassic(?) tholeiitic - basalt sequence in the lower Penon Blanco Formation. The deposits are part of an ophiolitic sequence that appears to have formed in an open-ocean spreading center environment. Felsic lava facies host the Kuroko-type deposits at the top of the Middle to Late Jurassic upper Gopher Ridge Formation, a dominantly bimodal sequence of meta-rhyolitic lavas and tuffs and meta-basaltic lavas. The tectonic setting appears to have been an arc-rift zone that formed during the transition from arc volcanism forming the lower Gopher Ridge Formation to younger basinal sedimentation forming the Mariposa Formation. The Besshi-type deposits are sediment-hosted in the Late Jurassic Mariposa Formation. They appear to have formed in the median part of a long linear basin between rifted arc segments. The inferred tectonic setting of the sulfide deposits was an early back-arc or interarc basin, which may have been related to transtensional tectonics.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectGeology, Structural -- Sierra Nevada (Calif. and Nev.)en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorTitley, Spencer R.en_US
dc.contributor.committeememberEastoe, Christopher J.en_US
dc.contributor.committeememberRuiz Joaquinen_US
dc.contributor.committeememberConey, Peter J.en_US
dc.contributor.committeememberGehrels, George E.en_US
dc.identifier.proquest9028151en_US
dc.identifier.oclc704433704en_US
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