CaltechAUTHORS
  A Caltech Library Service

Tectonic development of the Colorado Plateau Transition Zone, central Arizona: Insights from lower lithosphere xenoliths and volcanic host rocks

Chapman, Alan D. and Riggs, Nancy and Ducea, Mihai N. and Saleeby, Jason B. and Rautela, Ojashvi and Shields, Jessie (2019) Tectonic development of the Colorado Plateau Transition Zone, central Arizona: Insights from lower lithosphere xenoliths and volcanic host rocks. In: Geologic Excursions in Southwestern North America. Field guide (Geological Society of America). No.55. Geological Society of America , Boulder, CO, pp. 209-235. ISBN 9780813756554. https://resolver.caltech.edu/CaltechAUTHORS:20200506-140547902

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20200506-140547902

Abstract

A growing body of evidence suggests that continental arc lower crust and underlying mantle wedge assemblages native to the Mojave Desert (i.e., the southern California batholith) were displaced eastward during Laramide shallow-angle subduction, and reattached to the base of the Colorado Plateau Transition Zone (central Arizona) and farther inboard. On this field trip, we highlight two xenolith localities from the Transition Zone (Camp Creek and Chino Valley) that likely contain remnants of the missing Mojave lithosphere. At these localities, nodules of garnet clinopyroxenite, the dominant xenolith type at both studied localities, yield low jadeite components in clinopyroxene, chemically homogeneous “type-B” garnet, and peak conditions of equilibration at 600–900 °C and 9–28 kbar. These relations strongly suggest a continental arc residue (“arclogite”), rather than a lower-plate subduction (“eclogite”), origin. Zircon grains extracted from these nodules yield a bimodal age distribution with peaks at ca. 75 and 150 Ma, overlapping southern California batholith pluton ages, and suggesting a consanguineous relationship. In contrast, Mesozoic and early Cenozoic igneous rocks native to SW Arizona, with age peaks at ca. 60 and 170 Ma, do not provide as close a match. In light of these results, we suggest that Transition Zone xenoliths: (1) began forming in Late Jurassic time as a mafic keel to continental arc magmas emplaced into the Mojave Desert and associated with eastward subduction of the Farallon plate; (2) experienced a second ca. 80–70 Ma pulse of growth associated with increased magmatism in the southern California batholith; (3) were transported ~500 km eastward along the leading edge of the shallowly subducting Farallon plate; and (4) were reaffixed to the base of the crust at the new location, in central Arizona. Cenozoic zircon U-Pb, garnet-whole rock Sm-Nd, and titanite U-Pb ages suggest that displaced arclogite remained at elevated temperature (>700 °C) for 10s of m.y., following its dispersal, and until late Oligocene entrainment in host latite. The lack of arclogite and abundance of spinel peridotite xenoliths in Miocene and younger mafic volcanic host rocks (such as those at the San Carlos xenolith locality), and the presence of seismically fast and vertically dipping features beneath the western Colorado Plateau, suggest that arclogite has been foundering into the mantle and being replaced by upwelling asthenosphere since Miocene time.


Item Type:Book Section
Related URLs:
URLURL TypeDescription
https://doi.org/10.1130/2019.0055(09)DOIArticle
ORCID:
AuthorORCID
Chapman, Alan D.0000-0001-9865-603X
Ducea, Mihai N.0000-0002-5322-0782
Additional Information:© 2019 The Geological Society of America. Manuscript Accepted by the Society 17 June 2019; Published: September 04, 2019. This effort benefitted from field and lab assistance by D. Abboud, B. Hunter, and J. Thole; discussions with S. Esperança, H. Jiang, and D. Smith; insights from reviewers J. Chapman and C.-T. Lee; and editorial handling by the GSA editorial staff and P. Pearthree. This work was supported by NSF grants EAR-1524768 (to ADC) and EAR-1725002 (to MND) and the Romanian Executive Agency for Higher Education, Research, Development and Innovation Funding projects PN-III-P4-ID-PCE-2016-0127 and PN-III-P4-ID-PCCF-2016-0014 (to MND). The Arizona State Land Department and the San Carlos Apache Tribe are thanked for granting access to Stops 1 and 3, respectively, on this field trip.
Funders:
Funding AgencyGrant Number
NSFEAR-1524768
NSFEAR-1725002
Executive Agency for Higher Education, Research, Development and Innovation (Romania)PN-III-P4-ID-PCE-2016-0127
Executive Agency for Higher Education, Research, Development and Innovation (Romania)PN-III-P4-ID-PCCF-2016-0014
Series Name:Field guide (Geological Society of America)
Issue or Number:55
Record Number:CaltechAUTHORS:20200506-140547902
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200506-140547902
Official Citation:Alan D. Chapman, Nancy Riggs, Mihai N. Ducea, Jason B. Saleeby, Ojashvi Rautela, Jessie Shields, 2019. "Tectonic development of the Colorado Plateau Transition Zone, central Arizona: Insights from lower lithosphere xenoliths and volcanic host rocks", Geologic Excursions in Southwestern North America, Philip A. Pearthree; doi: 10.1130/2019.0055(09)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103045
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:06 May 2020 21:16
Last Modified:06 May 2020 21:16

Repository Staff Only: item control page