Kenneth L. Cameron
University of California, Santa Cruz
Publications 36
#1G. J. Nimz (UCSC: University of California, Santa Cruz)H-Index: 1
#2Kenneth L. CameronH-Index: 24
Last.S. L. MorrisH-Index: 1
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Granulite facies metamorphic rocks and ultramafic nodules, of lower crustal and upper mantle origin, respectively, occur as xenoliths in a host alkali basalt at the La Olivina peridot mine, approximately 150 km southeast of Ciudad Chihuahua. The La Olivina ultramafic xenoliths are of three compositional groups that are distinguished by clinopyroxene chemistry: a high magnesian (Mg/Mg+Fe = 0.90), high Cr 2 O 3 group (Group I); a moderately-magnesian (Mg/Mg+Fe = 0.76), high A1 2 0 3 , high TiO 2 g...
23 Citations
#1David S. Dowe (OU: Ohio University)H-Index: 2
#2R. Damian Nance (OU: Ohio University)H-Index: 34
Last.J. W. K. Lee (UCSC: University of California, Santa Cruz)H-Index: 1
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Exposed in the core of a NNW-trending frontal anticline of the Laramide fold-thrust belt of northeastern Mexico, the Granjeno Schist comprises a polydeformed assemblage of Paleozoic metasedimentary and metavolcaniclastic rocks and serpentinized mafic-ultramafic units. The earliest deformation (D1) predates emplacement of a leucogranite at 351 ± 54 Ma and may record obduction of this oceanic unit. Subsequent deformations (D2a-D2c) record tectonic juxtapositioning of the Granjeno Schist against th...
28 CitationsSource
#1Bodo Weber (Ensenada Center for Scientific Research and Higher Education)H-Index: 17
#2Kenneth L. Cameron (UCSC: University of California, Santa Cruz)H-Index: 24
Last.Peter Schaaf (UNAM: National Autonomous University of Mexico)H-Index: 32
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The Chiapas massif (CM) in southeastern Mexico is the crystalline basement of the southern Maya terrane, which is a crustal block that comprises mainly the Yucatan Peninsula, the Mexican states of Chiapas, Veracruz, and parts of Oaxaca. The CM is composed of igneous rocks and mediumto high-grade metamorphic rocks. Zircon fractions from all samples are discordant, yielding Late Permian lower-intercept ages and >1 Ga upper-intercept ages. The most precise results are from an orthogneiss that yield...
42 CitationsSource
#2J. Duncan Keppie (UNAM: National Autonomous University of Mexico)H-Index: 36
Last.Robert Lopez (Community College of Philadelphia)H-Index: 1
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The ~1 Ga Oaxacan Complex is the largest exposure of the Oaxaquia terrane of Mexico. Microprobe analysis of co-existing ortho- and clino-pyroxene, garnet, ilmenite and plagioclase indicate metamorphic conditions of 735 ± 5° C and 7.7 ± 0.1 kbar in the granulite facies, which was dated between ~998 and ~979 Ma using U–Pb isotopic analyses of zircon populations. Peak temperatures >800° C and isobaric cooling are indicated by the sporadic presence of sapphirine in metasediment and garnet–cordierite...
24 Citations
41 CitationsSource
#1Luigi Augusto Solari (UNAM: National Autonomous University of Mexico)H-Index: 23
#2J.D. Keppie (UNAM: National Autonomous University of Mexico)H-Index: 13
Last.Willis E. Hames (AU: Auburn University)H-Index: 16
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Inliers of f1.0–1.3 Ga rocks occur throughout Mexico and form the basement of the Oaxaquia microcontinent. In the northern part of the largest inlier in southern Mexico, rocks of the Oaxacan Complex consist of the following structural sequence of units (from bottom to top), which protolith ages are: (1) Huitzo unit: a 1012F12 Ma anorthosite–mangerite– charnockite–granite (AMCG) suite; (2) El Catro´n unit: z1350 Ma orthogneiss migmatized at 1106F6 Ma; and (3) El Marquez unit: z1140 Ma para- and o...
106 CitationsSource
#1J. Duncan Keppie (UNAM: National Autonomous University of Mexico)H-Index: 36
#2J. Dostal (Saint Mary's University)H-Index: 33
Last.R. Lopez (West Valley College)H-Index: 3
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Chemical and U � /Pb isotopic analyses of metaigneous rocks in the northern Oaxacan Complex in southern Mexico indicate that they form part of two granitic � /gabbroic suites intruded at � /1157 � /1130 and � /1012 Ma, which were metamorphosed under granulite facies conditions between � /1004 and 980 Ma. Although the older suite has both within-plate and arc geochemical signatures, the arc characteristics (enrichment of La and Ce relative to Nb, Ta, and Th) are inferred to result from crustal co...
124 CitationsSource
#1Robert Lopez (UCSC: University of California, Santa Cruz)H-Index: 6
#2Kenneth L. Cameron (UCSC: University of California, Santa Cruz)H-Index: 24
Last.Norris W. Jones (University of Wisconsin–Oshkosh)H-Index: 9
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Abstract A number of previous studies including two recent reconstructions of Rodinia have considered the Grenvillian basement of Mexico to be continuous with the Laurentian basement of Texas. Isotopic studies and U–Pb dating of zircons from Precambrian granitoids that occur as cobbles and boulders in a Paleozoic conglomerate exposed in the state of Coahuila, northeastern Mexico, indicate the region is underlain by Gondwanan rather than Laurentian basement. Essentially nothing was known of the b...
54 CitationsSource
#1Erik E. Scherer (UCSC: University of California, Santa Cruz)H-Index: 29
#2Kenneth L. Cameron (UCSC: University of California, Santa Cruz)H-Index: 24
Last.Janne Blichert-Toft (École normale supérieure de Lyon)H-Index: 64
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The highly elevated Lu/Hf of garnets with respect to other minerals, coupled with the new capability of routinely analyzing small samples (25 ng of Hf) by multiple-collector ICP-MS (MC–ICP–MS), makes the Lu–Hf garnet system a viable geochronometer. The robustness of Lu–Hf garnet-whole rock (gt-wr) ages, however, needs to be evaluated, and their closure temperature (TC) and potential effects of trace mineral inclusions need to be established. To constrain the TC of Lu–Hf relative to that of Sm–Nd...
277 CitationsSource
#1Carlos Schulze (UNAM: National Autonomous University of Mexico)H-Index: 4
Last.J.D. KeppieH-Index: 13
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