Petrologic significance of staurolites in the Llano Uplift

Carlson, W D; Reese, J F

Title: Petrologic significance of staurolites in the Llano Uplift

Full Record
Other Related Research

Abstract

The recent discovery of rocks with near-end-member Fe-staurolite in the SE Llano Uplift, together with the regional absence of Fe-Mg staurolite except as inclusion in garnet in a single nearby locality, confirms that the SE Uplift experienced a polybaric metamorphic history similar to that documented for the N and NW Uplift. The units containing Fe-rich staurolite are part of a unique suite of rocks within the Packsaddle Group (Rough Ridge Fm) exposed in Whites Creek. Although the predominant rock types in the Packsaddle Schist are felsic schists, felsic gneisses and amphibolites, this pelitic metasedimentary package includes interlayered andalusite-bearing rocks, quartzites, and muscovite schists. Although textural evidence is equivocal, growth of staurolite during dynamothermal metamorphism is indicated by the preferred orientation of elongate crystals parallel to the rock's dominant foliation. The unusual Fe-rich staurolites reported here are the only known occurrence of the mineral in the Uplift except for staurolite (X[sub Fe] = 0.72) described as inclusions within a large garnet from a locality in the Rough Ridge Fm [approximately]3 km to the west. The matrix surrounding this garnet is entirely devoid of staurolite. The contrast between these occurrences indicates that staurolite of ordinary Fe/Mg ratio grew during an early moderate-Pmore »« less

Authors:

Carlson, W D; Reese, J F ^[1]

Univ. of Texas, Austin, TX (United States). Dept. of Geological Sciences

Publication Date:: Mon Feb 01 00:00:00 EST 1993

OSTI Identifier:: 6003471

Report Number(s):: CONF-9303212-
Journal ID: ISSN 0016-7592; CODEN: GAAPBC

Resource Type:: Conference

Journal Name:: Geological Society of America, Abstracts with Programs; (United States)

Additional Journal Information:: Journal Volume: 25:1; Conference: 27. annual Geological Society of America (GSA) South-Central Section meeting, Fort Worth, TX (United States), 15-16 Mar 1993; Journal ID: ISSN 0016-7592

Country of Publication:: United States

Language:: English

Subject:: 58 GEOSCIENCES; GEOLOGIC FORMATIONS; MINERALOGY; PETROLOGY; TEXAS; ALUMINIUM SILICATES; GARNETS; GEOBAROMETRY; GEOLOGIC HISTORY; GEOTHERMOMETERS; GEOTHERMOMETRY; IRON SILICATES; METAMORPHIC ROCKS; METAMORPHISM; MINERALIZATION; RECRYSTALLIZATION; ALUMINIUM COMPOUNDS; DEVELOPED COUNTRIES; GEOLOGY; IRON COMPOUNDS; MEASURING INSTRUMENTS; MINERALS; NORTH AMERICA; OXYGEN COMPOUNDS; ROCKS; SILICATE MINERALS; SILICATES; SILICON COMPOUNDS; THERMOMETERS; TRANSITION ELEMENT COMPOUNDS; USA; 580000* - Geosciences

Citation Formats


                    Carlson, W D, and Reese, J F. Petrologic significance of staurolites in the Llano Uplift.  United States: N. p., 1993. 
        Web.

Copy to clipboard


                    Carlson, W D, & Reese, J F. Petrologic significance of staurolites in the Llano Uplift.  United States.

Copy to clipboard


                    Carlson, W D, and Reese, J F. 1993.  
        "Petrologic significance of staurolites in the Llano Uplift".  United States.

Copy to clipboard


                    
@article{osti_6003471,

  title        = {Petrologic significance of staurolites in the Llano Uplift},

  author       = {Carlson, W D and Reese, J F},

  abstractNote = {The recent discovery of rocks with near-end-member Fe-staurolite in the SE Llano Uplift, together with the regional absence of Fe-Mg staurolite except as inclusion in garnet in a single nearby locality, confirms that the SE Uplift experienced a polybaric metamorphic history similar to that documented for the N and NW Uplift. The units containing Fe-rich staurolite are part of a unique suite of rocks within the Packsaddle Group (Rough Ridge Fm) exposed in Whites Creek. Although the predominant rock types in the Packsaddle Schist are felsic schists, felsic gneisses and amphibolites, this pelitic metasedimentary package includes interlayered andalusite-bearing rocks, quartzites, and muscovite schists. Although textural evidence is equivocal, growth of staurolite during dynamothermal metamorphism is indicated by the preferred orientation of elongate crystals parallel to the rock's dominant foliation. The unusual Fe-rich staurolites reported here are the only known occurrence of the mineral in the Uplift except for staurolite (X[sub Fe] = 0.72) described as inclusions within a large garnet from a locality in the Rough Ridge Fm [approximately]3 km to the west. The matrix surrounding this garnet is entirely devoid of staurolite. The contrast between these occurrences indicates that staurolite of ordinary Fe/Mg ratio grew during an early moderate-P to high-P dynamothermal episode, but was destroyed during later low-P static metamorphism. In contrast, near-end-member Fe-staurolite originating in the early event survived later static metamorphism. These observations are consistent with the polybaric history (dynamic metamorphism at P[>=] [approximately]6--8 kbar followed by static recrystallization at P[approximately]2--3 kbar) deduced from assemblages, textures and thermobarometry on metamafic rocks from the N and NW Llano Uplift.},

  doi          = {},

  url          = {https://www.osti.gov/biblio/6003471},
  journal      = {Geological Society of America, Abstracts with Programs; (United States)},

  issn         = {0016-7592},

  number       = ,

  volume       = 25:1,

  place        = {United States},

  year         = {Mon Feb 01 00:00:00 EST 1993},

  month        = {Mon Feb 01 00:00:00 EST 1993}

}

Copy to clipboard

Conference:

Other availability

Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:

Export Metadata

Save to My Library

Similar records in OSTI.GOV collections:

The Grenville orogeny in the Llano Uplift, Texas: A record of collision and contraction along the southern margin of North America

Conference Reese, J - Geological Society of America, Abstracts with Programs; (United States)

Precambrian metamorphic rocks in the SE Llano Uplift record NE-directed ductile thrusting and regional-scale polyphase folding. This deformation is in response to Grenville-age shortening and crustal thickening associated with the collision of a south-lying tectonic block with the southern margin of North America. In the SE Llano Uplift, the most intense and pervasive deformational event, D2, is characterized in the Packsaddle Schist (PS) and Valley Spring Gneiss (VSG) by SSE-plunging, NE-verging isoclinal folds (F2) with an associated SW-dipping axial planar metamorphic layering (S2), and SW-dipping mylonite zones with kinematic indicators showing top-to-the-NE motion. In the Red Mountain and augen-bearing Bigmore »« less
Progressive low pressure metamorphism of metapelitic rocks from the Casco Bay area, southwestern Maine

Conference Grover, T; Lang, H; Gordon, T - Geological Society of America, Abstracts with Programs; (United States)

A prograde sequence of metapelitic rocks occurs in the Casco Bay area, southwestern Maine. Excellent exposure along the coast of Orrs Island, Harpswell Neck, and Small Point have allowed for the delineation of several metamorphic zones which show an increase in metamorphic grade from west to east across the area. These zones are, in order of increasing metamorphic grade, a garnet zone, a staurolite zone, a staurolite + andalusite zone and a sillimanite [plus minus] andalusite [plus minus] staurolite zone. The widespread occurrence of coexisting andalusite + sillimanite in the highest grade portion of the area, along with the presencemore »« less
Decompressional metamorphic P-T paths from kyanite-sillimanite-andalusite bearing rocks in north-central New Mexico

Conference Daniel, C; Thompson, A; Grambling, J - Geological Society of America, Abstracts with Programs; (United States)

Proterozoic rocks in six uplifts in northern and central New mexico display decompressional metamorphic P-T paths, apparently, related to crustal extension at a time near 1,440 Ma. Metamorphic P-T paths from the Picuris, Rincon, Truchas, Rio Mora, Sandia and southern Manzano Mountains are constrained by three independent techniques: (1) Al[sub 2]SiO[sub 5] and other mineral parageneses; (2) the Gibbs method applied to compositional zoning in garnet and plagioclase; and (3) a new technique based upon Fe[sup 3+] and Mn[sup 3+] zoning in andalusite. Aluminum silicate textures suggest that kyanite and subsequent sillimanite (commonly aligned parallel to the regional foliation andmore »« less
Cordierite reaction textures in semipelitic rocks from metamorphic zone IV in central Massachusetts: Their interpretation and possible p-t significance

Conference Schumacher, J; Robinson, P - Geological Society of America, Abstracts with Programs; (United States)

In central Massachusetts, examples of cordierite (CRD)-garnet (GAR) assemblages are rare outside of the Acadian metamorphic Zone VI (lower granulite facies). The previously known exceptions are limited to some gedrite-bearing assemblages within a distinct stratigraphic unit from Zone 2. Consequently, the discovery of CRD + GAR in a thin horizon within layered felsic and mafic gneisses from Zone IV was somewhat surprising. This horizon contains CRD, GAR, pale-green biotite (BIO), brown BIO, sillimanite (SIL), staurolite (ST), plagioclase (PLG) and quartz (QZ). In thin section, CRD has two modes of occurrence: (i) CRD blasts enclose fine mats of SIL needles thatmore »« less
Petrology and metamorphic history of metapelites in the Boehls Butte quadrangle, northern Idaho

Conference Carey, J; Rice, J - Geol. Soc. Am., Abstr. Programs; (United States)

Metapelitic rocks in the Goat Mountain area record a pre-Beltian anatectic event and two later metamorphic events correlated to the M2 and M3 events observed by Lang and Rice. The co-occurrence of all three aluminosilicates is the result of M2 kyanite-sillimanite growth and M3 andalusite growth. The conditions of M2 metamorphism are estimated at 675 +/- 50/sup 0/C and 9.3 +/- 1.5 kb as determined from a variety of geothermo/barometers. M2 AFM mineral assemblages include Grt-Bt-Ky+/-Sil+/-Str and Crd-Bt-Ky+/-Sil. Partitioning of Mg and Fe in garnet and staurolite is normal (K/sub D/ > 1) for relict staurolite enclosed by aluminosilicate ormore »« less

Similar Records