Contact metamorphism of impure dolomitic limestone in the Boulder Aureole, Montana

Rice, Jack M.

doi:10.1007/bf00374555

Cited by 79 publications

(39 citation statements)

References 11 publications

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“…In this section, calcite-dolomite geothermometry has been carried out on two samples of Poleta marble. For sample PF.71 (collected 0-5 m above the pluton margin), minimum temperatures of metamorphism of 510-530°C and 470-490°C are indicated using the models of Rice (1977) and Annovitz and Essene (1987), respectively. Similarly, at a structurally higher level (11-6 m above the pluton margin), minimum temperatures of metamorphism of 490-530°C and 450-490°C are estimated for sample PF.72.…”

Section: Traverse Cmentioning

confidence: 99%

The Papoose Flat Pluton of eastern California: a reassessment of its emplacement history in the light of new microstructural and crystallographic fabric observations

Law

Morgan

Casey

et al. 1992

Geological Society of America Special Papers

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One of the most outstanding apparent examples in N America of a forcibly emplaced pluton is the Papoose Flat Pluton of eastern California. Sideways expansion of this granitic pluton, during emplacement into a series of Cambrian shelf strata, has been regarded by early workers as resulting in the observed intense crystal plastic deformation of the pluton's mylonitic border facies and surrounding country rocks. This deformation is evidenced by up to 90% thinning of individual stratigraphic layers within the pluton's metamorphic aureole, although such intense penetrative deformation of the country rocks is not observed outside the aureole.Previously published quartz c-axis fabrics associated with this deformation (and presented on projection planes oriented perpendicular to lineation) were interpreted as being symmetrical with respect to foliation and lineation, implying almost coaxial deformation histories. Such fabrics could be interpreted as indicating that the pluton evolved by "ballooning" as a result of new magma being intruded into its core during emplacement. However, a major problem with applying the strict ballooning model to the Papoose Flat Pluton is that while oblate strains would be expected to develop in association with a ballooning mechanism, the mylonitic rocks of this elongate WNW-ESE-trending pluton and its aureole are characterised by both a strongly developed foliation, which is concordant with the pluton's margin, and an intense, NW-SE trending, shallow plunging stretching lineation.Previously published fabrics from the Papoose Flat Pluton and its metamorphic aureole have been rotated on to a projection plane oriented parallel to lineation and perpendicular to foliation. Examination of the fabrics in this projection plane has revealed that they are in fact dominantly asymmetric, and that a constant sense of asymmetry is detected across the pluton, suggesting a consistent (top-to-the-SE) shear-sense. This new interpretation is strongly supported by microstructural and petrofabric analysis of additional L-S tectonites collected, during recent fieldwork, from both the aureole and quartz veins within the pluton's gneissic border facies. Thus mylonite formation around the Papoose Flat Pluton could have involved large-scale consistently oriented translation and associated shearing, rather than passive "blister-like" coaxial deformation associated with pluton ballooning. It should be noted that mylonitic deformation is restricted to the western half of the pluton, features indicative of a more "permitted" emplacement mechanism being found in the eastern portion of the pluton.The detected top-to-the-SE shear-sense could be interpreted as indicating that the granitic material forming the western part of the pluton was forcibly intruded in a northwestward direction from the pluton source as a nearly solidified wedge beneath a static cover of sedimentary rocks. Alternatively, the detected shear sense could also be interpreted as indicating SE-directed thrusting of the cover rocks over the unde...

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Section: Traverse Cmentioning

confidence: 99%

The Papoose Flat Pluton of eastern California: a reassessment of its emplacement history in the light of new microstructural and crystallographic fabric observations

Law

Morgan

Casey

et al. 1992

Geological Society of America Special Papers

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“…Goldsmith (1958, 1955) and Goldsmith et al, (1955) used XRD to determine the MgCO 3 content in natural and synthetic samples to establish phase relationships in the CaO-MgO-CO 2 system from the concentration of 0 to 15 mol.% of MgCO 3 . Later on, calcite-dolomite thermometry has been widely used (e.g., Wada and Suzuki, 1983; Bowman and Essene, 1982;Iii et al, 1982;Nesbitt and Essene, 1982;Ralph and Diane, 1980;Rice, 1977;Suzuki, 1977;Puhan, 1976;Hatcher et al, 1973; Hutcheon and Moore, 1973;Sobol, 1973). Talantsev (1978Talantsev ( , 1976, Bickle and Powell (1977), and Barron (1974) evaluated the effect of FeCO 3 on calcitedolomite thermometry and reported that its effect is negligible at concentrations <1 mol.%.…”

mentioning

confidence: 99%

Metamorphic temperature investigation of coexisting calcite and dolomite marble––examples from Nikani Ghar marble and Nowshera Formation, Peshawar Basin, Pakistan

et al. 2016

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INTRODUCTIONDetermining peak metamorphic temperature of low grade rocks has always been a challenge. X-ray diffraction (XRD) is an established technique for the determination of constituent phases in solid-solution series. Differences in ionic sizes between substitute and host cations lead to systematic variations in unit-cell parameters and inter-planar spacings that can be measured using XRD. This approach has been widely used in analyzing rhombohedral Ca-Mg carbonates, for example, the composition of biogenic and inorganic (Ca, Mg)CO 3 crystals are often calculated by comparing the difference in d 104 value with the published determinative curves (Zhang et al., 2010;Raz et al., 2000; Falini et al., 1996; Bischoff et al., 1983;Milliman et al., 1971). At least five empirical curves are currently known in the literature (Bischoff et al., 1983;Milliman et al., 1971;Goldsmith et al., 1961Goldsmith et al., , 1955Goldsmith and Graf, 1958; Chave, 1952). Determinative curves based on synthetic magnesian calcite crystals are probably the most widely used (Milliman et al., 1971;Goldsmith et al., 1961;Goldsmith and Graf, 1958).Owing to the abundance of calcite and dolomite in the Earth's crust, knowledge of their limits of stability can be used to assess the conditions of temperature prevailing during their formation and subsequent metamorphism. The calcite-dolomite solvus in the system CaCO 3 -MgCO 3 was first investigated by Graf and Goldsmith (1955) and Harker and Tuttle (1955). They recognized that the temperature dependence of the amount of MgCO 3 in calcite in equilibrium with dolomite is potentially a precise method of estimating metamorphic temperatures. Goldsmith (1958, 1955) and Goldsmith et al., (1955) used XRD to determine the MgCO 3 content in natural and synthetic samples to establish phase relationships in the CaO-MgO-CO 2 system from the concentration of 0 to 15 mol.% of MgCO 3 . Later on, calcite-dolomite thermometry has been widely used (e.g., Wada and Suzuki, 1983; Bowman and Essene, 1982;Iii et al., 1982;Nesbitt and Essene, 1982;Ralph and Diane, 1980;Rice, 1977;Suzuki, 1977;Puhan, 1976;Hatcher et al., 1973; Hutcheon and Moore, 1973;Sobol, 1973). Talantsev (1978Talantsev ( , 1976, Bickle and Powell (1977), and Barron (1974) evaluated the effect of FeCO 3 on calcitedolomite thermometry and reported that its effect is negligible at concentrations <1 mol.%. Bickle and Powell (1977) reported that the metamorphic temperature of coexisting calcitedolomite samples from the Glockner area of the Tauern Window, Austria ranged from 410 to 490 o C. The solvus temperature determined from XRD data for Grenville calcite ranged from 415 to 485 o C (Sheppard, 1966). Höy (1970) estimated a temperature of 600 o C by using the calcite from brucite marble.

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“…However, the original Ca# could be obscured by polyphase evolution of the studied rock (Fig. 3).The magmatic origin of the R2 silicocarbonatite is further supported by the calcite-dolomite thermometer (Rice 1977) yielding temperatures of carbonatite formation between 660 and 800 °C (Tab. 1).…”

Section: Bulk-rock Chemistrymentioning

confidence: 61%

Carbonate-rich dyke in Roztoky Intrusive Complex - an evidence for carbonatite magmatism in the Eger Rift?

Rapprich¹,

Kochergina²,

Magna³

et al. 2017

J. Geosci.

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The possible presence of carbonatites in the Eger Rift (NW Bohemian Massif, Czech Republic) has been debated for several decades without any apparent resolution. Here, we document an almost 2 m thick dyke of a silicocarbonatite (23 wt. % SiO 2 , 27 wt. % CO 2 ) in the R2 (Roztoky nad Labem) drilling at the depth of 152.9-154.8 m. Despite the fact that the silicocarbonatite is associated with alkaline intrusive complex, its content of alkalis is rather low (Na 2 O + K 2 O = 2.5 wt. %), as are REE (ΣREE = 82.6 ppm). The stable isotope signature (δ

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Contact metamorphism of impure dolomitic limestone in the Boulder Aureole, Montana

Cited by 79 publications

References 11 publications

The Papoose Flat Pluton of eastern California: a reassessment of its emplacement history in the light of new microstructural and crystallographic fabric observations

The Papoose Flat Pluton of eastern California: a reassessment of its emplacement history in the light of new microstructural and crystallographic fabric observations

Metamorphic temperature investigation of coexisting calcite and dolomite marble––examples from Nikani Ghar marble and Nowshera Formation, Peshawar Basin, Pakistan

Carbonate-rich dyke in Roztoky Intrusive Complex - an evidence for carbonatite magmatism in the Eger Rift?

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