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

Abstract

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.

Laser-induced breakdown spectroscopic studies of calcite (CaCO3) marble using the fundamental (1064 nm) and second (532 nm) harmonic of a Nd:YAG laser

“…A naturally occurring calcite marble sample was collected directly from a fresh quarry of the Nikani Ghar Formation of the Lesser Himalayas for the present study. The characterization results for the different varieties of calcite and dolomite marble from this geological formation have been reported previously (Iqbal et al 2013, Fahad and Iqbal 2014, Fahad et al 2016a, 2016b, Fahad and Sundas 2018. Calcite marble can contain other phases like dolomite, quartz, and muscovite (Fahad et al 2016b).…”

“…The characterization results for the different varieties of calcite and dolomite marble from this geological formation have been reported previously (Iqbal et al 2013, Fahad and Iqbal 2014, Fahad et al 2016a, 2016b, Fahad and Sundas 2018. Calcite marble can contain other phases like dolomite, quartz, and muscovite (Fahad et al 2016b). X-ray diffraction (XRD) is a better tool for not only the identification of crystalline constituent phases of a sample but for the determination of their crystal structure as well; therefore, phase analysis was performed using powder XRD for the determination and affirmation of other mineral phase(s) present in our sample.…”

Optimization, characterization and adsorption properties of natural calcite for toxic As(III) removal from aqueous solutions

“…The most prominent peaks for the calcite phase were observed at 2θ = 29.47° and 47.6°, corresponding to d-spacing of 3.03 and 1.91 Å and hkl values of 104 and 024, respectively. A few low intensity peaks were also observed indicating the presence of quartz (2θ = 20.8°, 26.6° and 50.2°) and dolomite as minor phases (2θ = 60.7°) (Fahad et al, 2016;Fahad et al, 2018).…”

Elemental analysis of limestone by laser-induced breakdown spectroscopy, scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and electron probe microanalysis

“…Limestone comprises +95% CaCO 3 , while containing <5% proportion of other impurities, e.g. iron carbonate, magnesium carbonate (dolomite), sand, clay, feldspar, pyrite and quartz (Iqbal et al 2013, Fahad et al 2016b, Fahad and Sundas 2018. The presence of these impurities can cause problems while accessing the different applications of limestone requiring some specific chemical purity.…”