Apatite-rich pyrometamorphic rocks from Suweileh area, Jordan
- PDF / 10,231,655 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 52 Downloads / 135 Views
ORIGINAL PAPER
Apatite-rich pyrometamorphic rocks from Suweileh area, Jordan Nancy Al-Ajarmeh 1 & Hani Khoury 1 Received: 19 March 2018 / Accepted: 23 August 2018 / Published online: 7 September 2018 # Saudi Society for Geosciences 2018
Abstract Representative samples from the upper Cretaceous pyrometamorphic rocks from Suweileh area were investigated by using XRD, XRF, SEM/EDS, and microprobe techniques. Suweileh area is characterized by the presence of varicolored marble (dominated by green apatite-rich rocks) overlying bituminous marl and silicified limestone-phosphorite beds. The bituminous rocks are enriched with P, S, and F in addition to reduced sensitive trace elements that were inherited later by their metamorphic equivalents. The rocks were affected by severe tectonism that produced intensive fracturing which facilitated the chemical leaching. The mineralogy of the varicolored marble from Suweileh area is equivalent to Daba-Siwaqa and Maqarin areas in central and north Jordan. High-temperature and low-temperature groups of minerals were recognized. The first group is the result of pyrometamorphism produced from the spontaneous combustion of bituminous marl. The metamorphism was contemporaneous with tectonism of the Rift Valley. The second secondary group of minerals is the result of alteration by high alkaline waters followed by precipitation along the weakness zones. A hyperalkaline circulating water similar to the current issuing waters from Maqarin (north Jordan) was responsible for leaching and precipitation of anions and trace elements. A similar scenario was reported in north and central Jordan. The calculated structural formula of fluorapatite is Ca5.02 (P2.325, Si0.22, S0.0833) O12 F0.975. The apatite structure incorporates S and Si (inherited from the bituminous precursor) that substitute for P in the tetrahedral positions. Keywords Apatite . Pyrometamorphism . Varicolored marble . Mottled zone . Suweileh, Jordan
Introduction Suweileh area is located 16 km northwest of Amman (Fig. 1). The area was mapped by many authors and green apatite-rich metamorphic zone of upper Cretaceous age was recognized (McDonald Sir M, Partners 1965; Bender 1968, 1974; Sawariah and Barjous 1993). Phosphate-rich bituminous silicified limestone, bituminous marl, varicolored marble (apatiterich), and highly altered marble crop out in the study area. The excavations have indicated for the first time an anticlinelike structure with a direct contact between the bituminous marl and the varicolored marble (Ajarmeh 2014). The geology, mineralogy, and the origin of the marble from Suweileh area are similar to their equivalents in central Jordan (Daba-Siwaqa) and Maqarin in north Jordan (Khoury and Salameh 1986). Primary
* Hani Khoury [email protected] 1
Department of Geology, Faculty of Science, The University of Jordan, Amman, Jordan
high-temperature minerals and secondary low-temperature minerals were described as equivalent to the sanidinite hornfels facies of contact metamorphism (Wiesemann and Rosch 1969; Khoury and
Data Loading...
