Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

The Composition and Distribution of Nodular Monazite in the Marvast Upper Triassic Shales (Yazd-Iran)

Document Type : Original Research Paper

Authors
Masoud Alipour 1
Iraj Rasa 2
Mahmoud Mehrpartou 1
Ahmad Khakzad 2
Mohammad Hossein Adabi 2
1 Geological Survey of Iran, Tehran, Iran
2 Department of Geology, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran
Abstract
        Millimetric, lens like and flat cake like monazite nodules are found within the Upper Triassic sedimentary rocks in Marvast in the south of Yazd. Monazite is one of the several rare earth phosphate minerals. Marvast monazite has a chemical formula of (Ce, La, Nd, Eu) PO4. The size of grains changes from 0.1 to 2mm and the grains with a diameter of 0.3-0.8 mm are often prevail. Monazite nodules are gray and greenish-gray in color and often formed in earthy aggregates. Monazite has a numerous inclusions of light minerals (such as quartz, calcite and …) and is enriched in Light and Middle Rare Earth Elements (LREE & MREE). Marvast monazite is completely different from igneous type Monazites. The nodules are formed during diagenesis of the Upper Triassic- Lower Jurassic sedimentary sequences and exposed in the shales. These nodules are potentially useful means for dating the diagenetic duration of the Upper Triassic sedimentary rocks.
Keywords
Monazite nodules
Shale
Upper Triassic
Rare Earth Elements (REE)
Diagenetic

Subjects

Alipour, M. ,2006- Mineralogy, geochemistry and economic assessment of rare earth elements in Marvast monazite, Yazd province. Ph.D. thesis, Dep. of Geol., Univ. of Shahid Beheshti, 188 pp.
Bezrukov, P.L., 1979- Phosphorites on the sea floor and their origin. Marine Geology,31,317-32.
Donnot, M., Guigues, J., Luizac, P., 1973- Un nouveau type de gisement d,europium: La monazite grise a europium en nodules dans les schistes paleozoiques de Bretagne. Mineralium Deposita, 8, 7-18.
Evans, J.A., Zalasiewicz, J.A., 1996- U-Pb,Pb-Pb and Sm-Nd dating of authigenic monazite: implications for the diagenetic evolution of the welsh Basin. Earth and Olanetary Science letters , 144 ,421-33.
Evans, J.A., Zalasiewicz, J.A., 2002- Dating diagenetic monazite in mudrocks: Constraining the Oil window? Journal of the Geological Society ,London 159,619-22.
Matzco, J.J. & Overstreet, W.C. ,1977- Black monazite from Taiwan.Proceeding Geological Society of China, 20, 16-35.
Milodowski, A.E., Zalasiewicz, J.A., 1991-Redistridution of rare earth elements during diagenesis of turbidite/ hemipelagite mudrock sequenes of Liandovery age from central wales, Geological Society , 57,101-24.
Overstreet, W.C. ,1971- Monazite from Taiwan. U.S. Geological Survey Open –File Report.
Overstreet, W.C.,1967- U.S. Geological Survey, Prof. Paper, 530, 327 pp.
Ramsey, J. G. ,1967- Folding and fracturing of rocks. McGraw Hill.
Read, D. & Cooper, D.C., & Mcarthur, J.M. ,1987- The composition and distribution of nodular monazite in the Lower Palaeozoic rocks of Great Britain. Mineralogical Mag. 51، 271-280.
Rosenblum, S. & Mosier, E.L. ,1983- Mineralogy and occurrence of europium-rich dark monazite.U.S.Geological Survey Professional paper, 1181.
Schieber, J., 1988- Redistribution of rare-Earth elements during diagenesis of carbonate rocks from the Mid-Proterozoic Newland Formation, Momtanna, USA.Chemical Geology , 69,111-126.
Scientific Quarterly Journal of Geosciences
Volume 16, Issue 62
Winter 2007, vol. 16, no. 62
Winter 2007
Pages 158-165