Microfacies, Depositional Sedimentary Environment and Primary Carbonates Mineralogy of the Cretaceous Succession in Bashm Mountain, South of Centeral Alborz

Abstract

Cretaceous succession of Bashm mountain, located in south of Centeral Alborz, is a part of Alpine-Himalayan orogeny belt. In this paper, Cretaceous at the age of Albian-Turonian which consists well-beded dolomite and limestone, cherty limestone and massive limestone and which have become host rock for Lead and Zinc deposits is studied. 6 profiles of this Cretaceous were selected from Reza-Abad, Heydar-Abad and Reza-Barak abandoned mines, and Bozmolla occurrence. Their outcrops thickness varies between 290-540 m. Petrography of the studies area revealed that the sediments are consist of 15 carbonate facies. Most likely this facies have been deposited in inner, outer and mid ramp. Beside this, tectonic characteristics of forland basins which is dominant in Cretaceous time for this area, has revealed the presence of carbonate ramp. The most important diagenetic processes in these studied facies were biogenic processes, compaction, dissolution, cementation, neomorphism, dolomitization, dedolomitization and silicification. The most important mineralization processes related to porosities were found in intergranular, intercrystalline (in dolomite), joints, faults and karsts. Formation TD-ICP chemical analysis of Ca, Mg, Sr, Mn, Zn, Pb elements and INAA chemical analysis of Fe, Na elements for 6 samples of Cretaceous showed decreasing in Sr and Na and increasing in Fe and Mn elements. These result may suggest, the comparison of aragonites of warm areas and calcites of recent temperate during diagenes process. Comparing values of these elements with warm water Ordovician Gordon Limestone (Tasmania) and Mozduran carbonates (Upper Jurassic) showed mineralogy similarity between shallow carbonates of studied area and those which is mostly observed as an indicator of mineralogy of primary aragonite.

Keywords


]1[ نبوی، م. ح.، "زمین‌شناسی ناحیه سمنان"، چهار گوش شماره6661 سری 000/1:100 سازمان زمین شناسی و اکتشافات معدنی کشور (1366).

]2[ زحمتکش ق.، "میکرواستراتیگرافی رسوبات کرتاسه فوقانی شمال سمنان (منطقه دربند)"، پایان نامه کارشناسی ارشد، دانشگاه شهید بهشتی، دانشکده علوم زمین، (1375) ص 182.

[3] Flügel E., "Microfacies analysis of limestone", Springer-Verlag, Berlin (1982) 633.

[4] Flügel E., "Microfacies of carbonate rocks, analysis interpretation and application", Springer-Verlag, Berlin (2004) 976.

[5] Wilson J.L., "Carbonate facies in geological history", Springer-Verlag, New York (1975) 471.

[6] Bosence D., "A genetic classification of carbonate platforms based on their basinal and tectonic settings in the Cenozoic", Sed. Geol. 175 (2005) 49-72

]7[ فیض نیا س.، "سنگهای رسوبی کربناته"، انتشارات آستان قدس رضوی، (1377) ص 304 .

[8] Longman M.W., "Carbonate diagenetic textures from nearsurface diagenetic environments", AAPG 64 (1980) 461-487.

[9] Adabi M.H., Rao, C.P., "Petrographic and geochemical evidence for original aragonite mineralogy of Upper Jurassic carbonates (Mozduran Formation), Sarakhs area, Iran", Sed. Geol. 72 (1991) 253-267.

[10] Brand U., Veizer J., "Chemical diagenesis of a multicomponent carbonate system- 1: trace elements", J. Sed. Pet. 50 (1980) 1219-1236.

[11] Milliman J.D., "Recent sedimentary carbonates, I. marine carbonates", Springer-Verlag, Berlin (1974) 375.

[12] Rao C.P., "Geochemistry of temperate-water carbonates Tasmania, Australia", Mar. Geol. 71 (1986( 363-370.

[13] Rao C.P., "Petrography, trace elements and oxygen and carbon isotopes, Gordon Group carbonates (Ordovician), Floretine Valley, Tasmania, Australia", Sed. Geol. 66 (1990a) 83-97.

[14] Rao C.P., "Geochemical characteristics of cool-temperate carbonates, Tasmania, Australia", Carbonates and Evaporites 5 )1990b( 209-221.

[15] Rao C.P., "Geochemical differences between subpolar (Permian), temperate (Recent and Pleistocene) and tropical (Ordivician) carbonates, Tasmania, Australia", Carbonates and Evaporites 6 )1991( 83-106.

]16[ رحیمی ب.، "مطالعات ساختاری رشته کوه البرز در شمال دامغان"، پایان نامه دکتری، دانشگاه شهید بهشتی، دانشکده علوم زمین، (1381) ص 208.

]17[ آقا نباتی س. ع.، "زمین‌شناسی ایران"، سازمان زمین شناسی و اکتشافات معدنی کشور، (1383) ص 586.

[18] Steiger R., "Die Geologie der West-Firuzkuh-Area (Zentralelburz, Iran)", Mitteilung geologisches Institut, ETH-Zurich (1966) 145.

[19] Assereto R., "Geological Map of Upper Djadjerud and Lar Valleys (centrale Elburz, Iran) with Explanatory Notes" , Inst. Geol. Univ. Milano, ser G., pub 1 (1966) 232.

[20] Dellenbach J., "Contribution a l’etude geologique la la region situee a l’est de Teheran (Iran) "Fac. Sci. Univ. Strasbourg (France), (1964) 117.

[21] Dicson J.A.D., "A modified staining teqnique for carbonate in thin section", Nature 205 (1965) 207.

[22] Dunham R.J. "Classification of carbonate rocks according to depositional texture, in : W.E. Ham (ed.), Classification of carbonate rocks" , AAPG 1 (1962) 108-121.

[23] Wright V.R., "A revised classification of limestones", Sed. Geol. 76 (1992) 177-185.

[24] Chow N., James N. P., "Facies-specific, calcitic and bimineralic ooids from middle and upper Cambrian platform carbonates, Western Newfoundland, Canada", J. Sed. Pet. 57 (1987), 907-921.

]25[ خسرو تهرانی خ.، "شناخت رخسار‌ه‌های رسوبی در مقیاس میکروسکپی «میکروفاسیس‌ها»"، (1360) انتشارات دانشگاه تهران، ص 352.

[26] Grover JR. G., Read J.F., "Fenestral and associated vadose diagenetic fabrics of tidal flat carbonates, Middle Ordovician New Market Limestone, Southwestern Virginia", J. Sed. Pet. 48 (1978) 453-473.

[27] Pettijohn F.J., "Sedimentary rocks: 3rd edition", Harper & Row, New York (1975) 628 pp.

[28] Burchette T.P., Wright V.P., "Carbonate ramp depositional systems", Sed. Geol. 79 (1992) 3-57.

[29] Maliva R.G., Siever R., "Chertification histories of some Late Mesozoic and Middle Palaeozoic platform carbonates", Sedimentology 36 (1989) 907-926.

[30] Gates L.M., James N.P., Beauchamp B., "A glass ramp: shallow-water Permian spiculitic chert sedimentation, Sverdrup basin, Arctic Canada", J. Sed. Geol. 168 (2004) 125-147.

[31] Tucker M.E., "Sedimentary Petrology", BlackWells, Oxford (1991) 260.

]32[ بازرگانی گیلانی ک.، فرامرزی م.، "ژئومتری، پتروگرافی و ترکیب دولومیت کرتاسه شهمیرزاد، البرز مرکزی"، بیست و چهارمین گردهمایی علوم زمین (1384) ص 8.

[33] Rao C.P., "Cementation in cold-water bryozoan sand, Tasmania, Australia", Mar. geol., 40 (1981a) M25-M33.

[34] Rao C.P., "Critria for recognition of cold-water carbonate sedimentation: Berriedale Limestone (Lower Permian), Tasmania, Australia", J. Sediment. Petrol., 51 (1981b) 491-506.

[35] Bencini A., Turi A., "Mn distribution in the Mesozoic carbonate rocks from Lima Valley, Northern Apennines", Soc. Econ. Paleontologists and Mineralogists 44 (1974) 774-782.