رخساره‌ها، محیط رسوبی و کانی‌شناسی کربناتهای اولیه توالی کرتاسه کوه بشم، جنوب البرز مرکزی

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.