upper cretaceous in iran

between the lower and upper cretaceous there were some diastrophic movements, belonging to the austrain phase. these movements, which can be traced in many parts of north and central iran, caused extensive precenomanian erosion. even in southwest iran a wide spread discontinuity is reported at the base of the kazhdumi formation, which is possibly related to these movements. in the kopet - dagh area, also, in northeast iran, a discontinuity is reported at the top of the lower cretaceous. thus the cenomanian is transgressive on the albian or even older deposits and consists mainly of detritic, glauconitic sediments, which were deposited in a shallow environment. because of the orogenic or epeirogenic movemements in the time interval between cenomanian and sautonian (sub - hercynian) , turonian and coniacian sediments are missing in many parts of north, central and southwest iran. in the areas where sediments of this age are present, they consist mainly of pelagic, « oligostegina » limestone. the absence of these stages is caused probably rather by pre - santonian erosion, than by non - deposition, because pebbles of this age are occasionally found within younger sediments. in santonian time there was again a big marine transgression, and limestones and marls of this stage have been deposited in most parts of iran. in many parts of iran, where the post - cretaceous early tertiary erosion has not been deep enough, sediments of campanian and maestrichtian age occur. these sediments comprise either pelagic deposits or neritic, rudist: limestone. orogenic movements aesween lower and upper maestrichtian are reported from djandagh-biabank area. the formation of the « coloured melange » probably took place mainly in upper cretaceous time. the melange consists of a chaotic mixture of different sedimentary and ultrabasic rocks, which are confined to narrow and heavily thrusted zones in iran. at the end of the cretaceous and the beginning of the tertiary, strong orogenic movements of the laramide phase took place in north and central iran. in southwest iran and parts of the kopet _dagh ,these movements are mainly of epeirogenic type and caused only discontinuities between mesozoic and caenozoic sediments.