رﯾﺰرﺧﺴﺎره ﻫﺎ، ﻣﺤﯿﻂ رﺳﻮﺑﯽ و ﭼﯿﻨﻪ ﻧﮕﺎري ﺳﮑﺎﻧﺴﯽ ﺳﺎزﻧﺪ ﻗﻢ در ﻧﺎﺣﯿﻪ ﻣﺮق ﺟﻨﻮب ﻏﺮب ﮐﺎﺷﺎن

Microfacies, sedimentary environment, and sequence stratigraphy of the Qom Formation in the Maragh area (Southwest of Kashan)

ﺳﺎزﻧﺪ ﻗﻢ در ﻧﺎﺣﯿﻪ ﻣﺮق و در 20 ﮐﯿﻠﻮﻣﺘﺮي ﺟﻨﻮب ﻏﺮب ﮐﺎﺷﺎن ﺑﺎ ﺿﺨﺎﻣﺖ 216 ﻣﺘﺮ ﺷﺎﻣﻞ )ﺑﺨﺶ ﻗﺎﺋﺪه اي داراي واﺣﺪ ﻫﺎي ﺗﻮﻓﯽ(، ﺳﻨﮓ آﻫﮏ و ﺷﯿﻞ ﻣﯽ ﺑﺎﺷﺪ ﮐﻪ ﺑﻪ ﺻﻮرت ﻧﺎﭘﯿﻮﺳﺘﻪ ﺑﺮ روي ﺳﻨﮓ آﺗﺸﻔﺸﺎﻧﯽ اﺋﻮﺳﻦ و ﺑﻪ ﻃﻮر ﻧﺎﭘﯿﻮﺳﺘﻪ در زﯾﺮ ﺳﺎزﻧﺪ ﻗﺮﻣﺰ ﺑﺎﻻﯾﯽ ﻗﺮار دارد. ﺑﺮاﺳﺎس آﻟﻮﮐﻢ ﻫﺎي اﺻﻠﯽ و وﯾﮋﮔﯽ ﻫﺎي رﺳﻮﺑﯽ ﻧﻪ رﯾﺰ رﺧﺴﺎره ﮐﺮﺑﻨﺎﺗﻪ و ﯾﮏ رﺧﺴﺎره آواري ﺷﻨﺎﺳﺎﯾﯽ ﮔﺮدﯾﺪ. اﯾﻦ رﯾﺰ رﺧﺴﺎره ﻫﺎ ي ﮐﺮﺑﻨﺎﺗﻪ و رﺧﺴﺎره آوري در ﭘﻠﺖ ﻓﺮﻣﯽ از ﻧﻮع ﺷﻠﻒ ﺑﺎز رﺳﻮب ﮔﺬاري ﮐﺮده اﻧﺪ. اﯾﻦ ﭘﻠﺖ ﻓﺮم را ﻣﯽ ﺗﻮان ﺑﻪ ﺳﻪ ﻣﺤﯿﻂ ﺷﻠﻒ داﺧﻠﯽ )ﻻﮔﻮن ﻣﺤﺼﻮر و ﻧﯿﻤﻪ ﻣﺤﺼﻮر(، ﺷﻠﻒ ﻣﯿﺎﻧﯽ و ﺷﻠﻒ ﺧﺎرﺟﯽ ﺗﻘﺴﯿﻢ ﮐﺮد. ﺑﺮاﺳﺎس ﺗﻮزﯾﻊ ﻋﻤﻮدي رﯾﺰ رﺧﺴﺎره ﻫﺎ ﺳﻪ ﺳﮑﺎﻧﺲ رﺳﻮﺑﯽ ﮐﺎﻣﻞ درﺟﻪ 3 و ﯾﮏ ﺳﮑﺎﻧﺲ ﻧﺎﻗﺺ رﺳﻮﺑﯽ ﺗﺸﺨﯿﺺ داده ﺷﺪ.

The Qom Formation is located at the Maragh area (20 kilometers southwest of Kashan). The formation with 216 m thickness contains shale, tuff units in the lower section of the studied sequence, and limestones. Volcanic rocks unconformably are covered by the Qom Formation. The upper boundary of the Qom Formation with the Upper Red Formation is also unconformable. Nine microfacies and one terrigenous facies were identified based on the main components and sedimentological features. These microfacies and terrigenous facies were deposited on an open-shelf carbonate platform. Three environments were recognized in this carbonate platform. These environments include the inner shelf (restricted and semi-restricted lagoon), middle shelf, and outer shelf. In addition, three third-order and one incomplete depositional sequences were identified based on the vertical distribution of microfacies.