CONODONT BIOSTRATIGRAPHY FROM CARBONIFEROUS AND PERMIAN SUCCESSIONS OF PAMIR, CENTRAL IRAN AND TUNISIA

Abstract During my PhD thesis I have studied several conodont faunas from Upper Carboniferous and Permian from: Carboniferous and Permian sections from Central Iran, Permian sections from Tunisia and Permian/ Lower Triassic sections from North and South- East Pamir (Tajikistan). I have studied 43 samples from Central Iran (Bagh-e-Vang, Zaladou, Anarak 3 and Rahdar sections ), 86 samples from SE Pamir, Tajikistan ( Kurteke, Kuristyk, Kutal II and Kubergandy type sections), 30 samples for N Pamir, Tajikistan (Gundara and Bolorian Stratotype sections) and 31 samples from Tunisia (Halq Jemel, Merbah el Oussif, Tebaga Sensu Strictu sections) in order to make a taxonomycal revision of Upper Carboniferous and Permian conodont, to define the ages of these sections and to correlate the conodonts age to the fusulinids ones. During Upper Carboniferous and Permian, in fact, a strong provincialism, due to particular paleogeographic and paleoclimatic conditions, develops interesting both flora and fauna and resulting in many problems in biostratigraphic correlation. The main aims of this thesis is the correlation between the International Stratigraphic Timescale, based on conodonts, and the Tethyan timescale, a local biostratigraphic scale based on fusulinids. These studied areas have been choosen for their key- position during Upper Carboniferous and Permian assemblage of the supercontinent Pangea: during those periods Central Iran, SE and N Pamir belongs to Cimmerian Terranes while Tunisia was located in the Tethyan gulf. Sections located in the Cimmerian Terranes, during Lower and Middle Permian, were located in a mixed fauna area between cool and warm paleobiopriovinces, while Tunisia was located in a warm water province. In order to reconstruct the evolution of these four areas during the displacement of Cimmerian Terranes throughout Upper Carboniferous and Permian Conodont data have been integrated with paleomagnetic, lithostratigraphic and biocronostratigraphic data from other fossil groups, particularly from fusulinids. Central Iran: the Upper Carboniferous and Permian of Tabas area have been studied. The most significant section is the section of Bagh-e-Vang that is very rich both in conodonts and fusulinids. The age of Bagh-e-Vang section ranges from early Sakmarian to Upper Wordian. It was observed that the increasing of Mesogondolella, a deep-water genus, specimens respect to Sweetognathus, a shallow- water genus, from base to the top of the section reflect a deepening trend. Bagh-e-Vang section is interested faults and in order to solve this problem a new section west of Bagh-e-Vang have been sampled and studied: the Shesht- Angosht section. Conodonts in Zaladou, Rahdar and Anarak 3 section are very rare but the presence of fusulinids allow a correlation between these areas. Tunisia: from the Permian outcrops of Djebel Tebaga de Medenine I have found a well preserved population of the species Sweetognathus iranicus hanzongensis in Halq Jemel section and few specimens of the same species in Tebaga Sensu Strictu section. Sweetognathus iranicus hanzongensis is a typical of shallow and warm water ad his presence is coherent with the paleoenvironmental reconstruction of the Djebel Tebaga area (Angiolini et al., 2008). The presence of both fusulinids and conodonts in sample HJ32 from Unit V (Halq- Jemel section, Djebel Tebaga de Medenine) point to a Wordian age for this Unit. N Pamir: conodont fauna from this area is not very abundant but the Bolorian Stratotype section yielded the species Sweetognathus iranicus hanzongensis and Sweetognathus modulatus that point to a Kungurian age for the lower part of this section. SE Pamir: four sections have been studied. They are very rich in conodonts: the presence of both conodonts and fusulinids make possible to correlate the Tethyan and International timescales in this area. The age of Kubergandy section, on basis of conodonts, ranges from Kungurian to Roadian and the correlation with fusulinids allow to identify a Bolorian to Kubergandian age for this formation. Conodonts from the Gan Formation ranges from Kungurian to Capitanian, while the age of the fusulinids ranges from Murgabian/Midian to early Dzhulfian. Plus, fusulinids from the top of Gan Formation in Kutal 2 section indicating a Wuchapingian age: so the age of the entire Formation, identified using both conodonts and fusulinids ranges from Kungurian to Wuchapingian. For the base of Kurteke Formation is Kungurian/early Roadian on the basis of conodonts and latest Kubergandian/ early Murgabian for fusulinids. Serrations is a morphological character of great importance for Permian conodonts: in fact Permian gondolellids contains both serrated and non- serrated forms and the base of Roadian and Guadalupian have been defined on the base of the First Appearance Datum (FAD) of the serrated species Jinogondolella nankingensis. but the Permian profound provincialism and the recognition of geographic clines throughout conodonts open many question on conodont taxonomy: almost all the specimens of Jinogondolella present in the studied fauna of SE Pamir does not shows serrations and few specimens shows some trace of this character. This is a very interesting data that support the hypothesis that serration are under ecological control, and have been discussed with Prof. C. M. Henderson during his visit in Milan and during a period of study in Canada, Alberta, at University of Calgary and with Prof. Shuzhong Shen of the Chinese Academy of Sciences during his visit at University of Milan.