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543 CONODONT BIOSTRATIGRAPHY OF PERMIAN-TRIASSIC BOUNDARY DEPOSITS IN KOH-E-CHAH KALAND, NORTH OF ABADEH, IRAN PEYMAN SHOOSHTARIZADEH 1 AND MEHDI YAZDI 2 1 Islamic Azad University, Science and Research Branch, Tehran, Iran, email: [email protected]; 2 Faculty of Geoscience, University of Esfahan, Esfahan, Iran, email: [email protected] Abstract—The Koh-e chah kaland section is located 35 km north of Abadeh; 103 meters of this Upper Permian to Lower Triassic section were studied. This section consists of three lithologic units: the Upper Permian Unit 6 consisting of medium-bedded dolomitic limestone, the Upper Permian Unit 7 consisting of thin-bedded limestone, and the Lower Triassic unit, a gray, thin-bedded limestone. Systematic sampling and study on its conodonts led to the identification of 9 genera, 22 species and 9 conodont biozones: the lower Dzhulfian Clarkina leveni Zone of Unit 6, the Upper Dzhufian Clarkina transcaucasica Zone, Clarkina orientalis Zone and Clarkina longicuspidata Zone, the basal Changhsingian Clarkina hambastensis zone, the Clarkina bachmanni Zone (lower part of upper Changsingian), the upper Changhsingian Clarkina changxigensis Zone (all Unit 7), the Gangetian Hindeodus parvus Zone and Isarcicella isarcica Zone (Unit a). The Permian-Triassic boundary is characterized by the first appearance of Hindeodus parvus in sample K28. One of the Clarkina species is especially important because of its similarity to C. dukouensis, but younger than C. dukouensis. Also important is the first evidence of rare specimens of Clarkina abadehensis within the C. changxingensis-C. deflecta Zone, whereas in Iran and in Transcaucasia C. iranica begins only two conodont zones higher, in the C. iranica Zone. Therefore, C. iranica cannot be a synonym of C. abadehenis. Another important species is Mesogondolella n. sp., the successor of M. britannica Kozur, which characterizes the basal Zechstein of northwestern Europe. As Mesogondolella n. sp. occurs in the C. transcaucasica Zone, the base of the Zechstein must be older than the late Dzhulfian C. transcaucasica Zone. INTRODUCTION The newly discovered Koh-e-Chah Kaland section, described here, is situated 35 km north of Abadeh (Fig.1). The coordinates of the section are N31°33' and E52°26', and the altitude of this section is 2105 meters. This locality is well exposed and has only poor vegetation. This section belongs to the Sanandaj-Sirjan belt. PREVIOUS STUDIES Abadeh and areas to the southwest were investigated by British Petroleum Company in 1963. Taraz (1969, 1971) studied the Permian and Triassic boundary sequences in the Abadeh region. An Iranian-Japa- nese research group (1981) also conducted research on the area. Con- odonts from around the Permian-Triassic boundary of Iran (Kuh-e-Ali Bashi, Jolfa, northwest Iran) were first studied by Teichert et al. (1973). The results of comprehensive studies of Upper Permian and Lower Triassic conodonts were published in several papers, e.g., Kozur et al. (1975), Kozur and Mostler (1976), Kozur (1998, 2004a, 2005a, b, 2007), Kozur and Bachmann (2005). Kozur (2004a, 2005a) developed a de- tailed new Upper Permian to basal Triassic conodont zonation for the Tethys on the basis of conodonts from Iran, which can also be applied to South China and even to Greenland, in part. Korte and Kozur (2005) investigated stable isotopes and conodonts from the Upper Permian and basal Triassic of Abadeh, Jolfa and Shahreza. Kozur (2004b) and Szurlies and Kozur (2004) studied conodonts and magnetostratigraphy in the uppermost Permian and basal Triassic of Jolfa and discovered that there is no short reversal at the Permian-Triassic boundary. Heidari et al. (2000) investigated the geochemistry of Permian and Triassic strata in the Abadeh area. Golshani (2000) investigated the Upper Permian belt of Abadeh - Jolfa and compared it with southern China. Yazdi and Shirani (2002) studied the Permian-Triassic conodonts in the Hambast section and the Syed-Ali Akbar and Chahreseh sections. Ghaedi et al. (2008) studied the Permian-Triassic Boundary in the Benarizeh area (Koh-e- chah kaland). DISCUSSION The conodont content, biozonation and dating of this section are given in Table 1. One of the Clarkina species is especially important because it is very similar to C. dukouensis (lower Dzhulfian) (Fig. 2), but much younger (upper C. orientalis Zone, upper Dzhulfian). Previously, Mei found C. dukouensis in the upper Dzhulfian of section 4 of Teichert et al (1973; H. Kozur, personal commun., 2011) in Jolfa. He assigned this form to the lower Wuchiapingian C. dukouensis Zone, but the base of section 4 begins with reddish upper Dzhulfian beds of the C. transcaucasica and C. orientalis zones, whereas the lower Dzhulfian in Iran and Transcaucasia consists everywhere of gray and black sedi- ments. Important also is the first evidence of rare specimens of Clarkina abadehensis within the C. changxingensis-C. deflecta Zone, whereas C. FIGURE 1. Location of the investigated section and geological map of the investigated area 1:100000 (Hamzepour et al., 1998). Tanner, L.H., Spielmann, J.A. and Lucas, S.G., eds., 2013, The Triassic System. New Mexico Museum of Natural History and Science, Bulletin 61.
Transcript of 41-Shooshtarizadeh and Yazdi (P-T Iran).p65
543CONODONT BIOSTRATIGRAPHY OF PERMIAN-TRIASSIC
BOUNDARY DEPOSITS IN KOH-E-CHAH KALAND, NORTH OF ABADEH, IRAN
PEYMAN SHOOSHTARIZADEH1 AND MEHDI YAZDI2
1 Islamic Azad University, Science and Research Branch, Tehran, Iran, email: [email protected];2 Faculty of Geoscience, University of Esfahan, Esfahan, Iran, email: [email protected]
Abstract—The Koh-e chah kaland section is located 35 km north of Abadeh; 103 meters of this Upper Permian toLower Triassic section were studied. This section consists of three lithologic units: the Upper Permian Unit 6consisting of medium-bedded dolomitic limestone, the Upper Permian Unit 7 consisting of thin-bedded limestone,and the Lower Triassic unit, a gray, thin-bedded limestone. Systematic sampling and study on its conodonts led tothe identification of 9 genera, 22 species and 9 conodont biozones: the lower Dzhulfian Clarkina leveni Zone ofUnit 6, the Upper Dzhufian Clarkina transcaucasica Zone, Clarkina orientalis Zone and Clarkina longicuspidataZone, the basal Changhsingian Clarkina hambastensis zone, the Clarkina bachmanni Zone (lower part of upperChangsingian), the upper Changhsingian Clarkina changxigensis Zone (all Unit 7), the Gangetian Hindeodusparvus Zone and Isarcicella isarcica Zone (Unit a). The Permian-Triassic boundary is characterized by the firstappearance of Hindeodus parvus in sample K28. One of the Clarkina species is especially important because ofits similarity to C. dukouensis, but younger than C. dukouensis. Also important is the first evidence of rarespecimens of Clarkina abadehensis within the C. changxingensis-C. deflecta Zone, whereas in Iran and inTranscaucasia C. iranica begins only two conodont zones higher, in the C. iranica Zone. Therefore, C. iranicacannot be a synonym of C. abadehenis. Another important species is Mesogondolella n. sp., the successor of M.britannica Kozur, which characterizes the basal Zechstein of northwestern Europe. As Mesogondolella n. sp.occurs in the C. transcaucasica Zone, the base of the Zechstein must be older than the late Dzhulfian C. transcaucasicaZone.
INTRODUCTION
The newly discovered Koh-e-Chah Kaland section, described here,is situated 35 km north of Abadeh (Fig.1). The coordinates of the sectionare N31°33' and E52°26', and the altitude of this section is 2105 meters.This locality is well exposed and has only poor vegetation. This sectionbelongs to the Sanandaj-Sirjan belt.
PREVIOUS STUDIES
Abadeh and areas to the southwest were investigated by BritishPetroleum Company in 1963. Taraz (1969, 1971) studied the Permianand Triassic boundary sequences in the Abadeh region. An Iranian-Japa-nese research group (1981) also conducted research on the area. Con-odonts from around the Permian-Triassic boundary of Iran (Kuh-e-AliBashi, Jolfa, northwest Iran) were first studied by Teichert et al. (1973).The results of comprehensive studies of Upper Permian and LowerTriassic conodonts were published in several papers, e.g., Kozur et al.(1975), Kozur and Mostler (1976), Kozur (1998, 2004a, 2005a, b, 2007),Kozur and Bachmann (2005). Kozur (2004a, 2005a) developed a de-tailed new Upper Permian to basal Triassic conodont zonation for theTethys on the basis of conodonts from Iran, which can also be applied toSouth China and even to Greenland, in part. Korte and Kozur (2005)investigated stable isotopes and conodonts from the Upper Permian andbasal Triassic of Abadeh, Jolfa and Shahreza. Kozur (2004b) and Szurliesand Kozur (2004) studied conodonts and magnetostratigraphy in theuppermost Permian and basal Triassic of Jolfa and discovered that thereis no short reversal at the Permian-Triassic boundary. Heidari et al.(2000) investigated the geochemistry of Permian and Triassic strata inthe Abadeh area. Golshani (2000) investigated the Upper Permian belt ofAbadeh - Jolfa and compared it with southern China. Yazdi and Shirani(2002) studied the Permian-Triassic conodonts in the Hambast sectionand the Syed-Ali Akbar and Chahreseh sections. Ghaedi et al. (2008)studied the Permian-Triassic Boundary in the Benarizeh area (Koh-e-chah kaland).
DISCUSSION
The conodont content, biozonation and dating of this section aregiven in Table 1. One of the Clarkina species is especially importantbecause it is very similar to C. dukouensis (lower Dzhulfian) (Fig. 2), butmuch younger (upper C. orientalis Zone, upper Dzhulfian). Previously,Mei found C. dukouensis in the upper Dzhulfian of section 4 of Teichertet al (1973; H. Kozur, personal commun., 2011) in Jolfa. He assignedthis form to the lower Wuchiapingian C. dukouensis Zone, but the baseof section 4 begins with reddish upper Dzhulfian beds of the C.transcaucasica and C. orientalis zones, whereas the lower Dzhulfian inIran and Transcaucasia consists everywhere of gray and black sedi-ments. Important also is the first evidence of rare specimens of Clarkinaabadehensis within the C. changxingensis-C. deflecta Zone, whereas C.
FIGURE 1. Location of the investigated section and geological map of theinvestigated area 1:100000 (Hamzepour et al., 1998).
Tanner, L.H., Spielmann, J.A. and Lucas, S.G., eds., 2013, The Triassic System. New Mexico Museum of Natural History and Science, Bulletin 61.
544TABLE 1. Lithology, microfacies, conodont content, biozones and dating of the investigated section.
545TABLE 1. Continued. Lithology, microfacies, conodont content, biozones and dating of the investigated section.
546TABLE 1. Continued. Lithology, microfacies, conodont content, biozones and dating of the investigated section.
547TABLE 1. Continued. Lithology, microfacies, conodont content, biozones and dating of the investigated section.
548
FIGURE 2. Clarkina sp., samplek4, x 150.
TABLE 1. Continued. Lithology, microfacies, conodont content, biozones and dating of the investigated section.
iranica begins in Iran and in Transcaucasia only two conodont zoneshigher, in the C. iranica Zone. Therefore, C. iranica cannot be a syn-onym of C. abadehensis. Shen and Mei (2010) have mentioned that C.iranica is a synonym of C. abadehensis, but C. abadehensis occursmuch earlier. Another important species is Mesogondolella n. sp., thesuccessor of M. britannica Kozur, which characterizes the basal Zechsteinof northwestern Europe. As Mesogondolella n. sp. occurs in the C.transcaucasica Zone, the base of the Zechstein must be older than thelate Dzhulfian C. transcaucasica Zone.
CONCLUSIONS
The Koh-e chah kaland section is composed of three lithologicunits (Fig. 3): Unit 6 consists of medium-bedded dolomitic-calcitic lime-stone (lower Dzhulfian); Unit 7 is red, thin-bedded limestone (upperDzhulfian-Dorashamian); Unit a consists of gray, thin-bedded limestone(Lower Triassic). We found nine conodont genera and 22 species andidentify nine conodont biozones (Table 2). The Clarkina leveni Zonebelongs to the lower Dzhulfian (Unit 6), the Clarkina transcaucasica,Clarkina orientalis and Clarkina longicuspidata zones belong to theupper Dzhulfian, the Clarkina hambastensis Zone belongs to the basalChangsingian, the Clarkina bachmanni Zone belongs to the lower part ofupper Changsingian, the Clarkina changxingensis Zone indicates theupper Changsingian (all Unit 7), the Hindeodus parvus and Isarcicellaisarcica zones of Unit a indicate the Gangetian. The boundary betweenPermian and Triassic is characterized by the first appearance of Hindeodusparvus in sample K28. One of the Clarkina species is especially impor-tant because it is very similar to C. dukouensis (lower Dzhulfian) (Fig.2), but was found in much younger beds (upper C. orientalis Zone,
549
FIGURE 3. Stratigraphic column of the investigated section.
550
FIGURE 3. Continued. Stratigraphic column of the investigated section.
551
REFERENCES
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Ghaedi, M., Mosavi, M. and Yazdi, M., 2008, Scrutiny and biozonation ofPermiam-Triassic boundary in Benarizeh area, north of Abadeh: 2ndSymposium of Iranian Paleontological Society, 27-29 May 2008, Is-lamic Azad University of Khorasgan, p. 93-96.
Golshani, F., 2000, The Upper Permian in the Abadeh-Julfa Belt of Iran andthe Guadalupian-Lopingian Boundary: Permophiles, v. 37, p. 11.
Gullo, M. and Kozur, H., 1992, Conodonts from the pelagic deep-waterPermian of central western Sicily (Italy): Neues Jahrbuch fuer Geologieund Palaeontologie Abhandlungen, v. 184, p. 203-234.
Hamzepour, B. and Nazari, H.M., 1998, Geology report of Izadkhast (geo-logical map): Geology Survey of Iran, scale 1:100,000.
Heidari, E., Hassanzadeh, J. and Wade, W.J., 2000, Geochemistry of centralTethyan Upper Permian and Lower Triassic strata, Abadeh region, Iran:
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sic System in Abedeh Region, Central Iran: Memoirs of the Faculty ofScience, Kyoto University, Series of Geology and Mineralogy, v. 2, p.61-133.
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Kozur, H.W., 2004a, Pelagic uppermost Permian and Permian-Triassicboundary conodonts of Iran. Part 1: Taxonomy: Hallesches JahrbuchGeowissenschaft, v. 18, p. 39-68.
Kozur, H.W., 2004b, The age of the palaeomagnetic reversal around thePermian-Triassic boundary: Permophiles, no. 43, p. 25-31.
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upper Dzhulfian). Important also is the first evidence of rare specimensof Clarkina abadehensis within the C. changxingensis-C. deflecta Zone,whereas C. iranica first occurs in Iran and in Transcaucasia only twoconodont zones higher, in the C. iranica Zone. Therefore, C. iranicacannot be a synonym of C. abadehenis. Another important species isMesogondolella n. sp., the successor of M. britannica Kozur, which
characterizes the basal Zechstein of northwest Europe. As Mesogondolellan. sp. occurs in the C. transcaucasica Zone, the base of the Zechsteinmust be older than the late Dzhulfian C. transcaucasia Zone.
ACKNOWLEDGMENTS
We gratefully acknowledge Professor Heinz Kozur for his valu-able comments.
TABLE 2. Conodont distribution in the investigated section.
552tion of the conodont faunas: Hallesches Jahrbuch Geowissenschaft, B, v.19, p. 49-86.
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Kozur, H.W., 2007, Biostratigraphy and event stratigraphy in Iran aroundthe Permian–Triassic boundary (PTB): Implications for the causes ofthe PTB biotic crisis; in, Yin, H., Warrington, G. and Xie, S., eds.,Environmental and biotic changes during the Palaeozoic-Mesozoic tran-sition: Global and Planetary Change, Special Issue 55, p. 155-176.
Kozur, H.W. and Bachmann, G.H., 2005, Marine biostratigraphy and eventstratigraphy around the Permian-Triassic boundary (PTB) in Iran andits correlation with the continental biostratigraphy and event stratigra-phy in the Germanic Basin: New Mexico Museum of Natural History andScience, Bulletin 30, p. 154-158.
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Kozur, H., Mostler, H. and Rahimi-yazd, A., 1975, Beiträge zurMikropaleontologie permotriadischer Schichtfolgen, Teil II, NeueConodonten aus dem Oberperm und der basalen Trias von Nord- undZentraliran: Geologisch Palaeontologische Mitteilungen-Innsbruck, v.5, p. 1-23.
Mei, S.L., Zhang, K. and Wardlaw, B.R., 1998, A refined succession ofChanghsingian and Griesbachian neogondolellid conodonts from Meishansection, candidate for the global stratotype section and point of thePermian-Triassic boundary: Palaeogeography, Palaeoclimatology,Palaeoecology, v. 143, p. 213-226.
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553
PLATE CAPTIONSPLATE 1. 1, Clarkina leveni Kozur, Mostler, Pjatakova, 1975 - sample K1 -x 220. 2, Clarkina cf. liangshanensis,Wang Zhihao 1978 - sample K2 - x 260. 3, Mesogondolella n. sp. - sample K2-x 300. 4, Clarkina transcaucasicaGullo & Kozur 1992 - sample K2-x 430. 5, Clarkina guangyuanensis Dai & Zhang 1989 - sample K2-x 280. 6,Mesogondolella sp. - sample K2-x 250. 7, Clarkina orientalis Barskov & Koroleva 1970 - sample K4 - x 200. 8,Iranognathus movschovitschi (Kozur & Pjatakova) sample K4 - x 400. 9, Clarkina itálica Kozur 1992 - sampleK4 - x 340. 10, Clarkina inflecta Mei, Zhang & Wardlaw 1998 - sample K4 - x 230. 11, Ramiform element ofClarkina - broken M element -sample K4- x 280. 12, Ramiform element of Clarkina - posterior bar of Sa element- sample K4- x 330. 13, Ramiform element of Clarkina - broken anterior part of Pb element sample K4- x 200. 14,Clarkina longicuspidata Mei, Zhang and Wardlaw 1998 - sample K5- x 240. 15, Clarkina demicornis Mei &Wardlaw, 1994 - sample K4- x 200. 16, Clarkina n. sp. - sample K5- x 270. 17, Clarkina bizarrensis Mei &Wardlaw, 1994 - sample K7- x 190. 18, Clarkina hambastensis Kozur, 2005 - sample K7- x 230.
PLATE 2. 19, Clarkina inflecta Mei, Zhang & Wardlaw, 1998 - sample K13- x 150. 20, Ramiform element ofHindeodus (Sb ? element) sample K17- x 150. 21, Sa element of Hindeodus sample K17- x 150. 22, Hindeodusjulfensis Sweet, 1973 - sample K17- x 140. 23, Hindeodus typicalis Sweet, 1973 - sample K22- x 350. 24,Transitional form from Clarkina hambastensis Kozur,1998 to Clarkina wangi Dai & Zhang, 1987- sample K18 - x350. 25, Clarkina bachmanni Kozur - sample K24- x 350. 26, Clarkina deflecta Wang & Wang, 1981- sampleK25- x 350. 27, Clarkina abadehensis Kozur, 2004 - sample K25- x 350. 28, Clarkina changxingensis Wang &Wang, 1989 - sample K25- x 350. 29, Clarkina parasubcarinata Mei, Zhang & Wadlaw, 1998 - sample K25- x350. 30, Hindeodus parvus Kozur & Pjatakova, 1976 - sample K28- x 350. 31, Sc element of advanced Hindeodus- sample K29- x 350. 32, Ellisonia sp., Sa element - sample K35- x 360. 33, Isarcicella staeschei Dai & Zhang1989 - sample K30- x 290. 34, Hadrodontina sp., Pa element - sample K33- x 570. 35, Hadrodontina sp., Melement - sample K38- x 190. 36, Ellisonia sp. Sa element - sample K38- x 320. 37, Cornudina sp., Pa element -sample K39 - x 280. 38, Cornudina? sp., M element - sample K42- x 290. 39, M element of Ellisonia? - sampleK43- x 300.
554PLATE 1
555PLATE 2
