Earliest skeletal fossils from Precambrian–Cambrian boundary strata, Elburz Mountains, Iran

Abstract

The lithological and biotic succession across the late Precambrian to early Cambrian interval is outlined for the Dalir and Valiabad successions of the Elburz Mountains of Iran. The Lower Dolomite Member contains an assemblage of phosphatic tubes and other poorly preserved remains. The succeeding Lower Shale Member bears macroscopic chuariamorphid algae. Early skeletal fossil diversity rises through the Middle Dolomite Member, with the successive appearance of Protohertzina anabarica, Cambrotubulus decurvatus and Anabarites trisulcatus, culminating near the top of the dolomites with the appearance of Purella sp., Maikhanella multa, Tiksitheca licis and circothecids. This succession is compared with lower to upper parts of the Nemakit-Daldyn Formation of Siberia. The overlying Upper Shale Member bears phosphatic beds at its base with allathecids and an uncoiled pelagiellid (lAldanella sp.) that suggest comparison with lower Tommotian strata and the Precambrian-Cambrian boundary phosphorite event of southern and central Asia. A rich assemblage of molluscs appears high in the Upper Shale Member, including the Latouchella korobkovi group and the Pelagiella lorenzi group. The succession is broadly homotaxial with those from the Siberian Platform and Mongolia and those platforms bordering Gondwana (India, Kazakhstan, South China).

Ichnostratigraphy of the Ediacaran-Cambrian boundary: new insights on lower Cambrian biozonations from the Soltanieh Formation of northern Iran

“…The biostratigraphy of the Soltanieh Formation is poorly known and largely based on shelly fossils (Hamdi et al, 1989;Tashayoee et al, 2012) with very little published on ichnostratigraphy (CiabeGhodsi et al, 2006;Tashayoee et al, 2012). Small shelly fossils reported from the Soltanieh Formation are comparable with skeletal assemblages recorded in China and northern Siberia (Hamdi et al, 1989), containing elements of A. trisulcatus-P. anabarica and W. crosbyi assemblage zones of Meishucunian Stage, and the Pelagiella subangulata Taxon Zone of Qiongzhusian Stage (Steiner et al, 2007).…”

Chronostratigraphic and palaeogeographic significance of an early Cambrian microfauna from the Heraultia Limestone, northern Montagne Noire, France

“…This biozone was formerly dated from the Atdabanian Esakova and Zhegallo, 1996) but Brasier et al (1996) suggest a Tommotian age for this biozone based on several lines of evidence. This position was further followed by Gubanov (2002) and Li et al (2011) (Hamdi et al, 1989).…”

“…Oelandiella nazarovi (Zhegallo in Esakova and Zhegallo, 1996) has a smooth internal mold and regularly ribbed external mold. (Hamdi et al, 1989); Bayan-Gol Formation, Tommotian (Anabarella plana Zone and Watsonella crosbyi Zone), Salaany-Gol, Orolgay-Gol, Bayan-Gol, Tayshir and Hevte Tsakhir Nuruu, Western Mongolia Esakova and Zhegallo, 1996). Siberia: Kessyusa Formation, Nemakit-Daldynian to Tommotian (Anabarella plana Zone and Watsonella crosbyi Zone) at various Olenek Uplift sections (Valkov, 1987;Khomenthovsky and Karlova, 1993;Knoll et al, 1995); Member IV of the UstYudoma Formation and Sunnagin Member of the Pestrotsvet Formation, Nemakit-Daldynian to Tommotian (Purella antiqua Zone to Watsonella crosbyi Zone) at Dzhanda (Khomentovsky and Karlova, 1989;1993); Sunnagin Member, Pestrotsvet Formation, Tommotian (Watsonella crosbyi Zone) at the Gonam River, Mount 1291.1 (Khomentovsky and Karlova, 1993); Pestrotsvet Formation, Tommotian (Watsonella crosbyi to Lapworthella bella zones), Nemnekey section between the Gonam and Nemnekey rivers (Khomentovsky and Karlova, 1993), Aldan River, middle reaches of the Lena River, Fomich River and Eriechka River near Nemakit-Daldyn River mouth, northwestern flanks of the Anabar Uplift Kruse et al, 1995) and Selinde River near Mar-Kyuyel (Missarzhevsky, 1989;Khomenthovsky and Karlova, 1993); Medvezh'ya Formation, Tommotian (Watsonella crosbyi to Lapworthella bella zones), Kotuj River, northwestern flanks of the Anabar Uplift (Vostokova, 1962;Rozanov et al, 1969;Missarzhevsky, 1989;Kouchinsky, 1999;Parkhaev, 2004); Yudoman Formation, Tommotian (Lapworthella tortuosa subzone of the Dokidocyathus regularis Zone), 7 km west of Ugino Village .…”

“…The SSFs were firstly considered as problematic metazoans although poriferan, mollusc, and hyolith affinities were proposed by Matthews and Missarzhevsky (1975). Numerous subsequent studies of early Cambrian SSFs have been conducted, mostly from the Siberian platform (Sokolov et al, 1974;Sokolov and Zhuravleva, 1983;Khomentovsky and Karlova, 1993) and Yangtze platforms (Qian, , 1978a(Qian, , 1978b(Qian, , 1989Yu, , 1987bJiang, , 1980bJiang, , 1984Yin et al, 1980;Luo et al, 1980Luo et al, , 1982Luo et al, , 1984Xing et al, 1984;Qian and Bengtson, 1989;Steiner et al, 2004;Parkhaev and Demidenko, 2010), but also from Mongolia Esakova and Zhegallo, 1996), Kazakhstan (Missarzhevsky and Mambetov, 1981), India (Azmi and Pancholi, 1983;Bhatt et al, 1985;Brasier and Singh, 1987), Pakistan (Mostler, 1980), Iran (Hamdi et al, 1989), and France (Kerber, 1988). This polyphyletic informal group characterises the widely distributed "Tommotian Fauna", named after the early Cambrian stage of the regional Siberian chart (equivalent to the upper part of the Terreneuvian; Spizharski et al, 1986;Landing et al, 2007).…”

Contributions of Professor Martin Brasier to the study of early life, stratigraphy and biogeochemistry

“…While at Hull, Martin had helped to set up and run a highly successful micropalaeontology MSc course and was well known for his work on forams and other microfossils (Brasier 2012;Gooday & Gregory 2016). At the same time, Martin had been exploring his interest in the Precambrian and Cambrian, publishing seminal papers on topics including: the pre-trilobite 'small shelly fossils' of Nuneaton (Brasier et al 1978), India (Brasier & Singh 1987) and Iran (Hamdi et al 1989); the interaction between the Cambrian transgression and palaeobiology (Brasier 1980;Lindsay et al 1996;Peters & Gains 2012); stable isotopic evidence for biosphere -geosphere linkages during the Cambrian explosion ; and the relationship between palaeo-levels of nutrients and phosphogenesis (Brasier 1990a, b;Shields 2016). All this research surrounded one of the hottest topics of the time: the choice of the Global Stratotype Section and Point (GSSP) for the PrecambrianCambrian boundary, which was resolved while he was Chairman of the Cambrian Sub-Commission for Stratigraphy Brasier 2009;Geyer & Landing 2016).…”