Coral Tax on Omy and Sed I Men Tary En Vi Ron Ment
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Annales Societatis Geologorum Poloniae (2012), vol. 82: 291–330. PRO LIFIC DE VEL OP MENT OF PACHYTHECALIINES IN LATE BARREMIAN, BULGARI A: CORAL TAXON OMY AND SED I MEN TARY EN VI RON MENT Bo gus³aw KO£ODZIEJ1, Marin IVANOV2 & Vyara IDAKIEVA2 1 Insti tute of Geolog i cal Science s, Jagiellonian Uni ver sity, ul. Oleandry 2a, 30-063 Kraków, Poland; e-mail: [email protected] 2 Depart ment of Ge ology, Pale on tol ogy and Fos sil Fuels , Sofi a Univer sity ‘St. Kliment Ohridski’, 15 Tzar Osvoboditel Bd., 1000 Sofi a, Bul garia; e-mail: [email protected] a.bg; [email protected] a.bg Ko³odziej, B., Ivanov, M. & Idakieva, V., 2012. Prolific de vel op ment of pachythecaliines in Late Barremian, Bul garia: coral tax on omy and sed i men tary en vi ron ment. Annales Societatis Geologorum Poloniae, 82: 291–330. Ab stract: Di ver si fied and abun dant cor als of the suborder Pachythecaliina (or der Hexanthiniaria) are de scribed from Upper Barremian, biostromal reefs of the Emen Forma tion, Lovech Urgonian Group, north cen tral Bul garia. The cor als are mostly of the phaceloid growth form and rep re sent 14 spe cies (six new), 12 gen era (three new), be long ing to five fami lies. Pachythecaliines oc cur with the small, monopleurid cy lin dri cal rudist Mathesia darderi. The rudists frequently are densely clus tered, occur between coral branches or are in contact with them. Other cor als, with the ex cep tion of the phaceloid Calamophylliopsis, and other rudists, are rare. Non-lam i nated microbialite crusts pro vided ad di tional, struc tural sup port for bioconstruction de vel op ment. Microbialites (auto- micrites) can be inter preted as a product of mi crobial activ ity, or al terna tively, as a re sult of carbon ate precip i ta - tion, brought about by non-liv ing or ganic sub strates (organomineralization s.s.). In addi tion to microbialites, me- ta zo ans are en crusted by heterotrophic skel e tal mi cro or gan isms, while photophilic and oligotrophic micro- encrusters, usu ally common in other coral-bear ing lime stones of the Emen For mation, are very rare. The sec tion at the Rusalya Quarry (NW of Veliko Tarnovo), about 42 m thick, pro vides the sed i mentary and en vi ron mental con - text for the reefal biostromes. The ver ti cal bi otic and sed i mentary suc ces sion display s a gen eral shallowing trend: from the outer car bon ate plat form with bioclastic lime stones con tain ing small boundstone patches (cor als, but not pachythecaliines, Lithocodium aggregatum), to the in ner plat form with rudist biostromes. The pachythecaliine- rich biostromes, 2.5 m thick, were de vel oped in a low-en ergy en vi ron ment, re ferred to the dis tal part of the rudist-domi nated area of the platform . The devel op ment of microbialites was fa cil i tated by a low sedi menta tion rate, and possi bly by in creased nu tri ent level. Only poorly di ver si fied and non-phaceloid pachythecaliines oc cur in other coral-rich lime stones and marls of the Urgonian complex in Bul garia. The as semblage de scribed is the most remark able, Early Cre ta ceous coral com munity worldwide, with regard to pachythecaliines. Phaceloid pachythe- caliines are only more common in the Up per Ju ras sic rocks, be ing par tic u larly di ver si fied in the Tithonian–Lower Berriasian Štramberk Lime stone (Czech Re pub lic) and its equiv a lent in the Pol ish Outer Carpathians. How ever, their sed i mentary con text dif fers from that de scribed for the cor als of the Emen For mation. Key words: cor als, tax on omy, car bon ate plat form, palaeo ec ol ogy, Cre ta ceous, Fore-Bal kan, Bul garia. Manu script re ceived 12 November 2012, ac cepted 20 December 2012 IN TRO DUC TION Pachythecaliina Eliášová, 1976 (= Amphiastraeina fied in the Scleractinia. How ever, be cause of their skel e tal Alloiteau, 1952) is an exti nct suborder (Late Trias sic –Late ar chi tec ture, es pe cially in the Late Tri as sic Zardinophylli- Cre taceous) that has fo cussed the atten tion of coral re - dae Montanaro Gallitelli, 1975 and the Juras sic –Cre taceous searchers in the con text of the ori gin of cor als from the or - Amphiastraeidae Ogilvie, 1897 – simi lar to the late Palaeo- der Scleractinia Bourne, 1900 in the Middle Trias sic , and zoic plerophyllines – some authors clas sifie d them direct ly their possi ble rela ti on ship to the or der Rugosa Milne-Ed- into the Rugosa (Koby, 1888; Ogilvie, 1897) or assum ed wards et Haime, 1851. Many pachythecaliines dis play “ar- their rugosan an ces try (Cuif, 1975, 1977, 1981, 2010; Mel- chaic”, skel e tal fea tures, which are unique among post-Pala- nikova and Roniewicz, 1976; Stolarski, 1996). Alternati- eozoic cor als. These cor als usu ally were or still are clas si- vely, pachythecaliines (in a narrow or broad meaning) were 292 B. KO£ODZIEJ ET AL. Fig. 1. Gen eral lo ca tion of study area on geo log i cal map (1: 500 000) (af ter Cheshitev et al., 1989; mod i fied and cor rected) with lo ca - tion of sam pling sites for cor als, rudists Mathesia darderi, as well as ammonites, used for lo cal biostratigraphy classi fied as the sep a rate or der Hexanthiniaria Montanaro GEO LOG I CAL SET TING AND MA TE RIAL Gallitelli, 1975 (Montanaro Gallitelli, 1975; Eliášová, 1976b, 1978; Roniewicz, 2008; Melnikova and Roniewicz, During the Barremian–Early Aptian several carbon ate 2012; Morycowa, 2012). plat forms exist ed on the northern, Tethyan margin, lo cated Phaceloid (branched, built of par allel coral lites, pseu- in the pres ent terri tory of Bul garia (Lovech Urgonian Group, docolonial) pachythecaliine cor als were mod er ately com - Vratsa Urgonian Group, Russe Form ati on). In particular, the mon in the Late Ju ras sic and lo cally di ver si fied tax o nom i- Lovech Urgonian Group in the cen tral Fore-Bal kan (north cally (Tithonian–Lower Berriasian Štramberk Limeston e), cen tral Bul garia) con tains di verse coral and rudist as sem- but were rare during the Creta ceous . The coral com mu ni- blages. This Urgonian com plex con sists of four terrigene- ties, dom i nated by di ver si fied, phaceloid pachythecaliines, ous and four carbon ate form ati ons (Figs 1, 2; Khrischev, re cently dis cov ered in the Up per Barremian lime stones of 1966; Nikolov, 1969; PeybernÀs et al., 1998; re view in the Emen Form ati on in north centra l Bulgari a (Ko³odziej et Minkovska et al., 2002; Nikolov et al., 2007). Coral com - al., 2009, 2011b), are unique among post-Ju rassic coral co- mu niti es – from level-bot tom assem blages to coral-micro- mmunities. The aims of this paper are the taxo nomic and bialite reefs – rep re sent both clear- and tur bid-wa ter en vi - palaeoecological anal ysis of these cor als, as well as the in - ron ments. Up to now, more than 100 coral spe cies were de- ter pre ta tion of the sed i men tary en vi ron ment of pachytheca- scribed, mainly from soft marls, but were ana lysed more ra- liine-rich bioconstructions in the Emen Form ati on. rely with re spect to their palaeoec ol ogy (e.g., Toula, 1889; PACHYTHECALIINES IN LATE BARREMIAN, BUL GARIA 293 Fig. 2. Lithostratigraphic scheme of study area and strati graphic po sition of sam pling sites Zlatarski, 1967, 1968a, b, c; Tchechmedjieva, 2001; Ida- cinit y, re ferred to below as Veliko Tarnovo, col lected by the kieva, 2002, 2003, 2007, 2008; Idakieva and Ivanov, 2002; late Prof. Ryszard Marcinowski (Warsaw Univer sit y), but Ko³odziej et al., 2007; see also Ilcheva and Motchurova- the ex act col lect ing lo ca tion is un known. Dekova, 2011). Diver si fie d coral assem blages occur also in The Emen Form ati on, sit u ated in the middle part of the pure or marly limestone s (Ko³odziej et al., 2011c). How- Lovech Urgonian Group, was estab li shed by Khrischev ever, apart from the pres ent pa per, they have not yet been (1966) in the region of Emen vil lage, about 20 km NW of the sub ject of de tailed, tax o nomic pub li ca tions. Veliko Tarnovo (Fig. 1). The best out crops of this form ati on The pachythecaliine cor als studied oc cur in limestone s occur betwee n the Osum and Jantra Rivers, and the type of the Emen Form ati on in the Veliko Tarnovo (also transli t- sec tion is lo cated at the Al ex an der Stambolijski Dam near to erate d as Veliko Turnovo, Veliko Trnovo, Veliko Tyrnovo) Gorsko Kosovo village , 40 km west of Veliko Tarnovo. Pre- area. They were col lected mainly in quar ries at Rusalya and vious stud ies showed that the limestone s of the Emen Form a- Vishovgrad. Sam pling was supple m ented in the Zarapovo- tion were de posit ed on a shallow-wa ter, car bon ate plat form, ecotrack and Hotnitsa-ecotrack, re ferred to be low as Zara- largely in an open la goon.