Carboniferous calcareous algae and their associations in the San Emiliano and Lois-Ciguera Formations (Prov. León, NW Spain) L. Rácz Pie-issued 14-10-1964 Contents ABSTRACT 5 INTRODUCTION 7 CHAPTER I. GEOLOGICAL SETTING AND STRATIGRAPHY 9 Structural geology 9 Stratigraphy 10 Getino Formation 10 Sella Formation 12 Escapa Formation 13 San Emiliano Formation 14 Lithostratigraphic aspects 14 Biostratigraphicaspects 16 Lois-CigueraFormation 19 Lithostratigraphic aspects 19 Biostratigraphicaspects 22 CHAPTER II. LIMESTONE FACIES 26 Introduction 26 Limestone facies typeA 26 Lithologic characteristics 26 Biologicalcharacteristics 26 Limestone facies typeB 27 Lithologiccharacteristics 27 Biologicalcharacteristics 27 Limestone facies typeAB 29 Summary 30 CHAPTER III. PALEOECOLOGICAL CONSIDERATIONS 31 Introduction and terminology 31 Rhythmic stratification ofthe sediments 31 2 Contents Introduction 31 Description ofthe layer types 31 Limestone facies typeA 36 Limestone facies typeB 36 Cyclical sedimentation 36 Bathymetric considerations 38 Introduction 38 Bathymetric consideration offlora and fauna 40 The concept of"phase" and itsbathymetric application 43 The classification ofthe limestones, according to their origin and manneroforganism accumulation 45 Fragmental limestones 46 Skeletal limestones 46 The classification ofthe limestones, according to their origin and maturity 47 Qualitative and quantitativeanalysis ofthe rock building organisms 51 Introduction 51 Method 51 Fossil associations ofthe most important rock building organisms 51 Calcareous algae 51 Gastropoda 51 Brachiopoda 52 Foraminifera 52 Coelentcrata 52 Echinodermata 52 Summary 53 Change ofthe biofraction within amember 53 Analysis ofthe limestones, according to their composition and en- vironnement 57 Mixedbeds 57 Beds ofcalcareous algae 58 Theposition ofthe calcareous algaein a lithologicalunit .... 58 San Emiliano Formation 58 Lois-CigueraFormation 60 Algal beds in aminor cycle 60 Algal beds in alimestone member 62 Echinoderm beds 65 Brachiopod beds 67 Facies typeB 67 Facies typeA 67 Foraminiferabeds 69 Bryozoan beds 70 Gastropodbeds 70 The participation ofvarious organisms in the composition ofthe biofraction 71 The adaptability and rapid multiplication ofthe organisms during Contents 3 anenvironmentalchange 72 The change is strength ofwave action, reflected by the fossil asso- ciations within abed 73 In astrong waveaction environment 74 In aweak wave action environment 74 Theorigin ofthe dwarffauniflora in the mixed beds 75 Paleogeographicaldistribution 76 Concludingremarks 77 CHAPTER IV. REMARKS ON THE STRATIGRAPHY OF THE CALCA- REOUS ALGAE AND THEIR SYSTEMATIC DESCRIPTIONS 79 The stratigraphic value ofthe calcareousalgae 79 Thebiostratigraphic units ofthe calcareousalgae 79 Chronostratigraphiclimits ofthe calcareous algalzones .... 84 Systematic descriptions 85 Phylum Rhodophycophyta Papenfuss, 1946 Red algaeofuncertain affinities, Johnson, 1961 85 Genus Amorfía RÁcz gen. nov 85 Amorfiajalinki RÁcz spec,nov 86 Genus ArchaeolithophyllumJohnson, 1956 Archaeolithophyllum missouriensum Johnson 86 Archaeolithophyllumjohnsoni RÁcz spec,nov 87 Genus CuneiphycusJohnson, 1960 CuneiphycusaliquantulusJohnson 88 Genus Komia Korde, 1951 Komia abundans Korde 88 Genus Petschoria Korde, 1951 Petschoria elegansKorde 90 Genus Pseudokomia RÁcz gen. nov 90 Pseudokomia cansecoensis RÁcz spec,nov 91 Genus UngdarellaMaslov, 1950 Ungdarellauralica Maslov 92 Phylum ChlorophycophytaPapenfuss, 1946 Family DasycladaceaeKützing orth. mut. Stizenberger, 1860 . . 92 Genus AnthracoporellaPia, 1920 Anthracoporellaspectabilis Pia 92 GenusBeresella Machaev, 1937 Beresella hermineae RÁcz spec, nov 93 Genus Dvinella Chvorova, 1949 Dvinella comata Chvorova 94 Genus EpimastoporaPia, 1922 Epimastopora bodoniensis RÁcz spec,nov 95 Epimaslopora rolloemisRÁcz spec, nov 97 Epimastoporaspec 98 4 Contents Genus MacroporellaPía, 1912 Macroporellaginkeli RÁcz spec,nov 98 Genus MellporellaRÁcz gen. nov 99 Mellporella anthracoporellaformisRÁcz spec, nov 100 Mellporellabeundermani RÁcz spec, nov 101 Genus UraloporellaKorde, 1950 Uraloporellasieswerdai RÁcz spec, nov 101 GenusZaporellaRÁcz gen. nov 102 Zaporellacantabriensis RÁcz spec, nov 103 Family Codiaceae (Trivisan) Zanardini, 1843 103 GenusDonezellaMaslov, 1929 103 Donezella lutuginiMaslov 104 Donezella lunaensis RÁcz spec, nov 105 Genus EugonophyllumKonishi & Wray, 1961 Eugonophyllum mulderi RÁcz spec,nov 106 Genus Ortonella Garwood, 1914 Ortonella myrae RÁcz spec,nov 106 Phylum Schizophyta (Falkenberg) Engler, 1892 „Section" Porostromata Pia, 1927 107 Genus Girvanella Nicholson & Etheridge, 1880 Girvanellaspec 107 Genus OsagiaTwenhofel, 1919 Osagia spec 108 „Section"SpongiostromataPía, 1927 108 Genus Pycnostroma Gürich, 1906 Pycnostroma spec 108 REFERENCES 109 PLATES Geological and Locality Map in back pocket. Abstract This study of the calcareous algae in the limestone deposits ofthe two formations (San Emilianoand Lois-Ciguera) in NW Spain is based onfieldobservations and microscopical study. It was possible in the field to divide almost all the limestone members into smaller units onthe basis ofphysical, chemical and biologicalcomposition oftherocks. After studying the organic content ofthe rocks, it appeared that there was a close connection between their lithological and biological composition. With these aspects known, it became a factthatunits with agiven composition alternated in a regularsequence. This offered the possibility ofrecognisingacyclical sedimentation withinasinglelimestonemember. Considering the special properties ofthe cyclical sedimentation,such as the fact that it is only found in CaCO3 containing layers and the small size ofthe cycles, the name minor cycle has been suggested for such deposits. Two facies types canbe distinguished: (1) originating in a quietmilieu, and (2) facies originating in a disturbed milieu (thesewere called limestone facies type A and limestone facies typeB, respectively). Itis typical ofthe limestones which were depositedin facies typeA, that,amongst other properties, they have very little terrigenous material in their matrix, while those offacies typeB contain large quantities in their matrix. A mixture between the twofacies types was also observed and called facies typeAB. The microscopical study was aimed to investigate: 1. the characteristics ofthe limestone construction, 2. the quantitative composition of the fauna and flora over the whole area; in a member in aminor cycle, and in abed, 3. certainenvironmental changes,which affectedthecompositionoftheorganicmaterial. A detailed study has shown that two types oflimestone arepresent, with respect to origin, manner of accumulation, and texture. These are skeletal and fragmental limestones. The skeletal limestonescanoccur as reefs and as banks. Proportionately, there areasmany banks asfragmentallimestones, and fewer reef limestones. It became clear, from the quantitative analysis, that the algae were by far the most important rock builders. Brachiopods, Foraminifera, corals, and gastropods also form a considerablefraction. There arefewer bryozoans, trilobites and ostracodspresentin detectable numbers. In the qualitative analysis, various associations oforganisms were found,which must be considered as constant associations. It has thus been established that associations of, gastropods with red algae (mainly specimens ofthe genus Archaeolithophyllum), brachiopods with bryozoans and echinoderms, corals with blue green algae, Foraminifera with algae and echinoderms, are often found. On the other hand, gastropods are found with brachiopods and bryozoans, Foraminifera with brachiopods and bryozoans, and calcareous algae with brachiopods and bryozoans, can be considered as less frequent associations. An exception is theassociationofbrachiopodswithgastropodsandred algae,in ooliticbeds.These elements, however, lived in a special environment and this resulted in anexceptional composition of dwarf elements. Sometimes,clear changes could be seen in the compositionofthe flora and fauna within abed. These changescanbe qualitativeand quantitative. Itis noticeable,in mostechinoderm beds, thatthe percentageofbrachiopod fragmentsincreases fromthe bottom tothe top.The composition ofother beds also shows such changeswith other types oforganicremains. The algal beds can generally be divided into three parts, onthe basis oftheir biofractioncom- position. This canbe explained by changesin oneormore ofthe environmental components. Until now, noattention has been paid toastudy ofthe rich algal flora in theCarbonif- 6 Abstract erous deposits ofNWSpain. 21 genera (4new) and 26 species (15 new ones)havenowbeen described. There are 8 species (7 genera) ofred algae, 15species (11 genera) ofgreen algae, and 3 species ofblue-greenalgae. The systematic position ofthe red algae,which arefound in the area, has not yet been fully determined,thus twonewly described genera Amorfia and Pseudokomia have been placed in the first group— according toJohnson'susage the”Red algae ofuncertain affinities”, together with the genera Cuneiphycus,Komia, Archaeolithophyllum, Petschoria, and Ungdarella. Three new species ofred algae are described: Archaeolithophyllum johnsoni,Amorfiajalinki, and Pseudokomia cansecoensis. The largest proportion ofthe green algae belongtothe familyDasycladaceae, 11 species (8 genera) are described in the presentwork, nine ofthese being new. These are Beresella hermineae, Epimastopora bodoniensis, Epimastopora rolloensis, Epimastoporasp., Macroporellaginkeli,Mellporellabeundermani,Mellporellaanthracoporella- formis, Uraloporella sieswerdai, and Zaporellacantabriensis. The new genera are Mellporella and Zaporella. 4 new species of the family Codiacea are described (3 genera), 3 ofthese species are new: Donezella lunaensis, Eugonophyllum mulderi, and Ortonella myrae. Strongarguments, onthe basis ofalgal body construction, were found for placing the new species, Donezella lunaensis, in the familyCodiaceae. The blue-green algae could not be specifically determinedbecause of their generally poorly preserved structures. Of these, Girvanella sp., Osagia sp., and Pycnostroma sp., were described. INTRODUCTION In the last few years, students ofthe "Geologisch- en Mineralogisch Instituut der Rijksuniversiteit teLeiden"have beenstudying the southernslope oftheCantabrian mountainchain, under the guidance ofProfessor Dr. L. U. de Sitter, to construct ageological map. The area, in which the presentstudy was carriedout, lies in the most northerly part ofthe province ofLeón in NW Spain. The northern limit of the study was the watershed, at thesame timethe province border between León and Oviedo (Asturia). Theupperreachesofthe four following rivers: Rio Bernesga, Torio, Curueño, and the Porma, cross the area in a N - S direction. The first and last form thewestern and eastern borders, respectively. The southernlimitis taken from the line which goes through the villages Villamanin, Getino, and Campillo, from west to east. The geological mapping work was carried out between the years 1960 and 1964. W. J. Jalink and H. J. Evers worked between the Rio Bernesga and the Río Torio,from north to south; W. F. Beunderman, C. A. Mulder, L. Rácz, C. F. Winkler Prins between the Río Torio and the Río Curueño; J. H. Oosterbaan, P. J. Verwoerd, and A. J. Bijwaard between the Río Curueñoand the Rio Porma, at the time these were all students at the "Geologisch- en Mineralogisch Instituut derRijksuniversiteit te Leiden". On the basis ofthe datawhich they gathered, the Geological Department of the Leiden University constructed the map which was used here. Recently a geological map has been published which covers a much larger area, with a 1 : 100,000 scale (de Sitter, 1962). Under the leadership of Professor Dr. A. Brouwer, students and co-workers carried outa stratigraphic andpaleontological investigation in differentformations andvariouspartsofthe Cantabrianmountainchain.Oneofthesestudies ispresented in the present work. As far as could be seen from the literature, no systematic description of the Carboniferous calcareous algae in NW Spain has yet been pu- blished. Thus the description of the microplant fossils in the present work can be described as the first step in their recognition as important rock builders. There is very little about the stratigraphic history ofthe area between the Rio Bernesga andthe RioPorma, inthe literature.Only recently haveafewpublications appeared (Wagner, 1963; Brouwer and Van Ginkel, 1964). Wagner's work was concerned with the rocks ofBashkirian age (=■- Namurian limestones, shalesandsandstones ofWagner) inthe southernpart (nappe structures) ofthe area and is based ona smallamount ofdataand describedingeneral terms. Brouwer and Van Ginkel give a very good general lithostratigraphic description ofall the Carboniferous deposits on the southern side of the mountains. On the basis of well considered arguments, they give a terminology pertaining to the formationclassificationofthe Carboniferous deposits in NW Spain. Helped by the fusulinid fauna they constructed a biozone classification, which is synchronized with that ofthe Russian Carboniferous deposits. A detailed stratigraphy of these rocks has not yet been established. Iamindebtedto W.J.Jalink, C.A. Mulder, W. F. Beunderman, C.F. Winkler Prins, and A. J. Bijwaard, who were kind enough to offer parts of their sample collections. I would like to thank Professor Dr. A. Födvari of the Mineralogical and Geological Institute of the "Kossuth" University of Debrecen (Hungary) 8 Introduction forhis willingness tosend anexcellent collectionofcalcareous algae, as comparative material. ToProfessorDr. J. H.Johnson oftheColoradoSchool ofminesatGolden (U.S.A.) and Professor Dr. R. Endoofthe SaitamaUniversity at Urawa (Japan) I express thankfulness for their help by sending a few of their publications and advice in connection with the determinationofthe calcareous algae. Dr. C. E. de Groot of the Museumof Mineralogy and Geology at Leiden and Dr. J. Kull- mann (Geologisch-Paláontologische Institut at Tubingen) gave their help by iden- tifying afew corals and goniatites, respectively. Mr. B. Leigh made alarge contri- butionto thepreparation oftheEnglish text. For thecareful typing ofthe manuscript I am indebtedtoMiss Th. H. Sieverts, and for drawing to Mr. I. Santa. I would like to thankMr. J. F. Hoogendoorn for the illustrations and Mr. J. Schipper for the preparation ofmore than a thousand thin sections. CHAPTER I GEOLOGICAL SETTING AND STRATIGRAPHY STRUCTURAL GEOLOGY The deposits oí'the area can be principally divided into two longitudinal units; a northern one, which mainly consists ofCarboniferous deposits, ofMoscovian age and younger, in smaller amounts there are also Devonian and Lower Paleozoic rocks; and a southern one where the Carboniferous deposits are older than Mos- covian, with Devonian and Lower Paleozoicrocks. The two units were called the Leónidesand Asturides (de Sitter, 1959). They differ in various aspects and are dividedby an (imaginary) line, theLeón-line. TheLeónidessouth ofthe linewere divided into variouszones (de Sitter, 1962), ofwhich thearea underpresentstudy formed the central and western regions of the Bernesga-Esla zone, named after thetwo limiting rivers. In the areathereis analternationbetweenLower Paleozoic and Devonian rocks with Lower-and MiddleCarboniferous*(Bashkirian) deposits, which arose through nappe structures. From the most northerly nappes there fall two complete (Forcada and Bodón respectively) and one partial (Cayo) in the studiedarea (see map). The structural history ofthe Leónides can be summarized as follows (Oele, 1964, p. 7): "After a Precambrian diastrophism, thefirst tectonic movement during the Paleozoic was a tilting and subsequent erosion of the northern part of the Leónides just before the Famennian. The main movement, however, took place just before or during early-Westphalian times (Sudetic phase), while later phases ofthe Hercynian folding resulted in arefolding ofthe previously-created structures. The Alpine orogeny placed the rocks in theirfinalposition". The main orogenetic phase, in the Bernesga-Esla region, was very active. Its activity is expressed by the origin of many thrust sheets. In the stratigraphically most developed Bodón nappe there is a very well formed syncline (Cármenes syncline) ofCarboniferous and Devonian rocks, which arose before or during the overthrusts. In the Asturides, north ofthe León-line, there is a thick mass ofMiddle Car- boniferous(Moscovian) rocks. In theNEofthearea there areLower Carboniferous, Devonian, and Lower Paleozoic deposits. At the southern edge ofthe areathere are a few small units of Stefanian deposits. This structural unit was called the Pajares-Isidro area, (de Sitter, 1962), and the area underpresent study lies in the western and central regions ofit. The Middle Carboniferous rocks show a very complicated folding pattern. The Asturian phase was undoubtedly the main orogenetic phase causing this. Its effects are expressed in mainly isoclinally folded anticlines and synclines of varying size. Because of the irregularity ofthe limestone deposits, it is not always possible to follow the layers, which makes an interpretation more difficult. In the NEpart ofthe area, the Lower Paleozoic, Devonian, and Lower Car- boniferous rocksasintheLeónides, show nappestructures. Between the Rio Torio * According to the Russian system. 10 L. Racz: Associations of Calcareous Algae and Bernesga thereare in afewregions, as onthewest sideof' the Pormainalarger area, Stefanian deposits to be found. These are composed of conglomerates and shales. The latteroften contain coal layers. The Stefanian deposits lie discordantly onthe Middle Carboniferousrocks. STRATIGRAPHY The Carboniferous deposits, of the area, belong to the following formations (see also fig. 1 and 2 and map): CeaFormation, Lois-Ciguera Formation, San EmilianoFormation, Escapa Formation, SellaFormation, GetinoFormation. Of the abovenamedformations, theLois-Ciguera and the Cea Formations are not foundin the southern surface structures. It is the purpose ofthis study to consider the faciesand stratigraphic value ofthe calcareous algae. Considering, that these microplants are usually associated with other organic remains, it was considered desirable to broaden the basis ofthe study. There has thus been a concentration on the paleoecological problems, astudy of the numericaland typical associations offlora and faunaand a reconstruction ofthe environmentin which they existed. Only two formationsweresuitableforsuch a study, the San Emilianoandthe Lois- Ciguera Formation, which containa fossil "paradise" and are, therefore, a strati- grapher's "eldorado". This is the reason why these two formationswere thoroughly studied. Only the most characteristic properties of the other four formations are mentioned. GetinoFormation.Devonian - Carboniferous boundary The top ofthe Devonian deposits is generally called the Ermitage Formation.The Ermitage Formation consists of red, coarse grained decalcified sandstone, with fossil pockets of brachiopods and crinoid stems. Among others in the brachiopod fauna, thereisSpiriferverneuili, *which is anindicatorofUpper Devonianage. There are several localities found, in the area, where the sandstone is overlaid with a coarsegrained, grey, hard limestone bank, which is 2.50—3.00 meters thick. The passage, fromsandstone tolimestone, is gradual; first thereis a calcareoussandstone, then a sandy-limestone, which progresses into a pure limestone. The intermediate zone is about0.70—1.20 meters thick. Few well preserved fossils are found in the limestone. None ofthe examples ofbrachiopods canbe identifiedas Spirifer verneuili. A microscopical examinationhas shown thatfossil composition ofthelimestone is identicalto thatofthe sandstone; the calcifiedlimestonematrix contains crinoid stemremains, and brachiopod shellfragments. Because thetransformationis gradual, ineach locality thereis agood continuity between the limestonesand theunderlying sandstone, there can be no doubt that this limestone bank represents the highest Devonian deposits in the area and are ofFamennianage. The entire thickness of the Ermitage Formationis 7 to 18 meters. * T. F. Krans (personal communication) advises that the correct identificationshould be: Cyrtospirifer verneuili (Murch). Cyrtospirifer cf. almadenensis Paeckelm. and Cyrtospirifer aff. tenticulum(deVerneuil).