Carboniferous calcareous algae and their associations in the San Emiliano and Lois-Ciguera ...

113 Pages·2012·8.6 MB·English

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).