[ -, ["," [' " r v'~ ' STRATIGRAPHICAL AND MICROPALEONTOLOGICAL t- -, DATA ON THE TERTIARY OF SOUTHERN PIEMONT i (NORTHERN ITALY) I l '. - STRATIGRAPHICAL AND MICROPALEONTOLOGICAL DATA ON THE TERTIARY OF SOUTHERN PIEMONT (NORTHERN ITALY) STRATIGRAPHICAL AND MICROPALEONTOLOGICAL DATA ON THE TERTIARY OF SOUTHERN PIEMONT (NORTHERN ITALY) by c. C. VERVLOET SCHOTANUS & lENS UTRECHT NV - UTRECHT MAART 1966 CONTENTS Index of genera and species among the planktonic Chapter V: Chronostratigraphy and larger Foraminifera . 7 1. General. 47 2. Conclusions Abstract . 9 49 Acknowledgements 9 MICROPALEONTOLOGY Chapter VI: Systematics Chapter I 1. General remarks, Lineages and Classification 50 Introduction 11 2. Planktonic Foraminifera 51 3. Larger Foraminifera Family Lepidocyclinidae 58 Chapter II Family Miogypsinidae . 60 Historical Review . 13 Family Nummulitidae . 61 Family Discocyclinidae 61 Selected references . 62 STRATIGRAPHY Plates I-XII . 66-89 Chapter III: Lithostratigraphy ILL USTRATIONS 1. Introduction 16 2. Description of the sections. 16 Text figures 1-6: A. Section I: Ceva area . 18 1. Outline Map of Southern Piemont, with the areas B. Section II: Spigno Monferrato area 20 studied in detail . 11 C. Section III: Acqui-Molare area. 26 2. Profile between the Monte Ronzone and the Rio D. Section IV: Serravalle Scrivia area. 28 Mazzapiedi (Tortona-Garbagna area) . 34 E. Section V: Tortona-Garbagna area 31 3. Formations and Members of the sections I-V, and 3. The types of earlier described stages . 35 their arrangement, according to the Italian Geo­ logical Maps 36 4. Type sections, the Biostratigraphy and Chrono­ Chapter IV: Biostratigraphy stratigraphy from Upper Eocene to Upper Mio­ 1. Introduction 37 cene . 48 2. A. Planktonic foraminiferal Zonation. 37 5. Data obtained from the Nephrolepidina spp. at B. Zonation by means of Larger Foraminifera 39 some localities in Piemont (N. Italy) . 59 3. Areal distribution of the zones . 46 6. Determination table of the Miogypsina spp. from 4. General conclusions . 46 several localities in Southern Piemont (N. Italy) 60 5 Plates I-XII: Tables I-V: (in the text) Lithological columns of the areas studied. I, II: Schematic drawings of some planktonic Fo­ raminifera . 66-69 Tables VI-X: Distribution charts of planktonic and III-XI: Planktonic foraminiferal species and variants larger Foraminifera of the areas studied. 70-87 XII: Photoplate of thin sections of Lepidocyclina Table XI: (in the text) and Miogypsina s.s. 8&-99 The correlation and zonation of the sections I-V in Southern Piemont by means of planktonic and Larger Maps I-V: (in the text) Foraminifera 45 I: Ceva area; II: Spigno Monferrato area; III: Acqui­ Molare area; IV: Serravalle Scrivia area; V: Tortona­ Garbagna area. 6 INDEX OF GENERA AND SPECIES AMONG THE PLANKTONIC AND LARGER FORhMINIFERA STUDIED page plate fig. page plate fig. Discocyclina sp. 78 ruber 55 Globigerapsis subquadratus 55 X 4 semiinvoluta 67 III 2 pyramidalis 55 XI 1 Globigerina trilobus 55 X 1,2 ampliapertura 51 I 5 Globoquadrina angustiumbilicata 52 VII 2 altispira 55 V 1 VIII 3 dehiscens 54 IV 4 bulloides 52 VI 2 quadraria 54 ciperoensis 54 Globorotalia concinna 52 V 3 barisst<nensis 57 VIII 4 VII 1 centralis 57 I 4 euapertura 51 cerro-azulensis 57 I 1-3 globularis 52 II 11 III 1,6 VI 3 menardii 57 IX 4 IX 1 llltOZea 57 VIII 1,2 increbescens 53 IX 3 mayert 53 VI 1 scitula 57 IX 2 nepenthes 53 VII 3 Hastigerina obesa 53 II 9 aequilateralis 56 V 2 siphonifera 56 II 8 opimanana 53 IV 3 Lepidocyclina parabulloides 52 N ephrolepidina praebulloides 52 morgam 59 tf.5 pseudoampliapertura 51 praemarginata 59 XII 1--4, tf.5 quadripartita 53 Miogypsina regularis 53 II 10 globulina 61 XII 5; tf. 6 rohri 53 II 5 gunteri 61 XII 6 III 4 tf.6 sellii 54 III 5 intermedia 61 tf.6 tripartita 53 III soclm 61 tf.6 venezuelana 54 II Nummulites woodi 52 3 intermedius (2) 61 Globigerinita 6,7 vascus (1) 61 dissimilis 54 I 6 Orbulina IV 1 glomerosa 56 11 2 umcava 54 IV 2 suturalis 56 II 1,3 humilis 54 VI 4 unwersa 56 II 4 Globigerinoides VII 4 bisphericus 55 X 3 Pseudohastigerina elongatus 56 XI 3,4 micra 58 obliquus 55 XI 2 7 ABSTRACT During the years 1959-1963 stratigraphical investigations Correlation by means of the zonation with these larger and were carried out in Southern Piemont (Northern Italy) along planktonic Foraminifera leads to interesting stratigraphic results. five traverses, taken at right angles to the strike of the strata, 1. In the correlation of the sections II, III and IV only slight which range in age from Eocene to Pliocene. differences with the Italian Geological Map have been met These sections are important in that they include the rype with, but in the sections I and V there are large deviations sections of some Neogene stages (Langhian, Serravallian and from this map. Tortonian) and some classical localities, such as Moliere and 2. The type Langhian appears to begin closely above the Costa Lupara. The sequences of these sections (numbered I-V) show large Orbulina surface. For the assumed chronological interval discrepancies in lithology as well as in the thickness between between Helvetian and Tortonian the author suggests to use the term Serravallian rather than Langhian, because the latter the corresponding units. To avoid confusion a number of forma­ tions and members are introduced for each of the sections. has commonly been erroneously considered to be the equi­ valent of the Burdigalian. The limits between the successive Parts of the sections are barren but in most portions numerous stages Burdigalian, Helvetian, Serravallian and Tortonian can planktonic foraminifera were found. They could be used to be correlated with biozones of planktonic Foraminifera. establish ten biozones, successively I: the semi-involuta Zone, II: the cerro-azulensis Zone, III: the Globigerina Zone, IV: the 3. Furthermore it was found that the beginnings of the genera Globigerinoides-Globoquadrina Zone, V: the Globorotalia Zone, Globigerinoides and Globoquadrina do not coincide with the VI: the bisphericus Zone, VII: the Orbulina Zone, VIII: the Oligocene-Miocene boundary. Both genera start their range menardii Zone, IX: the nepenthes Zone, and X: the obliquus in the Late Oligocene already. Zone. 4. Among the general conclusions of a paleogeographic nature In addition some of the larger Foraminifera were investigated we may note, that the transgression over the metamorphic in more detail, in particular the Nephrolepidina and Miogypsina basement of the Massif of Voltri and Ligurian Alps advanced species. The embryonic-nepionic apparatus of Lepidocyclina prae­ in westward direction during Rupelian and probably Chattian marginata and Lepidocyclina morgani were compared on a bio­ times. metric basis. Only a part of the phylogenetic series of the Mio­ 5. In the most eastern section (Tortona-Garbagna area) the gypsinidae was encountered, namely from M. gunteri to M. Miocene sequence is not complete, as sediments, corres­ intermedia. ponding to at least two of the biozones are lacking here. ACKNOWLEDGEMENTS My sincere thanks are due to Professor Dr. G. H. R. VON My grateful memories go to the late Prof. C. SOCIN (Turin) KOENIGSWALD (Utrecht), who kindly facilitated this study, and and to his wife, whose generous hospitaliry I enjoyed several whose keen interest in the problems has stimulated the work. times. Many ideas of Prof. SOCIN have found expression in this His encouragement has been most helpful in the preparation of paper. this paper. Gratitude is also due to Dr. P. MARKS and Dr. J. E. VAN HINTE I am under great obligation to Dr. C. W. DROOGER (Utrecht), (Utrecht), for their never-failing willingness to read my paper who read and criticised the entire manuscript, whose suggestions and in clearing up many doubtful points. greatly stimulated my investigations and without whose con­ structive remarks and insight this paper would never have been The Maps, Tables and Textfigures have been ably drawn by finished. Mr. A. VAN DOORN, whereas Mr. J.]. VERMAAT illustrated the specimens of the foraminifera. Address of the author: Dr. C. C. Vervloet, 4204 - 19th Str. S.W.,Calgary (Alberta), Canada. 9 Chapter I INTRODUCTION The area of Southern Piemont (text fig. 1), to which In the attempt to contribute to the solution of the this paper refers, has attracted the interest of geologists correlation difficulties that have arisen, the present paper from the early 19th century onwards, and it derives its will deal in detail with five selected sections, some of them importance from the fact, that a number of authors have including these type sections, and generally at right angles based several stratigraphical units (stages) of the Upper to the strike of the strata in the hilly country of Le Langhe. Paleogene and the Neogene on the formations exposed The sections are numbered I-V from West to East, here, and on their fossil content. and have been named after the villages or towns of: Ceva, In the course of time the interpretation of these stages Spigno Monferrato, Acqui-Molare, Serravalle Scrivia and has frequently been changed, but some of the names Tortona-Garbagna respectively. Some of the other names (Langhian, Tortonian) are still widely used. in text fig. 1 refer to classical, fossiliferous localities, 4 30' 0­ I ~ LEGEND I D AreQs invC'Stigated in ddoil ~ Basement rocks. o • Figure 1 Outline Map of Southern Piemont, with the areas studied in detail. 11 such as Mollere (near Ceva) and Costa Lupara (near erosion on the other, which have given rise to a series Dego). of cuestas. The area is approximately limited by the upper course The general strike of the strata is decided by the topo­ of the river Tanaro in the West, the rivers Borbera and graphy of the basement of the Ligurian Alps and the Castellania in the East, the Massif of Voltri and the Northwestern Apennines.