THE HISTORY of the FLORA and VEGETATION of GEORGIA (South Caucasus)
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GEORGIAN NATIONAL MUSEUM INSTITUTE OF PALEOBIOLOGY Irina Shatilova, Nino Mchedlishvili, Luara Rukhadze, Eliso Kvavadze THE HISTORY OF THE FLORA AND VEGETATION OF GEORGIA (South Caucasus) Tbilisi • 2011 Paleobotanical investigations have been carried out in Georgia (South Caucasus) since the early 20th century. In this work, we bring together the great body of research on fossil material from Georgia’s Phanerozoic deposits to provide descriptions of the floras, plant communities and paleogeographic conditions of past geological epochs. The paleofloras of Western Georgia, from the stratotypical region of Eastern Paratethys, are considered in particular detail as the Black Sea deposits provide a continuous fossil record spanning the entire Neogene and Quaternary. These sediments, dated biostratigaphically using marine fauna, contain rich paleobotanical material of both macrobotanical remains and palynomorphs. Pollen and spore assemblages from complete sections of various Upper Miocene, Pliocene, Pleistocene and Holocene stages have been interpreted using the landscape-phytocenological method, providing an almost uninterrupted reconstruction of vegetation and climate dynamics in Georgia. The work also contains complete flora lists of various stratigraphical units, palynological diagrams, maps of fossil localities and paleogeographical maps of Georgia. Editors: David Lordkipanidze Abesalom Vekua Reader: Simon E. Connor ISBN 978-9941-9105-3-1 © Georgian National Museum, 2011 CONTENTS Introduction ...................................................................................................................................................5 THE PALEOZOIC The Carboniferous ...................................................................................................................................... 7 THE MESOZOIC The Jurassic ..................................................................................................................................................11 The Early Jurassic ............................................................................................................................11 The Middle Jurassic ........................................................................................................................13 The Cretaceous ...........................................................................................................................................25 THE CENOZOIC The Paleogene .............................................................................................................................................29 The Eocene ........................................................................................................................................30 The Oligocene ..................................................................................................................................32 The Neogene ................................................................................................................................................40 The Miocene ..........................................................................................................................................41 The Lower Miocene ........................................................................................................................41 The Middle Miocene ......................................................................................................................44 The Upper Miocene .......................................................................................................................53 The Sarmatian .................................................................................................................................53 The Meotian (Western Georgia) ................................................................................................58 3 The Pliocene and Eopleistocene (Western Georgia) ..........................................................79 The Pliocene ....................................................................................................................................79 The Pontian .......................................................................................................................................80 The Kimmerian ................................................................................................................................84 The Kuyalnician (Egrissian) .......................................................................................................101 The Eopleistocene ..................................................................................................................... 103 The Gurian ......................................................................................................................................103 The Pliocene and Eopleistocene (Eastern Georgia) ......................................................... 111 The Pliocene .................................................................................................................................111 The Akchagilian ...........................................................................................................................111 The Eopleistocene ..................................................................................................................... 113 The Apsheronian .........................................................................................................................113 The Pleistocene (Western Georgia) ......................................................................................... 119 The Chaudian ................................................................................................................................119 The Old Euxinian and Uzunlarian ..........................................................................................128 The Karangatian and New Euxinian ......................................................................................130 The Holocene ..................................................................................................................................... 139 Conclusion .................................................................................................................................................. 165 reziume .....................................................................................................................................................171 References .................................................................................................................................................. 178 4 INTRODUCTION Georgia is situated in the central and western parts of the South Caucasus re- gion, between the Black and Caspian Seas. It is a mountainous country with three major orographic systems within its borders: the mountain systems of the Greater and Lesser Caucasus; the intermontane depressions (Colchian, Kartlian and Alaza- nian); and the South Georgian volcanic highland (Fig.1). Fig.1. Topographic map of Georgia. In spite of its diverse natural conditions, Georgia encompasses two principal regions – Western and Eastern – which differ markedly from each other. Western Georgia is characterized by a warm and humid climate, promoting the develop- ment of lush forest vegetation. This is the so-called Colchian botanical province, where some relicts of Tertiary floras are preserved even today. Quite a different picture can be seen in Eastern Georgia, where vegetation typical of a more arid, continental climate is distributed over large areas. 5 In 1990, the N. Ketskhoveli Institute of Botany of the Georgian Academy of Sciences published the “Materials on the History of the Flora and Vegetation of Georgia” (Shatilova, Ramishvili, 1990). This work provides an extensive review of factual data, although, owing to a lack of paleobotanical data, the floras of some stratigraphical units were not described in any great detail. While subsequent investigations have not managed to fill all of the gaps in knowledge, and, from a paleobotanical point of view, our knowledge of Paleo- zoic and Paleocene floras is still relatively poor, rich palynological material from the Late Cenozoic has been collected over the last 20 years. These materials were interpreted using the landscape-phytocenological method, which allows the de- velopment of the flora and vegetation to be reconstructed. Under the influences of the abiotic and biotic factors, the fossil record indicates that changes in vegeta- tion composition led to the formation of Georgia’s current vegetation complex and its high biodiversity. 6 THE PALEOZOIC THE CARBONIFEROUS Within Georgian territory, Janelidze (1942) distinguished the labile folded zones of the Greater Caucasus and the Anticaucasus, separated by a stable zone called the Georgian Block. A scheme of Georgia’s tectonic structure is given in Fig. 2. Fig.2. Scheme of tectonic structure of Georgia (after P. Gamkrelidze, 1964) Key: I. The anticlinal Greater Caucasus; II. The folded system of the Greater Caucasus southern slope; III. The Georgian Block (intermontane depression); IV. The Adjara-Trialetian system; V. The Artvino-Bolnisian Block. According to I. Gamkrelidze (2000), the following systems are found in Geor- gia: the folded system of the Greater Caucasus (Kavkasioni), the Transcaucasian (South Caucasus) intermontane region and the folded system of the Lesser Cau- casus (Antikavkasioni). 7 In