DACIAN BASIN - GeoEcoMar

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190 Chapter 8. The Paleoenvironmental Significance of Clay in the Dacian Basin FIGURE 8.1. Clay deposits with evident internal bedding. A and B - Early Dacian. Sărăţel River, Plopeasa village (Buzău County). C - Sarmatian (s. l.). Milcov River, Reghiu (Vrancea County) FIGURE 8.2. Homogeneous, non-stratified clay in fluvial deposits. A - Sarmatian (s. l.). Milcov River, Reghiu (Vrancea County). B - Late Maeotian, Vlădeşti (Argeş County)
8.2. Clay facies and sedimentary sequences 8.2. CLAY FACIES AND SEDIMENTARY SEQUENCES For the identification of the paleoenvironmental significance of the two types of clay, it is important to examine the sandy units and/or the sedimentary sequences associated with the clay facies. In the Maeotian and Early Dacian-dated littoral deposits from the Dacian Basin, the stratified clay often show up as a basal term of the coarsening upward sequences. The littoral Late Maeotian stratified clay from Bizdidel River (Pucioasa) alternate with coarsening upward sand and has thin sandy interbeds with wave ripples (Fig. 8.3 A). The homogeneous type of clay sediments were frequently found together with the sand sediments accumulated in the fluvial environment. This clay facies is the upper term, the finest-grained one, of the fining upward fluvial sequences (Fig. 8.3 B). The limit with the sand sediments of the next fining upward sequence which is overlying the homogeneous clay, is sharp, non-transitional. In the upper fluvial part of the Late Maeotian deposits investigated in the Bizdidel River section, the stratified clay facies appears in crevasse splay sequences (Fig. 8.4) as a basal term of the sequence. In this case, the coarsening upward sequences show up in a thick fluvial succession with dominant homogeneous clay. The clay facies changes, becomes stratified, at the base of the coarsening upward unit. 8.3. SEDIMENT ACCUMULATION PALEOENvIRONMENT AND THE CLAY FACIES The Late Maeotian – Early Pontian sediment cropping out on the Bizdidel River display a succesion of littoral to fluvial paleoenvironments. The study of these sediment (Jipa, Olteanu, 2003) had as one of its targets the environments of the clay (stratified and non-stratified) deposits. In the Late Maeotian deposits from the Bizdidel River geological section the stratified clay appear associated with sands accumulated in the following sedimentation environments: ■ shoreline environment (fair-weather or storm dominated); this environment is indicated by the coarsening upward sedimentary units with wave ripples and hummocky cross lamination; the stratified clay represents fair-weather moments sometimes preceding the storm weather; ■ fluvial dominated deltaic environment, represented by coarsening upward units with current structures (but without wave or storm-generated lamination) intercalated in littoral deposits; in this case the clay can be attributed to the prodelta microenvironment; 191
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Dan C. Jipa, Cornel Olariu DACIAN B
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Dedicated to the memory of Prof. Gh
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NATIONAL INSTITUTE OF MARINE GEOLOG
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CONTENTS Foreword and Acknowledgeme
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Contents Chapter 7. The Point Bar F
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FOREwORD AND ACkNOwLEDgEMENTS The s
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PLATE 1. Location of the Dacian Bas
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18 Chapter 1. Dacian Basin. General
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The analysis of the paleogeographic
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42 Chapter 2. Dacian Basin paleogeo
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58 FIGURE 2.14. Paleogeography and
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68 Chapter 3. Sediment Thickness Di
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Sedimentation in the brackish-water
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84 Chapter 4. Dacian Basin Physiogr
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94 Chapter 5. Littoral Sedimentary
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Fluvial sedimentation played a majo
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136 Chapter 6. Upper Neogene Fluvia
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138 Chapter 6. Upper Neogene Fluvia
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Page 158 and 159: The large and continuous rock expos
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Page 200 and 201: The evolution and architecture of a
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Page 232 and 233: 230 Chapter 11. From Brackish-Marin
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240 Chapter 11. From Brackish-Marin
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Ai n s w o r t h r. B., Cr o w l e
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258 References hA m o r, g., et al.
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260 References mA C A r o V iC i, n
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262 References ră d A n, s.C., 200
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264 References VAsilieV, i., Kr iJ
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DACIAN BASIN - GeoEcoMar

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