DACIAN BASIN - GeoEcoMar

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164 Chapter 7. The Point Bar Facies in the Jilţ Quarry (Romanian Deposits) FIGURE 7.8. Micro-cross lamination in the fine/very fine-grained sand facies. A. Trough cross aspect of the micro-ripples. B. Climbing micro-cross lamination. Early Romanian, Jilţ Quarry, Mătăsari (Gorj County)
7.2. The sedimentological description of the Jilţ point bar deposits The sediments are coarser-grained (fine sand) and their sedimentary structures occur as larger units (medium scale cross-lamination) at the lower part of the fine and very fine-grained sand facies (Fig. 7.9). Thin clayey intercalations (3 - 7 cm thick) appear within the fine and very fine sands. The inclined mud intercalations occur from the base of the upper, silty-clay facies and develop down-slope towards the base of the fine-grained sand sub-facies. The oblique pattern of the clay intercalations within the Jilţ sand makes obvious the point bar character with large scale inclined stratification (sensu Thomas et al., 1987). In the eastern part of the point bar deposits, the coarse-grained facies is missing and the vertical sequence begins with the fine-grained sand facies. At the base of the eastern part of the point bar, the fine sand facies shows very large crosslamination structures (Fig. 7.10), as well as frequent pebble clay accumulations. 7.2.3. The medium and coarse-grained sand facies The facies of the medium and coarse sand sediments represent the lower part of the point bar sequence in the Jilţ Quarry. In addition to coarse grain size, the occurrence of large scale current structures is a defining character of the lower point bar facies. The current structures are trough-cross strata (Fig. 7.11 A, E, F), extending along the trough axis for several meters (Fig. 7.11 B). Sometime, the foreset units are centimetres thick, occurring as thin (1 - 4 cm) inclined sand layers separated by silt laminae (Fig. 7.11 C). On one occasion current ripples have been observed on the top of the large scale cross-laminated structures (Fig. 7.11 C). Thin clayey interbeds (mud drapes) extend into the upper part of the lower Jilt point bar facies, but are not visible in the lower part of the coarse sand facies. A thin bed (10 - 50 cm) of fine gravel (Fig. 7.11 F) marks the basal limit of the point bar sequence. FIGURE 7.9. Medium scale cross-lamination at the lower part of the fine and very fine grained facies. Jilţ South Quarry, E13 mining front 165
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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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Page 116 and 117: 114 Chapter 5. Littoral Sedimentary
Page 136 and 137: Fluvial sedimentation played a majo
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Page 192 and 193: 190 Chapter 8. The Paleoenvironment
Page 200 and 201: The evolution and architecture of a
Page 202 and 203: 200 Chapter 9. Source-Areas in the
Page 214 and 215: 10.1. SEDIMENT ACCUMULATION AREAS I
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214 Chapter 10. History of the Daci
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230 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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