Geochemistry of Nearshore Sediments from the North
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GEOCHEMISTRY OF NEARSHORE SEDIMENTS FROM THE NORTH AEGEAN SEA, GREECE by FANI SAKELLARIADOU A thesis submitted for the degree of Doctor of Philosophy of the University of London Applied Geochemistry Research Group Royal School of Mines Imperial College of Science and Technology July 1987 2 To my parents Leonidas and Alexandra, To Leonidas, To Mary 3 ABSTRACT The surface sediments of North Aegean Sea comprise modern terrigenous detrital material (introduced by river runoff and coastal erosion), reworked older sediments and biogenic matter. Fine-grained sediments near major river mouths reflect fluvial input. Sands in the mid-shelf region of Samothraki plateau represent deposition during earlier, lower sea levels. Aluminium and iron rich, fine-grained sediments in Kavala gulf consist of reworked material. Supply and distribution of sediments on Samothraki and Strymonikos plateaux are affected by a westwards flowing nearshore current and a west-east trending nearshore canyon, respectively. The former transports the Evros runoff westwards and the latter directs the Strymon runoff downslope. Within the study area, lerissos gulf surface sediments are significantly enriched in Mn, Fe, Ni, Zn and Cu. The enrichments express the mineralization onland (mixed sulphide deposits, Cu-bearing porphyry stocks and Mn-oxide deposits). In buried sediments off Stratoni, Mn, Fe and Zn concentrations increase dramatically close to the surface. This trend is probably related to contamination deriving from coastal mining activities. The buried sediments of North Aegean Sea mainly comprise clay and carbonate matter. In some of them, an upward migration of Mn due to diagenetic remobilization is observed. In all surface and subsurface sediments, more than 50% of Ti, Al, Fe, K, Ba, V, Cr, Li, Co, Ni, La, Mg, Be, P, Cu and Zn is hosted in the lattice structure of aluminosilicate minerals. Significant proportions of Mn, Fe, Zn, Pb, Ni and Co are associated with the Fe,Mn-oxides. The carbonates contain mainly Ca and Sr. In the Samothraki plateau surface sediments the Cu affinity for organic matter is pronounced. The highest proportions of Pb, Zn, Cu, Ni and Mn not bound to aluminosilicates occur in the lerissos gulf sediments, confirming that their origin is related to onland mineralization and mining activities. Although various enrichments were determined in some sediments, economic deposits of any of the elements studied are unlikely to occur in the upper parts of the North 4 Aegean Sea sediments. However, it is demonstrated that the detection of mineralized areas onland (e.g. eastern Halkidiki peninsula) is feasible through the geochemical study of nearshore sediments. 5 Table of Contents Eaoa Abstract 3 Table of contents 5 List of Tables 11 List of Figures 15 Acknowledgements 26 Chapter I Introduction 1.1 General introduction, project outline and aims 27 1.2 Thesis structure 30 1.3 General morphological and geological setting 30 1.3.1 Main rivers 30 1.3.2 Composition of rocks on the mainland 31 1.3.3 Composition of rocks on islands 32 1.4 Bathymetry 33 1.5 Hydrography 37 1.6 Nature of sediments offshore 37 1.6.1 Strymonikos area 37 1.6.2 Samothraki plateau 37 1.6.3 General discussion 38 1.7 Previous geochemical and mineralogical investigations 39 Chapter II Analytical techniques 2.1 Bulk chemical analysis 41 2.1.1 Lithium metaborate technique 41 2.1.1.1 Outline of the technique 41 2.2 Mineral acid attack 42 2.2.1 Outline of the technique 42 2.3 Comparison between method A and method B 42 2.4 Selective sequential extraction analytical procedure 50 2.4.1 Introduction 50 2.4.2 Methods 50 2.5 Calcium carbonate and organic carbon determinations 57 2.5.1 Calcium carbonate determination : outline of thetechnique 57 2.5.2 Organic carbon determination : outline of the technique 57 2.6 X-Ray Diffraction 58 Chapter III The Samothraki plateau 3.1 Surface sediments 59 3.1.1 Sediment composition 59 3.1.1.1 Distribution of rock fragments, quartz, heavy minerals, 59 biogenic matter and carbonates 6 3.1.1.1.1 Rock fragments 59 3.1.1.1.2 Quartz 60 3.1.1.1.3 Heavy minerals 60 3.1.1.1.4 Biogenic carbonate particles 61 3.1.1.1.5 Carbonates 61 3.1.1.2 Distribution of organic carbon and results from XRD and 62 SEM studies 3.1.1.2.1 Organic carbon 62 3.1.1.2.2 XRD results 63 3.1.1.2.3 SEM results 64 3.1.2 Bulk geochemistry of offshore sediments and of those on 72 the adjacent coast 3.1.2.1 Silicon 72 3.1.2.2 Calcium 72 3.1.2.3 Aluminium 73 3.1.2.4 Iron 73 3.1.2.5 Potassium 74 3.1.2.6 Magnesium 75 3.1.2.7 Titanium 75 3.1.2.8 Strontium 75 3.1.2.9 Phosphorus 76 3.1.2.10 Barium 76 3.1.2.11 Manganese 77 3.1.2.12 Zirconium 77 3.1.2.13 Chromium 78 3.1.2.14 Vanadium 78 3.1.2.15 Zinc 78 3.1.2.16 Lanthanum 79 3.1.2.17 Nickel 79 3.1.2.18 Copper 80 3.1.2.19 Cobalt 80 3.1.2.20 Beryllium 80 3.1.3 Multivariate Statistical Analysis 91 3.1.3.1 Introduction 91 3.1.3.2 Correlation Matrices 92 3.1.3.3 Cluster analysis 95 3.1.3.3.1 Box-Cox transformed data 95 3.1.3.3.2 Raw, untransformed data 95 3.1.3.4 Factor analysis 99 3.2 Buried sediments 102 3.2.1 Description of the cores 102 3.2.1.1 Core THR 7 102 3.2.1.2 Core THR 22 102 3.2.2 Bulk geochemistry of subsurface offshore sediments 103 3.2.2.1 Core THR 7 103 3.2.2.2 Core THR 22 103 3.3 Summary 106 Chapter IV The Strymonikos gulf, plateau and triangle, and the Kavala gulf 4.1 Surface sediments 108 4.1.1 Sediment composition 108 4.1.1.1 Distribution of rock fragments, quartz, heavy minerals, 108 biogenic matter and carbonates 7 4.1.1.1.1 Rock fragments 108 4.1.1.1.2 Quartz 109 4.1.1.1.3 Heavy minerals 109 4.1.1.1.4 Biogenic carbonate particles 111 4.1.1.1.5 Carbonates 111 4.1.1.2 Distribution of organic carbon and results from XRD and 111 SEM studies 4.1.1.2.1 Organic carbon 111 4.1.1.2.2 XRD results 111 4.1.1.2.3 SEM results 113 4.1.2 Bulk geochemistry of offshore sediments and of those on 120 the adjacent coast 4.1.2.1 Silicon 120 4.1.2.2 Aluminium 120 4.1.2.3 Calcium 121 4.1.2.4 Iron 121 4.1.2.5 Potassium 121 4.1.2.6 Magnesium 122 4.1.2.7 Titanium 122 4.1.2.8 Phosphorus 123 4.1.2.9 Manganese 123 4.1.2.10 Barium 123 4.1.2.11 Strontium 124 4.1.2.12 Zirconium 124 4.1.2.13 Vanadium 125 4.1.2.14 Chromium 125 4.1.2.15 Zinc 126 4.1.2.16 Nickel 127 4.1.2.17 Lanthanum 127 4.1.2.18 Copper 127 4.1.2.19 Cobalt 128 4.1.2.20 Beryllium 128 4.1.3 Multivariate Statistical Analysis 139 4.1.3.1 Strymonikos group 139 4.1.3.1.1 Correlation Matrices 139 4.1.3.1.2 Cluster analysis 142 4.1.3.1.2.1 Box-Cox transformed data 142 4.1.3.1.2.2 Raw, untransformed data 142 4.1.3.1.3 Factor analysis 145 4.1.3.2 Kavala group 148 4.1.3.2.1 Correlation Matrices 148 4.1.3.2.2 Cluster analysis 151 4.1.3.2.2.1 Box-Cox transformed data 151 4.1.3.2.2.2 Raw, untransformed data 151 4.1.3.2.3 Factor analysis 154 4.1.3.3 Comparison between the Strymonikos and Kavala groups 156 4.2 Buried sediments 157 4.2.1 Description of the cores 157 4.2.1.1 Core STR 1 157 4.2.1.2 Core STR 2 157 4.2.1.3 Core STR 4 157 4.2.1.4 Core STR 11 158 4.2.1.5 Core STR 12 158 4.2.1.6 Core STR 27 159 4.2.1.7 Core STR 28 159 4.2.1.8 Core KB 3 159 8 4.2.1.9 Core KB 5 159 4.2.1.10 Core KB 7 160 4.2.1.11 Core KB 11 160 4.2.1.12 Core KB 12 160 4.2.2 Bulk geochemistry of subsurface offshore sediments 161 4.2.2.1 Core STR 1 161 4.2.2.2 Core STR 2 161 4.2.2.3 Core STR 4 161 4.2.2.4 Core STR 11 162 4.2.2.5 Core STR 12 162 4.2.2.6 Core STR 27 162 4.2.2.7 Core STR 28 163 4.2.2.8 Core KB 3 163 4.2.2.9 Core KB 5 163 4.2.2.10 Core KB 7 164 4.2.2.11 Core KB 11 164 4.2.2.12 Core KB 12 164 4.3 Summary 177 Chapter V The lerissos gulf 5.1 Surface sediments 178 5.1.1 Sediment composition 178 5.1.1.1 Distribution of rock fragments, quartz and heavy minerals 178 5.1.1.1.1 Rock fragments 178 5.1.1.1.2 Quartz 179 5.1.1.1.3 Heavy minerals 179 5.1.1.2 Carbonates 179 5.1.1.3 Organic carbon 179 5.1.1.4 XRD results 180 5.1.2 Bulk geochemistry of offshore sediments and of those on 186 the adjacent coast 5.1.2.1 Silicon 186 5.1.2.2 Aluminium 186 5.1.2.3 Calcium 186 5.1.2.4 Iron 187 5.1.2.5 Potassium 187 5.1.2.6 Magnesium 187 5.1.2.7 Titanium 188 5.1.2.8 Manganese 188 5.1.2.9 Phosphorus 188 5.1.2.10 Barium 189 5.1.2.11 Strontium 189 5.1.2.12 Zinc 190 5.1.2.13 Chromium 190 5.1.2.14 Vanadium 190 5.1.2.15 Zirconium 191 5.1.2.16 Nickel 191 5.1.2.17 Copper 191 5.1.2.18 Lanthanum 192 5.1.2.19 Cobalt 192 5.1.2.20 Beryllium 192 5.1.3.