The Mavuradonha Layered Complex: Neoproterozoic ... - ArchiMeD

More documents

Recommendations

Info

2 Geology of the study areas 28 mainly exposed in the central part at the base of Chimwaya Hill. Shearing is also observed in the gneisses documented as pressure shadows formed on garnets. These garnets show a shear-sense of top-to-the-North.
3 Analytical methods 29 3 Analytical methods More than 200 representative samples were collected for geochemistry during three field trips in 1998 and 1999, each sample weighing between 3 and 5 kg. Two hundred additional hand specimens were collected for microprobe and microscopic investigations. Rock crushing (jaw crusher only) of 100 samples and sawing of all rock slices were performed at the Geology Department, University of Zimbabwe, Harare. A homogeneous split of 500 g from the crushed samples was used for geochemistry and isotope chemistry. Mineral separation of samples from the Ocellar granitoid gneiss was undertaken at the Geology Department, University of Zimbabwe in Harare. Since zircons were observed in several thin sections, the remaining splits of the metagabbros were reduced to a grain size < 400 µm in a roller mill in order to obtain material for mineral separation. Sixty-five samples were chosen for geochemistry, and a homogeneous split of each sample was ground in an agate mill in order to obtain a fine powder. The powders were dried overnight at 110 °C before powder and glass tablets were prepared. Loss on ignition (LOI) was determined gravimetrically at 1100 °C with modifications after Lechler & Desilets (1987). Major elements (except FeO) and trace elements were analysed by XRF on glass tablets and powder tablets respectively, using a Phillips SRS 200 fluorescence spectrometer. The calibration was based on international and laboratory whole-rock standards. FeO was separately determined by potentiometric titration with a Cerium solution on a semiautomatic Methrom-titriprocessor. Between 100 and 200 mg whole-rock powder was dissolved in a mixture of H2SO4-HF and subsequently heated in a platinum crucible. The solution was added to a mixture of saturated H3BO3-H3PO4 solution and titrated automatically. Concentrations of Fe2O3 were calculated using values of Fe2O3 determined by XRF and results obtained by titration for FeO. The Mg-numbers have been calculated using the following definition: Mg# = MgO/(MgO + FeO), in which FeO is the value analysed by titration. Accuracy was controlled by repeated measurements against several international and in-house standards, and the results (Appendix II, Table 1) are in good agreement with the recommended values. Precision for trace element analysis was verified by preparation and analysis of two powder tablets per sample. The variation for trace element concentrations measured in both tablets was 1 ppm for concentrations between 1 and 15 ppm and less than 2 ppm for element concentrations lower than 100 ppm. Variation was less than 5 ppm for concentrations of elements higher than 100 ppm. For Sr and Nd isotopic analyses, sample preparation followed the procedure of White and Patchett (1984). Whole-rock powders (35 to 500 µg) were spiked with a mixed 85 Rb/ 84 Sr and 149 Sm/ 150 Nd tracer. The spiked samples were dissolved in Teflon ® beakers
Page 1 and 2: The Mavuradonha Layered Complex: Ne
Page 3 and 4: All views and results presented in
Page 5 and 6: Table of contents Acknowledgements
Page 7 and 8: 6.2.3.4 Summary and interpretation
Page 9 and 10: This project was part of the Mainz-
Page 11 and 12: utile ages ranging from 526 ± 7 to
Page 13 and 14: Alter von 899 ± 46 Ma untermauert.
Page 15 and 16: 1 Introduction 1 1 Introduction 1.1
Page 17 and 18: 1 Introduction 3 1993). In the West
Page 19 and 20: 1 Introduction 5 Moreover, the stru
Page 21 and 22: 1 Introduction 7 Zambezi Belt Mount
Page 23 and 24: 1 Introduction 9 metamorphosed unde
Page 25 and 26: 1 Introduction 11 on minerals with
Page 27 and 28: 2 Geology of the study areas 13 Zam
Page 29 and 30: 2 Geology of the study areas 15 The
Page 31 and 32: Plate I Plate I-1: View at the land
Page 33 and 34: Plate I Plate I-3: Layering in the
Page 35 and 36: Plate I Plate I-5: Compositional la
Page 37 and 38: Plate I Plate I-7: Shearzone within
Page 39 and 40: 2 Geology of the study areas 25 def
Page 41: 2 Geology of the study areas 27 Two
Page 45 and 46: 3 Analytical methods 31 Mineral sep
Page 47 and 48: 3 Analytical methods 33 U-Pb rutile
Page 49 and 50: 3 Analytical methods 35 microscopic
Page 51 and 52: 4 Petrology and metamorphic evoluti
Page 57 and 58: Am II-1 II-2 Pl II-3 Grt Pl Cpx Cpx
Page 63 and 64: Plate III 49 Plate III-8: Corona te
Page 65 and 66: Pl III-4 Am III-5 III-6 Am Pl Am Op
Page 93 and 94:
5 Geochemistry 79 a) Gabbro / Norit
Page 95 and 96:
5 Geochemistry 81 Chimwaya Hill Inl
Page 97 and 98:
31 28 25 22 19 16 13 10 2.5 1.6 1.4
Page 99 and 100:
5 Geochemistry 85 25 20 15 10 5 Ga
Page 101 and 102:
5 Geochemistry 87 The trace element
Page 103 and 104:
5 Geochemistry 89 1000 900 800 700
Page 105 and 106:
5 Geochemistry 91 600 500 400 300 2
Page 107 and 108:
5 Geochemistry 93 proposed for gabb
Page 109 and 110:
5 Geochemistry 95 1000 900 800 700
Page 111 and 112:
6 Geochronology and zircon-cathodol
Page 113:
Page 116 and 117:
6 Geochronology and zircon cathodol
Page 120 and 121:
Page 122 and 123:
Page 125 and 126:
6 Geochronology and zircon cathodol
Page 127:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
7 Sm-Nd, Rb-Sr and Pb-Pb isotopic s
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
8 Petrogenetic and geotectonic impl
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
Page 170 and 171:
Page 172 and 173:
9 Interpretation in the regional co
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
References 164 References ARANOVICH
Page 180 and 181:
References 166 COMPSTON, W., WILLIA
Page 182 and 183:
References 168 GRAHAM, C.M. and POW
Page 184 and 185:
References 170 JOHN, T., SCHENK, V.
Page 186 and 187:
References 172 KROGH RAVNA, E. (200
Page 188 and 189:
References 174 MEZGER, K., HANSON,
Page 190 and 191:
References 176 POLLER, U. (1999): A
Page 192 and 193:
References 178 TEERTSTRA, D.K. and
Page 194 and 195:
Appendix 180 Appendix A-I Geology o
Page 196 and 197:
Appendix A-I. Geology of the study
Page 198 and 199:
Appendix A-I. Geology of the study
Page 200 and 201:
Appendix A-II. Analytical methods v
Page 202 and 203:
Appendix A-II. Analytical methods v
Page 204 and 205:
Appendix A-III. Petrology and metam
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Appendix A-III. Petrography and met
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Appendix A-IV. Geochemistry xlviii
Page 244 and 245:
Appendix A-IV. Geochemistry l Table
Page 246 and 247:
Appendix A-IV. Geochemistry lii Tab
Page 248 and 249:
Appendix A-IV. Geochemistry liv Tab
Page 250 and 251:
Appendix A-IV. Geochemistry lvi Tab
Page 252 and 253:
Appendix A-IV. Geochemistry lviii T
Page 254 and 255:
Appendix A-V. Geochronology and cat
Page 256 and 257:
Page 258 and 259:
Page 260 and 261:
Page 262 and 263:
Appendix A-VI. Sm-Nd, Rb-Sr and Pb-
Page 264 and 265:
Appendix A-VI. Sm-Nd, Rb-Sr and Pb-
Page 266:
Curriculum vitae 181 Curriculum Vit
show all

The Mavuradonha Layered Complex: Neoproterozoic ... - ArchiMeD

Create successful ePaper yourself

Delete template?

Save as template?