The Lithological and Structural Characterisation of the Sperlingputs Shear Zone in Southern Namibia. by Jason Linekela Indongo Thesis presented in fulfilment of the requirements for the degree of Master of Science in the Faculty of Science at Stellenbosch University Supervisor: Dr. Jodie Miller Co-Supervisor: Dr. Paul Macey December 2017 Stellenbosch University https://scholar.sun.ac.za II DECLARATION This thesis is a presentation of my original research work. Wherever contributions of others are involved, every effort is made to indicate this clearly, with due reference to the literature, and acknowledgement of collaborative research and discussions. I declare that I am the sole author thereof (save to the extent explicitly otherwise stated), that reproduction and publication thereof by Stellenbosch University will not infringe any third party rights and that I have not previously in its entirety or in part submitted it for obtaining any qualification. Date: December 2017 Copyright © 2017 Stellenbosch University All rights reserved JL Indongo Sperlingsputs Shear Zone System Stellenbosch University https://scholar.sun.ac.za III ACKNOWLEDGEMENTS In this very special occasion I would like to express my deepest gratitude and appreciation to Dr Jodie A. Miller (University of Stellenbosch) for supervising this project. I cannot extend my appreciation enough for all your help and patience over difficult few years. Acknowledging you for the valuable time, advice, criticism and correction that you gave to this thesis from the beginning up to the end of the writing. I would like to thank Dr. Paul Macey for the invaluable input in this study. I would also like to extend my appreciation to the members of the southern Namibia joint mapping project between the Geological Survey of Namibia and Council for Geosciences, South Africa. Finally, thanks are also due to my fiancée, daughter, family and colleagues. Thank you all. JL Indongo Sperlingsputs Shear Zone System Stellenbosch University https://scholar.sun.ac.za IV Table of Content Table 2- 1: Tectonostratigraphic nomenclature used by researchers .................................................. 11 Table 2- 2 Summary of the tectonic events within the Namaqua Sector of the NMP ( Joubert, 1971; Blignault, 1977 and Macey et al., 2015) ............................................................................................... 17 JL Indongo Sperlingsputs Shear Zone System Stellenbosch University https://scholar.sun.ac.za V Table of Figures Figure 1-1: Locality map of the study area ( red rectangle) within the wide dispersed Namaqua Metamorphic Province in the southern Namibia immediately north of the Orange River. The map is indicating the position and extent of the SPSZS (white sold lines) and other major relative shear zones such as Marshall Rocks Pafadder shear zone (MRPZS) and Eureka shear zone (ESZ) delineated from the stacked Landsat Image (RGB 321). The bolded dotted line represented the southernmost edge of the Southern Namaqua Front, that marks the tectonic boundary between the Vioolsdrif domain (VD) and Pella domain (PD) within Richtersveld Magmatic Arc (RMA). In the adjacent area to the study area, are the four Gordonia Klippen namely; Keimasmond (KM), Kum kum (KK), Tantalite Valley (TV) and Sandfontein (S). ----------------------------------------------------------------------------------------- 5 Figure 1-2: Various remote sensing dataset used partly in the study area (2818CA): A. high resolution hyperspectra false color (2_3_4) band combination, B. Hyperspectral Near-true colour (RGB 28_9_3) image. C; Radiometric ternary image and D; Magnetic (First Derivative) image. Sourced from GSN database ----------------------------------------------------------------------------------------------------------------------- 7 Figure 2-1: Tectonostratigraphic position of the RMA of the Namaqua sector of the NMP, modified from Macey et al. (2015) after Hartnady et al. (1985), Thomas et al. (1994), Cornell et al. (2006) and Moen and Toogood (2007) 12 Figure 2-2: The tectonostratigraphic map showing the extent of the SPSZS (red dotted rectangle) in relationship with two other Namaqua sector shear zones, namely the ESZ and the MRPSZ, compiled from the recent 1:50 000 scale of Macey et al. (2015) and Thomas et al. (2016). 19 Figure 3-1: The simplified lithological map for the entire study area compiled from the 1: 50 000 scale geological of 2818CA, (Indongo et al., 2014) 2817DA and 2817DB (Indongo & shifotoka et al., 2015). The map is showing the position of all the major rocks of the Orange River Group and the Vioolsdrif Intrusive Suite. In addition, the map also shows the position of the Southern Namaqua Front (white dotted line) that mark the boundary between Pella and Vioolsdrif Domain. 24 Figure 3-2: The simplified geological map of the southern part of the study area, showing the position of Nous and Tsams formation. 26 Figure 3-3: Weakly to un-deformed basalt & basaltic-andesite of the ORG within the lower grade greenschist Vioolsdrif domain of the RMA. (a) & (b); un-disrupted millimetre to centimetre scale volcanic primary structures (flow bands) within the basalt. (c); un-deformed 2 mm to 1 cm plagioclase porphyroclasts within the basaltic andesite. (d); the mm to 2 cm elongated quartz filled JL Indongo Sperlingsputs Shear Zone System Stellenbosch University https://scholar.sun.ac.za VI amygdales. (e); photomicrograph (FOV=4.5 mm) of the porphyritic basaltic andesite consists hornblende and sausseritized plagioclase porphyroclasts sit within the fine grained intermediate- mafic groundmass. (f) Photomicrograph (FOV=4.5 mm) of the medium-fine grained basaltic andesite, consists of mm scale laminar of hornblende and biotite band verses feldspar dominant band. 28 Figure 3-4: The rhyolite variant across the study area, (a) fine to medium grained weakly sheared quartz-feldspar porphyry, (b) a millimetre scale flow bands of the aphanitic rhyolite with conchoidal fractures, (c) & (d) weakly deformed millimetre to centimetre scale flow bands within the rhyolite, (e) photomicrograph (FOV=4.5 mm) shows a porphyritic texture, revealed by sub-angular to rounded quartz phenocrysts within the fine grained groundmass of feldspar, biotite and quartz. The quartz phenocrysts have weak endulose extinction and the feldspar also displayed a poorly developed twinning. (f) Photomicrograph (FOV=4.5 mm) of the very fine-medium grained (aphanitic-dacite), showing aligned small sub-vertical elongated aggregates of biotite verses feldspar and quartz, resembling a millimetre scale lamination. 30 Figure 3-5: (a) & (b); the felsic and intermediate pyroclastic volcanic rocks with 0.5 cm to 6 cm irregular to sub-angular randomly oriented rhyolitic to andesitic fragments. (c) & (d); the layered elongated 2cm to 30 cm long, basaltic and andesitic fragments within the very fine to glass mafic matrix (agglomerate). 31 Figure 3-6: (a) plane view picture of the Vuursdood gabbros forming 20 m to 100 m wide intrusive bodies within the Orange river Group volcanic rocks. (b) & (c); close look pictures of the weakly deformed medium grained micro gabbro, (d) very coarse grained gabbro. 33 Figure 3-7: field photographs of the Porphyritic Granodiorite of the Goodhouse Subsuite within the Vioolsdrif domain. (a) plane view image of the rigid granodiorite bobs within the SPSZS. (b, c & d); close look photographs showing the porphyritic texture, biotite variety and the unstable plagioclase that mainly altered into epidote at field observation scale. (e) & (f) Photomicrographs (FOV=4.5 mm) of the very Coarse grained porphyritic granodiorite, whereby the porphyritic texture defined by 2mm wide altered plagioclase phenocrysts set within the medium grained groundmass of the recrystallized aggregates of sub+grains quartz. 35 Figure 3-8: shows a textural and composition range of the equigranular granodiorite. (a) distance view photograph of the equigranular granodiorite (b) very coarse grained type granodiorite dominated by quartz and k-feldspar, with minor biotite and hornblende, (c) medium-coarse grained biotite-hornblende spotted granodiorite, (d) medium grained equigranular biotite-rich granodiorite consisting of ellipsoidal basalt xenolith. 36 JL Indongo Sperlingsputs Shear Zone System Stellenbosch University https://scholar.sun.ac.za VII Figure 3-9: (a) distance plane view photograph of the batholitic Ramansdrif granite that forms a very sharp intrusive contact with the porphyritic granodiorite of the Goodhouse Subsuite along the Haib River toward the Orange River. (b) & (c) the variation of k-feldspar phenocrysts within the granite across the study area. (d) & (e) photomicrographs (FOV=4.5 mm) of porphyritic granite, consists of millimetre scale microcline phenocrysts set in a medium grained quartz aggregate groundmass. 38 Figure 3-10 (a) & (b) distance view photograph of the medium-fine grained leucocratic alkali granitic dyke, cross-cut the early Vioolsdrif intrusive bodies and the ORG volcanic rocks. (c) metre wide fine to medium grained Ramansdrif dyke (Rd) within the coarse grained Ramansdrif granite. (d) outcrop photograph showing the medium grained alkaline dyke consists of plagioclase that is partly altered into epidote and fine grained shiny mica (sericite). 39 Figure 3-11: shows the petrography and texture variation of the biotite-hornblende gneisses within the Pella domain In the RMA. (a) medium-coarse grained biotite-hornblende gneiss interpreted derived from the granodiorite of the Goodhouse Subsuite, (b) & (c) medium-fine