GEO305F: IGNEOUS AND METAMORPHIC PETROLOGY
FIRST TERM FIELD TRIP TO THE LOWER ORANGE RIVER REGION

PHOTO GALLERY
N7 highway from Cape Town to Springbok, winding through high grade granulites and granitic orthogneisses of the Mesoproterozoic Namaqua Province
Swartkop Mine, Viooldrif South, our source of high purity quartz to clean our milling equipment
View east towards Swartkop, a metagabbro intrusion cut by granitoids and later pegmatites, which contain mica and feldspar worked at Swartkop Mine Neoproterozoic mafic dykes cutting Palaeoproterozoic granitoids, Vioolsdrif South
Thin roof pendant of acid metavolcanic within granite, Vioolsdrif South Xenolithic block of metagabbro in granite, Vioolsdrif South
Sheets of granite in the contact zone with the metavolcanic country rock, Koubank Gorge, Vioolsdrif Dipping flows of basaltic andesite lava, Orange River Group, Koubank Gorge, Vioolsdrif

Acid horizon within mafic lavas, Orange River Group, Koubank Gorge, Vioolsdrif

Thinly bedded tuffaceous volcanics, Orange River Group, Koubank Gorge, Vioolsdrif
Greenschists developed from mafic lavas in a vertical shear zone, Koubank Gorge, Vioolsdrif Normal fault cutting Nama strata and its granite basement, Koubank Gorge, Vioolsdrif
Section showing granite basement, overlain by cream coloured Nama strata (Kuibis quartzites), and in turn overlain by orange Karoo sediments (Dwyka glacial shales) Orange coloured Dwyka glacial sediments overlying granite basement, Orange River, Vioolsdrif
Typical woolsack weathering developed on massive granite outcrops, Vioolsdrif Cliffs of dark Nama limestone strata overlooking Vioolsdrif
Xenoliths of older phases of the Vioolsdrif Granitoid Suite (Gd and V) in adamellitic granite (Ad), N7 highway roadcut Vertical aerial photo of the Nous Wells area
Nous Wells, surrounded by grey granodiorite (right) intruded by red leucogranite (centre) Campsite in the midst of Vioolsdrif leucogranite, Nous Wells area
View south over the Nous Wells area, with andesitic and rhyolitic metavolcanics (foreground) intruded by Vioolsdrif granitoids (distance) View north from the top of Kruiskop down the Nous River
Neoproterozoic mafic dyke of the Gannakouriep swarm cutting Vioolsdrif granite, N7 highway Typical woolsack weathering developed on massive granite outcrops, Vioolsdrif

Dark limestone strata of the Nama Group at Noordoewer Orange River cutting through Dwyka glacial shales (foregound) and folded Nama limestone (distance), Kotzedrif
Section through glacial strata of the Dwyka Formation, Kotzedrif Laminated shales overlain by massive tillite, Dwyka Formation, Kotzedrif
Centimetre scale bulbous fracture surface typical of shale, Dwyka Formation, Kotzedrif Fragments of thin fissile shale developed on Dwyka outcrops, Kotzedrif
Quartzite dropstone with internal structure, Dwyka Tillite, Kotzedrif

Section through a carbonate lens formed by diagenetic precipitation within the Dwyka glacial shales, with characteristic cone-in-cone internal structure
Circular outline of the cone-in-cone structures, from the top Oblique view of a cone-in-cone concretionary structure, diagenetic carbonate lens within Dwyka glacial shales
Striations developed on Nama limestone caused by glacial ice action, base of Dwyka Tillite, Kotzedrif Talus breccia of Nama limestone scratched and polished by glacial ice, base of the Dwyka Tillite, Kotzedrif
Shiny polished surface with striations caused by glacial action, base of the Dwyka Tillite, Kotzedrif Bedding parallel parting causing the oblique fractures in outcrops of Dwyka glacial shales, Kotzedrif
View across the Orange River to Provenance Camp, Kotzedrif Karoo shales of the Dwyka Formation crop out on the Orange River at Aussenkehr, with metasediments and metavolcanics of the Orange River Group in the distance
Karoo shales of the in foreground are cut by a dark dolerite sill, building the Tandjiesberg near Aussenkehr Vertical jointing and the dark brown colour distinguishes the Karoo dolerite sill intruded into the grey Karoo shales

Vertical columnar jointed developed in the Tandjiesberg dolerite sill, Aussenkehr

 Dipping Nama limestone overlain by orange glacial strata of the Dwyka Formation, Gamchab Monocline
View up the Gamchab Gorge from its junction with the Orange River, showing the Numees and Nama strata tilted in the monoclinal structure Gamchab Gorge section with Vioolsdrif granite at the base, overlain by dark grey Numees strata, succeeded by pale thinly bedded Kuibis quartzites of the Nama Group
Dark bostonite dyke cuts up through Numees strata at the base of the section, but is cut off at the disconformable contact with the overlying Nama quartzites, Gamchab Gorge Section along the Gamchab monocline, showing dark limestone overlying pale quartzites of the Nama Group
View of the Gamchab monocline, with a steeply dipping section through Karoo, Nama, Numees strata, resting on Vioolsdrif granite basement (L to R)awk canoe on the Orange River Orange River Group metavolcanics overlain by Dwyka glacial deposits defining a palaeovalley
View south down the Sjambok River, towards the intense bostonite dyke swarm cutting granite of the Richtersveld Igneous Province Big bend in the Orange River at Sjambokkloof
Colour aerial photo of the Sjambok bend in the Orange River View across the Orange River in flood at Sjambok
Irregular dyke terminations in the Sjambok swarm
Thick dark bostonite dykes cutting the Sjambok Granite form the rapids on the Orange River
Fluorite workings at Sjambokkloof Orange River canyon at Grootpenseiland, with red granites cutting across older basement granitoids
Grootpenseiland is formed by a split in the channel of the Orange River Outline of the alkaline ring complexes at Grootpenseiland
Potholes cut by the Orange River into syenites of the Grootpenseiland Complex Basal contact between the Tandjiesberg dolerite sill and hornfelsed Karoo sediments, upper Gamchab River
Curved ridges of alkali syenite in the southern part of the Kanabeam Complex Aerial oblique view of the lower Orange River upstream from Vioolsdrif
Western margin of the Kanabeam Complex (foreground), with thin slivers of Karoo strata (Dwyka Tillite) preserved against a fault scarp (backround) Dark dolomite cliffs of the Marinkas Quellen carbonatite complex
Aerial photo of the Fish River showing the terrain around Ai-Ais (X) Rose quartz veins associated with pegmatites in the grey gneisses exposed in the tributary valleys heading down to the Fish River Canyon near Ai-Ais

Pegmatite veins cutting Namaqua grey gneisses, road to Ai Ais Old photo of the Ai-Ais camp on the Fish River before major development of the resort
More recent photo of the Ai Ais camp View down the Fish River Canyon from Ai-Ais
Aerial photo of the Fish River Canyon in the vicinity of the viewpoint Aerial oblique view of the Fish River Canyon
Tight entrenched meander in the Fish River Canyon, Main viewpoint Scene from the Fish River canyon main viewpoint, to the SW
View into the Fish River Canyon from the top of the Sulphur Springs Trail Angular unconformity between basement Namaqua gneisses and the overlying Nama Group, Fish River Canyon
Migmatitic Namaqua gneisses cut by mafic dykes, cut off by the Nama strata, Fish River Canyon Mafic dyke cutting up through basement augen gneiss to the Nama unconformity, Fish River Canyon
Contact between a mafic dyke and reddened augen gneiss Mafic dyke cutting through basement augen gneiss and cut off by the sub-Nama unconformity, Fish River Canyon

 

 Contact between the mafic dyke and the basement augen gneiss, Fish River Canyon

Tightly folded Gariep strata of the Driegatberg, Rosh Pinah