Dykes Photogallery

OTHER DYKE SWARMS
(Located in the SW and NW Cape region)

DYKES ASSOCIATED WITH THE CAMBRIAN CAPE GRANITE SUITE, SW CAPE


Dolerite dyke cutting coarse porphyritic Cape Granite, Hoedjies Punt, Saldanha Bay	Dolerite dyke filling an en echelon fracture set, Hoedjies Punt, Saldanha Bay	Mafic dykes (hornblende lamprophyre) intruding Vredenburg Granite, Groot Paternoster Point	Mafic dyke cutting across magmatic layering in Vredenburg Granite, Paternoster

En-echelon dyke geometry, Paternoster	Partly digested xenoliths in a mafic dyke, Paternoster	Deflected mafic dyke, Cape Columbine	Two generations of mafic dyke cutting at right angles, Cape Columbine

CRETACEOUS-TERTIARY ALKALINE DYKES
(Lamprophyres, Bostonites and Dolerites in Western Namaqualand)


Brand-se-baai, an inlet eroded into a wide mafic dyke, Atlantic Coast	Remnant of the mafic dyke preserved against Gariep sediments (hornfelsed limestones), Brand-se-baai	Alkaline lamprophyre sheet cutting thinly bedded metaquartzites, Brand-se-baai	Alkaline lamprophyre sheet cutting thinly bedded metaquartzites, Brand-se-baai

Alkaline lamprophyre dyke cutting thinly bedded metaquartzites, Brand-se-baai	Contact between brown lamprophyre dyke and quartzites, Brand-se-baai	Dark dolerite dyke, Brand-se-baai	Alkaline lamprophyre dyke cutting metacrbonates, Brand-se-baai

Bostonite dyke (syenitic composition) cutting Namaqua gneisses	Dolerite dyke cutting Namaqua gneisses	Dolerite dyke cutting Namaqua gneisses	Dolerite dyke cutting Namaqua gneisses

Thin stringer of dolerite within augen gneiss	Dolerite dyke cutting Namaqua gneisses	Epidote-rich alteration zones following fractures in dolerite dyke	Thin septa and screens of gneiss country rock with a dolerite dyke

Glomeroporphyritic dyke cutting the wide dolerite dyke	View over the later glomeroporphyritic dyke as it enters the wide dolerite dyke	Close up of the glomeroporphyritic dyke cutting granite gneiss	Dark bostonitic dyke cutting Namaqua pink gneisses

MIDDELPLAAT DYKE SWARM
(Late orogenic potassic lamprophyre dykes associated with the Spektakel intrusive suite, Western Namaqualand)


Middelplaat potassic lamprophyre dyke swarm, Steinkopf	Deformation/recrystallisation fabric developed in a Middelplaat lamprophyre dyke	Reworking of the dyke/gneiss contact, Middelplaat dyke, Steinkopf

KAROO DOLERITES IN THE CALVINIA DISTRICT
(Intrusive phase of the Karoo continental flood basalt province)


Hantam dolerite sill, forming an impressive escarpment overlooking Calvinia in the western Karoo	Basal contact of the Hantam dolerite sill	Thermal induration of the Karoo strata (Ecca shales) beneath the basal contact of the Hantam dolerite sill	Irregular trangression of the basal intrusive contact down into the Karoo strata; a vein of remobilised felsic material penetrates up into the dolerite

Hantam dolerite sill outcropping on the skyline, showing well devloped columnar jointing	Hantam dolerite sill overlooking the town of Calvinia	Hangnest dolerite sill, a highly evolved quartz dolerite that featured in the benchmark paper by Walker and Poldervaart	Hangnest dolerite sill, outcrops in the foreground, with the cliff former above built of hornfelsed Karoo sediments

Dolerite dyke cutting Ecca shales of the Karoo sequence, Blaauwkrantz Pass, Calvinia district

KAROO IGNEOUS PROVINCE
(Intrusives and Extrusives from other parts of Southern Africa)


Inclined dolerite sheet intruding Beaufort strata, Barkly Pass	Inclined dolerite dyke cutting Karoo red beds, Golden Gate; note thermal effects along contacts	Inclined dolerite sheet cutting Karoo red beds, Golden Gate; note thermal effects along the contacts	Thin inclined dyke cutting Karoo sandstones of the Clarens Formation, Barkly Pass

Dolerite dyke cutting Calrens Formation sandstones, W Lesotho	Dyke cutting basalt lavas, E Lesotho	Inclined low angle sheet cutting Beaufort strata, N1 highway near Colesberg	Xenolith of Karoo sediment enclosed and fractrured by dolerite, Barkly Pass

Tongue of Karoo sediment prised off the roof of a large dolerite sill, N3 highway between Pietermaritzburg and Durban	Thin screen of Karoo sediment in dolerite, transforms from baked sediment on right to remobilised granophyre at the left	Partly detached screens of Karoo strata in the roof of a large dolerite sill, N3 highway between Pietermaritzburg and Durban	Vertical jointing in the dolerite controls the development of impressive mesa topography, Valley of Desolation, near Graaf Reinet

Columnar jointing developed in a dolerite sill, Eastern Cape	Curvilinear columnar jointing developed in an intrusive plug of dolerite within basalt lava flows, Eastern Cape	Three Sisters, Beaufort West district, formed by the differential weathering of a dolerite sill; featured in the benchmark paper by Walker and Poldervaart	Execution Rock, an isolated mesa of dolerite, between Umtata and Port St Johns (featured in the benchmark paper on the Karoo Dolerites by Walker and Poldervaart in 1949)

Mont aux Sources, in the famous Drakenberg Escarpment of Kwazulu-Natal; Karoo basalt lavas build the sheer cliffs	The sheer Drakensberg Escarpment of Karoo basalt looms over the underlying Karoo strata, Mont aux Sources	Pipe amygdales developed at the base of a basalt lava flow, Sani Pass	Pillow structures developed in subaqueous basalt lavas, Eastern cape

ETENDEKA IGNEOUS PROVINCE
(Dolerite sills, dykes; basalts and quartz latites in north-western Namibia)


Isolated peaks carved from basalt and quartz latite lavas, with a dolerite sill emplaced under Karoo sandstones in the foreground, Huab River area	Andy Duncan, a long-time researcher of the Etendeka, surveys the vast plateau lava field	Dolerite dykes cutting through the basement metamorphic complex of the Pan-African Damara Sequence, near Brandberg