Lower Karroo Research Articles

The Karroo Graben of Metangula Northern Mozambique

This paper presents the results of the first detailed study of the whole of the Karroo Supergroup in the Metangula graben area. The deposit is situated principally in a graben structure with several smaller basins attached to it. The same Karroo graben system continues through Tanzania to coastal Kenya. The graben reaches a maximum depth of 10 km in the central part. The Karroo Supergroup is divided into three. The upper Karroo consists of more than 5 km of cyclical fluvial sequences forming the main graben infilling. The middle Karroo consists of 600 m of red mudstones with six fossil reptile bone levels. The lower Karroo consists of up to 330 m of sandstones and silts with frequent carbonaceous horizons. The datation of the deposits is based on one reptile zone ( Cistecephalus-Zone) and three palynological assemblage zones. This biostratigraphy was only established for the lower, the middle and lowest part of the upper Karroo. The lower Karroo is of a lower, middle and upper Ecca age (Permian). The middle Karroo is mainly of lower Beaufort age with the Ecca-Beaufort boundary situated at its lowermost part. The upper Karroo has a possible age of Beaufort up to Stormberg. The Permian-Triassic boundary corresponds roughly to the middle-upper Karroo transition and the upper Karroo probably continues into the early Jurassic. These rocks have been correlated with the Karroo sediments of other basins in southern and eastern Africa, on palaeontological and lithological grounds. It is postulated that the lower and middle Karroo were deposited in a lacustrine and/or fluvial regime in a basin with a different form than the upper Karroo graben. This graben was formed and filled during the upper Karroo by braided rivers and mostly by meandering rivers. The provisionary estimates of coal reserves in the Lunho Valley (SW edge of Metangula graben) is about 118 million and 376 million tons with ash contents of 35–40% or 40–45%, respectively.

Lower Karroo pollen and spore assemblages from the coal measures and underlying sediments of the Siankondobo coalfield, Mid‐Zambezi valley, Zambia

Abstract A palynological investigation of three boreholes in the Lower Karroo of the Kazinze area of the Siankondobo coalfield (GS 31, 35 and 36), has indicated pollen and spore assemblages in the coal measures and underlying arenaceous beds. The arenaceous sediments occuring at the bottom of the Karroo succession, are part of the Siankondobo Sandstone Formation. They are relatively unfossiliferous, although rare thin mudstone intercalations found in one of the boreholes (GS 36), contain assemblages dominated by monosaccate forms (Cannanoropollis obscurus and Plicatipollenites indicus). The Gwernbe Coal Formation, (Ecca series), which rests unconformably on the Siankondobo Sandstone Formation contains at its base a dominantly arenaceous member (Maamba Sandstone), and in one of the boreholes (GS 31) carbonaceous shale intercalations contain mainly trilete spores e.g. Punctatisporites gretensis, Acanthotriletes filiformis and Apiculatisporis levis. Overlying the Maamba Sandstone is a coal seam (Main Seam), which in turn is overlain by carbonaceous mudstones with thin coal seams. The Main Seam and the carbonaceous mudstones, are generally dominated by trilete and striate and non‐striate disaccate forms e.g. Punctatisporites gretensis, Acanthotriletes filiformis, A. tereteangulatus, Apiculatisporis levis, Leioiriletes directus, Protohaploxypinus limpidus, P. goraiensis, Vesicaspora ovala and V. potoniei; one notable exception to this is the upper part of GS 31 where Incertae sedis forms are the most common. The information obtained from the three wells suggests that three concurrent range zones can be recognized and a tentative zonation has been proposed. The Siankondobo coalfield assemblages show many similarities to those recorded from the lower and upper part of the Luwumbu Coal Formation some 1,000 kilometers to the north‐east, in the north Luangwa Valley of Zambia. Common to both areas is the high proportion of monosaccates in the beds underlying the carbonaceous sediments, followed by a general dominance of triletes and disaccates (striate and non‐striate) throughout most of the carbonaceous sediments, although dominance of triletes does occur in some instances in the lowermost carbonaceous beds.

Pollen and spore assemblages in the Luwumbu Coal Formation (Lower Karroo) of the North Luangwa Valley, Zambia, and their biostratigraphic significance

Pollen and spore assemblages from the Luwumbu Coal Formation (Lower Karroo) of the northern part of the Luangwa Valley, Zambia, are described. Two assemblages have been recognised, one from banded siltstones and mudstones in the lower part of the formation, and the other from the overlying carbonaceous sediments of the upper part of the formation. The older assemblage is dominated quantitatively by monosaccate forms ( Cannanoropollis and Plicatipollenites), and is generally similar to assemblages recorded by other workers from the Lower Karroo glacial and peri-glacial rocks of Zaire. The younger assemblages comprises a variety of supra-generic groups; the most common forms are disaccate (striate and non-striate) and trilete, but monosaccate, polyplicate, colpate, monolete and alete forms all occur. Genera which are especially common include Protohaploxypinus, Vesicaspora and Acanthotriletes. Cannanoropollis is abundant in the lower part of the younger assemblage. In general, the assemblage is similar to that recorded from the upper part of the Lower Coal Measures of the Ketewaka/Mchuchuma coalfield of Tanzania.

Palynological studies in the Lower Karroo of Rhodesia and the republic of South Africa

Twenty-four samples from Lower Karroo deposits in Rhodesia, Malawi, Mocambique and the Republic of South Africa, ranging in age from Middle Ecca to Lower Beaufort (Lower to Upper Permian) were macerated for palynological investigation. Seven samples yielded identifiable miospores and these are systematically described. They include 76 species comprising 45 spore-pollen genera, 13 belonging to triletes, 3 to monoletes, 2 to aletes, 10 to monosaccates, 5 to nonstriate bisaccates, 10 to striate-bisaccates and 1 each to polyplicates and monocolpates. Two new genera, viz., Surangeaspora and Sahialetes, and 12 new species are established (Leiotriletes giganticus, Lophotriletes robustus, Leschikisporis verrucosus, Surangeaspora coniata, S. densa, Zonareticulatisporis reticulata, Laevigatosporites longus, Sahialetes cephalus, S. minutus, Platysaccus monosaccoidus, Cuneatisporites juxtasaccus and Strotersporites longus). All 7 assemblages are dominated by bisaccates; pteridophytic spores represented by triletes and monoletes rank second. Monosaccates are ill-represented in all but one sample and aletes, polyplicates and monocolpates are rarely encountered. The palynological assemblages of the 7 samples are compared with other Gondwana assemblages from Africa and India.

Geology and Oil of Sakamena Basin, Malagasy Republic (Madagascar)

Structure and evolution of the Malagasy sedimentary belt were controlled, during Paleozoic and Mesozoic (Karroo) times, by north-northeast-south-southwest (East Coast)- and north-northwest-south-southeast (Bongolava)-trending faults. These two fault trends correspond to old lines of weakness (faults and flexures), which had a role in the Precambrian evolution of the Malagasy basement. In southwest Madagascar, the Manalobe, Ilova, and Iakomby (East Coast trend) fault lines are known to strike east-west, whereas the Andranopasy-Befandriana fault lines (Bongolava trend) strike southwestward. They were active during Karroo deposition, and they frame the region where Malagasy Karroo rocks are found. No Karroo formations are known southwest of the Andranopasy-Befandriana fault lines. On the northeast side of the fault lines a Lower Karroo basin (Sakoa) lies between the crystalline basement on the east and Manalobe en echelon lines on the west; Middle and Upper Karroo basins (Sakamena and Isalo) are between the basement on the east and the Ilova fault line on the west; a basin of mixed-facies sedimentary rocks of Middle Jurassic age (Dogger; Sakaraha basin) lies between the Ilova and Iakomby fault lines. West of the Iakomby fault a completely marine Liassic to Cretaceous series lies directly on the crystalline basement. The Sakoa, Sakamena, and Isalo basins originated by successive downward movements of the blocks outlined by the crystalline Precambrian backbone of Malagasy Island on the east and the Manalobe, Ilova, and Iakomby, Andranopasy-Befandriana faults, which always determined the western and southwestern boundaries of these basins. The Sakoa and Sakamena basins were of a mediterranean type, of restricted circulation. As indicated by several surface and subsurface hydrocarbon shows, naphthogenic conditions certainly existed within the Sakamena basin, and probably within Sakoa basin as well. From the structural and paleogeographic interpretation of Sakoa and Sakamena basins here presented, these basins, and particularly their cul-de-sac southern part, seem to deserve a reexamination from the point of view of oil exploration.

KAROSS: A computer‐aided storage and retrieval system for lower karroo stratigraphic palynology

Abstract KAROSS is a computer‐aided information storage and retrieval system for an information bank on Lower Karroo (Permian rocks of Africa) stratigraphic palynology. The information bank can be questioned either from the main computer installation or from remote terminal. The retrieval programs are designed to serve the general needs of a microfloral basinal analysis project. The types of problems solved by KAROSS are: (a) given one or more variables list one or more other(s); and (b) given one or more variables punch in a specified format one or more other(s) using (specified) codes for discrete data. The latter mode of output allows direct input into statistical or CALCOMP plotter programs.

A preliminary survey of Tilapia nurseries on Lake Kariba during 1967/68

Young Tilapia on Lake Kariba show a marked preference for shallow water but this is complicated by fluctuating lake levels, the floating weed Salvinia auriculata and the Tigerfish Hydrocynus vittatus. Tilapia nurseries found to date occur on shallow sloping shores predominently in the bush cleared areas and overlie Lower Karroo and Marly Sandstones. They are characterised by having a minimum of Salvinia coverage and a diversity of emergent and submerged aquatic plant growth arranged in fairly definate zones. Rising lake levels provide the most favourable conditions for young Tilapia in the shallow, temporary nurseries. Receding water levels force the fish into Cerotophyllum and Potamogeton beds of the deeper water. Tilapia do not leave cover until a length of between 17 cm and 19 cm is attained. Above this size they are considered reasonably safe from Hydrocynus. The impact on Tilapia of three nocturnal predators is considered insignificant at the present time. Salvinia has the effect of causing lower oxygen tensions and retardation of essential submerged aquatic vegetation and is considered detrimental to the Tilapia fishery. Submerged aquatic plants are highly desirable to protect young Tilapia from predation during receding water levels.

Possible ice-margin fluctuations in the Dwyka series in Rhodesia

The succession of Lower Karroo rocks in a horehole in the mid-Zambezi valley in Rhodesia is described. The Dwyka Series is 334 ft. thick and contains three cycles of coarse to fine sediments. These are interpreted as being controlled by the periodic advance and retreat of mountain glaciers situated on the east side of a fresh water lake. Each cycle consists of a coarse lower part, comprising tillites and/or fluvioglacial outwash gravels, followed by fine limnoglacial shales. The limnoglacial varvites give an indication of the length of time between a glacial retreat and readvance, which amounts to 15,000–20,000 years. It is considered that these intervals are too short for a tectonic control of sedimentation and that periodic advances and retreats of ice margins account better for the observed changes in the grade of the sediments. This fresh water Upper Carboniferous lake was marginally situated in relation to the main glaciated region of this part of Gondwanaland.

Lamellibranchia and Plants from the Lower Karroo Beds of Northern Rhodesia

AbstractA small collection of non-marine lamellibranchs and plants from the Madumabisa Shales of the Gwembi district of Northern Rhodesia is described. It includes a new species of the genus Kidodia, Palaeomutela rhomboidalis, and P. neglecta, associated with Glossopteris indica. The Madumabisa Shales may be correlated with similar beds in Southern Rhodesia assigned to the Tapinocephalus zone of the South African Lower Beaufort Series, and are of Upper Permian age.

The Total Solar Eclipse of October 1

THE weather conditions throughout the belt of totality in South Africa at the time of the total eclipse of October 1 were favourable and came up to the highest expectations. Dr. J. Jackson, H.M. Astronomer at the Cape, who made observations at Calvinia, described the eclipse as the best of the four that he had seen, and a perfect one in every way for astronomical observations. The sky was cloudless throughout and there was not even a breeze to shake the instruments. The conditions in the clear dry air of the arid regions of the Lower Karroo had promised to be so good that, before the War, extensive preparations had been made for observations to be made in this area by parties from Great Britain, Holland, the United States and elsewhere. It is unfortunate that the plans were almost completely upset by the War and that at a time when theoretical advance is dependent upon information that the eclipse observations were expected to provide, so favourable an opportunity has in large measure been lost.

The Calcareous Tufa Deposits of Buxton, near Taungs, Cape Province

A few miles to the west of, and running approximately parallel to, the main Rhodesian Railway from Kimberley and the Cape, there is a well defined line of hills, which is the eastern edge, and forms the scarp face of, the Kaap Plateau. Between this plateau and the railway is a belt of flat low-lying ground through which the Great Harts River runs southwards to the Vaal. In the vicinity of Taungs Station, between Warrenton and Vryburg, the scarp line is running nearly due north and south, and is only four to five miles distant from the railway; followed southwards it gets farther away from the railway and assumes a more south-westerly course. The Kaap Plateau is formed of dolomite of the Campbell Rand Series of the Transvaal System, corresponding to the dolomite in the Transvaal. The formation dips gently to the west at angles of 2–3°. Along the escarpment the dolomite rests conformably on dolomite shales, the latter frequently forming a series of terraces from the base of the plateau upwards. Lying unconformably against the dolomite to the east are the Lower Karroo Beds, which are largely concealed by secondary limestone and the recent alluvium of the Harts River basin.

II.—Notes on Fossil Plants from the Witteberg Series of Cape Colony

The specimens described below were sent to me for examination by Professor Schwarz from the Albany Museum, Grahamstown; they were collected from a thin seam of shale in the Grahamstown district in the Witteberg Series. This series, so named from the Wittebergen in the south of the Karroo, consists of a group of shales, sandstones, and quartzites, which are placed at the summit of the Cape Series below the plant-bearing and glacial beds of the Lower Karroo system. The Witteberg Series have afforded a very few fossils; these include imperfectly preserved fragments of Lepidodendroid plants and an abundance of the fossil known as Spirophyton, referred by some authors to the vegetable kingdom and by others regarded as probably inorganic.

II.—On the Dentition of the Palate in the South African Fossil Reptile Genus Cynognathus

The Cynodont reptilia from the Lower Karroo rocks of South Africa, characterized by relatively large incisors and relatively small, sharp-pointed, molar teeth, were grouped under the type genus Lycosaurus as Lycosauria. The removal of matrix from the palate of Ælurosaurus showed that in one member of the group at least the palate carries patches of teeth, each of which has the form of a small blunt flattened cone. From the fact that no Cynodont skull is available in which the mandible is free from the head, the nature of the palatal dentition is imperfectly known.

On a Collection of Fossil Plants from South Africa

1. I ntroduction . Since the publication of my account of the ‘Fossil Floras of Cape Colony’ in the fourth volume of the ‘Annals of the South African Museum’ (1903) additional records of some of the floras have been obtained from several localities by members of the Geological Survey of that Colony. It is this recently-acquired material, forwarded to me for examination by the Director of the geological staff, Mr. A. W. Rogers, which forms the subject of the present communication. The majority of the specimens were collected from the Molteno Beds and from the Burghersdorp Beds; a few were obtained from the Uitenhage Series, a higher geological horizon; and others from the Lower Karroo rocks. The Lower Karroo plants are dealt with in a separate paper by Mr. Leslie and myself on the Vereeniging flora; the Uitenhage species are described elsewhere. With the exception of Schizoneura africana , a Permian species from the lowest beds of the Beaufort Series, we are now concerned with the Molteno and Burghersdorp species alone. It is customary to divide the Karroo system of Cape Colony into three sections: the Lower Karroo, comprising, in ascending order, the Dwyka Series and the Ecca Series; the Middle Karroo or Beaufort Series; and the Upper Karroo or Stormberg Series. The uppermost strata of the Beaufort Series have been named the Burghersdorp Beds, from the typical development of the rocks in the neighbourhood of Burghersdorp, a small town about 30 miles south of the frontier of the Orange-River Colony, on the

On the Significance of Pneumatic Foramina in Fossil Bones

In a paper “On a Pneumatic Type of Vertebra from the Lower Karroo Rocks of Cape Colony” (Ann. & Mag. Nat. Hist., ser. VII, vol. xiv, November, 1904, pp. 336–344), by Professor H. G. Seeley, F.E.S., the author makes (on p. 341) some interesting remarks on pneumatic foramina in fossil bones which appear sufficiently important to reproduce here:—“Doubt has of late been current concerning the significance of pneumatic foramina in fossil bones, and is put forward verbally and in print by Professor H. F. Osborn. In an article in the Century Magazine for September, 1904, similar in scope to the lecture given at Cambridge in August to the British Association, he enunciates the same views. Writing of Ornitholestes, Professor Osborn remarks:— ‘Externally its bones are simple and solid-looking, but, as a matter of fact, they are mere shells, the walls being hardly thicker than paper, the entire interior of the bone having been removed by the action of the same marvellous law of adaptation which sculptured the vertebræ of its huge contemporaries. There is no evidence, however, that these hollow bones were filled with air from the lungs, as is the case of the bones of birds.’