Thesis (MSc)--University of Stellenbosch, 1989. / AFRIKAANSE OPSOMMING: Senosoiese sedimente langs die suidooskus van die
Kaapprovinsie is periodiek deur verskeie outeurs vir meer as
'n eeu bestudeer. In hierdie aanbieding word die
Iiteratuur saamgevat en vele dubbelsinnige stratigrafiese
onderverdelings en definisies opgeklaar.
Die Senosoiese afsettings kan volgens oorsprong
geklassifiseer word as marien, eolies en fluviaal. Die
mariene afsettings, synde strand-, nabystrand-, estuarien of
lagunale afsettings geassosieerd met transgressiewe/
regressiewe kusIyne, word nou op grond van kenmerkende
litologiese, paleontologiese sowel as ouderdomsverskille
onderverdeel in die Paleogeen Bathurst, Neogeen Alexandria
en Kwaternere Salnova Foraasies. Die Laat-Plioseen tot
Vroeg-Pleistoseen Nanaga Formasie, Middel- tot Laat-
Pleistoseen Nahoon Formasie en die Holoseen Schel• Hoek
Formasie vorm die kus-eoliese afsettings. AI die mariene
en marienverwante (eoliese} formasies, gekenmerk deur
kalkige klastiese afsettings, is saamgegroepeer in 'n
nuutgedefinieerde Algoa Groep. Fluviale afsettings word
onderverdeel in die Martindale, Kinkelbos, Bluewater Bay,
Kudus Kloof en Sunland Formasies.
Die onderskeie afsettings word gekorreleer met verskillende
seevlakstande deur geologiese tye.
Die vroegste Senosoiese
transgressiewe/regressiewe siklus het in die Vroeg-Paleoseen
begin en die hoogste aangetekende elevasie vir die era
bereik. Die Bathurst Formasie is waarskynlik gedurende
hierdie regressie afgeset. 'n Tweed~ kleiner transgressie/
regressiesiklus het plaasgevind gedurende die Laat-Eoseen
tot Vroeg-Oligoseen. Sover tans bekend, kan geen afsetting
in die dagsoomgebied van die Algoa Groep definitief met
hierdie siklus in verband gebring word nie. Die volgende
siklus, wat 'n transgressiewe maksimum van c. 250 m bereik
het, het begin in die Middel-Mioseen en verstryk in die
Vroee Plioseen. Mariene planasie van die kusplatform het
gedurende die transgressie plaasgevind terwyl die Alexandria
Formasie wat tans bo 120 m geleë is, gedurende die regressie
afgeset is. Die Vroeg-Plioseen transgressie het waarskynlik
'n maksimum huidige hoogte van c. 120 m bereik,
waartydens o.a. die 120 m branderstoep en "Humansdorpterras"
gekerf is. Die Alexandria Formasie tans geleë tussen 60 en
120 m, is afgeset gedurende die Laat-Plioseen regressie.
Hierdie regressie het verskeie relatief lang stilstande, wat
waarskynlik die 106-m, 90- tot 100-m en 84-m branderstoepe
verklaar, ondervind. Selfs die 60-m en 52-m kuslyne kon
tydens hierdie regressie gevorm het. Voorlopige
paleontologiese getuienis dui egter daarop dat die 60-m
kuslyn 'n transgressiewe maksimum van 'n daaropvolgende
siklus verteenwoordig, gevolg deur 'n regressie met minstens
een beduidende stilstand by 52 m. Die Alexandria Formasie
geleë tussen c. 60 en 30 m, is waarskynlik gedurende hierdie
regressie gedeponeer, waartydens ook die Bluewater Bay,
Kinkelbos en Kudus Kloof Formasies afgeset is.
Gedurende die Kwaternêre transgressie/regressiesiklusse,
waarvan minstens vier aangedui word, is die Salnova Formasie
(afwesig bo 30 m) afgeset. Die Nahoon Formasie, wat ook op
groot skaal op die kontinentale bank ontwikkel is, is
gedeponeer gedurende die laaste twee Pleistoseen glasiale
toe seevlakke tot benede -100 m gedaal het. Die Schelm
Hoek Formasie wat tans nog afgeset word, het ontstaan uit
die transgressiewe maksimum van die Flandriese transgressie
aan die begin van die Holoseen. / ENGLISH ABSTRACT: Cenozoic sediments along the south-east coast of the Cape
Province have been studied intermittently for more than a
century by various authors. In this presentation the
literature is reviewed and many ambiguous stratigraphic
subdivisions and definitions are clarified.
The Cenozoic deposits can be classified, according to
origin, as marine, aeolian and fluvial. The marine
deposits, being
lagoonal deposits
either beach, nearshore, estuarine or
associated with transgressive/regressive
shorelines, are now subdivided on the grounds of distinct
lithological, palaeontological as well as age differences
into the Palaeogene Bathurst, Neogene Alexandria and
Quaternary Salnova Formations. The Late Pliocene to Early
Pleistocene Nanaga Formation, the Hiddle to Late Pleistocene
Nahoon Formation and the Holocene Schelm Hoek Formation
constitute the coastal
and marine-related
aeolian deposits. All the marine
(aeolian) formations, which are
characterised by calcareous clastics, have been grouped
together in a newly defined Algoa Group. Fluvial
deposits are subdivided into the Martindale, Kinkelbos,
Bluewater Bay, Kudus Kloof and Sunland Formations.
The various deposits are correlated with different stands of
sea-level through geological time. The earliest Cenozoic
transgression/regression cycle started in the Early
Palaeocene and reached the highest recorded altitude for the
era. The Bathurst Formation was probably deposited during
this regression. A second lesser transgression/regression
cycle occurred in the Late Eocene to Early Oligocene. As
far as is presently known, no deposit in the outcrop area of
the Algoa Group can be definitely related to this cycle.
The next cycle, which reached a transgressive maximum of c.
250 m, started in the Middle Miocene and terminated in the
Early Pliocene. Marine planation of the coastal platform
took place during the transgression, whilst the Alexandria
Formation presently situated above 120 m, was deposited
during the regression. The Early Pliocene transgression is
considered to have reached a maximum present-day elevation
of c. 120 m, during which the 120 m marine bench and
"Humansdorp Terrace", amongst others, were carved. The
Alexandria Formation presently situated between 60 and
120 m, was deposited during the Late Pliocene regression,
which experienced several relatively long stillstands which
probably account for the 106 m, 90 t.o 100 m and 8.4 m
benches. Even the 60 m- and 52 m-shorelines could have
been formed during this regression. Preliminary
palaeontological evidence, however, suggests that the 60 m shoreline
represents a transgressive maximum of a subsequent
cycle followed by a regression with at least one significant
stillstand at 52 m. The Alexandria Formation situated
between c. 60 and 30 m, was probably deposited during this
regression, which also saw the deposition of the Bluewater
Bay, Kinkelbos and Kudus Kloof Formations.
During the Quaternary transgression/regression cycles, of
which at least four are indicated, the Salnova Formation
(absent above 30 m) was deposited. The Nahoon Formation,
which is also extensively developed on the continental
shelf, was deposited during the last two Pleistocene
glacials, when sea-levels receded to less than -100 m. The
Schelm Hoek Formation, which is still being deposited,
originated from the transgressive maximum of the Flandrian
transgression at the start of the Holocene.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/67134 |
| Date | 08 1900 |
| Creators | Le Roux, F. G. |
| Contributors | Le Roux, J. P., Halbich, I. W., Stellenbosch University. Faculty of Science. Dept. of Earth Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xvi, 247 p. : ill. |
| Rights | Stellenbosch University |
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