Eifelian–Givetian (Middle Devonian) high-paleolatitude storm- and wave-dominated shallow-marine depositional systems from the Bidouw Subgroup (Bokkeveld Group) of South Africa

2019 ◽  
Vol 89 (11) ◽  
pp. 1140-1170 ◽  
Author(s):  
Cameron R. Penn-Clarke ◽  
Bruce S. Rubidge ◽  
Zubair A. Jinnah
Keyword(s):  
South Africa ◽  
Sea Level ◽  
Middle Devonian ◽  
Large Scale ◽  
Sea Level Change ◽  
Relative Sea Level ◽  
Shallow Marine ◽  
Sequence Stratigraphic ◽  
Level Change ◽  
Depositional Systems

ABSTRACT The sedimentology of the Eifelian–Givetian (Middle Devonian) Bidouw Subgroup in the Clanwilliam Sub-basin of South Africa has been reassessed. Four distinct lithofacies associations are recognized (A–D) and are representative of the deposits of offshore (Os), offshore transition zone to distal lower shoreface (OTZ-dLSF), proximal lower shoreface (pLSF), and upper shoreface–beach (USF-Beach) paleoenvironments. These paleoenvironments are arranged as several T-R-controlled storm- and wave-dominated shallow-marine depositional systems. The presence of storm- and wave-dominated shallow-marine depositional systems in the Bidouw Subgroup, as well as the preceding Emsian–Eifelian (Early–Middle Devonian) Ceres Subgroup provides an alternative explanation to storm- and wave-dominated delta and mixed wave- and-tide-dominated delta models that have previously been proposed for the Bokkeveld Group. Sequence-stratigraphic analysis of the Bidouw Subgroup suggests that although sedimentation occurred during two large-scale second-order transgressive events, the succession was predominantly regressive. Third-order and fourth-order transgressive–regressive (T-R) sequences are more numerous with respect to the preceding Ceres Subgroup, suggesting that the driver for T-R cyclicity and relative sea-level change was more active during the Eifelian–Givetian than in the Emsian–Eifelian of South Africa. These data are important since relative sea-level change and its effects on paleoenvironmental change at high paleolatitudes during the Devonian Period are poorly known.

scholarly journals Sequence stratigraphy and eustatic sea-level change: the role of micropalaeontology

1992 ◽  
Vol 11 (2) ◽  
pp. 112-112 ◽  
Author(s):  
M. D. Simmons ◽  
C. L. Williams
Keyword(s):  
Sea Level ◽  
Sequence Stratigraphy ◽  
Short Note ◽  
Sea Level Change ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Sequence Stratigraphic ◽  
Level Change ◽  
Sedimentary Sequences

Abstract. Following the May 1992 meeting in Dijon, which initiated an international project on the “Sequence Stratigraphy of European Basins”, it seems an appropriate time to consider the contribution micropalaeontology can make to the science of sequence stratigraphy. In this short note, we assume that readers are familiar with sequence stratigraphic terminology; if not, see Van Wagoner et al. (1988).WHAT ARE THE CHALLENGES FACING SEQUENCE STRATIGRAPHY?Demonstrating global eustatic sea-level change. We accept that the basic sequence stratigraphy model put forward by Peter Vail and his colleagues (see Van Wagoner et al., 1988 for a summary) is a powerful tool for describing many sedimentary successions, and that the associated eustatic sea-level curve (Haq et al., 1987) has some validity. Our own observations on numerous sedimentary sequences around the world suggest that local and global eustatic events exist, and that relative sea-level curves can be constructed, but it should be remembered that the timing and magnitude of many global eustatic events are still to be established. As most workers in the field will be aware, much of the evidence to support the Haq et al. curve has not been published. The Sequence Stratigraphy of European Basins Project will go some way to rectify this, but it should be borne in mind that there can be an unfortunate tendency to use the Haq et al. curve for dating in its own right - i.e. fitting relative sea-level changes seen in a succession to the curve. If this is done, then the global . . .

scholarly journals On the geophysical processes impacting palaeo-sea-level observations

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yusuke Yokoyama ◽  
Anthony Purcell
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Global Climate ◽  
Sea Level Change ◽  
Sea Level Changes ◽  
Factors Affecting ◽  
Ice Volume ◽  
Level Change ◽  
Recent Developments ◽  
Geophysical Processes

AbstractPast sea-level change represents the large-scale state of global climate, reflecting the waxing and waning of global ice sheets and the corresponding effect on ocean volume. Recent developments in sampling and analytical methods enable us to more precisely reconstruct past sea-level changes using geological indicators dated by radiometric methods. However, ice-volume changes alone cannot wholly account for these observations of local, relative sea-level change because of various geophysical factors including glacio-hydro-isostatic adjustments (GIA). The mechanisms behind GIA cannot be ignored when reconstructing global ice volume, yet they remain poorly understood within the general sea-level community. In this paper, various geophysical factors affecting sea-level observations are discussed and the details and impacts of these processes on estimates of past ice volumes are introduced.

scholarly journals Refining Estimates of Polar Ice Volumes during the MIS11 Interglacial Using Sea Level Records from South Africa

2014 ◽  
Vol 27 (23) ◽  
pp. 8740-8746 ◽  
Author(s):  
Florence Chen ◽  
Sarah Friedman ◽  
Charles G. Gertler ◽  
James Looney ◽  
Nizhoni O’Connell ◽  
...  
Keyword(s):  
South Africa ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Sea Level Change ◽  
Polar Ice ◽  
Level Change ◽  
Isostatic Adjustment ◽  
West Antarctic ◽  
Numerical Predictions

Abstract Peak eustatic sea level (ESL), or minimum ice volume, during the protracted marine isotope stage 11 (MIS11) interglacial at ~420 ka remains a matter of contention. A recent study of high-stand markers of MIS11 age from the tectonically stable southern coast of South Africa estimated a peak ESL of 13 m. The present study refines this estimate by taking into account both the uncertainty in the correction for glacial isostatic adjustment (GIA) and the geographic variability of sea level change following polar ice sheet collapse. In regard to the latter, the authors demonstrate, using gravitationally self-consistent numerical predictions of postglacial sea level change, that rapid melting from any of the three major polar ice sheets (West Antarctic, Greenland, or East Antarctic) will lead to a local sea level rise in southern South Africa that is 15%–20% higher than the eustatic sea level rise associated with the ice sheet collapse. Taking this amplification and a range of possible GIA corrections into account and assuming that the tectonic correction applied in the earlier study is correct, the authors revise downward the estimate of peak ESL during MIS11 to 8–11.5 m.

scholarly journals Corrigendum: Late Devensian and Holocene relative sea-level change in North Wales, UK

2011 ◽  
Vol 26 (7) ◽  
pp. 768-768
Author(s):  
M. J. Roberts ◽  
J. D. Scourse ◽  
J. D. Bennell ◽  
D. G. Huws ◽  
C. F. Jago ◽  
...  
Keyword(s):  
Sea Level ◽  
Sea Level Change ◽  
Relative Sea Level ◽  
Level Change ◽  
North Wales

scholarly journals Relative sea‐level change and postglacial isostatic adjustment along the coast of south Devon, United Kingdom

2008 ◽  
Vol 23 (5) ◽  
pp. 415-433 ◽  
Author(s):  
Anthony C. Massey ◽  
W. Roland Gehrels ◽  
Dan J. Charman ◽  
Glenn A. Milne ◽  
W. Richard Peltier ◽  
...  
Keyword(s):  
United Kingdom ◽  
Sea Level ◽  
Sea Level Change ◽  
Relative Sea Level ◽  
Level Change ◽  
Isostatic Adjustment

Historical rates of salt marsh accretion on the outer Bay of Fundy

2001 ◽  
Vol 38 (7) ◽  
pp. 1081-1092 ◽  
Author(s):  
Gail L Chmura ◽  
Laurie L Helmer ◽  
C Beth Beecher ◽  
Elsie M Sunderland
Keyword(s):  
Salt Marsh ◽  
Sea Level ◽  
Sea Level Change ◽  
Bay Of Fundy ◽  
Relative Sea Level ◽  
Early 19Th Century ◽  
Level Change ◽  
Pollen Stratigraphy ◽  
Accretion Rates ◽  
Marsh Accretion

We examine rates of salt marsh accumulation in three marshes of the outer Bay of Fundy. At each marsh we selected a site in the high marsh with similar vegetation, and thus similar elevation. Accretion rates were estimated by 137Cs, 210Pb, and pollen stratigraphy to estimate rates of change over periods of 30, 100, and ~170 years, respectively. These rates are compared with records from the two closest tide gauges (Saint John, New Brunswick, and Eastport, Maine) to assess the balance of recent marsh accretion and sea-level change. Averaged marsh accretion rates have ranged from 1.3 ± 0.4 to 4.4 ± 1.6 mm·year–1 over the last two centuries. Recent rates are similar to the rate of sea-level change recorded at Eastport, Maine, suggesting that they are in step with recent sea-level change but very sensitive to short-term variation in relative sea level. Based on the pollen stratigraphy in the marsh sediments, the marsh accretion rate was higher during the late 18th to early 19th century. Higher rates probably were due to local increases in relative sea level as a result of neotectonic activity and may have been enhanced by increased sediment deposition through ice rafting.

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