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The Knysna Lignites: a new look at the Neogene palaeoecology of South Africa

This project is being conducted with Professor Peter Holmes (University of the Free State) and Dr Dave Roberts (Council for Geoscience, South Africa) and is funded by the Palaeontological Scientific Trust (South Africa). The work focuses on enhancing our understanding of the ecological evolution of southern Africa, and in particular the floral evolution of the region during the last c. 20 million years. Our understanding of South Africa’s remarkable floral diversity and its sensitivity of long-term environmental change is extremely poor, even for the Late Quaternary. For the Miocene and Pliocene it is extremely poor, but it is during these epochs that many of the botanical families in the Cape Flora are thought to have diversified. At the same time, much of the western half of the sub-continent became progressively more arid as the Benguela upwelling zone developed. Lignite deposits on the south coast near to the town of Knysna have been known about for some time, but have received little systematic study. Our recent work (Carr et al., 2010) suggested that these may be much younger (post mid-Miocene) than previously thought, placing their deposition within this key late Neogene diversification / aridification period. The project will use a combination of traditional palaeoecological techniques (e.g. pollen analysis), field mapping and cutting edge stable isotope geochemistry to refine our understanding of regional palaeoenvironments and palaeoecologies during this important period in southern Africa’s climatic and ecological evolution.

Novel bio-molecular insights into dryland ecosystem dynamics

The project, initially funded by the Leverhulme Trust (2010-2012), concerns the composition and fate of organic matter (OM) in semi-arid environments. Dryland environments are traditionally poor settings for organic matter preservation and tracking the fate of organic carbon in these regions is challenging. The work focuses on the processes associated with the preservation/degradation plant-derived macromolecules in drylands. It is hypothesised that some classes of recalcitrant macromolecules will be preferentially preserved within dryland soils, although this has never been directly tested. More fundamentally, there have been relatively few studies on the composition of organic matter and fundamental mechanisms of OM degradation within semi-arid environments. This project focuses on the drought-adapted vegetation and associated soils of the succulent Karoo biome of South Africa, spanning both north-south and east-west climatic gradients within this region. It involves the application of a range of techniques, including lipid biomarker analysis, compound specific stable isotope analyses and py-GC/MS analyses of plants, modern soils and Quaternary sedimentary sequences. The work is being carried out at Leicester by Dr Andy Carr and Dr Arnoud Boom in conjunction with Professor Mike Meadows (University of Cape Town) and Dr Brian Chase (Institut des Sciences de l’Evolution de Montpellier).

Novel bio-molecular insights into dryland ecosystem dynamics.jpg

Left: Aloë dichotoma (Quiver Tree) – impressive tree aloes in the Northern Cape Province of South Africa.
Right: View from Van Rhyn’s Pass, overlooking the Knersvlakte of the northern Western Cape Province.

Long term palaeoenvironmental and palaeoecological change the Llanos savannas, Colombia

This new research project, funded by the National Geographic Society, is being carried out in collaboration with Dr Simon Armitage from Royal Holloway, University of London and Professor Bibiana Bilbao from Universidad Simón Bolivar (Caracas). The project is investigating the palaeoenvironmental record of the tropical savannas of Colombia (Llanos Orientales). In particular, we are focusing on the relict (stabilized) dune systems, which have been previously hypothesized to have formed during phases of aridity during the Late Quaternary. The dunes are found in close association with wetlands and palm swamps, which is also enabling the development of complementary palaeoecological archives (pollen and stable isotope records).

lqp sampling dune sands

Sampling dune sands in the Colombian Llanos.

Quaternary evolution of the southern and western Cape coastlines

Ongoing research is investigating the Tertiary-Quaternary marine marginal sedimentary archives of the southern and western coastlines of South Africa. These deposits, which comprise cemented ancient dunes (“aeolianite”) and raised marine sediments contain abundant palaeoenvironmental evidence; including evidence for the human occupation of this coastline throughout the Late Pleistocene. This research has developed the first systematic chronologies of aeolianite deposition in this region, while ongoing work is exploring the use of stable isotope data from terrestrial gastropods and marine bivalves for palaeoenvironmental and palaeo sea surface temperature reconstructions.

Quaternary evolution of the southern and western Cape coastlines.jpg

Left: Tertiary and Quaternary coastal sediment sequences exposed on the West Coast of South Africa.  Right: Cemented dune sands (aeolianite) overlying a buried soil (palaeosol) dating to the last interglacial period (c. 125,000 years ago) Still Bay, South Africa.

Biomarker and organic geochemical proxies for palaeoecological change in southern Africa

Current research is investigating the use of plant biomarkers and stable isotopes as a means to reconstruct palaeoecological change in southern Africa. This includes assessing the preservation of recalcitrant plant-derived macro-molecules in dryland soils and sediments using pyrolysis gas chromatography mass spectrometry techniques (Py-GC/MS). Such compounds may be preferentially preserved in dryland regions and may offer insights into long-term ecological change in environments that are generally poor at preserving organic matter over long timescales.

Biomarker and organic geochemical proxies for palaeoecological change in southern Africa

Left: A pyrogram from a typical soil, revealing the presence of plant-derived lignin (phenols) and aliphatic macromolecules. Right: Chromatogram of a lipid extract from a fossil Dassie midden, revealing a collection of vegetation and animal-derived metabolites.

Late Quaternary palaeoenvironmental reconstruction in the Tehuacán Valley, Mexico

The semi-arid Tehuacán Valle in south central México was an important region of cultural development in Mesoamerica and is also the place where domesticated maize originated. It is currently recognized as an area of outstanding biological endemism and is one of the most bio-diverse dryland ecosystems of the world. This cultural and natural diversity has taken shape under the influence of climatic variations during the thousands of years and to understand its origins and maintenance it is crucial to know the magnitude and directions of these past environmental changes. This research utilises the Quaternary geomorphologic and stratigraphic records, preserved in this region and is a range of geochemical geochronological techniques (radiocarbon and luminescence dating. These data will provide an environmental context for the evolution of major patterns of floral diversity in the Tehuacán Valley.

Late Quaternary palaeoenvironmental reconstruction in the Tehuacán Valley, Mexico

The Late Quaternary and Early Holocene of the Sahara Desert

The palaeoenvironmental reconstruction of drylands is a difficult task, largely because many drylands are erosional in nature, and there is poor preservation of both evidence and potentially dateable material.  Work conducted by Sue McLaren and collaborators is currently focussing on palaeoenvironments in the Sahara Desert and includes the analysis of lake deposits associated with the early Holocene climate optimum, as well as geoarchaeological investigations.

The Late Quaternary and Early Holocene of the Sahara Desert.jpg

Organic geochemistry of Laguna Pedro Palo

Laguna Pedro Palo lies at 2200 m above sea-level in the Colombian Eastern Cordillera and represents a strategic location for reconstructing of the region's palaeoecological dynamics. A 12 m sedimentary record retrieved from 20 m of water provides a continuous record of environmental change over the last 40,000 years. 'Fossil' lipid biomarkers are providing fascinating insights into the changing biogeochemical pathways operating within the lake water, as well as changes in the regional ecology surrounding the site.

Organic geochemistry of Laguna Pedro Palo

Left:  Coring the Laguna Pedro Palo. Right: Chromatogram showing a range of unique biomarkers from Laguna Pedro Palo, providing insights into an ancient aquatic environment.

High-resolution of palaeoenvironmental change at Fúquene Lake, Colombia

Located on the High Plain of Bogota-Bocayacá Province (2500 m above sea-level), the Fúquene Lake sedimentary record reveals high resolution evidence of Tropical Andean palaeoenvironmental change through Marine Isotope Stages 9-3 (c. 350,000-30,00 years ago). A multi-proxy approach (XRF, fossil pollen and diatom analyses, particle-size analyses) is providing unprecedented insights into Neotropical environmental change during the Middle to Late Pleistocene.

High-resolution of palaeoenvironmental change at Fúquene Lake, Colombia

Palaeoecology of the Grand Savanna

In conjunction with Universidad Simón Bolivar, Venezuela, this project is investigating the vegetation dynamics and fire history at the Grand Savannas of the Canaima Natural Park in Venezuela.  Application of various proxy techniques including fossil pollen and charcoal analyses, as well as stable isotope analyses at a range of sites will allow the reconstruction of a shifting forest –savanna transition throughout the Holocene.  Also under investigation is the historical human impact by the Pemon community, which has been associated with forest fragmentation.

Palaeoecology of the Grand Savanna

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