Professor Roderick Brown
- Professor of Earth Sciences (School of Geographical & Earth Sciences)
Developing and designing new applications of the analytical methods of Fission Track Analysis and U-Th/He Analysis of accessory minerals to constrain tectonic and geomorphic processes. Specific areas of interest include applications to understanding long-term landscape evolution, determining erosion rates and sediment yields over geological time scales and understanding the role of tectonics, climate and eustasy in controling rates of long-term landscape change.
Terrestrial Cosmogenic Nuclides
Developing methods and strategies for integrating in-situ produced cosmogenic nuclide abundance measurements on surface mineral samples with low-temperature thermochronologic data to constrain rates of landscape forming processes over geologically relevant time scales.
Geodynamics & Landscape Evolution
Investigating the coupling between deep Earth processes (like mantle convection) and the generation and evolution of large scale topography.
Remote Sensing & Digital Geoscience
Developing new strategies and methods for using high resolution satellite derived data sets (such as multi & hyperspectral surface reflectance data and digital elevation data) to measure and visualise the Earth's surface topography with the aim of improving understanding of the processes responsible for controlling its morphology and evolution.
Augrabies Gorge, Orange River, South Africa
ASTER VNIR Image (321RGB) draped over a 30m resolution digital elevation model of the landscape derived from the nadir and backward looking IR image pair (ASTER Band 3N and 3B) (Top=East). Note the strong structural control on the morphology of the gorge (alignment of main channel with dominant fracture/joint orientations). The tributary draining to the Orange River from the north (i.e. left hand side) is the Molopo River.
Brandberg and Messum Crater, Namibia
Landsat 742RGB Image of Brandberg and Messum Crater, both features are early Cretaceous alkali-granite ring complexes which intrude deformed Pan African (~500Ma) age metamorphic rocks of the Damara Orogen (Top=North).
Amis Valley, Brandberg, Namibia
Photograph looking west-northwest showing remnants of Karoo (Permo-Triassic) volcano-sedimentary strata dipping gently to the north and into the ring fault marking the caldera structure of the Early Cretaceous Brandberg alkali-granite ring complex as shown in the satellite image above (Photograph: Roderick Brown).
The image below combines two different digital data sets (seasat marine gravity data and 1km resolution digital elevation data) to represent the topography of the African continent and the tectonic fabric within the surrounding ocean basins.
Large scale morphotectonic setting of the African continent
Image created with ERMapper using the GTOPO30 digital elevation data combined with marine gravity data from Sandwell and Smith (1997).
Sandwell, D. T., W. H. F. Smith, Marine gravity anomaly from Geosat and ERS 1 satellite altimetry, Journal of Geophysical Research, v. 102, No. B5, p. 10039-10054, 1997.
Resolving the age of the first order topography of Africa
This project is funded by the Natural Environment Research Council (NERC) for 2010-2013.
Objectives: The primary objective of this project is to test the following hypothesis;
Hypothesis: The first-order topography of Africa is younger than 30 million years old, which will resolve a long standing debate concerning the origin and age of the first-order topography of Africa. The resulting data will also provide detailed information relevant to the discussion concerning how large passive continental margin escarpments form by providing detailed quantitative estimates of the pattern and amount of erosion across the continental margin.
This objective will be achieved by;
1) Determining a high quality suite of AFT and AHe ages from 6 deep bore holes augmented by surface samples (total of c. 105 AFT and AHe analyses).
2) Determining robust, quantitative constraints on the timing, rate and magnitude of erosion that created the present escarpment in southern Africa by using a new technique enabling the joint inversion of both the AFT and AHe data to simultaneously obtain the thermal history and an estimate of the palaeothermal-gradient from a complete suite of bore hole samples.
Brown, R.W., Beucher, R., Roper, S. , Persano, C., Stuart, F. and Fitzgerald, P. (2013) Natural age dispersion arising from the analysis of broken crystals, part I. Theoretical basis and implications for the apatite (U-Th)/He thermochronometer. Geochimica et Cosmochimica Acta, 122, pp. 478-497. (doi:10.1016/j.gca.2013.05.041)
Brown, R., Summerfield, M.A. and Gleadow, A.J.W. (2002) Denudational history along a transect across the Drakensberg Escarpment of southern Africa derived from apatite fission track thermochronology. Journal of Geophysical Research: Solid Earth, 107, (doi:10.1029/2001JB000745)
Prof Roderick Brown, Dr Cristina Persano, Dr Fin Stuart (SUERC). 2010-2013. Resolving the age of the first order topography of Africa, £513,000, (Natural Environment Research Council (NERC), Grant Number NE/H008276/1). Co-investigators; Prof Kerry Gallagher, Géosciences Rennes, Université de Rennes 1, France.
A/Prof BP Kohn Prof AJ Gleadow Prof RW Brown Mr KG Osadetz. 2005-2007. From crystal to craton: unravelling the low-temperature thermal evolution and long-term stability of cratonic lithosphere, £113,000, (Australian Research Council Discovery Project DP0556642). Co-Investigators: BP Kohn, AJW Gleadow (University of Melbourne), KG Osadetz (Canadian Geological Survey).
Prof AJ Gleadow A/Prof BP Kohn Prof RW Brown Dr JM Fletcher Prof F Chemale Jr. 2006-2008. Reconstructing the morphotectonic evolution of rifted continental margins from low-temperature thermochronology, £130,000 (Australian Research Council Discovery Project DP0665127). Co-Investigators: Prof AJ Gleadow Dr BP Kohn (University of Melbourne), JM Fletcher (CICESE, Mexico), Prof F Chemale Jr. (Rio Grande do Sul University, UFRGS, Brazil).
Prof AJ Gleadow Dr BP Kohn Dr RW Brown Dr JM Fletcher. 2003-2005. Integrated Chronologies and Dynamics of Continental Extension, £120,000 (Australian Research Council Discovery Project DP0345931). Co-Investigators: Prof AJ Gleadow Dr BP Kohn (University of Melbourne), JM Fletcher (CICESE, Mexico).
Prof AJ Gleadow Dr BP Kohn Dr RW Brown Mr MS Krochmal. 2003-2006. Developing a fully automated analytical system for the next generation of fission-track thermochronology, £150,000 (Australian Research Council Linkage Project LP0348767). Co-Investigators: Prof AJ Gleadow Dr BP Kohn (University of Melbourne), MS Krochmal (Autoscan Systems Pty Ltd).