Helen Lever

Sedimentology, especially of mixed carbonate-clastic systems Stratigraphy, especially Eocene-Oligocene Unconformities, their formation, interpretation and influence on fluid flow Paleoclimate change and paleoclimate proxies My research interests have arisen out of my experience, both of my graduate research projects involved sequence stratigraphic interpretations of shallow marine sediments, firstly a Tertiary mixed siliciclastic-carbonate succession from the West Coast of the South Island of New Zealand, then a purely siliciclastic Permian succession from the Carnarvon Basin, onshore Western Australia. I am now interested in pursuing stratigraphic questions relating to the Tertiary of New Zealand, but also a more general interest in how unconformities (sequence boundaries) form, how to recognise them in the rock record, and how they might affect fluid flow in subsurface successions. I also have an interest in the climatic change between early Tertiary Greenhouse conditions and late Tertiary Icehouse conditions, in part because of the relationship of this change to the New Zealand stratigraphy, but also because this climate change represents the most recent large-scale step change in the Earth’s climate, prior to any anthropogenic influence on the complex systems involved.

Born in Christchurch, New Zealand, my first two degrees were at Canterbury University. The focus of my masters project (supervised by Malcolm Laird and Doug Lewis) was on the sedimentology, paleogeography and basin development of the Eocene Rapahoe Group, a succession of calcareous sandstones and mudstones that accumulated in an active fault-controlled extensional basin. The thesis involved studies of the fauna for age control, including rhodoliths, echinoderms, brachiopods and microfossils, as well as sedimentological and ichnological studies for environmental controls. The basin was elongate and extended from south of the field area to the offshore to the north. The eastern margin was controlled onshore by the Paparoa Fault Zone, currently reactivated as a reverse fault, but the western margin was buried offshore by more recent sediments and consequently was not well known. The basin was subdivided into subsections controlled by changes in the basin-margin fault style and the presence of linking faults across the basin floor. The Rapahoe Group sediments comprised a transgressive-regressive sequence, bounded by unconformities. After finishing my MSc, I moved to Townsville, Queensland, Australia, where I did a PhD under the supervision of Professor Robert M Carter. My PhD project focussed on cyclicity in the Kennedy Group, mid to late Permian siliciclastic sediments in the Carnarvon Basin, Western Australia. The sediments are exposed in the Kennedy Ranges, and are noticeably cyclic, especially in the uppermost formation, where significant thicknesses of mudstone were deposited during sea-level highstands. Measured sections taken in the field were digitised in various ways, and then analysed by several variants of spectral analysis and wavelet analysis. The analysis detected regular cyclicity, almost impossible to duplicate by random autocyclic mechanisms. The ratio of cycles of different lengths was compared to predictions of Milankovitch cycle length in the Permian, and reasonable to good matches were found. The presence of cycles of rise and fall in sea-level of the magnitude required by the deposited cycles suggests significant volume of polar ice still present at the beginning of the Late Permian when these cycles were deposited. After my PhD, I spend several years teaching part-time at Canterbury University, while researching the tricky problem of the Marshall Paraconformity, and other issues of New Zealand mid-Tertiary stratigraphy. Finally I was appointed as a Lecturer in Geoscience, at Heriot-Watt University in 2006. Since then I have completed a PGCert in Academic Practice, and gone on to be awarded a Highly Commended in the Learning and Teaching awards for the introduction of self-assessment tests into our virtual learning environment for the benefit of the students studying both here and by distance learning. I am now the director of one of our newest MSc programmes, now called Petroleum Geoscience.