DPhil: Sniffing out global volcanic fingerprints using mercury in Quaternary sedimentary records

December 20, 2018
WDG

I am pleased to announce the opening up of a new DPhil position at the University of Oxford Department of Earth Sciences that I will be involved with. The main supervisor for the project is Prof. Tamsin Mather and the position is part of her recently funded European Research Council project. The project is entitled “Sniffing out global volcanic fingerprints using mercury in Quaternary sedimentary records”.

For full details of the project click here and how to apply click here.

Field work in Ecuador

July 27, 2017
WDG

IBEDs Crystal McMichael hard at work sampling sediments in the Andes

IBEDs Crystal McMichael hard at work sampling sediments in the Andes

Insights into recent field work in Ecuador by a team lead by Crystal McMichael can be found in a recent blog from our collaborators at the Instituto Geofisico, Escuela Politecnica Nacional, Quito (Ecuador).

Trabajo colaborativo entre Volcanólogos y Palenólogos potenciará el conocimiento sobre el Paleoclima en el Valle de Latacunga en los últimos 20 mil años by Patricia Mothes

Keen PhD Thesis 2015

September 30, 2015
WDG

Hayley Keen getting excited about sediments during fieldwork in Ecuador (2012). Photo: J. Malley

Hayley Keen getting excited about sediments during fieldwork in Ecuador (2012). Photo: J. Malley

Keen, H.F. (2015) Past environmental change on the eastern Andean flank, Ecuador. PhD Thesis, Department of Environment, Earth & Ecosystems, The Open University.

Abstract
The eastern Andean flank of Ecuador (EAF) contains some of the world’s most biodiverse ecosystems. Andean montane forests are threatened due to anthropogenic pressures and both current and projected climate change. This thesis examines the palaeoecological history of two stratigraphic sequences (Mera Tigre West [MTW] and Mera Tigre East [MTE]) obtained from the Ecuadorian modern lower montane forest. The sediments preserved were analysed using eight analytical techniques, allowing an insight into the ecosystem’s potential response to projected changes derived from their past responses. Palaeoecological studies on the EAF are rare, and those that do exist are debated relating to: i) the inference of robust ecological data from pollen records in floristically diverse locations, and ii) the past source area of sediments preserved in fluvially exposed sequences, potentially leading to contamination with older material.

A statistical sub-sampling tool was developed (debate i), capable of producing statistically robust count sizes for each pollen sample; MTW and MTE count sizes ranged from 196-982 showing the diversity within sequences. The depositional environment of MTE was analysed, investigating sediment provenance throughout (debate ii). Results found that large scale volcanic events were critical in the preservation of the sediments, whereas fluvial influence caused a regional sediment source area in the upper stratigraphy, impacting on the palynological interpretation of MTE. Pollen records demonstrated the presence of a diverse vegetation community with no modern analogue at MTE (abundant taxa (>15 %): Hedyosmum, Wettinia, Ilex) and upper montane forest at MTW (Alnus, Hedyosmum, Podocarpus). Fire was not the main driver for the vegetation reassortment at either site (MTW correlation coefficient: -0.37, MTE: 0.16). The two sites have demonstrated the EAF plays host to floristically dynamic ecosystems, susceptible to drivers of change (fire and landscape) and should be considered when predicting the montane forests’ future response to environmental change.

Supervisors: Dr. William D. Gosling (The Open University/University of Amsterdam), Dr. Encarni Montoya and Dr. Sarah Sherlock (both The Open University).
Examiners: Dr. Dunia Urrego (University of Exeter), and Prof. David Gowing (The Open University).
Chair: Dr. Mark Brandon (The Open University).

To borrow a copy from The Open University Library click here.

Publications (so far): Continue Reading

Lake coring equipment

July 17, 2013
WDG

Trecking with sediment corer in the high Andes of Peru

Trecking with sediment corer in the high Andes of Peru

When it comes to collecting sediments from lakes its all about having the right tools for the job. Working in remote areas of the tropics we tend to favour the Colinvaux-Vohnout corer; supplied by Vince Vohnout at Geo-core). The advantages of this system are:

  1. its light-weight nature (can be backpacked or donkeyed into field sites), and 
  2. the cam system (which allows hammering to penetrate tough sediments).

    Eric Martinez carrying an Avon Redstart back out from Laguna Khomer Kotcha (Williams et al., 2011)

    Eric Martinez carrying an Avon Redstart back out from Laguna Khomer Kotcha (Williams et al., 2011a)

With the right platform (two banana boats and an A-frame) we have manged to retrive c. 20 m of sediment from  20 m of water (c. 40 m of drill rod extended); Lake Pacucha, Peru (Hillyer et al., 2009). More typically we use two Avon Redstart inflatables and a platform following the design of Colinvaux et al. (1999).

Recent debate on the International Paleolimnology Association list server saw recommendations for a number of other systems.

Including: UWITECH gravity corer, Pylonex gravity corer, Aquatic Research Instrument products, and modified systems by Jason Curtis at University of Florida.

I would be interested if anyone has any thoughts on the relative merits of these systems (or others) and there capabilities.

Photos and references below:

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Sediment sampling on the Andean flank, Ecuador

October 10, 2012
HayleyKeen

One of the key goals of the fieldtrip to Ecuador (August-September) was to sample organic and volcanic (tephra) layers from sedimentary exposures with the aim of obtaining new information about past envrionmental change in the region. Our Ecuadorian collaborator, Dr Patricia Mothes (Instituto Geofisico), had identified four of sites she thought might be useful too us: El Fatima Dique, Mera “2” Dique, El Rosol and Vinillos. 

Fatima section

At the Fatima site, near Puyo, a thin organic bed was sampled sandwiched between volcanic ash deposits. Wood macrofossils from this deposit have been dated to the last glacial period.

For further descriptions of what we found and field photos read on…

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