Thursday, 14 September 2017
On Day 1 (after the health and safety induction) we began our week long experiment to extract Carbon Dioxide (CO2) gas from Calcium Carbonate (CaCO3) samples which could then be analysed in a mass spectrometer. The first stage in this experiment was to weigh out our carbonate samples into small test tubes, drop these into larger glass vials containing phosphoric acid and then attach these to the vacuum pump (see above photo) so that overnight all the air could be removed. We then allowed the phosphoric acid and sample to mix by shaking the larger vessel and leaving it in a 25.2oC water bath overnight so that the reaction could be fully completed and all at the same temperature. The next day we then had to extract the CO2 gas which had been formed by the reaction. To do this we reattached the vessel to the vacuum pump and then used liquid nitrogen (which was at -196oC) to sublime the CO2 whilst we removed any other remaining gases. The gas was also passed through an acetone water trap to remove any water which would have later damaged the mass spectrometer.
Once all of our samples had been extracted we then attached them to the mass spectrometer and left them to be analysed. It was especially interesting to learn in detail how the mass spectrometers work and see all of the components up close. I had not previously known about the use of a reference gas or the requirements of different machines to analyse different isotopes – the ones we were using looked specifically at Carbon-13 and Oxygen-18. On our final day we were able to collect and analyse our results, from the graphs we plotted we were able to see that the loch from which the samples were collected had gradually changed from a freshwater environment to a marine one. This was due to the increase in sea levels at the end of the last glacial period 12,000 years ago.
Whilst we were waiting for our main experiment to progress we were also introduced to many other areas of the lab. This included using microbalances, tweezers and mini spatulas to weigh out very very small amounts (70-150mg) of one of the BGS internal standards of freeze dried broccoli! Whilst frustrating at times, this has certainly given me a much greater appreciation of the meticulous and painstaking preparation of samples required to conduct good research.
We also helped prepare rock sediment samples from Vietnam and Tanzania for analysis, this involved daily emptying and refilling of (many) beakers in order to wash the samples of debris and dirt. Once the samples had dried out we then scraped them out of the beakers and used a mortar and pestle to grind them into a fine powder before depositing them into small vials ready to be analysed.
Monday, 11 September 2017
I have just had the opportunity to spend a week and a half in a very wet, rainy Sierra Leone, working with Kathryn Goodenough as part of a two-year partnership project, funded by the Department for International Development (DFID), that is focusing on building a lasting legacy around capacity in the extractives sector. Sierra Leone has been left reeling in recent decades with a brutal ten-year long civil war that finally ended in 2002, the recent Ebola Crisis, and now a catastrophic landslide in the capital, Freetown. My role in country was to run an introductory petrology course to some of the geologists in the National Mining Agency (NMA). Recently refurbished, the Agency has purchased two microscopes to enable them to study rocks in thin section. This is something we at BGS take for granted, but for the NMA, this will be a tremendous step forward. My first challenge was getting four boxes of thin sections that will form the core of a teaching collection at the NMA into country. According to UK customs, thin sections are an offensive weapon, and I very nearly had them confiscated! The flight was spent in nervous anticipation of arriving in Sierra Leone with four boxes of fragmented glass, but fortunately, the boxes survived the baggage handling intact!
|A view of the microscope lab|
We arrived in country following weeks of exceptionally heavy rain – one estimate we heard was that the rain in August had been 3 times greater than the norm – and believe me, when it rains here, it RAINS! It’s the first time I’ve had to give lectures and battle with the noise of the rain in order to be heard!
Friday, 1 September 2017
Hi, my name is Jo and I began my PhD at the British Geological Survey and School of Earth Sciences, University of Bristol in September 2016. My research aims to further our understanding of preservation potential of mineralising systems located in the shallow submarine environment (<100 m). In this blog, I will share with you an aspect of my field season on the Greek island of Milos from this summer.
Dynamic submarine processes can help or hinder preservation, potentially resulting in either a bonanza or a failed ore deposit. Therefore, it is important to understand the dynamic processes and the preservation potential, to determine whether the shallow submarine environment is prospective for future mineral exploration and exploitation. The island of Milos, located in the Cyclades, Greece, provides an ideal on-land laboratory having emerged 1.4 million years ago. The island’s topography reflects the paleo-seafloor, and allows us to directly study and sample mineralised and hydrothermally altered paleosurfaces that formed in the shallow submarine environment.
I have recently returned from my field season where we drove approx. 2000 km (a similar distance from Nottingham to Rome) around winding roads of a 13 by 23 km island over a period of five weeks. The first challenge of the trip included learning to adapt to a Jimny Jeep that was not happy to be in first gear or reverse.
I was joined in the field by my main supervisor, Jon Naden, for a handful of days prior to the rest of the party. This was a great opportunity to visit mineralised and altered outcrops, which I had only read about in literature. This was vital in helping my understanding of hydrothermal systems and begin to visualise how my PhD project will pan out. More students from the University of Bristol and Ottawa shortly joined us for a week, alongside researchers from the University of Athens - the island was certainly busy.
One aspect I am keen to research involves how mineralisation differs from the western ancient hydrothermal system in comparison to the active system located in the east. In order to observe the active submarine environment and witness the potential ore-forming environment, we collaborated with PhD students Jonathan Teague and Dean Connor from the School of Physics, University of Bristol, whom have experience building and deploying low-cost remotely operated underwater vehicles (ROVs) and unmanned aerial vehicles (i.e. drones; UAVs). With knowledge from the University of Athens, we deployed a BlueROV2, equipped with a GoPro Hero 5 off the southern coastline of Milos Island. This was entirely controlled via a laptop and Xbox 360 controller onshore, which allowed the ROV to move a maximum distance of 100 m offshore.The aim of this pilot study allowed us to decipher the location of active venting fields – were they randomly dispersed or was there a structural or permeability control? Knowing the NW-SE horst-graben structural control on the island, we inferred this lineament out to the southern coastline. Alongside rotten-egg smelling fumaroles located in the cliff faces, we were able to decipher two likely venting locations to deploy the ROV. The rotten-egg odour is indicative of sulfur in the form of H2S: a gas coming directly from an underlying magma chamber.
|1. Setting up the office for venting exploration.|
2. The ROV in action.
Three days were spent identifying and undertaking reconnaissance mapping within an area of 1 km2 where we successfully found venting sites. The team from the School of Physics, University of Bristol undertook a Structure-from-Motion (SfM) photogrammetry program, to produce high-resolution 3D topographic reconstructions of the seafloor. Thousands of images taken with the GoPro Hero 5 contribute to a handful of bathometry models. Despite the huge volume of data, this is a much cheaper option.
Since the vents are relatively shallow (<7 m), we returned to the area during the evening to snorkel which was the perfect treat to end an incredibly hot day hiking to outcrops. Luckily, the sun was still shining, which meant the visibility conditions underwater were perfect. Often, you could use your sense of smell to locate the venting fields. Patches where bubbles were rising often resembled the temperature of a hot bath (approx. 60oC). We avoided swimming directly over these areas due to the corrosive nature of the escaping gases.
Unlike the ROV, we had to be patient with the weather in order to fly the drone. Rain and strong winds often set us behind schedule. For safety purposes, a team of four was needed: two would secure the location to prevent the public from being close to the flight area, whilst the pilot and computer-operator would liaise to ensure the drone was following the pre-planned flight lines. We chose terrain-challenging locations to create photogrammetry models, which would enable remote fieldwork with a 10 cm resolution. When discussing my research and its implications back home, it will now be much easier for the audience to follow my thinking if I display the landscape and rocks to them, as if they were on fieldwork with me.
This was a great opportunity to be part of a student-led
research project with a diverse range of skillsets, with the full backing of
our supervisors. We are currently writing our first paper and eager to develop
the project further and revisit the venting site next spring.
4. UAV Pilot undertaking a test survey.
My supervisory team consists of Jon Naden (BGS), Frances Cooper and Brian Tattitch (University of Bristol), Stephen Grebby (University of Nottingham), Dan Smith (University of Leicester) and Graham Ferrier (University of Hull).
Jo can be found on Twitter using the handle @geologyjomiles
Photography credit: Jonathan Teague, firstname.lastname@example.org
Photography credit: Jonathan Teague, email@example.com