Friday, 30 October 2015

Soil Geochemistry for agriculture and health...by Michael Watts & Martin Broadley

Four RS-DFID PhD students from Malawi, Zambia and Zimbabwe. 
In September we launched our Royal Society-Department for International Development (RS-DFID) doctoral training programme, Soil geochemistry for agriculture and health, in Harare.  The programme runs from 2015-2020 and is being co-ordinated by the joint University of Nottingham (UoN) / British Geological Survey (BGS) Centre for Environmental Geochemistry (CEG).

This is an incredibly exciting programme, involving core PhD projects based at partner institutions in Malawi (Lilongwe University of Agriculture and Natural Resources, Department of Agricultural Research), Zambia (University of Zambia, University of the Copperbelt, Zambian Agricultural Research Institute), and Zimbabwe (University of Zimbabwe, Chemistry & Soils Research Institute). One PhD project is on understanding selenium/iodine dynamics in tropical soils (Ivy Ligowe, based in Lilongwe); one is on managing soil zinc and iron supply to crops in smallholder systems (Grace Manzeke, based in Harare); one is on metal speciation in soils affected by mining (Belinda Kaninga, based in Copperbelt/Lusaka).

There are other aligned PhD projects registered at UoN, focusing on wider agriculture and public health questions developed in collaboration with our African partners. These include Felix Phiri, a human nutritionist from Malawi (Director of Nutrition, Ministry of Health) who is aiming to develop urinary biomarkers of selenium status, and Elliott Hamilton, from BGS, who will work on improving our understanding of chromium speciation and bioavailability in tropical soils.  Elliott will work closely with Belinda in Zambia. Felix and Elliott are both combining part-time PhD studies with their day-jobs, and we hope to bring other students into the network on this ‘professional’ basis in the coming years. We have one more PhD full-time student within the CEG, Olivier Humphrey who will focus on the highly specific analytical method development for measuring iodine dynamics through elemental speciation and isotope geochemistry. Olivier’s work is very much linked to Ivy’s PhD, which will focus more on developing soil management strategies.
Delegates attending RS-DFID network-training event in Harare.


During a wonderful two weeks in Harare, hosted by the University of Zimbabwe, ~30 participants engaged with technical and generic training activities, as well as specific project development meetings. Training sessions included those on Geographical Information Systems (GIS), sampling/geostatistics, stable isotope techniques, ethics, data management and technical writing. Many people contributed directly and remotely.  The meeting also included an assessment of the projects capacity strengthening (CS) goals and guidance on using appropriate metrics tools to demonstrate progress from the Capacity Research Unit from the Liverpool School of Tropical Medicine.  Our consortium chose the University of Zimbabwe for the programme launch in part because of their strengths in GIS.  The next training session will be in the UK in May 2016, then Lilongwe in September 2016.

There are many opportunities for developing new joint PhD projects, in Malawi, Zambia, Zimbabwe, UK and linking with activities elsewhere in Africa. There are also many opportunities for getting involved in specific training activities (participation and delivery!).


Wednesday, 28 October 2015

Quality Accreditation in Inorganic Geochemistry...by Charles Gowing

The Inorganic Geochemistry Laboratories in Nottingham successfully achieved re-accreditation to the Quality Standard ISO 17025 (competence of testing and calibration laboratories) and the Environment Agency's Monitoring Certification Scheme (MCERTS) for soils.

The laboratories have held accreditation to ISO 17025 since 1998. Maintenance of this accreditation is by re-accreditation every four years and ongoing competence is assessed annually via external audit by independent experts from the UK Accreditation Service (UKAS). Accreditation for laboratory data output demonstrates a standard for the quality of analyses against an internationally recognised standard, namely ISO 17025.

Why is this important?

  • Many external clients in industry commission only laboratories who have appropriate accreditation for commercial or regulatory purposes.
  • Accreditation against ISO 17025 provides an internationally recognised Standard of quality that is accepted by our clients and partners around the world.
  • Accreditation provides confidence in the quality of data outputs which helps to bolster submissions for research funding to appropriate funding bodies.
  • Experience in evolving an accredited management since 1998 provides a wealth of experience when Inorganic Geochemistry are employed in overseas science partnerships or capacity strengthening projects e.g. Afghanistan, Kyrgyzstan, Nigeria, Liberia, Malawi, Tajikistan, Zambia, Zimbabwe (see previous blog).

What is covered?
Analysis of water by ICP-MS. 
The scope of accreditation includes determination of cation, anion and aqueous parameter concentrations in natural and experimental water samples and for determination of pH in soil samples.

Although this does not cover all of our laboratory techniques it does cover the most common techniques required specifically by clients or regulatory authorities. Moreover, the IG laboratories management system is central to the ISO 17025 accreditation and all other methodologies and techniques are operated within this environment.

Why are not all of the techniques included in ISO 17025?

The IG laboratories provide a range of specialist analyses that are research focussed for our own activities or bespoke for external clients and collaborative research. Therefore, these methodologies require a degree of flexibility on a project by project basis that would not be possible to achieve with formal accredited status of individual methods and would not be cost efficient. However, the ISO 17025 environment and mind set is embedded within all of the IG activities to demonstrate confidence in data output, whether it is for bespoke analytical packages requested by clients or data reported through peer review publication.

Additional recognition of high data quality in Inorganic Geochemistry

The quality of the analysis we provide is reinforced by regular participation in independently organised Proficiency Testing Schemes, which supply samples for analysis blind to the analyst.

Analysis of river water by ion chromatography. 
The reputation of the Inorganic Geochemistry laboratories is recognised by our contribution to the Steering Committees of two of these schemes: Contest, run by Laboratory of the Government Chemist (LGC); and GeoPT, run by the International Association of Geoanalysts (IAG).

Inorganic Geochemistry routinely provides primary source analysis for candidate Reference Materials (RM) to a number of reference material producers, including Geological Surveys across the world, LGC and IAG, exemplified this summer by excellent performance in analysis carried out for 23 elements in a hard water standard (LGC 6026) and 4 anions in a River Water Reference Material (LGC 6020). In terms of accuracy, the data we provided were among the highest quality of all of the preferred supplier laboratories in the UK.

In addition, our excellence in this field is reflected as one of the preferred laboratories to some of the principle suppliers of certified reference materials to industrial and academic laboratories. The provision of reference materials is an opportunity for the future, with potential to reinforce the external reputation of the Inorganic Geochemistry laboratories.

Dr Charles Gowing is the UKAS Quality Manager for the Inorganic Geochemistry Laboratories in The Centre for Environmental Geochemistry.

Monday, 26 October 2015

The International Ocean Discovery Program (UK) Student Conference 2015...by Rowan Dejardin

The Joides Resolution (JR), the IODP’s flagship vessel
(courtesy of UK-IODP).
In late September 2015 29 PhD students from across the UK headed to Northumberland to learn about the scientific work carried out by the International Ocean Discovery Program (IODP). After registering at the University of Newcastle the group were taken by coach to Allendale, in the beautiful North Pennines AONB, and the conference got off to an excellent start with a hearty meal! This was followed by a talk from Kate Littler, from the University of Exeter, describing a typical day in the life aboard the Joides Resolution (JR), the IODP’s flagship vessel, and an exciting live Skype tour of the JR. The first full day of the conference began with an introduction to the UK-IODP from conference convener Sean Burke, after which all the students presented ‘elevator pitches’ on their research, with the best pitch winning a spot presenting at the IODP general conference. This proved to be a very successful session revealing the wide range of science that is possible when working on material collected by the IODP, from the investigation of past climate to planetary formation, from evolution to invasive jellyfish! It was also a good opportunity to practice presenting research in a conference environment, vital to all early career researchers.

After an excellent lunch and following discussion of how to apply for an IODP expedition and the site survey requirements for such a proposal, led by Bridget Wade (UCL) and David Long (BGS), we moved on to the practical part of the conference: formulating a proposal for an IODP expedition! In teams of around six people our mission was to develop an expedition proposal, a process that would normally take many months, in less than 24 hours. The proposal needed to encompass as many of the four core research areas of the IODP science plan (Climate and Ocean Change, Biosphere Frontiers, Earth Connections, and Earth in Motion) as possible, in addition to being scientifically and logistically feasible, as well as safe.  After initial discussions, the team I was part of decided that we would be able to shoehorn all our various scientific objectives into one expedition to the Southern Ocean. Our objective decided we retired for yet another feast provided by our wonderful hosts at Deneholme House, to prepare ourselves for the busy day ahead!

A group photo of the delegates (and organisers) at the UK-IODP 2015 conference in Newcastle.
The morning of the final day of the conference proved to be a frantic one as we raced to gather the information that would allow us to present our proposal to the conference after 2 pm. Although the activity was quite frenzied will still found time to design a striking logo for our team’s proposal, an important part of any IODP expedition! Against all odds all five teams were able to reveal their proposals in a series of excellent presentations, with a very diverse range of scientific targets advanced, that stimulated a lot of feedback from the other students and the IODP scientists who were running the event.

The logo designed as part of the
conference to represent a
(fictitious) research proposal.
The meeting had been organised so that it was possible for attendees to head to the UK-IODP general conference, being held at the University of Newcastle the following day. This was a great opportunity to see proposals for future expeditions (with some interesting parallels with some of our own ideas!), preliminary results from recent expeditions, and the ongoing science from older expeditions.

Overall the student conference was a really useful event allowing all the attendees to meet up with lots of other researchers a similar stage in their careers, hopefully creating lots of contacts for future collaborations, as well as learning a lot about the work of the IODP and about the process of proposing an expedition. I look forward to being able to attend future events and would highly recommend any other PhD students working in this area to do so too.


By Rowan Dejardin (University of Nottingham and the British Geological Survey PhD student). Rowan is supervised at the University of Nottingham by Dr Sev Kender and Dr George Swann, at the British Geological Survey by Prof Melanie Leng, and at the British Antarctic Survey bd Dr Vicky Peck and Dr Claire Allen. 


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Tuesday, 20 October 2015

How to heat a city...by Ashley Patton & David Boon

Ashley Patton and Gareth Farr measuring groundwater temperatures
at the famous Brains Brewery using a specially adapted water
level ‘dipper’ equipped with a thermometer and conductivity meter.
No beer was consumed during the survey, honest! 
Ashley Patton and David Boon from BGS Wales explain how an exciting new project in Wales is helping to tackle fuel poverty through urban geology.   

For the last year BGS scientists have been monitoring shallow groundwater temperatures across the city of Cardiff, and surprisingly they found that the ground beneath the city is significantly warmer than expected. The heat lost from buildings and sewers in cities is naturally stored in the ground, as well as released to the atmosphere, in a process referred to as the ‘Urban Heat Island’ effect.  Our work has shown that, in Cardiff at least, this anthropogenic effect has increased the groundwater temperature from 11 to 14o Celsius in many places.  So why not use this abundant source of free, low-carbon heat to warm poverty stricken homes in the city?

To learn more about our project read on...

A flooded basement in the city centre shows
how shallow the water table is under the city. 
Cardiff, a city of some 350,000 people, was once the largest exporter of coal in the world, however the majority of its docks are now infilled and there has been significant urban redevelopment over the last 20 years. Cardiff is underlain by geologically young ‘superficial’ deposits such as estuarine and river alluvium deposited by rivers and marine waters, and sands and gravels deposited from glacial melt waters at the end of the last ice age.  The shallow sand and gravel deposits hold significant quantities of groundwater which can be readily accessed by drilling boreholes into the ground. Using 168 existing groundwater level monitoring boreholes distributed throughout the city we measured the seasonal temperature of the groundwater at 1m depth intervals using a thermometer attached to a long wire. In Cardiff groundwater is often encountered just 3-4m below the surface making GSHP systems more cost effective to deploy compared to standard deep borehole systems that require larger water pumps. The image on the right provides an interesting illustration of depth to groundwater below the city. We found that the groundwater in Cardiff is several degrees warmer than expected (Patton et al., 2015) making it an attractive prospect for the development of ground source heat systems. To help planners and developers make the most of this resource we produced a city-wide map showing the distribution of the groundwater temperature and it caused developers to reconsider their future renewable energy strategy for city.

A shallow groundwater temperature map for the city of Cardiff (average 2014 spring time temperatures, in degrees Celsius) (after Patton et al., 2015). 
A local partnership formed between the BGS, City of Cardiff Council, Cardiff Harbour Authority and WDS Green Energy Ltd led to a follow-on project funded by Energy Catalyst InnovateUK in 2015. As proof of concept for a city-scale underground heat capture system, we are installing an open-loop ground source heating system in a local nursery school and monitoring the sustainability of the system.  Boreholes have been drilled to abstract water from the sand and gravel aquifer. The video below shows a cable percussion (or shell and auger) drilling rig installing one of the boreholes to be used for the ground source heating system.  Groundwater will be pumped from the aquifer so it can be passed through a heat exchanger, then returned into the ground via a second borehole. This type of system is called an ‘open-loop’ ground source heat pump. The heat we remove will be used to generate hot water to keep the school warm during the winter, whilst also helping to increase energy security, as well as reducing CO2 and our reliance on conventional fossil fuels.


Future work in 2015/16 will involve analysis of groundwater temperature and chemistry data, and installation of the first telemetered urban groundwater temperature network in the UK, which you will shortly be able to view live via a BGS Webportal. We are also creating a 3D geological model to support subsurface planning and sustainable integration of future systems.  Watch this space...



Wednesday, 14 October 2015

The Urbino Summer School in Paleoclimatology… by PhD students Hennie Detlef and Amy Sparkes

Hennie Detlef 
From 15 July to 1 August, 71 students from all over the world came together in the small town of Urbino, Italy to attend the 12th Urbino Summer School in Paleoclimatology (USSP). After several long hours spent travelling, at times asking ourselves why anyone would choose such a small, relatively remote town for a summer school, we finally arrived and the reason instantly became clear. Urbino, a World Heritage Site set in the spectacular hills of the Marche region, has retained most of its beautiful old town with the university and accommodation situated right in the centre!

The scientific backgrounds of the students were as diverse as their nationalities, but all of us had at least one thing in common; an eager interest in how the Earth’s system and climate has evolved through the past. It was great to engage with a wider scientific community of young researchers all interested in the same area. USSP illustrated the breadth of palaeoclimatology as not only the students but also the faculty, an amazing group of scientists researching at the forefront of our field, was as varied as it possibly could be.

USSP Field Trip 
After an icebreaker party on the first evening, lectures began the next day. The first week was spent learning about basic palaeoclimatological approaches, including biostratigraphy, the construction of age models, climate modelling and sessions on biotic and geochemical proxies. After a one day field trip to the PETM and the K-T boundary, sessions became more analytical with orbital analyses of data collected in the field, providing some hands-on experience with “astrochron” and climate modelling in general. Towards the end of the summer school we travelled through Cenozoic time learning about the newest insights on key geological intervals, from the PETM to the Holocene. Not only did the lectures prove invaluable; so did the interaction with both faculty and other students during poster sessions and breaks. This opportunity was more than helpful, enabling us to discuss our research, exchange ideas, seek opinions on our research questions and data interpretation and foster future collaboration possibilities. Even though it could be a little intimidating to approach some of the world-leading scientists in our field, they encouraged discussion and were always happy to help.

Amy Sparkes 
We were fortunate enough to attend USSP with the help of an ECORD scholarship and would recommend attending USSP to anyone interested in palaeoclimatology. It is a fantastic opportunity to advance your knowledge of fundamental palaeoclimatological principles and increase your understanding of how proxy data interpretation and climate modelling interact. Best of all, it is a chance to meet like-minded people at the same stage of their research careers. The last day in Urbino felt a bit like the last day of summer camp when you have to say goodbye to all your new friends and go back to reality, but everyone went home bursting with new ideas and enthusiasm about their research! We are very grateful to all those who made USSP such a fulfilling and unforgettable experience. This year’s USSP shirts are green and pink, so watch out for us at the next Conference!


By BGS BUFI student Hennie Detlef with help from Amy Sparkes (both from Cardiff University)

Hennie is being supervised by Dr Sindia Sosdian, Dr Carrie Leah, Prof Ian Hall (Cardiff University) and Dr Sev Kender, Prof Melanie Leng (BGS).

Friday, 9 October 2015

How quickly do streams lose their natural fizz?...by Lou Maurice and Gareth Farr

Lou testing the field equipment during a wet and
 windy November morning
Carbon dioxide (CO2) is a well known greenhouse gas that is produced both naturally and by human activity. It is important to be able to measure the amounts of CO2 that enter the atmosphere as this enables climate change scientists to put better data into their models, helping them to improve predictions of future climate changes.


Interestingly, streams and rivers are one of the many natural sources of CO2. Biological activity, mainly respiration, produces CO2 in soils, streams and rivers, which is eventually lost into the atmosphere.  In order to calculate the amount of CO2 that is lost from streams, the rate of gas loss from the water needs to be measured.  It is this process that Lou Maurice and I investigated using tracer tests.

Yes it is as cold and wet as it looks!
 Gareth collects elevation survey data to
calculate the slope of a stream
We chose an upland area of South Wales as our study area, not just because of its remote beauty and excellent country pubs, but because it offered numerous streams of varying slope all on the same geology: important factors for our experiment.

The first step was to measure the flow of water in the stream. We did this using a method called ‘salt dilution’, which involves adding small amounts of salt upstream at a known and constant rate, and measuring the peak concentration downstream. After a few calculations, we can compute the velocity of the stream.

Lou collects a sample using a syringe and special
metal gas sample container. the water is injected
 from the bottom to ensure any air bubbles are removed,
then they are taken to the BGS labs in Wallingford
where they are processed   
To measure the rate at which CO2 would be lost from the stream, we injected an inert gas at a constant rate into the top of the stream section at the same time as the salt. The inert gas is sulphur hexafluoride (SF6) and acts in a similar way to CO2, so is a good ‘proxy’ for the CO2 in the stream. We were then able to measure how much of the inert SF6 gas was lost from the stream as the water flowed downhill.  It is then possible to calculate the rate at which CO2 gas would be lost over that section of stream.  We repeated this experiment in both low flow conditions in the summer and high flow conditions in the late autumn to see how changes in flow could affect the loss of CO2 from streams and rivers.

Our initial results look promising and we hope to be able to show differences between CO2 loss from streams with steep and shallow gradients, under both high and low flow conditions. In the future we hope to be able to ‘scale up’ these findings to calculate CO2 loss from streams and rivers across the UK.

We need to understand how different flow conditions affect the loss of CO2 from streams so we visited the same stream sections in low flow conditions e.g. summer (left) and then again in high flow conditions e.g. autumn (right) 

Wednesday, 7 October 2015

Working together to combat environmental pollutants and inform agricultural strategies...by Michael Watts

My team at the British Geological Survey has hosted four Commonwealth Professional Fellowships from Pakistan, India, Malawi and Zimbabwe since 2012.  The scheme funded by the Commonwealth Scholarship Council UK (CSCUK) provides support for professionals in the Commonwealth to undertake training at a host institute in the UK.  Here a few of the Fellows give an account of their experience and opportunities arising from such a Fellowship in the UK.

‘It was like my dream came true,” says Dr Mousumi Chatterjee, ‘when I opened the email informing of my success in attaining a Commonwealth Professional Fellowship. I was happy as I was going to experience everything that I had wanted to learn for the previous three years of postgraduate and post-doctorate training at the University of Calcutta.’  Mousumi, a biogeochemist working on mercury pollution in the Indian Sundarban wetland ecosystem, wanted to highlight the mercury exposure of different fish within an estuarine food chain, in order to measure direct human exposure levels. ‘My desire was fulfilled when I started my Professional Fellowship with BGS. Not only is the BGS well equipped with sophisticated analytical facilities, but the organisation also provided me with expert guidance and a friendly environment, and encouraged me in the new practical implementation of scientific ideas.’

Mousumi Chatterjee - University of Calcutta / University of Reading 
During her Professional Fellowship in 2013, Mousumi used the BGS Inorganic Geochemistry laboratories to determine mercury contamination in a variety of edible fish, polychaete worms and bivalve molluscs.  ‘The results were fascinating, as the level of mercury contamination signified the feeding habits of different species of fish.’

Mousumi benefited from several scientific exchanges during her stay. ‘I visited the Marine Sciences Department at the University of Bangor, where I learnt how to extract the otolith (a small fish ear bone), which acts as a recorder of environmental chemistry, from hilsha fish. This resulted in a research collaboration with the Indian Institute of Science, Bangalore after my return to India. I also had the opportunity to attend and present my research findings at the International Conference of Mercury as a Global Pollutant 2013, held in Edinburgh, which brought together the world’s leading experts on mercury contamination of the environment.’

‘My Professional Fellowship was fruitful enough not only to implement independent research ideas in my home country of India, but also to build long-lasting research networks with the BGS. I am still in contact with Michael and now we are collaborating to work on global road dust pollution. I enjoyed every moment at the BGS, whether it was working in the laboratory or hanging out with colleagues in the canteen.’

Dr Munir Zia - Fauji Fertilizer Company (FFC), Pakistan
Munir Zia - ‘I had an opportunity to get hands-on experience for trace element analyses of soils, waters and grains to better understand soil-to-transfer of key minerals. Another area of professional development was to learn about the handling of large amount of analytical data and its GIS integration. After completion of a Fulbright Scientist Award, FFC assigned me as the R&D Coordinator however, being a scientist I was lacking in necessary management experience relevant to R&D. The professional training at BGS in 2012 enabled me to introduce collection of georeferenced soil samples across Pakistan. The FFC farmer education programme collects and analyses 25,000 soil samples every year, therefore, introduction of geo-referencing will enable us to transform this effort into national scale soil fertility maps. Generation of such maps will enable FFC to pinpoint areas that are deficient in trace minerals and other essential elements. Our effort in developing national scale maps will help strengthen crops bio-fortification programmes being run by HarvestPlus Pakistan, to which we are a local partner. We are also in a process to establish a Fertilizer Research Centre in Pakistan, the first of its kind in this country. The opportunity provided by CSCUK was invaluable in developing a network of partners and skills training. Since my first visit to BGS in 2012, I have returned several times through alternative funding opportunities to continue a joint programme of research and more recently with academics at the University of Nottingham through the joint Centre for Environmental Geochemistry’

Grace Manzeke from the University of Zimbabwe and Salome Mkandwire from the Malawian Department of Surveys also undertook a CSCUK Fellowship in 2015 (see previous blog).  For Grace, support from the CSCUK Fellowship provided a solid start prior to her commencing a project funded by the Royal Society-DFID on geospatial characterisation of micronutrient deficiency in Zimbabwean soils, starting summer 2015 (see previous blogs by Michael Watts and Grace Manzeke).

For all of the Commonwealth Fellows, it was important to expose them to the variety of opportunities in the UK, from work through to visiting the variety of tourist and scenic locations. They were initially helped in doing so, but soon unleashed the enthusiasm for exploring the UK and grew to enjoy the environment and culture. From a host perspective, there are the obvious opportunities to develop collaborative networks and partners, but also an opportunity for other members of a team or junior scientists to broaden their horizons through training or working alongside Fellows from overseas.

By Dr Michael Watts, Head of Inorganic Geochemistry, Centre for Environmental Geochemistry, British Geological Survey.

Papers from the Fellows:

Chatterjee M, Sklenars L, Chenery SR, Watts MJ, Rakshit D and Sarkar SK. (2014). Assessment of Total Mercury (HgT) in sediments and biota of Indian Sundarban Wetland and adjacent coastal regions, Environment and Natural Research, 4(2): 50-64

Zia M, Watts MJ, Gardner A, Chenery SR. (2015). Iodine status of soils, grain crops and irrigation waters in Pakistan, Environmental Earth Sciences, 73, 7995-8008.

Monday, 5 October 2015

Learning to drill...by Jonathan Dean

Jonathan Dean from the Stable Isotope Lab at the British Geological Survey has just returned from a lake drilling training course in the Republic of Macedonia. Here he discusses what he learnt. 

Aerial view of Lake Ohrid 
The International Continental Drilling Program (ICDP) is an organisation that gives scientists money and technical support to allow them to drill deep holes in the Earth to retrieve sediment and rock. These projects aim to answer key questions about the Earth, such as how earthquakes occur, how mountains form and how the climate changed in the past. UK scientists have been involved in many of these big drilling projects over the last few years. For example, I'm currently investigating half a kilometre of tubes of lake sediment that were drilled in Ethiopia, as described in a previous blog post. We think these sediments extend back to over half a million years ago. By looking at how the chemical composition of the sediments varied between different points in the past, we're reconstructing how climate changed through time. Our aim is to understand what the natural drivers of climate change are and whether or not climate change could explain why our species decided to migrate out of Ethiopia from around 100,000 years ago onwards to populate the rest of the world.

Lake Ohrid 
Every year, ICDP organise a training course for scientists, and this year I was one of 20 people from 5 continents to be lucky enough to attend. We were based on the shores of Lake Ohrid in the Republic of Macedonia, where another drilling project funded by the ICDP was carried out in 2013. It is one of the oldest lakes in the world, probably existing for well over one million years, and has many species that are not found anywhere else on Earth. As Jack Lacey described previously, they drilled down 569 metres below the lake bed. The sediments are being analysed in Germany and the UK, including in the Stable Isotope Lab at the BGS.

Drilling platform on Lake Prespa 
For the training course, we started by driving to another lake, Prespa, in the middle of which is the tripoint border between Macedonia, Greece and Albania. German scientists were undertaking another drilling campaign, and were able to see lake sediment coring in action. We also drove around on a boat setting off explosions in the water behind us, and the way these sound waves bounced off the lake bed was recorded by devices carried by the boat. This technique is used to find where the most undisturbed sediments are on the lake bed – the best place from which to drill sediment cores.

The following two days were comprised of lectures and discussions with the scientists who worked on the Lake Ohrid project about the practicalities of taking many hundreds of metres of sediment cores in a lake that has waters nearly 300 metres deep. There were some interesting talks on the analyses being undertaken on the sediments from Ohrid. We also learnt a lot about the process of developing deep drilling projects and writing the funding applications. Such large, multi-million pound projects require an experienced, international team and lots of logistical and scientific planning if they are to be successfully funded and then carried out.


The training course was really useful – it improved my understanding of the process of drilling lake sediments and gave me a better appreciation of how to manage the analysis of the sediments after the fieldwork has ended. I would thoroughly recommend people applying for next year’s course!

Friday, 2 October 2015

How do deep ocean trenches form?...by Sev Kender

Sev Kender at his microscope 
One of the biggest questions remaining to be answered in plate tectonics is how subduction zones start, or ‘initiate’. Plate tectonics and seafloor spreading was a ground-breaking theory discovered in the mid-20th-Century that explained much of geology, and started our modern discipline. Before it there was no single accepted theory of why oceans and mountains formed, why continents look like they used to be linked together, and why animals of different continents appeared to have long-lost common ancestors. Here Sev Kender tells us about some recent advances in the science… 

Subduction zones, like the deep Mariana Trench off the south coast of Japan, are where one plate is pushed under another as they move towards each other. The underlying plate is consumed into the Earth’s mantle, and creates hot magma that erupts from volcanoes on the surface of the overlying plate (e.g. the Northern Mariana Islands). It is quite problematic to explain how a piece of passive ocean crust should suddenly break apart and start to form a trench, and there are two leading models that exist to explain how a subduction zone may start: ‘spontaneous’ (one side sinks because it is more dense) or ‘induced’ (forced by pressure from another, distant, source). But it is difficult to test these ideas, because the process cannot be observed happening today. Subduction zones persist for many millions of years, and the initiation period happened millions of years ago in most cases.

The location of the research into the crust
 of the Izu-Bonin-Mariana arc
One way to understand subduction zone initiation is to drill a long borehole into the ocean crust on the overlying plate, to test the composition and age of the crust, and to see how it behaved (in terms of sea level changes), before the subduction started. The problem is that millions of years of time since the initiation has allowed kilometres of sediment to pile up on top and obscure the crust.

Myself and 30 other scientists travelled to the Philippine Sea in summer 2014 on the drillship JOIDES Resolution, operated by the International Ocean Discovery Program, to drill into the crust of the Izu-Bonin-Mariana arc. This is an extinct ocean trench zone south of Japan, where the modern-day Mariana Trench initiated. In our article in Nature Geoscience  we report how we successfully collected 1.5 km of borehole through the overlying sediments and into the crust itself, dating the rocks with microfossils and magnetic field reversal ‘magnetochrons’ (known past reversals that have been dated by other techniques in other records).

We found the crust to be much younger than expected (Eocene, about 50 million years old), a stunning discovery indicating that we needed to readjust our ideas of how the subduction zone formed. The crust has chemical characteristics indicating it was formed at the time the subduction zone started, rather than much earlier. The crust may have formed in an extensional setting through seafloor spreading, in some ways similar to that formed at mid-ocean ridges today, although in this case near the newly-formed subduction zone.

Mid-ocean ridges are where fresh new oceanic crust is formed and are the opposite of subduction zones. There are numerous 'transform faults' near ridges today, enormous fractures through the crust that form due to the spreading plates interaction with the curvature of the earth.

A thin section through the young crust 
One idea is that the subduction zone formed along a previous line of weakness in one of these fracture zones, but our records do not prove this. They do, however, show that the initiation was probably 'spontaneous' rather than 'induced', as the crust was formed in an extensional setting and did not become uplifted before formation. This has allowed us to begin understanding the process of subduction initiation, and further analyses over the coming years of the rocks collected will help us refine this new model, and understand the evolution of the Izu-Bonin-Mariana arc since its inception.
By Sev Kender (Research Fellow within the Centre for Environmental Geochemistry, BGS-University of Nottingham). 

Follow Sev on twitter @SevKender 



Images

Sev Kender at his microscope

The location of the research into the crust of the Izu-Bonin-Mariana arc  

A thin section through the young crust