Geology

Earth-shaking Science

Some rocks, which are composed of several different minerals and organic derivatives (for example coal) are water bearing. How they store and lose water is important in some geological fields as this can give clues about how and why earthquakes happen, and about structural changes within the rocks relative to temperature.

At the University of Rome Tre, Giancarlo Della Ventura and his colleagues are using the Linkam FTIR600 stage to look the loss of water in leucite, a common silicate mineral found in lavas. Using the FTIR600 stage the scientists have demonstrated the ability to monitor the process across samples a few µm thick, and obtain time/dehydration curves.

This loss of water can be very fast. In order to study this dynamic reaction in-situ under non-ambient conditions it is necessary to capture high resolution images quickly. This can be achieved by using the Linksys32-DV software that also controls the stage temperature. Non-equilibrium processes of geological interest and dehydration processes in other minerals can also be studied using the FTIR600 stage and the Linksys32-DV software. 

Leucite and the FTIR stage

In one experiment a small crystal fragment was heated constantly at 5°Cmin-1, dehydrating smoothly until at 400°C it is almost anhydrous. Images are taken at 1°C intervals, using a 15x objective, illuminating ~170x170µm2 areas to enhance the contrast of the water band at the edge of the crystal.

In a second experiment, a crystal was heated quickly at 50°Cmin-1 up to 300°C, where it had lost approximately 50% of its water. The sample was held at 300°C and images were taken at intervals to show the continued dehydration of the sample. After 150min the sample was nearly anhydrous.      

Giancarlo Della Ventura commented the greatest benefit of using a Linkam stage is the “possibility to do experiments in situ, i.e. during the thermal treatment.”

We like to think Linkam stages are being used for earth-shattering science and our equipment certainly has a part to play investigating earthquakes.

By Caroline Feltham

A Repeat Offender

Most people would describe the grounding of planes, the uprooting of families, and loss of life in a fire criminal. But these events can all be caused by a volcanic erruption - a natural event which is famously hard to predict.

This unpredictable nature is partly due to a lack of knowledge; every volcano has its own character and an accurate evaluation of each one is required. The magma ascent path, the nature of the plumbing systems, volatile contents - and the size and activity of the reservoirs themselves - are all important factors in predicting a volcano’s behaviour. The depth and shape of magma reservoirs has a huge influence on the physical-chemical properties of the magma and also on the expulsion of volatiles.

Not much is known about the volcanoes that comprise the islands of the Azores in spite of the large number of studies carried out in the past. Consistent models for the internal structure of volcanoes are still lacking, with important consequences for the volcanic hazard assessment of the area. The number, size and location of magma reservoirs beneath the islands are poorly known.

The THMSG600 stage is enabling scientists to learn more about the worlds volcanoes.

Vittorio Zanon, researcher of the Centro de Vulcanologia e Avaliação de Riscos Geológicos, University of the Azores, is collecting information on the reservoir locations and processes of magmas. To accomplish this he is studying numerous fluid inclusions using microscopy, a Linkam THMSG600 stage, and Raman spectroscopy. These techniques provide information on the composition of gas species co-existing with magma at depth, and on the pressure conditions of fluid entrapment. In this way he can obtain the depths of mineral crystallization, and therefore, the depths of magma reservoirs.

He has now been able to build a 2D model of the magma ascent path through the crust, determine the crust thickness, and the existence of a shallow area suitable for reservoir formation.

All this information aids the geologists in predicting the behaviour of the volcanoes in question. I am not saying that the geologists will be able to prevent an eruption, stall, or indeed divert the flow, - as was so sensationally accomplished in the movie 'Volcano' - but knowing when it is going to re-offend is certainly a start.

 

An Ongoing Fascination

At Linkam we are fascinated by our planet and the research scientists are doing to understand it better. One subject we like to hear more about is volcanoes. Look back at our “Exploring Vulcan’s Forge“ and “Application of the Linkam TS1400XY heating stage to MI studies” blog posts and you will see that our stages are helping scientists at the forefront of this research.

Tomorrow night, at 8pm on BBC 2, "Volcano Live" is the final of a 4 part documentary looking at volcanoes and how they form a part of our world.  Kate Humble and Professor Iain Stewart look to the future of volcanic forecasting. They also identify an Icelandic volcano which could put the eruption of Eyjafyallajokull in the shade.


Exciting stuff! Hope you enjoy it. I know I will.

Caroline Feltham

 

Myths and mines

Prerequisites for a treasure hunt, old style.

Put down the whip and hat. Move over Indiana Jones. Its time for a new style of explorer.  

Gone are the days of dusty maps and mythical golden cities, these days the chances of finding gold, and other resources, requires a more scientific approach.

Geologists around the world are using microscopes and heating stages to explore the subterranean world of our planet and find its buried riches.

Using a THMSG600 Linkam stage, scientists at the Department of Physics and Earth Science from the University of Parma are investigating gold deposits from the Lepaguare valley mining district in Honduras. 

The Lepaguare is a mining district that hosts several precious metal vein deposits. These deposits mainly consist of gold and sulphide and are found alongside thick quartz veins within pre-Mesozoic metamorphic rocks. Inside the veins, the quartz crystals are rich in fluid inclusions (FI) which can be studied to provide an understanding of the history of the gold deposits.       

We don't expect to see a THMSG600 in the next Indiana Jones movie, but we live in hope.

By Caroline Feltham