Geology, stratigraphy, water and CSG a bit more understood

A CSIRO researcher recently provided me with a copy of a conference paper on the Clarence-Moreton Basin that I have been searching for (Doig & Stanmore 2012). I was looking for this information for quite some time as I thought there was much to be learned from it. This is because the research was based upon coal seam gas (CSG) exploration results. It did not disappoint me at all. I have previously blogged on the stratigraphy of the basin but frequent visitors will be aware that there has been a hiatus on this topic. This is because I knew more information had been compiled as a result of gas exploration in the region. In particular this was to do with the Grafton Formation and Kangaroo Creek Sandstone. You can read my previous posts but note that Doig & Stanmore (2012) propose to reclassify these units (see figures 1 and 2 on this post). The information my previous posts were based upon Wells and O’Brien (1994). This is still the most comprehensive guide to the basin but now there is potentially some significant refinements.

Interpretation of the stratigraphy of the upper sequences of the Clarence-Moreton Basin
after Wells & O'Brien (1994) and Willis (1994)

Doig & Stanmore (2012) noted that CSG exploration drilling has provided important clues to the layers that make up the Clarence-Moreton basin that were inferred only through limited field exposure. Drilling provides a nice continuous profile which can be compared to other drill holes and to outcropping information. In the case of Doig & Stanmore (2012) this has completely redrawn the stratigraphy of the upper Clarence-Moreton Basin.

Reviewed Clarence-Moreton Basin stratigraphy after Doig & Stanmore (2012)

I will go into more detail in future posts but I note that Doig & Stanmore (2012) have made some major changes to the Grafton Formation. In particular, they have identified two new distinct members of the formation. The Piora Member and the Rappville Member. As for the underlying Kangaroo Creek Sandstone, this spatially and significant unit has been demoted simply to a member of a newly proposed formation called the Orara Formation. The Orara Formation itself has two distinct formations the demoted Kangaroo Creek Sandstone Member and the new Bungawalbin Member. (See figure 2).

The Woodenbong beds don’t get a guernsey at all in this paper. I suspect that this is because it would better fit into either the Bungawalbin Member of the Kangaroo Creek Sandstone or the Piora Member of the Grafton formation. More work needs to be carried out to make it more certain.

Clearly we do not understand much about the Clarence-Moreton Basin. Even the shallowest geological components! Knowledge keeps improving the more people investigate. The paper provides further interest because identification of the stratigraphic units and geochemical data obtained provide an indication of the risk associated with groundwater resources and CSG production. So as usual, further blog posts are required.

References/bibliography:
*Doig, A. & Stanmore, P. (2012). The Clarence-Moreton Basin in New South Wales; geology, stratigraphy and coal seam gas characteristics. Paper presented at the Eastern Australian Basins Symposium IV, Brisbane.
*Wells, A.T. & O’Brien (1994). Geology and Petroleum Potential of the Clarence-Moreton Basin, New South Wales and Queensland, Australian Geological Survey Organisation, Bulletin 241.

The Game of Thrones - Geological Map

Time again to delve into the region of geological fantasy. I have previously noticed that Middle-Earth from the J.R.R. Tolkien’s Lord of the Rings has had its climate modelled. But I’ve never seen anybody actually recreate a fantasy world’s geology, until now. Miles Traer and Mike Osborne from Stanford University has done just that. He has created a geological map and recreated the geologic history of the lands from the series Game of Thrones.

I’ve only watched one episode of Game of Thrones myself. I found it a little to confronting and violent. Yet, the storyline was very good. I can see why people really like the series. Though I’m a little surprised that someone is obsessed enough to develop a geological history of the area.

Miles Traer’s blog on the geology of Westeros and Essos can be found here.

Mike Osborne’s account of the geology of the Game of Thrones lands can be found on the American Geophysical Union Blog here.

Clarence-Moreton Basin CSG Bioregional Assessment with some Philosophy

I was fortunate enough to be invited to a short presentation on hydrology and coal seam gas in the Clarence-Moreton basin last week. It was particularly good, in part, since lunch was provided and one of the presenters from the CSIRO ended up being someone I knew but had not seen for nearly a year. The topic of the presentation was an assessment that has recently commenced on the effects of coal seam gas (CSG) on water resources. Alas, it is something that the media has all but ignored. So a bit of information and a bit of philosophy in the blog post today!

This year a large investigation (a bioregional assessment) into all the possible effects of CSG on water commenced in earnest. It is a project funded by the Federal Government with many scientific project partners including the CSIRO. The project is based exclusively in the first case, on the compilation of scientific information. It is at arms-length from government and politics, so it is entirely technical. Therefore, this assessment is something which I personally find interesting and feel is of great value. The project scope has been set up by the Independent Expert Scientific Committee on Coal Seam Gas and Large Mining Development. The committee was established in 2012 and works under the authority of the Environmental Protection and Biodiversity Conservation Act 1999. A link to the CSIROs summary of its involvement can be found here.

The Clarence-Moreton basin bioregional assessment itself is one part of many bioregional assessments in numerous Australian coal basins. These assessments are themselves divided up into many different components including hydrogeology, ecology, ecotoxicology, environmental protection and many others. The presentation that I attended was specifically related to the hydrogeological modelling that is being developed. It briefly covered the different data sources and data limitations that were going to go into the modelling. It was good to see the thoughtfulness and consideration given to all the hydrogeological issues. Sometimes just figuring out what needs to go into a model is very hard in itself… but by far the hardest task is making sure the modelling reflects the real world. This is because of the varying amounts of "weighting" required to each of the input variables.

However, one of the things that saddens me is the lack of media time this assessment has been given. Many people are concerned that not enough is known about CSG activities in our region or in Australia or even more broadly, around the world. The media tends to focus on the conflicts that are occurring and not on the advances in technical knowledge that will lead to better decision making in the near future. The media does not seem to like reporting on things that we are learning but instead increases the confusion about matters that could lead to social conflict. Conflict, not cooperation seems to sell newspapers these days.

I was also a little saddened by some questions that were asked of the CSIRO presenters. One (Environmental Economics and Policy Academic!) asked whether it was ethical to undertake this assessment because it may lead to a CSG development being regarded as “safe”. To consider an increase in human knowledge of the world in which we live un-ethical is a big worry for me. Especially from a senior academic. In many ways it questions the very basic concepts of scientific endeavour. Having a scientific background, I feel we should not avoid learning something new because the facts that may arise could potentially contradict with a pre-determined world view. We are of-course moving from science to philosophy. I know my philosophical motives in life are to use knowledge to give the best outcomes for the environment and people that live in our region.

So, to end on this philosophical note: I recommend thinking about the knowledge that we have and how we use or ignore it. The media practice of looking only at conflict and dumbing down its stories on scientific and technical matters is well entrenched. I’m starting to genuinely believe that the media is making it harder to distinguish between facts and opinions purely in the media’s self-interest of creating a story to make money from. Recognising this is helpful to understanding where scientific information can guide us in the right decisions, as such I provide here a link to an ABC presentation on the media by an excellent modern day philosopher (one of my favourite non-science authors) Alain De Botton.

Where Does the Groundwater Flow?

There has been renewed interest in groundwater resources in the Northern Rivers of late. In part this is due to peoples concern about "unconventional" gas exploration and production in the area. Surprisingly, less known is the release of Rous Water's Future Water Strategy which includes groundwater as first on the list for new water sources. Rous Water is a major bulk drinking water supplier in the region. I've previously covered an area within the coastal sands groundwater source called the Woodburn Sands but this was a cursory look and I'd not covered where the groundwater actually goes.

Groundwaters do not exist as an underground lake in our region
Image courtesy of International Association of Hydrologists

Groundwater is often seen as a bit of an unknown, a black box, or some kind of underground lake (see the cartoon). It is quite difficult to observe and therefore people can get the wrong idea of what goes on underground.

One area that is not understood is that groundwater usually discharges somewhere. Sometimes groundwater discharge is obvious through springs. But where it intersects with permanent surface water it is much less obvious. The Evans Head area is a good example of where discharge from the Woodburn Sands aquifer and broader Coastal Sands aquifers is concealed.

Spring-fed creek on Chinaman's Beach.

While walking along Chinaman's Beach south of Evans Head during a recent long dry spell, I couldn't help notice the dark coloured water flowing over parts of the beach. This is one of those discharge areas I'm talking about (most people might be more used to seeing freshwater flowing over a beach from contaminated urban stormwater drains). The coastal sands above Chinaman's Beach holds groundwater and slowly discharges it at the beach. The dark colour of the water is from dissolved humic matter from coastal vegetation soaking into the sand. Tasting the water it was apparent there was no salt in it and understanding the groundwater area I knew it was clean. The springs I observed on Chinaman's Beach were obvious areas of groundwater discharge. The vegetation in the springs was lush and clearly reliant on the groundwater. This is formally known as as groundwater dependent ecosystems.

The lesser known discharge is not all through visible springs like those on Chinaman's Beach. Much of the discharge from the coastal sands aquifers is actually concealed by the sea. It might be a surprise to many in some areas just off the coast there are zones with freshwater. The amount of water that can be discharged underground into the sea can exceed the discharge from terrestrial springs (e.g. Santos et al. 2009). These are the undersea equivalent of the Chinaman's beach springs. This is interesting from a aquatic ecology point of view because it may mean that there are ecosystems in the ocean that are dependent on freshwater! That is, groundwater dependent ecosystems in the sea.

Groundwater is an interesting feature of our region. It is a source of drinking water, irrigation water and even industrial water. It is often important as some ecosystems are dependent on it. It is also surprising since ecosystems can be dependent on fresh groundwater even when out to sea.

Postscript: about a month after this blog post a story emerged in the local newspaper about sinkholes or zones of quicksand on Chinamans Beach. These quicksand 'pits' look just like typical groundwater discharge areas. The Northern Star article can be found here.


References/Bibliography:
*Santos, I.R, Burnett, W.C., Chanton, J., Dimova, N. & Patterson, R. (2009). Land or Ocean?: Assessing the driving forces of submarine  groundwater discharge at a coastal site in the Gulf of Mexico. Journal of Geophysical Research. vol114.

Filling a gap with weathering textures

I've been a bit slack lately in posting. I usually have a post ready to go on the first day of every month with a few more over the month. But not so this time. It seems that life just hasn't given me the time to write over the last few weeks. So instead no post at all, here are a few pretty pictures of weathering patterns from the area.

Phyllite of the Neranleigh-Fernvale beds. In this case the darker part of the rock has been preferentially eroded by wind and wave action creating the early stages of a tessellated pavement. The quartz veins that are present stand proud from the surface. Technically this is not actually weathering per se... but oh well it looks pretty.

Weathering of the cross-bedding in this sample of Kangaroo Creek Sandstone develops a very pretty pattern.

Differential weathering in phyllite of the Neranleigh-Fernvale beds. The fabric of the rocks leads to some minerals being more susceptible to weathering by reactive sea water.

Fracking qualifies for aged pension

Over on the About Geology Blog, Andrew Alden shows us that yesterday was the 65th anniversary of Hydraulic Fracturing (Fracking/Fraccing). I was quite surprised to learn that this “unconventional” technique was developed in my grandparent’s generation. In his blog post Andrew points out some of the controversies in the United States about “Fracking” and provides his opinion on the practice. I don’t want provide to provide any opinion here about the Australian situation, just to outline a very quick summary of how it is used.

Having said the above, I think it is important to mention that there is some differences in experience between Australia and the United States. The main difference being that any chemicals used in “Fracking” must be fully disclosed (unlike the USA where they are much more secretive). Another difference is that in the USA “Fracking” is most commonly used in “Shale Gas” formations where it has been reportedly been linked to many problems with regard to aquifer cross-connection and contamination. Coal Seam Gas in the USA are also a situation where Fracking is frequently used, though this has very few of the same issues of Shale Gas fracking (Blackam 2014).

In Australia “Fracking” is frequently used in “Tight Gas” situations where directional drilling alone is impractical. This practice is especially common in the Moomba Gas Fields of Queensland and South Australia now this field has become depleted in the easily accessible “Conventional” gas. Hydraulic fracturing is also sometimes used in Coal Seam Gas situations. In the Northern Rivers I understand there has only been one case of hydraulic fracturing which was used in a “tight” situation.

This is by no-means a clear bill of health for unrestricted use of the practice of Fracking. Many questions still remain about what damage the practice can cause (e.g. Batley & Kookana 2012).

I’ve done some posts on the different natural gas sources and summarised them on this page. Until I actually do a blog post on what hydraulic fracturing actually is, I recommend this summary from the CSIRO. Alternatively, this CSIRO/Industry publication, though developed in partnership with the gas industry is actually even more detailed and very good.

References/Bibliography:

*Batley, G.E. & Kookana, R.S. 2012. Environmental issues associated with coal seam gas recovery: managing the fracking boom. Environmental Chemistry. vol9 p425-428
*Blackam, M. 2014. Source, Fate and Water-Energy Intensity in the Coal Seam Gas and Shale Gas Sector: An Exploration of the relationship between energy and water in the unconventional gas sector. Water, Journal of the Australian Water Association. vol41 No.1 p51-56

Armidale submerged

Armidale is well known for its height above sea level, with some areas above 1000m it is at a relatively high altitude by Australian standards. The city is located in the New England, ‘Northern Tablelands’ which provides an indication of the landscape in which it is situated. The area resembles a very large plateau with comparatively light rolling hills compared with the nearby escarpment and edges of the tablelands. In fact, Armidale is just a tiny bit to the east of the crest of the Great Dividing Range. Surprisingly, this area was in part inundated by a lake, or lakes.

Examples of some rocks that make up the Armidale beds
The big sample at the front has been partially turned into silcrete.

One of the headwaters of the Macleay River, Dumaresq Creek flows through Armidale. In places this creek, as well as other creeks in the area, have cut through the basalt rock that covered the area. A description of this process was covered in an earlier post. In this post I’d like to describe the sediments that lie under the basalt. These are Eocene (or earlier) sediments named by Voisey (1942) the Armidale Series, now known as the Armidale beds.

The Armidale beds are comprised of fluvial (river) and lacustrine (lake) deposited sediments. These are principally conglomerates, siltstones, sandstones and shale. Interestingly, the shales are laminated possibly as a result of seasonal deposition in a lake. They also contain abundant plant fossils. The material that makes up the sediments is particularly obvious in the conglomerate. The conglomerate clasts are derived from the older underlying geology, for example clasts of jasper, quartzite and granites.

The Armidale beds occur in small remnant areas (the balance of the beds having been eroded away). These remnants occur throughout the Armidale area but almost as far away as Wollomombi to the west, near Dangars Falls to the south-east and Kellys Plains to the south-west. Voisey 1942 named this area Armidale Lake which is a palaeo-lake that only exists now in the sediments that it left. The formation of Armidale Lake occurred either before or during the volcanism that ended up covering a majority of the Armidale region in blankets of basalt lava (lavas of the Central Volcanic Province). In fact, the Armidale beds were preserved by this blanket of basalt both directly and through metamorphism beds in the area of contact. This metamorphism of the Armidale beds created a layer of hard silcrete (once known as greybilly) which itself was resistant to erosion and helped preserve the underlying un-silcretized sediment from being washed away.

The picture above is an example of the Armidale Beds that occur near the Armidale garbage disposal centre. A very accessible example is located on Madgwick Drive on the way to the University. It is actually one of the best remaining exposures of the unit and has been used for years by local schools and the university. Indeed, Banaghan & Packham 2000 have the road cutting as a stop on their Armidale-Yarowych geological tour.

References/bibliography:

*Branagan,, D.F. & Packham, G.H. 2000. Field Geology of New South Wales. Department of Mineral Resources.

*Fitzpatrick, K.R. 1979 The Armidale area. Geological Survey of New South Wales. Geological Excursion Handbook 1

*Voisey, A.H. 1938. The Geology of the Armidale District. Proceedings of the Linnean Society of New South Wales.

*Voisey, A.H. 1942. The Geology of the County of Sandon, NSW. Proceedings of the Linnean Society of New South Wales. V67.