Thursday, 1 October 2015

An appeal for help

Sometimes it is hard to ask for help. To reveal yourself as vulnerable and as being in need is hard. Being a man and the expectations that come with that to be a father, a husband, a protector and provider are not easy to do. But what happens when you realise that you can’t do one or some of those things. The only thing is to ask for help. That is what I am doing with this blog post. Forgive me for using this geology blog to ask for personal help but that is what my family is in need of.

I have a five year old daughter. She was recently blessed with a wheelchair and help with physiotherapy with the help of many people from Dick Smith to the congregation of the church we are part of. But we are now again in need. She has recently commenced a programme to get her eating again. She has not eaten food by mouth for over two years. The specialist therapists now think she should be able to with the help of more specialists and hospital support in Adelaide. The cost of this programme is immense.

My daughter, Eleanor has been thrust into the media while we ask for help. Even a Television crew are coming to our house from South Australia tomorrow morning. Eleanor has been on the Daily Mail, the Northern Star, the Northern Rivers Echo and National websites such as Mammamia. My wife blogs about her and Eleanor’s journey and there is probably the most detailed information available. But we do have a fund raising website which we are promoting and asking people to contribute. Please help us if you can.

Links to the stoes can be found here:

Northern Star

Northern Rivers Echo

Daily Mail Australia



Rodney Holland (Geology Rod)

Monday, 21 September 2015

Cooking the rocks at Emerald Beach

I have always been interested in the little things in life. The things that don’t get the attention that everything else seems to get. This even applies to rocks and rock outcrops. It applies to a little headland that I visited on a trip to Coffs Harbour earlier this year. The headland has no name but lies on the northern side of Emerald Beach and the village of the same name. It is made from a granite-like rock of a poorly understood suite of intrusions in north eastern NSW.

Boulder on Emerald Beach. Note the xenolith at the bottom
The rock is formally called the Emerald Beach Monzogranite. It is the eastern most granite on the Australian continent is also one of the youngest rocks in the New England area. The Emerald Beach Monzogranite has been dated at 228.5Ma and part of an informally super suite of granites called the Coastal Supersuite (Chisholm et al 2014). Originally the unit was formerly defined as the Emerald Beach Adamellite (Korsch 1978) but has been renamed to reflect the most up-to-date nomenclature. However, the name Monzonite (and hence Adamellite) is misleading. The composition of the rock is consistent with the definition of Granodiorite (Plagioclase Feldspar abundance greater than that of Potassium Feldspar (Korsch 1971, Chisholm et al 2014). No reference to Monzogranite (or Adamellite) have been made and the samples I’ve seen were plagioclase feldspar dominant so the present classification appears erroneous. Maybe the name Emerald Beach Granodiorite might be more correct.

The dating of the Emerald Beach Monzogranite was only conducted in the last couple of years. It is an example of using multiple techniques together to get an answer. The mineral Zircon is formed in magma chambers of granite and granite-like composition. This is a very stable mineral. Zircon locks up uranium in small amounts and this uranium undergoes radioactive decay to lead. By measuring the proportions of uranium to lead it is possible to determine how long ago the zircon had formed. By this method Chisholm et al 2014 narrowed the age down to about 228.5 million years old. This is the Upper Triassic era which was the time of the best known dinosaurs.

Xenoliths of country rock are present in the rock (you can see an example in the picture above). These darker coloured xenoliths are inclusions of country rock which has been caught up in the magma chamber and have not quite been completely melted into the rest of the liquid rock. In the case of the Emerald Beach Monzonite the xenoliths are slightly elongated and display a preferred orientation. This orientation is probably caused by following the direction of intrusion of the molten rock (Korsch 1971).

The intrusion of the magma heated up the surrounding rock into which it had been emplaced. This heating up forms what is termed a contact metamorphic aureole (a metamorphic zone of effect). The Emerald Creek Monzonite had heated the muds in the surrounding deep sea Coramba Bed rocks to such an extent that new minerals were formed including very small but abundant crystals of biotite mica. Biotite mica forms at approximately 500 degrees Celsius (but varies by pressure) and disintegrates when hotter than about 800 degrees. Therefore the temperature of the molten rock was probably at least this. This type of contact metamorphic rock is referred to as hornfels.

It is an interesting example how little aspects again can tell a lot about how rock forms. Preferred orientation of xenolith inclusions and the formation of biotite in the surrounding rock show both the direction that the magma was moving and its temperature at the time. Have a look if you are in the area and see if you can spot some of the xenoliths. Those that are really in the know can say that the Emerald Creek Monzonite seems to have been incorrectly named.


*Chisholm, E.I., Blevin, P.L. and Simpson, C.J. 2014. New SHRIMP U–Pb zircon ages from the New England Orogen, New South Wales: July 2012–June 2014. Record 2014/52. Geoscience Australia
*Korsch, R.J. 1971. Palaeozoic Sedimentology and Igneous Geology of the Woolgoolga District, North Coast, New South Wales. Journal and Proceedings of the Royal Society of New South Wales. Vol. 104.
*Korsch, R.J. 1978. Stratigraphic and Igneous Units in the Rockvale-Coffs Harbour Region, Northern New South Wales. Journal and Proceedings of the Royal Society of New South Wales. Vol. 111.

Friday, 4 September 2015

Baseline CSG methane in groundwater

A friend recently let me know that a paper that one of his students wrote for the Journal of Hydrology had been published. I had a very minor involvement in the formative stages of the paper which came about indirectly as a result of the protests of many local people about potential coal seam gas (CSG) and other natural gas types in the region. The paper (Atkins et al 2015) is essentially the results of a data collection exercise but has some interesting techniques and findings about the baseline concentrations of gas in groundwater bores in the Richmond Valley area.

Methane concentration for different geological environments
(after Atkins et al 2015)
91 water samples were collected from government and private bores in geological units overlying the target CSG geological formations in the Clarence-Moreton Basin (e.g. the Walloon Coal Measures). These units were quite diverse and ranged from sedimentary rocks of the Piora Member of Grafton Formation and the Kangaroo Creek Sandstone (recently reclassified as the Orara Formation), basalt lava flows of the Lismore, Astonville and Kyogle Basalts and Quaternary aged alluvium including coastal sands and riverine sedimentary environments.
Special glass water sample containers were used to collect the samples. These were then injected with a carbon dioxide and methane free gas to create a clean “air bubble”. The methane and carbon dioxide naturally dissolved in the water will then come into equilibrium with the “air bubble”. The resulting gas from the bubble can then be extracted and the concentration and isotopic composition of the carbon in the two compounds determined by an electronic analyser. The isotopic signature can then be assigned to recent biological formation (biogenic) or geologically derived (thermogenic) origin.
The end result was annoyingly quite not straight forward. The concentration of methane showed no obvious relationship to the chemistry of the groundwater. However there was a relationship between geological units. Methane concentration was very low in the basalt aquifers and relatively higher than the Clarence-Moreton basin sedimentary rocks and much higher in the Quaternary alluvium of the Richmond River valley floodplain and coastal sands systems. So there was more methane in some of the aquifers that were the less likely to be connected to any CSG formations! Quite counter-intuitive.
The isotopic signatures did not really help clear up this confusion very much. There appeared to be a large thermogenic component to the coastal sands and flood plain aquifer systems sometimes at concentrations greater than the formations that should be the thermogenic CSG source. Why? It was noted by some CSIRO scientists working in the Great Artesian Basin that sometimes biogenic gas can be oxidised and then be chemically reduced back to methane and this process favours the thermogenic isotopes. So, It gives the impression of thermogenic gas.
This means that the methane gas concentration is related to the biological activity in and around the aquifer. The shallowest groundwater systems are the most connected with surface water and biological processes and therefore these have the highest concentrations of methane. The Clarence-Moreton Basin sediments are not connected with the CSG and natural gas rich formations.
This means that if companies like Metgasco do commence gas operations in the area there is a statistical background that can be used to compare if anyone becomes concerned about methane in their water bores. Interestingly, it also shows that methane in groundwater is probably not a good method to search for natural gas in the region. It might apply to other areas like the Great Artesian basin but apparently there are good barriers between CSG and non-aquifers in the Northern Rivers. This is good news since if something does go wrong it is now more easy to identify if it has impacted upon any groundwater.


Atkins, M.L., Santos, I.R. & Maher, D.T. 2015. Groundwater methane in a potential goal seam gas extraction region. Journal of Hydrology: Regional Studies. V4.

Sunday, 23 August 2015

Hillgrove Monzogranite

Hillgrove is known for its mining history. The fortunes of the place have been directly related to gold and antimony mining for more than a hundred years. Armidale in comparison was tiny, a village in comparison with Hillgrove at its peak. Hillgrove still operates a mine for antimony and gold but is now quite a sleepy place with a handful of inhabitants. Most people working in the mine commute from Armidale. But the mine itself is not what I want to write about, it is about the attractive rock that is known as the Hillgrove Monzogranite. Despite its name the Hillgrove Monzogranite is not the extensive source of gold and antimony that is mined in the area. Most of the ore mineralisation is either directly or indirectly related to the nearby Bakers Creek Diorite or remobilisation of material from the adjacent marine sedimentary rocks.
Hillgrove Monzogranite on the Waterfall Way

According to the Australian Stratigraphic Names Database the Hillgrove Monzogranite was until recently known as the Hillgrove Adamellite (Adamellite being the outdated synonym for Monzogranite). It was previously classified as part of the Hillgrove suite which in turn is part of the Hillgrove Supersuite.  However, based on geochemical properties (and possibly just to confuse people) the Hillgrove Monzogranite is no longer considered part of the Hillgrove suite instead just being a member of the Hillgrove supersuite! However, it is clearly one of the S-type plutonic rocks collectively known as the New England Batholith (Bryant et al 2003).

Monzonite is unsurprisingly the dominant rock type of the Hillgrove Monzonite. It is an S-Type granite (derived from melted sedimentary rock). It is comprised mainly of quartz and feldspars (roughly equal potassium feldspar and sodium-calcium Feldspar), quartz, biotite mica and hornblende. The biotite often shows a foliation, which is a preferred alignment in the rock. The age of the Hillgrove monzogranite is estimated at between around 270 to 290 million years. To my knowledge, the age has not been directly measured but instead is based on its relationship to the surrounding rocks with their either calculate or approximate ages.

The landscape formed by the Hillgrove Monzogranite is one of my favourites. It forms a relatively large plateau which contains low rolling hills and lovely boulder outcrops. These outcrops often form lovely torrs (see pictures) formed by “onion-skin” weathering. Water enters cracks in the rock and during winter this freezes and expands gradually wedging the layers off the boulder. This is correctly termed frost wedging.

The Bakers Creek gorge has cut into some of the unit near the Hillgrove area but overall the appearance of the country is quite gentle. The rock unit extends a long distance from the location of Argyle in the west almost to Chandler Gorge in the east. The Waterfall Way (Armidale-Dorrigo Road) crosses in and out of the Hillgrove Monzogranite and Girrakool Beds into which it has intruded. Therefore it is an easy stop on the road when travelling this route.

The soils are sandy and not very fertile leading to an area used for cattle and sheep grazing on native and improved sown pastures. The forest is an open dry sclerophyll snow-gum type bush which is one of the typical environments of the New England high country. I love the appearance of this country. It is the quintessential high-lean New England landscape.
*Ashley, P.M. & Craw, D. 2004. Structural controls on hydrothermal alteration and gold-antimony mineralisation in the Hillgrove area, NSW, Australia. Mineralium Deposita v39.
*Bryant, C.J., Chappell, B.W. & Blevin, P.L. 2003. Granites of the Southern New England Orogen. Abstracts of the Ishihara Symposium: Granites and Associated Metallogenesis. GEMOC, Macquarie University

Friday, 7 August 2015

Don't you hate it when...

Don't you just hate it when you have information to share but you are not permitted by contracts and commercial in confidence so share it? Our society is more and more being constrained by bureaucratic regulations set up by people who are career managers but have very little understanding of the real world. Little understanding that science and engineering knowledge benefit all people and that some perceived public image issue is more important than the wider good. This means that innovation can be stifled... at least in my personal opinion. The perceived public perception of scientific discoveries hinders the development of knowledge from Climate Change to Panadol!

By way of one a specific local example, I was helping an environmental centre have a ground water bore installed. The Department of Education which runs the environmental centre put absurd restrictions on access to the groundwater. One such limitation was that school children had to wear gloves when touching the groundwater in case it was contaminated. After running some tests it is apparent that the groundwater is actually better quality than the filtered tank water that they are currently drinking... but still the safety controls need to be in place! I'm happy to drink the water but the children must still wear gloves... go figure!

Another example is a cutting edge research project in the Woodburn-Evans area. The information gained from this research is very important for most coastal sand groundwater systems in eastern Australia. Alas, the words from a senior manager in a NSW government department are that no scientific information gained from the research is to be released to the public in the short term. What a shame. I understand that people are risk adverse today especially with regards to perceived public opinion but I don't think scientific knowledge should be hidden away.

On a slightly different note I have received a copy of an in-press paper on Coal Seam Gas monitoring in the Northern Rivers area. I provided some minor assistance in the paper and so an author kindly showed me before it was published. It is expected to be released in a few weeks and is likely to be in the newspapers too. Keep an eye out for those three letters C, S & G.
Sorry for the rant... just had to get that off my chest... hopefully a less opinionated post coming up shortly!

Tuesday, 14 July 2015

Northern Rivers Geology Immortalized by the National Library of Australia!

People will have noticed that I have been very quiet of late. Unfortunately there are many family matters which are taking all my spare time and therefore this blog is suffering in the short term. The local newspaper ran a story about my family that may help to illustrate where my efforts are presently focused. A big thanks to Lismore City Lions Club, the congregation at Cross Roads Presbyterian Church and many anonymous donors who have helped our family recently.

However, even though I've been unable to post further stories on this blog I was chuffed to be contacted by the National Library of Australia seeking permission to be added to their web archive called PANDORA. The National Library describes PANDORA thusly:
The National Library's PANDORA web archive has been building a collection of Australian websites since 1996. Many of the significant sites preserved by PANDORA, such as the Sydney 2000 Olympic Games website are no longer available on the web.
So, wow! A big honour to be asked and one that I will accept. I was wondering what would happen to all my posts if blogger hit the wall. 

Thursday, 14 May 2015

New England Geological Tour 2015

Just a quick note to let people know that the Australian Institute of Geoscientists (AIG) and the Geological Society of Australia (Queensland Branch) will be jointly running a field trip to the New England area of New South Wales and southern Queensland over the June long weekend 6th to 8th June). The field trip follows a one day seminar by the AIG. 

Geoz reports thusly:
6 - 8 June 2015 GSAQ–AIG Field Conference: New England District Regional and Economic Geology
A joint GSA–AIG field trip to the New England Orogen, with a preceding one-day seminar.
As a prelude to the Field Conference, GSAQ and Queensland Branch of the AIG
are proposing to run a one day seminar “New England Orogen, Regional and Economic Geology - an update” to showcase recent advances in the understanding of the New England Orogen.
 The main focus sessions of the pre-field trip seminar will include:
  • The New England Orogen – geology, granites and tectonic setting
  • Mineralisation styles of the northern and central New England Orogen
  • Geochemistry applications in the New England Orogen
  • Intrusive related mineralisation styles of the southern New England Orogen
The Field trip will start from Brisbane and and include tours and presentations in the Stanthorpe, Texas, Tenterfield and Drake areas.

Accomodation and some meals are included in the cost of the field trip. For more information on the field trip contact the GSA or AIG, for more information on the Brisbane pre-trip seminar contact the AIG.