Kimberley warm Springs
The Kimberley Warm Springs in northern Tasmania are a hidden gem.
Hidden in the quiet town of Kimberley lies this geothermal phenomenon.
The springs are located within the Kimberley Warm Springs Reserve, which is managed by the Park and Wildlife Service Tasmania. The reserve has a landscaped pool measuring approximately 13 metres by 20 metres and 1.2 metres deep, a sheltered barbeque area, a car park and public toilets.
Access to the site is from Warm Springs Road on Morrison Street.
Far from the usual tourist attractions, these geothermal springs pump hot water from the depths into a generously sized natural pool. The springs have a constant temperature. The chemical composition of the water suggests that it derives its heat from hotter materials beneath the surface.
Warm, relaxing and beneficial - thermal springs, are water springs where the ground water is more than twenty degrees and they come to the surface from deep layers of earth and rocks.
Thermal spring in Kimberley springs from a spring in an alluvial plain surrounding the Mersey River in Kimberley. The flow volume increases towards a small dam about 200 metres away, where the estimated flow rate is in the range of 750-1500 litres/minute. The temperature rises in this section of the river. The content of dissolved solids is quite low for groundwater and it contains mainly bicarbonate and calcium ions. A gas bubbling up from the base of the spring contains up to 6% C02.
Geology of the Kimberley area
The spring rises at the southern end of a northwestern alluvial strip about 10 km long and up to 1.5 km wide that surrounds the Mersey River. The northwestern extension of this alluvial plain runs parallel to the structural trend of the nearby older rocky landscape. The flow direction of the Mersey River in this area was obviously controlled by these structures. South of the source the Permian sediments are unconformably over Ordovician sandstone. Most of the eastern and western edges of the alluvial plain are bounded by Permian rocks that have been intruded by the Jurassic Dole rite. Precambrian quartzite occurs on the northern edge of the alluvial plain.
The alluvial deposits consist of sand, clayey sand and gravel.
Heat source
The water is warmer than surface water and must come into contact with hotter material than the material near the surface. The usual and most likely explanation is that the water comes from a considerable depth, where the temperature is naturally higher. The temperature below the surface normally increases by about 1°C per 30 m and the temperature of the near-surface groundwater is normally 1-2 above the mean annual air temperature. The mean annual temperature of towns near Kimberley is between 10.7° and 11. 2°.
The water would need to flow out of its heat source zone fairly quickly to minimize any temperature loss as it rises through the cooler upper zones.
A fault zone, where the rock is more brecciated and permeable, would provide a possible channel for the water to rise quickly.
What makes the hot spring water so hot?
As already mentioned, in general - the deeper the water - the hotter it gets. The reason for this is that that is where the magma is located. If there is a "crack" or thrust fault (one layer of the crust breaks open and is pushed over another), an enormous amount of heat can be transferred from the magma mica into the surrounding rock through this fault. These hot pockets can extend up to the surface, but the further away from the heat source - the magma - the less heat energy is still in the rock layers. Now if you imagine that water down there, with all the heat energy transferred from the rocks along this thrust fault to the water... the water gets hotter and hotter and hotter... and more water coming off the surface, creating more pressure... Heat + pressure = velocity. The faster the water rises to the surface along this thrust fault, the less time it has to lose its heat. Ergo: This is what makes spring water so hot.
We learned above that we can have cool springs where the water has not really absorbed a measurable amount of heat. There are also thermal springs where the water is slightly warmer than the air temperature, and the warm or hot springs where the water is hot.
How hot the water of a hot spring is depends on a number of factors:
1. The geothermal gradient of the region.
2. The depth that the groundwater has reached.
3. The rate of hot water surfaces. Normally, hot water at depth cannot push its way up through the rock quickly enough to retain the heat that is lost when it rises to cooler layers, so it stops rising before it reaches the surface. If it reaches the surface fast enough, it becomes very hot. If it takes a long time to reach the surface, the water will have cooled down sufficiently before it reaches the surface.
The extent to which the hot water mixes with normal groundwater near the surface means that the hot springs that are created have different temperatures.
These are springs formed by rainwater heated by geothermal mechanisms.
1. Precipitation and snow sink deep into the earth
2. When moving underground, the temperature rises by 2-3 degrees Celsius about every 100 meters. For example, if it is 20 degrees at the surface, the temperature at 1,000 meters below will be 40-50 degrees! This heat heats up the water that has sunk to the ground.
3. Alternatively, the cooled magma deep underground becomes bands of very hot rock.
These can also heat underground water.
4. This heated water then rises and gushes out as natural springs. It can also be drilled down to create a spring.
Conclusions
The spring in Kimberley has a temperature that is about II-12°C higher than would be expected for near-surface groundwater. This higher temperature is probably caused by the fact that the water rises quickly from deeper layers. The water contains a relatively low concentration of dissolved solids, the main components being bicarbonate and calcium ions. Gas bubbles emerging from the base of the spring are enriched with carbon dioxide in relation to the air. The carbon dioxide can originate from the decomposition of carbonate rocks at depth or it can be dissolved by rainwater seeping through the unsaturated zones above the water table. Soil air and soil vapour have a much higher concentration of carbon dioxide than the atmosphere. The flow volume of the spring has not been measured, but seems to be at least in the range of 750-1500 l/min.
Please answer the following questions to log this earthcache.
To answer the questions you need a thermometer to measure the water temperature - measuring range: 0 to 50 degrees celsius
1. Measure the temperature of the water in the spring basin near the small bridge
2. With the recorded temperature and the average annual temperature around Kimberley, given that the spring is located in a tectonically inactive region, determine the minimum depth from which the warm water rises? Let us assume that there is no change in the temperature of the hot water at depth and on the surface, and that the geothermal gradient follows a linear function. This question only serves to get an idea of how deep the reservoir of the hot springs is if the temperature of the reservoir is similar to the temperature of the warm water at the surface.
3. Name at least 2 minerals that can be found in the thermal water.
4. Observe an outlet of the spring in the lake, describe the structure and justify your statement.
5. The famous photo!
Please take a nice picture with the “Spring pool” in the background.
The correct answers and the photo are as Log-requirement.
Send an email with your answers to sissifalke1@gmail.com
After submitting the answers can log their equal, if not something is wrong, we'll get.
You need not wait for our Log-requirement.
Enjoy this geological expedition very much and good luck!
Team sissifalke
REFERENCES ANONYMOUS, 1977. Mineral waters of our country. Korea Today. 255 (1). A~KINSON, T.C., 1977. Carbon dioxide in the atmosphere of the unsaturated vzone: an important control of groundwater hardness in limestones. J. Hydrol. 35: 111-123. GOL'DFAIL', L.G.; OPPENGEIM, D.G., 1973. Balneology. Great Soviet Encyclopedia. 600-601.