How weather and climate influences speleothem growth and paleo-climate isotopic records

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dc.contributor.authorWaring, CLen_AU
dc.contributor.authorHankin, SIen_AU
dc.date.accessioned2020-06-12T06:25:15Zen_AU
dc.date.available2020-06-12T06:25:15Zen_AU
dc.date.issued2014-07-07en_AU
dc.date.statistics2020-05-15en_AU
dc.description.abstractSpeleothem growth band variations in chemical and isotopic composition are used to infer paleo-climatic conditions. Interpretation of speleothem paleoclimatic records may be improved by matching analysed subsamples to the represented elapsed time and prevailing weather or climatic conditions. Analysed subsamples may represent a month for rapid growth speleothems or many years for slow speleothem growth. Speleothem growth may also be seasonally biased affecting the paleo-climate record. To better understand the temporal fine scale of speleothem growth patterns we have principally used CO2 concentration in cave air. As CaCO3 is precipitated to accrete a new speleothem layer, CO2 is released into the atmosphere. However, CO2 may also come from other sources. To discriminate between different sources a real-time isotopic CO2 analyser, located near the entrance to Chifley Cave, is used. Cave air is sequentially sampled for 10mins from 4 internal and 2 external locations and analysed for H2O, CH4, CO2, and δ13CCO2. The 3 principal sources of CO2 are external air, speleothem growth and soil-air. The proportion of each CO2 source contributing to the total cave air CO2 is calculated for each sampled Chifley Cave location. CO2 exhaled from passing tour groups is often recorded as a minor rapid increase before subsiding to the previous background levels over 10–15 mins. Cave air CO2 shows a seasonal (summer maximum) and often a diurnal cycle, from a minimum late morning to a maximum in the late evening caused by ventilation of external low CO2 air. Differences between the external temperature and the near constant cave air temperature causes a buoyancy contrast which drives bidirectional cave air ventilation. On hot days cool cave air (11°C) sinks into the Grand Arch and is replenished by sucking external air from the Plughole cave opening. The slightly lower cave atmospheric pressure on hot days also causes soil-air rich in CO2 to seep into Chifley Cave, notably at the bottom of Katies Bower. On cold winter days relatively buoyant warm cave air escapes via the Plughole 70 m above and through minor fissures reversing the summer pattern. A detailed description (10 min sampling for 2 years) of the speleothem growth pattern in response to external temperature variation is presented.en_AU
dc.identifier.citationWaring, C., & Hankin, S. (2014). How weather and climate influences speleothem growth and paleo-climate isotopic records. Presentation to the Australian Earth Sciences Convention 2014 (AESC 2014), 22nd Geological Convention, Newcastle NSW, 7-10 July 2014, (pp. 226). Retrieved from: http://aesc2014.gsa.org.au/assets/Various-reg-partner-opp-workshop-summ-/AESC-Abstract-Proceedings.pdfen_AU
dc.identifier.conferenceenddate10 July 2014en_AU
dc.identifier.conferencenameAustralian Earth Sciences Convention 2014, Newcastle NSW, AESC 2014. 22nd Geological Conventionen_AU
dc.identifier.conferenceplaceNewcastle, New South Walesen_AU
dc.identifier.conferencestartdate7 July 2014en_AU
dc.identifier.govdoc9558en_AU
dc.identifier.pagination226en_AU
dc.identifier.urihttp://aesc2014.gsa.org.au/assets/Various-reg-partner-opp-workshop-summ-/AESC-Abstract-Proceedings.pdfen_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/9632en_AU
dc.language.isoenen_AU
dc.publisherGeological Society of Australiaen_AU
dc.relation.ispartofseries0729 011 X;en_AU
dc.subjectPaleoclimatologyen_AU
dc.subjectWeatheren_AU
dc.subjectCavesen_AU
dc.subjectGeologic structuresen_AU
dc.subjectClimatesen_AU
dc.subjectCarbon dioxideen_AU
dc.subjectAiren_AU
dc.titleHow weather and climate influences speleothem growth and paleo-climate isotopic recordsen_AU
dc.typeConference Abstracten_AU
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