Abstract
Recent interest in the shale gas potential of the Karoo Basin has highlighted the metamorphic effects that Jurassic dolerite intrusions may have had on the Lower Ecca Group black shales. We explore the use of metamorphic petrology and Ti in biotite geothermometry to constrain conductive heat flow modelling of a thermal aureole adjacent to two closely spaced, thin dolerite sills intruded into these black shales. Our numerical heat flow modelling shows that a 45 m thick sill may heat a ~100 °C host rock to 650–700 °C at the contacts, and to ~350 °C, 45 m away from the contact. Mineral phase equilibrium modelling constrains minimum temperatures of ~375 °C up to 13 m above the two sills and cooler temperatures farther away and below the sills. Titanium in biotite (TIB) geothermometry results are varied, suggesting disequilibrium conditions within the contact aureole.
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References
Aarnes I, Svensen H, Connolly JAD, Podladchikov YY (2010) How contact metamorphism can trigger global climate changes: Modeling gas generation around igneous sills in sedimentary basins. Geochim Cosmochim 74:7179–7195. doi:10.1016/jgca2010.09011
Aarnes I, Svensen H, Poltea S, Planke S (2011) Contact metamorphic devolatilization of shales in the Karoo Basin, South Africa, and the effects of multiple sill intrusions. Chem Geol 281:181–194. doi:10.1016/jchemgeo201012007
Barker CE, Bone Y, Lewan MD (1998) Fluid inclusion and vitrinite-reflectance geothermometry compared to heat-flow models of maximum paleotemperature next to dikes, western onshore Gippsland Basin Australia. Int J Coal Geol 37:73–111
Bowers JR, Kerrick DM, Furlong KP (1990) Conduction model for the thermal evolution of the Cupsuptic aureole, Maine. Am J Sci 290:644–665
Botha BW (2010) An Overview of Andalusite from Southern Africa: Geology and Mineralogy. The Southern African Institute of Mining and Metallurgy, Refractories 2010 Conference, 8p
Brown R, Gallagher K, Duane M (1994) A quantitative assessment of the effects of magmatism on the thermal history of the Karoo sedimentary sequence. J Afr Earth Sci 18:227–243
Burgess SD, Bowring SA, Fleming TH, Elliot DH (2015) High-precision geochronology links the Ferrar large igneous province with early-Jurassic ocean anoxia and biotic crisis. Earth Planet Sci Lett 415:90–99
Caddick MJ, Thompson AB (2008) Quantifying the tectono-metamorphic evolution of pelitic rocks from a wide range of tectonic settings: mineral compositions in equilibrium 156:177–195. doi:10.1007/s0041000802806
Connolly JAD (2005) Computation of phase equilibria by linear programming : A tool for geodynamic modeling and its application to subduction zone decarbonation. Eart Planet Sci Lett 236:524–541
Duncan RA, Hooper PR, Rehacek J, Marsh JS, Duncan AR (1997) The timing and duration of the Karoo igneous event, southern Gondwana. J Geophys Res 102:127–138. doi:10.1029/97JB00972
Du Toit JJL (1967) QU 1/65 geophysical well logging. Report, Geological Survey, South Africa, No 24/5/67
Falloon TJ, Green DH and Danyushevsky LV (2007) Crystallization temperatures of tholeiite parental liquids: Implications for the existence of thermally driven mantle plumes. Geol Soc of Am, Special Papers 430: 235–260.
Geel C, Schulz HM et al (2013) Shale gas characteristics of Permian black shales in South Africa: Results from recent drilling in the Ecca Group (Eastern Cape). Energy Procedia 40:256–265. doi:10.1016/jegypro20130803
Henry DJ, Guidotti CV (2002) Titanium in biotite from metapelitic rocks: Temperature effects, crystal-chemical controls, and petrologic applications. Am Min 87:375–382
Johnson MR, van Vuuren CJ, Visser JNJ, Cole DI, Wickens HV, Christie ADM, Roberts DL Brandl G (2006) Sedimentary rocks of the Karoo Supergroup. In: Johnson MR, Anhaeusser CR and Thomas RJ (eds). The Geology of South Africa, Geological Society of South Africa, Johannesburg/Council for Geoscience, Pretoria, pp. 461–499
Jones MQW (2003) Thermal properties of stratified rocks from Witwatersrand gold mining areas. J SA Inst Min Metall 173–186
Lindeque A, de Wit MJ, Ryberg T, Weber M Chevallier L (2011) Deep crustal profile across the Southern Karoo basin and beattie magnetic anomaly, South Africa: An integrated interpretation with tectonic implications. S Af J Geol 114:265–292. doi:10.2113/gssajg11434265
Pattison DR, Capitani C et al (2011) Petrological consequences of variations in metamrophic reaction affinity. J Met Geol. doi:10.1111/j15251314201100950
Robie RA, Hemingway BS (1984) Entropies of kyanite, andalusite, and sillimanite: additional constraints on the pressure and temperature of the Al2SiO5 triple point. Am Min 69:298–306
Rowsell DM, de Swart AMJ (1976) Diagenesis in Cape and Karoo sediments, South Africa and its bearing on hydrocarbon potential. Trans Geol Soc S Af 79:81–145
Scheiber-Enslin SE, Webb SJ, Ebbing J (2014) Geophysically Plumbing the Main Karoo Basin, South Africa. S Af J Geol 117:275–300. doi:10.2113/gssajg1172275
Smithard T, Bordy EM, Reid D (2015) The effect of dolerite intrusions on the hydrocarbon potential of the Lower Permian Whitehill Formation (Karoo Supergroup) in South africa and Southern Namibia: A preliminary study. S Af J Geol 118(4)489–510. doi:10.2113/gssajg.118.4.489
Svensen H, Jamtveit B, Planke S, Chevallier L (2006) Structure and evolution of hydrothermal vent complexes in the Karoo Basin, South Africa. J Geol Soc Lon 163:671–682
Svensen H, Corfy F, Ploteau S, Hammer O, Planke S (2012) Rapid magma emplacement in the Karoo Large Igneous Province. Earth Planet Sci Lett 325–326:1–9
Tinker J, de Wit MJ, Brown R (2008) Linking source to sink: Evaluating the balance between onshore erosion and offshore sediment accumulation since Gondwana break-up, South Africa. Tectonophysics 455:94–103
Thompson AB, Connolly AD (1992) Migration of metamorphic fluid: some aspects of mass and heat transfer. Earth Sci Rev 32:107–121
Viljoen JHA (1990) K-bentonites in the Ecca Group of the south and central Karoo. S Af J Geol 94:576–579
Visser JNJ (1992) Deposition of the Early to Late Permian Whitehill Formation during a sealevel highstand in a juvenile foreland basin. S Af J Geol 95:181–193
Walther JV, Wood BJ (1984) Rate and mechanism in prograde metamorphism. Contrib Mineral Petrol 88:246–259
Wang D, Lu X, Zhang X, Xu S, Hu W, Wang L (2007) Heat-model analysis of wall rocks below a diabase sill in Huimin Sag, China compared with thermal alteration of mudstone to carbargilite and hornfels and with increase of vitrinite reflectance. Geophys Res Let 34:L16312. doi:10.1029/2007GL030314
Wang D, Manga M (2015) Organic matter maturation in the contact aureole of an igneous sill as a tracer of hydrothermal convection. J Geophys Res Sol Earth 120:4102–4112 doi:10.1002/2015JB011877
Wohletz K (2008) KWare Heat3D. http://www.lanl.gov/orgs/ees/geodynamics/Wohletz/KWare/Index.htm
Acknowledgments
Thanks to Maarten de Wit and AEON-ESRI for providing funding which enabled the collection of samples at the Council for Geoscience core shed in Pretoria. The use of the Jeol JXA 8230 Superprobe at Rhodes University, sponsored by the NRF/NEP grant 40113 (UID 74464) is also kindly acknowledged. Thank must also go to Steffan Buettner of Rhodes University and Dr. Bastien Linol (NMMU) for their constructive review of this work. This is AEON publication number 159.
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Moorcroft, D., Tonnelier, N. (2016). Contact Metamorphism of Black Shales in the Thermal Aureole of a Dolerite Sill Within the Karoo Basin. In: Linol, B., de Wit, M. (eds) Origin and Evolution of the Cape Mountains and Karoo Basin. Regional Geology Reviews. Springer, Cham. https://doi.org/10.1007/978-3-319-40859-0_8
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