Hostname: page-component-cd9895bd7-mkpzs Total loading time: 0 Render date: 2024-12-23T15:17:07.008Z Has data issue: false hasContentIssue false
  • English
  • Français

Lithological control on fracture cementation in the Keuper Marl (Triassic), north Somerset, UK

Published online by Cambridge University Press:  14 September 2017

QINGFENG MENG ,
JOHN HOOKER  and
JOE CARTWRIGHT
QINGFENG MENG*
Affiliation:
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK
JOHN HOOKER
Affiliation:
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK
JOE CARTWRIGHT
Affiliation:
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK
*
*Author for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The spatial arrangement of gypsum veins as preserved natural hydraulic fractures have been characterized in the Triassic Keuper Marl Formation (UK), a caprock for hydrocarbon reservoirs and CO2 sequestration. The marls cropping out are subdivided into five discrete fracture units based on the presence and abundance of gypsum veins. The nodular gypsum in evaporite horizons provides excess gypsum for nodule-rooted horizontal gypsum veins. Our petrographic observations demonstrate that the development of gypsum veins in beds lacking macroscopic evaporites is closely associated with disseminated gypsum cement in the marls. We interpret that the gypsum veins in marl are sourced from disseminated gypsum cements in the host rocks, based on stratigraphic correlations, and much lower Sr concentrations than gypsum nodules. Gypsum was transported to adjacent veins mainly through diffusion in the low-permeability marls. The localization of gypsum veins and varied Sr concentrations of veins and nodules indicate that the diagenetic fluids are a mix of connate water with meteoric water rather than brines transported from evaporite beds along faults to non-evaporite beds. This results in the absence of gypsum fillings in fractures in rocks without primary gypsum cements. The study implies that the cementation of natural fractures in low-permeability rocks can highly depend on the presence of cement minerals in the host rock.

Keywords

mudstonefracture cementationfracture stratigraphyhydraulic fracture
Type
Original Article
Information
Geological Magazine , Volume 155 , Issue 8 , November 2018 , pp. 1761 - 1775
Copyright
Copyright © Cambridge University Press 2017 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Armitage, P., Worden, R., Faulkner, D., Aplin, A., Butcher, A. & Espie, A. 2013. Mercia Mudstone Formation caprock to carbon capture and storage sites: petrology and petrophysical characteristics. Journal of the Geological Society 170, 119–32.Google Scholar
Armitage, P., Worden, R., Faulkner, D., Butcher, A. & Espie, A. 2016. Permeability of the Mercia Mudstone: suitability as caprock to carbon capture and storage sites. Geofluids 16, 26–42.Google Scholar
Arthurton, R. S. 1980. Rhythmic sedimentary sequences in the Triassic Keuper Marl (Mercia Mudstone Group) of Cheshire, northwest England. Geological Journal 15, 43–58.Google Scholar
Attendorn, H. G. & Bowen, R. 1997. Radioactive and Stable Isotope Geology. Springer Science & Business Media, Berlin.Google Scholar
Aydin, A. 2000. Fractures, faults, and hydrocarbon entrapment, migration and flow. Marine and Petroleum Geology 17, 797–814.Google Scholar
Benton, M. J., Cook, E. & Turner, P. 2002. Permian and Triassic Red Beds and the Penarth Group of Great Britain. Peterborough: Joint Nature Conservation Committee.Google Scholar
Bickle, M. & McKenzie, D. 1987. The transport of heat and matter by fluids during metamorphism. Contributions to Mineralogy and Petrology 95, 384–92.Google Scholar
Bloodworth, A. & Mineralogy group, BGS. 1993. Clay mineral stratigraphy of the Mercia Mudstone Group in the Nottingham area. Research report WG/93/29. British Geological Survey, Keyworth.Google Scholar
Bons, P. D. 2000. The formation of veins and their microstructures. Journal of the Virtual Explorer 2, 12.Google Scholar
Bons, P. D., Elburg, M. A. & Gomez-Rivas, E. 2012. A review of the formation of tectonic veins and their microstructures. Journal of Structural Geology 43, 33–62.Google Scholar
Cartwright, J., Huuse, M. & Aplin, A. 2007. Seal bypass systems. AAPG bulletin 91, 1141–1166.Google Scholar
Cobbold, P. R., Zanella, A., Rodrigues, N. & Loseth, H. 2013. Bedding-parallel fibrous veins (beef and cone-in-cone): worldwide occurrence and possible significance in terms of fluid overpressure, hydrocarbon generation and mineralization. Marine and Petroleum Geology 43, 1–20.Google Scholar
Cosgrove, J. 1995. The expression of hydraulic fracturing in rocks and sediments. In: Fractography: Fracture Topography as a Tool in Fracture Mechanics and Stress Analysis (ed. Ameen, M. S.), pp. 187–96. Geological Society, London, Special Publication no. 92.Google Scholar
Cosgrove, J. 2001. Hydraulic fracturing during the formation and deformation of a basin: A factor in the dewatering of low-permeability sediments. AAPG bulletin 85, 737–48.Google Scholar
Dart, C. J., McClay, K. & Hollings, P. N. 1995. 3D analysis of inverted extensional fault systems, southern Bristol Channel basin, UK. In: Basin Inversion (eds Buchanan, J.G. & Buchanan, P. G.), pp. 393–413. Geological Society, London, Special Publication no. 88.Google Scholar
Dronkert, H. 1987. Diagenesis of Triassic evaporites in northern Switzerland. Eclogae Geologicae Helvetiae 80, 397–413.Google Scholar
Engelder, T. & Lacazette, A. 1990. Natural hydraulic fracturing. In Proceedings of the International Symposium on Rock Joints (eds Barton, C. & Stephansson, O.), pp. 35–43. Rotterdam: Balkema.Google Scholar
Fisher, D. M., Brantley, S. L., Everett, M. & Dzvonik, J. 1995. Cyclic fluid flow through a regionally extensive fracture network within the Kodiak accretionary prism. Journal of Geophysical Research: Solid Earth 100, 12881–94.Google Scholar
Gale, J. F. & Holder, J. 2008. Natural fractures in the Barnett Shale: Constraints on spatial organization and tensile strength with implications for hydraulic fracture treatment in shale-gas reservoirs. In: The 42nd US Rock Mechanics Symposium (USRMS). American Rock Mechanics Association. San Francisco, 29 June–2 July.Google Scholar
Gale, J. F. & Holder, J. 2010. Natural fractures in some US shales and their importance for gas production. In: Petroleum Geology: From Mature Basins to New Frontiers – Proceedings of the 7th Petroleum Geology Conference (eds Vining, B. A. & Pickering, S. C.), pp. 1131–40. Geological Society, London, Petroleum Geology Conference Series no. 7.Google Scholar
Gale, J. F., Laubach, S. E., Olson, J. E., Eichhubl, P. & Fall, A. 2014. Natural fractures in shale: A review and new observations. AAPG Bulletin 98, 2165–216.Google Scholar
Gallois, R. 2001. The lithostratigraphy of the Mercia Mudstone Group (mid-late Triassic) of the south Devon coast. Geoscience in south-west England. Proceedings of the Ussher Society 10, 195–204.Google Scholar
Glen, R., Hancock, P. & Whittaker, A. 2005. Basin inversion by distributed deformation: the southern margin of the Bristol Channel Basin, England. Journal of Structural Geology 27, 2113–34.Google Scholar
Grunau, H. R. 1987. A worldwide look at the cap-rock problem. Journal of Petroleum Geology 10, 245–65.Google Scholar
Gustavson, T. C., Hovorka, S. D. & Dutton, A. R. 1994. Origin of satin spar veins in evaporite basins. Journal of Sedimentary Research 64, 88–94.Google Scholar
Henderson, I. & McCaig, A. 1996. Fluid pressure and salinity variations in shear zone-related veins, central Pyrenees, France: implications for the fault-valve model. Tectonophysics 262, 321–48.Google Scholar
Hobbs, P., Hallam, J., Forster, A., Entwisle, D., Jones, L., Cripps, A., Northmore, K., Self, S. & Meakin, J. 2002. Engineering geology of British rocks and soils: Mudstones of the Mercia Mudstone Group. Research report RR/01/002, British Geological Survey, Keyworth.Google Scholar
Hooker, J. N., Cartwright, J., Stepehnson, B., Silver, C. R. P., Dickson, A. J. & Hsieh, Y. 2016. Fluid evolution in fracturing black shales, Appalachian Basin. AAPG Bulletin, doi: 10.1306/10031616030.Google Scholar
Howard, A., Warrington, G., Ambrose, K. & Rees, J. 2008. A formational framework for the Mercia Mudstone Group (Triassic) of England and Wales. Research report RR/08/004, British Geological Survey, Keyworth.Google Scholar
Ichikuni, M. & Musha, S. 1978. Partition of strontium between gypsum and solution. Chemical Geology 21, 359–63.Google Scholar
Ingram, G. M. & Urai, J. L. 1999. Top-seal leakage through faults and fractures: the role of mudrock properties. In: Muds and Mudstones: Physical and Fluid-Flow Properties (eds Aplin, A. C., Fleet, A. J. & MacQuaker, J. H. S.), pp. 125–35. Geological Society, London, Special Publication no. 158.Google Scholar
Kasprzyk, A. 2003. Sedimentological and diagenetic patterns of anhydrite deposits in the Badenian evaporite basin of the Carpathian Foredeep, southern Poland. Sedimentary Geology 158, 167–94.Google Scholar
Kellaway, G., Welch, F. B. A. & Ivimey-Cook, H. 1993. Geology of the Bristol district: memoir for 1: 63 360 geological special sheet (England and Wales). London: HM Stationery Office.Google Scholar
Keulen, N., Den Brok, S. & Spiers, C. 2001. Force of crystallisation of gypsum during hydration of synthetic anhydrite rock. In: 13th DRT Conference: Deformation Mechanisms, Rheology, and Tectonics. Noordwijkerhout, The Netherlands, 2–4 April.Google Scholar
Kushnir, J. 1980. The coprecipitation of strontium, magnesium, sodium, potassium and chloride ions with gypsum. An experimental study. Geochimica et Cosmochimica Acta 44, 1471–82.Google Scholar
Kushnir, J. 1982. The composition and origin of brines during the Messinian desiccation event in the Meditterranean Basin as deduced from concentrations of ions coprecipitated with gypsum and anhydrite. Chemical Geology 35, 333–50.Google Scholar
Lander, R. H. & Laubach, S. E. 2015. Insights into rates of fracture growth and sealing from a model for quartz cementation in fractured sandstone. Geological Society of American Bulletin 127, 516–38.Google Scholar
Laubach, S. E. 2003. Practical approaches to identify sealed and open fractures. AAPG Bulletin 87, 561–79.Google Scholar
Laubach, S. E., Reed, R. M., Olson, J. E., Lander, R. H. & Bonell, L. M. 2004. Coevolution of crack-seal texture and fracture porosity in sedimentary rocks: cathodoluminescence observations of regional fractures. Journal of Structural Geology 26, 967–82.Google Scholar
Laubach, S. E., Olson, J. E. & Gross, M. R. 2009. Mechanical and fracture stratigraphy. AAPG Bulletin 93, 1413–26.Google Scholar
Lee, H. P., Olson, J. E., Holder, J., Gale, J. F. W. & Myers, R. D. 2015. The interaction of propagating opening mode fractures with preexisting discontinuities in shale. Journal of Geophysical Research: Solid Earth 120, 169–81.Google Scholar
Leslie, A. B., Harwood, G. M. & Kendall, A. C. 1997. Geochemical variations within a laminated evaporite deposit: evidence for brine composition during formation of the Permian Castile Formation, Texas and New Mexico, USA. Sedimentary Geology 110, 223–35.Google Scholar
Leslie, A. B., Spiro, B. & Tucker, M. 1993. Geochemical and mineralogical variations in the upper Mercia Mudstone Group (Late Triassic), southwest Britain: correlation of outcrop sequences with borehole geophysical logs. Journal of the Geological Society 150, 67–75.Google Scholar
Lu, F. H., Meyers, W. J. & Hanson, G. N. 2002. Trace elements and environmental significance of Messinian gypsum deposits, the Nijar Basin, southeastern Spain. Chemical Geology 192, 149–61.Google Scholar
Lu, F. H., Meyers, W. J. & Schoonen, M. A. 1997. Minor and trace element analyses on gypsum: an experimental study. Chemical Geology 142, 1–10.Google Scholar
Machel, H. G. 1985. Fibrous gypsum and fibrous anhydrite in veins. Sedimentology 32, 443–54.Google Scholar
Mandl, G. 2005. Rock Joints. Berlin: Springer.Google Scholar
Mohamed El Tabakh, B. & Warren, J. K. 1998. Origin of fibrous gypsum in the Newark rift basin, eastern North America. Journal of Sedimentary Research 68, 88–99.Google Scholar
Murray, R. 1964. Origin and diagenesis of gypsum and anhydrite. Journal of Sedimentary Research 34, 512–23.Google Scholar
Ogata, K., Senger, K., Braathen, A. & Tveranger, J. 2014. Fracture corridors as seal-bypass systems in siliciclastic reservoir-cap rock successions: Field-based insights from the Jurassic Entrada Formation (SE Utah, USA). Journal of Structural Geology 66, 162–87.Google Scholar
Old, R. 1991. Geology of the Country around Redditch. Lanham, Maryland: Bernan Press (PA).Google Scholar
Oliver, N. H. & Bons, P. D. 2001. Mechanisms of fluid flow and fluid–rock interaction in fossil metamorphic hydrothermal systems inferred from vein–wallrock patterns, geometry and microstructure. Geofluids 1, 137–62.Google Scholar
Philipp, S. L. 2008. Geometry and formation of gypsum veins in mudstones at Watchet, Somerset, SW England. Geological Magazine 145, 831–44.Google Scholar
Phillips, W. J. 1972. Hydraulic fracturing and mineralization. Journal of the Geological Society 128, 337–59.Google Scholar
Playa, E., Orti, F. & Rosell, L. 2000. Marine to non-marine sedimentation in the upper Miocene evaporites of the Eastern Betics, SE Spain: sedimentological and geochemical evidence. Sedimentary Geology 133, 135–66.Google Scholar
Putnis, A., Prieto, M. & Fernandez-Diaz, L. 1995. Fluid supersaturation and crystallization in porous media. Geological Magazine 132, 1–13.Google Scholar
Rosell, L., Orti, F., Kasprzyk, A., Playa, E. & Peryt, T.M. 1998. Strontium geochemistry of Miocene primary gypsum: Messinian of southeastern Spain and Sicily and Badenian of Poland. Journal of Sedimentary Research 68, 63–79.Google Scholar
Ruffell, A. 1990. Stratigraphy and structure of the Mercia Mudstone Group (Triassic) in the western part of the Wessex Basin. Proceedings of the Ussher Society 7, 263–67.Google Scholar
Ruffell, A. 1991. Palaeoenvironmental analysis of the late Triassic succession in the Wessex Basin and correlation with surrounding areas. Proceedings of the Ussher Society 7, 402–7.Google Scholar
Rustichelli, A., Di celma, C., Tondi, E., Baud, P. & Vinciguerra, S. 2016. Fibrous gypsum veins as diffuse features and within fault zones: the case study of the Pisco Basin (Ica desert, southern Peru). Journal of the Geological Society 173, 405–18.Google Scholar
Seedhouse, J. & Racey, A. 1997. Sealing capacity of the Mercia Mudstone Group in the East Irish Sea Basin: implications for petroleum exploration. Journal of Petroleum Geology 20, 261–86.Google Scholar
Shearman, D., Mossop, G., Dunsmore, H. & Martin, M. 1972. Origin of gypsum veins by hydraulic fracture. Institution of Mining and Metallurgy Transaction, Section B: Applied Earth Science 81, 149–55.Google Scholar
Smith, E. G., Rhys, G. H. & Goossens, R. 1974. Geology of the Country around East Retford, Worksop and Gainsborough. British Geological Survey, Keyworth.Google Scholar
Talbot, M., Hoim, K. & Williams, M. 1994. Sedimentation in low-gradient desert margin systems: A comparison of the Late Triassic of northwest Somerset (England) and the late Quaternary of east-central Australia. Geological Society of America, Special Papers 289, 97–117.Google Scholar
Taylor, S. 1983. A stable isotope study of the Mercia Mudstones (Keuper Marl) and associated sulphate horizons in the English Midlands. Sedimentology 30, 11–31.Google Scholar
Trude, J., Graham, R. & Pilcher, R. 2012. Salt-related structures on the Bristol Channel coast, Somerset (UK). In: Salt Tectonics, Sediments & Prospectivity (eds) Alsop, G. I., Archer, S. G., Hartley, A. J., Grant, N. T. & Hodgkinson, R.), 533–44. Geological Society, London, Special Publication no. 363.Google Scholar
Tucker, M. 1977. The marginal Triassic deposits of South Wales: continental facies and palaeogeography. Geological Journal 12, 169–88.Google Scholar
Tucker, M. E. 1978. Triassic lacustrine sediments from South Wales: Shore-Zone, Evaporites and Carbonates. In Modern and Ancient Lake Sediments (eds. Matter, A., & Tucker, M.E.), pp. 205–224. Oxford: Blackwell.Google Scholar
Warrington, G. 1974. Studies in the palynological biostratigraphy of the British Trias. I. Reference sections in west Lancashire and north Somerset. Review of Palaeobotany and Palynology 17, 133–47.Google Scholar
Warrington, G. 1980. A Correlation of Triassic rocks in the British Isles. Oxford: Blackwell Scientific.Google Scholar
Warrington, G. & Ivimey-Cook, H. 1992. Triassic. In: Atlas of Palaeogeography and Lithofacies (eds Cope, J. C. W., Ingham, J. K. & Rawson, P. F.), pp. 97–106. Geological Society of London, Memoir no. 13.Google Scholar
Whittaker, A. & Green, G. W. 1983. Geology of the Country around Weston-super-Mare. Memoirs of the Geological Survey of Great Britain. HM Stationery Office, London.Google Scholar
Williams, J., Holloway, S. & Williams, G. 2014. Pressure constraints on the CO2 storage capacity of the saline water-bearing parts of the Bunter Sandstone Formation in the UK southern North Sea. Petroleum Geoscience 20, 155–67.Google Scholar
Wilson, A. 1990. The Mercia Mudstone Group (Trias) of the East Irish Sea Basin. Proceedings of the Yorkshire Geological and Polytechnic Society 48, 1–22.Google Scholar
Wilson, A. 1993. The Mercia Mudstone Group (Trias) of the Cheshire Basin. Proceedings of the Yorkshire Geological and Polytechnic Society 49, 171–88.Google Scholar
Wiltschko, D. V. & Morse, J. W. 2001. Crystallization pressure versus “crack seal” as the mechanism for banded veins. Geology 29, 79–82.Google Scholar
Supplementary material: File

Meng et al supplementary material

Table S1

Download Meng et al supplementary material(File)
File 22.2 KB