A clastic dike is a seam of sedimentary material that fills an open fracture in and cuts across sedimentary rock strata or layering in other rock types.
Clastic dikes form rapidly by fluidized injection (mobilization of pressurized pore fluids) or passively by water, wind, and gravity (sediment swept into open cracks). Diagenesis may play a role in the formation of some dikes. Clastic dikes are commonly vertical or near-vertical. Centimeter-scale widths are common, but thicknesses range from millimetres to metres. Length is usually many times width.
Clastic dikes are found in sedimentary basin deposits worldwide. Formal geologic reports of clastic dikes began to emerge in the early 19th century.Darwin, C., 1833–1834, Geological observations on the volcanic islands and parts of South America visited during the voyage of the H.M.S. “Beagle” (2nd Edition), p. 438Hay, R., 1892, Sandstone dikes in northwestern Nebraska, GSA Bulletin, 3, pp. 50–55Case, E.C.; 1895, On the mud and sand dikes of the White River Miocene, Ithaca, N.Y., American Geologist, 24, pp. 248–254Crosby, W.O., 1897, Sandstone dikes accompanying the great fault of Ute Pass, Colorado, Essex Institute Bulletin, 27, pp. 113–147Diller, J.S., 1890, Sandstone dikes, GSA Bulletin, 1, pp. 411–442Several c. 1850 references to dikes in Newsom, J.F., 1903, Clastic dikes, Bulletin of the Geological Society of America, 14, pp. 227–268
Terms synonymous with clastic dike include: clastic intrusion, sandstone dike, fissure fill, soft-sediment deformation, fluid escape structure, seismite, injectite, liquefaction feature, neptunian dike (passive fissure fills), paleoseismic indicator, pseudo ice wedge cast, sedimentary insertion, sheeted clastic dike, synsedimentary filling, tension fracture, hydraulic injection dike, and tempestite.
Environments of formation Clastic dike environments include: Clastic dikes associated with earthquakes – A large variety of dikes are found in the geologic record. However, clastic dikes are typically produced by seismic disturbance and liquefaction of high water content sediments. Examples of this type are many.G. Neef, A clastic dike-sill assemblage in late Miocene (c. 6 Ma) strata, Annedale, Northern Wairarapa, New Zealand, 1991, New Zealand Journal of Geology & Geophysics, Vol. 34: 87–91 Peterson, C.D., 1997, Coseismic paleoliquefaction evidence in the central Cascadia margin, USA, Oregon Geology, 59, pp. 51–74Audemard, F.A.; de Santis, F., 1991, Survey of liquefaction structures induced by recent moderate earthquakes, Bulletin of the International Association of Engineering Geology, 44, pp. 5–16 Clastic dikes are paleoseismic indicators in certain geologic settings.Ettensohn, F.R.; Rast, N.; Brett, C.E. (editors), Ancient Seismites, GSA Special Paper, 359 Several qualitative, field-based systems have been developed to help distinguish seismitesSeilacher, A., 1969, Fault-graded beds interpreted as seismites, Sedimentology, 13, pp. 15–159 from soft sediment deformation features Groshong, R.H., 1988, Low-temperature deformation mechanism and their interpretation, GSA Bulletin, 100, pp. 1329–1360 formed by non-seismic processes.Allen, C.R., 1975, Geological criteria for evaluating seismicity, GSA Bulletin, 86, pp. 1041–1057Greb, S.F.; Ettensohn, F.R.; Obermeier, S.F., 2002, Developing a classification scheme for seismites, GSA North-central & Southeastern Section Annual Meeting Abstracts with ProgramsWheeler, R.L., 2002, Distinguishing seismic from nonseismic soft-sediment structures: Criteria from seismic-hazard analysis, in Ettensohn, F.R.; Rast, N.; Brett, C.E. (editors), Ancient Seismites, GSA Special Paper, 359, pp. 1–11Obermeier, S.F.; Olson, S.M.; Green, R.A., 2005, Field occurrences of liquefaction-induced features: a primer for engineering geologic analysis of paleoseismic shaking, Engineering Geology, 76, pp. 209–234Montenat, C.; Barrier, P.; d'Estevou, P.O.; Hibsch, C., 2007, Seismites: An attempt at critical analysis and classification, Sedimentary Geology, 196, pp. 5–30
Results from analytical modeling of clastic dike injection in soft rocksLevi, T.; Weinberger, R.; Eyal, Y., in press 2010, A coupled fluid-fracture approach to propagation of clastic dikes during earthquakes, Tectonophysics indicate propagation occurred at a rate of approximately 4 to 65 m/s at driving pressures of 1–2 MPa. Emplacement duration (<2 s) is similar to the speed with which acoustic energy (pressure waves) moves through partially lithified sedimentary rock.
Clastic dikes associated with debris flows –
Sandstone dikes formed by downward injection are found along Black Dragon wash upstream of the famous petroglyphs area, San Rafael Swell, Utah.
Clastic dikes associated with impact craters –
Sandstone dikes with cataclastically deformed sand grains, sourced in the Permian White Rim Sandstone, are found within Upheaval Dome, Canyonlands National Park, Utah,Mashchak, M.S.; Ezersky, V.A., 1980, Clastic dikes of the Kara Crater Pai Khoi, Lunar and Planetary Sciences, 11, pp. 680–682Mashchak, M.S.; Ezersky, V.A., 1982, Clastic dikes in the impactites and allogenic breccias of the Kara astrobleme (northeast slopp. of the Pai-Khoi Range) (article in Russian), Lithology and Economic Minerals, 1, pp. 130–136Sturkell, E.F.F.; Ormo, J., 1997, Impact-related clastic injections in the marine Ordovician Lockne impact structure, central Sweden, Sedimentology, 44, pp. 793–804Huntoon, P.W., 2000, Upheaval Dome, Canyonlands, Utah: Strain indicators that reveal an impact origin, in Sprinkel, D.A.; Chidsey, T.C.; Anderson, P.B. (editors), Geology of Utah's Parks and Monuments, Utah Geological Association Publication, 28, pp. 1–10, revised 2002: http://www.utahgeology.org/Topical_papers_2003_UGA28.htm , s2cid 150387489Kenkmann, T., 2003, Dike formation, cataclastic flow, and rock fluidization during impact cratering: an example from the Upheaval Dome structure, Earth and Planetary Science Letters, 214, pp. 43–58 at Roberts Rift,Huntoon, P.W.; Shoemaker, E.M., 1995, Roberts Rift, Canyonlands, Utah, A natural hydraulic fracture caused by comet or asteroid, Ground Water, 33, pp. 561–569 and elsewhere.Wittmann, A.; Kenkamnn, T.; Schmitt, R.T.; Hecht, L.; Stöffler, D., 2004, Impact-related dike breccia lithologies in the ICDP drill core Yaxcopoil-1, Chicxulub impact structure, Mexico, Meteorics & Planetary Science, 39, pp. 931–954Hudgins, J.A.; Spray, J.G., 2006, Lunar impact-fluidized dikes: Evidence from Apollo 17 Station 7, Taurus-Littrow Valley, Lunar and Planetary Science, 37, p. 1176 Commonly, the fill is composed of angular grains, evidence that the injected material was lithified prior to impact and was crushed during injection into fractures (preexisting or impact-formed).
Clastic dikes associated with salt domes – Clastic dike swarms associated with salt dome diapirism are reported from the Dead Sea region.Marco, S.; Weinberger, R.; Agnon, A., 2002, Radial clastic dykes formed by a salt diapir in the Dead Sea Rift, Israel, Terra Nova, 14, pp. 288–294
Clastic dikes associated with glaciers – Sand injection features are reported to have formed under heavy loads and confining pressures beneath grounding glacial ice.Goldthwait, J.W.; Goldthwait, L.; Goldthwait, R.P., 1951, Geology of New Hampshire, Part 1: Surficial Geology, New Hampshire State Planning and Development Commission, 44 pp.Larsen, E.; Mangerud, J., 1992, Subglacially formed clastic dikes, Sveriges Geologisha Undersdhning, 81, pp. 163–170Boulton, G.S.; Caban, P., 1995, Groundwater flow beneath ice sheets: Part II – Its impact on glacier tectonic structures and moraine formation, Quaternary Science Reviews, 14, pp. 563–587Dreimanis, A.; Rappol, M., 1997, Late Wisconsinan sub-glacial clastic intrusive sheets along the Lake Erie bluffs, at Bradtville, Ontario, Canada, Sedimentary Geology, 111, pp. 225–248
Clastic dikes in resistant bedrock – Though unusual, a significant number of reports describe sedimentary material intruding fractured crystalline bedrock, usually within fault zones. Some of the articles referenced here describe lithified clastic dikes.Cross, W., 1894, Intrusive sandstone dikes in granite, GSA Bulletin, 5, pp. 225–230Birman, J.H., 1952, Pleistocene clastic dikes in weathered granite-gneiss, Rhode Island, American Journal of Science, 250, pp. 721–734Vitanage, P.W., 1954, Sandstone dikes in the South Platte Area, Colorado, Journal of Geology, 62, pp. 493–500Harms, J.C., 1965, Sandstone dikes in relation to Laramide faults and stress distribution in the southern Front Range, Colorado, GSA Bulletin, 76Niell, A.W.; Leckey, E.H.; Pogue, K.R., 1997, Pleistocene dikes in Tertiary rocks – downward emplacement of Touchet Bed clastic dikes into co-seismic features, south-central Washington, GSA Abstracts with Programs, 29, p. 55 Clastic dikes in storm deposits – Cyclic stresses from large waves can cause wet sediments to fluidize, forming various types of soft sediment deformation features including clastic dikes.Dalrymple, R.W., 1979, Wave-induced liquefaction: A modern example from the Bay of Fundy, Sedimentology, 26, pp. 835–844Alfaro, P.; Soria, M., 1998, Soft-sediment deformation structures induced by cyclic stress of storm waves in tempestites (Miocene, Guadalquivir Basin, Spain), Terra Nova, 10, pp. 145–150Martel, A.T.; Gibling, M.R., 1993, Clastic dykes of the Devono-Carboniferous Horton Bluff Fm, Nova Scotia: Storm-related structures in shallow lakes, Sedimentary Geology, 87, pp. 103–119Olson, S.M., 2007, Downward penetrating clastic dikes as indicators of tsunamis? GSA Southeastern Section Abstracts with Programs, 39, p. 25 (#14-5)
Clastic dikes in the Columbia Basin
Tens of thousands of clastic dikes (1 mm–350 cm wide, up to 50 m deep) penetrate sedimentary and bedrock units in the Columbia Basin of Washington, Oregon and Idaho. Their origin remains in question. The dikes may be related to loading by outburst floods. Other evidence suggests they are sediment-filled desiccation cracks (mudcracks). Some have suggested the dikes are ice wedge casts or features related to the melting of buried ice.Lupher, R.L., 1944, Clastic dikes of the Columbia Basin Region, Washington and Idaho, Geological Society of America Bulletin, 55, pp. 1431–1462 Earthquake shaking and liquefaction are also suggested to explain the dikes (i.e., sand blows).
The silt-, sand-, and gravel-filled dikes in the Columbia Basin are primarily sourced in the Touchet Formation (or the Touchet-equivalent Willamette Silt) and intrude downward into older geologic units, including: Pleistocene hillslope colluvium with developed caliche horizons in the Umatilla Basin near Alderdale, Washington Pleistocene landslide deposits along Hwy 14 in the Columbia Gorge (Umatilla Basin) Pleistocene Clearwater Gravels in the Lewiston BasinGarwood and Bush, 2005Webster et al., 1982, Late Cenozoic gravels in Hells Canyon and the Lewiston Basin, WA and OR, in Bonnichsen and Breckenridge (editors), Cenozoic Geology of Idaho, Idaho Bureau of Mines and Geology Bulletin 26