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.

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. Clastic dikes are paleoseismic indicators in certain geologic settings. Several qualitative, field-based systems have been developed to help distinguish seismites from soft sediment deformation features formed by non-seismic processes.

  Results from analytical modeling of clastic dike injection in soft rocks indicate propagation occurred at a rate of approximately 4 to 65m/s at driving pressures of 1–2MPa. Emplacement duration (<2s) 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, at Roberts Rift, and elsewhere. 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.

• Clastic dikes associated with glaciers –

• Sand injection features are reported to have formed under heavy loads and confining pressures beneath grounding glacial ice.

• 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.

• Clastic dikes in storm depositss –

• Cyclic stresses from large waves can cause wet sediments to fluidize, forming various types of soft sediment deformation features including clastic dikes.

Clastic dikes in the Columbia Basin

Tens of thousands of clastic dikes (1mm–350cm wide, up to 50m 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. 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 Basin

• "Pre-late Wisconsin" outburst flood and flood-related deposits (includes the "ancient cataclysmic flood deposits" of Allen et al., 2009) in the Walla Walla Valley/Pasco Basin and Columbia Gorge

• Post-basalt basin fill sediments (Dalles Group, etc.) exposed in tributary stream valleys downstream of Wallula Gap

• Miocene-Pliocene Snipes Mountain Conglomerate in the Yakima Valley at Granger, Washington

• Miocene-Pliocene Ringold Formation in the Pasco Basin

• Miocene-Pliocene Ellensburg Formation at Craig's Hill near Ellensburg, Washington (outside Missoula flood track)

• Miocene-Pliocene Ellensburg Formation at Foster Coulee (WDFW Foster Ck Wildlife Area) near Bridgeport, Washington

• Miocene Columbia River Basalt (CRB) in the Walla Walla Valley and Pasco Basin at Gable Mountain

• Latah Formation (interbeds in CRBs) west of Finley, Washington along Hwy 397 and elsewhere

In 1925, Olaf P. Jenkins described the clastic dikes of eastern Washington state as follows:

See also

• Dike (geology)

• Igneous intrusion#Dikes

• Sheeted dyke complex

References

Further reading

• Beacom, L.E.; Anderson, T.B.; Holdsworth, R.E., 1999, Using basement-hosted clastic dykes as syn-rift palaeostress indicators; an example from the basal Stoer Group, northwest Scotland, Geological Magazine, 136, pp. 301–310

• Chown and Gobeil, 1990, Clastic dykes of the Chibougamau Formation: distribution and origin, Canadian Journal of Earth Sciences, v.27, pp. 1111–1114

• Buckland, 1839, Transactions of the British Association for 1839, p. 76

• Crossen, K., 2009, Is till the only evidence of ice advance? What 15 year of post-surge retreat have revealed beneath Bering Glacier, Alaska, GSA Abstracts with Programs, Abstract #247-8

• Cuvier & Brongniart, 1822, Sandstone pipes near Paris, France (Description geognostiques des Environs de Paris), pp. 76, 134, 141

• Dana, J.D., 1849, Wide sandstone dikes in bluffs near Astoria, OR, pp. 654–656 in Geology, Volume 10 of the U.S. Navy Exploring Expedition 1838–1842, under the command of Charles Wilkes, C. Sherman publisher, Philadelphia, 18 volume set

• Gozdzik, J.; Van Loon, A.J., 2007, The origin of a giant downward directed clastic dyke in a kame (Belchatow mine, central Poland), Sedimentary Geology, 193, pp. 71–79

• Haluszczak, A., 2007, Dike-filled extensional structures in Cenozoic deposits of the Kleszczow Graben (Central Poland), Sedimentary Geology, 193, pp. 81–92

• Kirkby, J.W., 1860, On the occurrences of "sand pipes" in the magnesian limestones of Durham, The Geologist (London), pp. 293–298, 329–336

• Le Heron, D.P.; Etienne, J.L., 2005, A complex subglacial clastic dyke swarm, Solheimajokull, southern Iceland, Sedimentary Geology, 181, pp. 25–37

• Lyell, C., 1839, Sand pipes near Norwich, England, London and Edinburgh Philosophical Magazine, 3rd series, v. XV, p. 257

• Monroe, J.N., 1950, Origin of the clastic dikes in the Rockwall area, Texas, Field & Laboratory, 18

• Murchison, R.I., 1827, Quartz sandstone veins in grit near Kintradwell in Somersetshire, Transactions of the Geological Society of London, 2nd series, v. ii, p. 304. And Murchison, R, 1829, On the coal-field of Brora in Sutherlandshire, and some other stratified deposits in the north of Scotland, Transactions of the Geological Society, Second Series, 2, pp. 293–326

• Pavlow, A.P., 1896, On dikes of Oligocene sandstone in the Neocomian clays of the District of Altyr, in Russia, The Geological Magazine, New series, v. iii, pp. 49–53

• Prestwich, J., 1855, On the origin of the sand and gravel pipes in the chalk of the London Tertiary district, Quarterly(?) Journal of the Geological Society of London, v. ii, pp. 64–84

• Ransome, F.L., 1900, A peculiar clastic dike near Ouray, Colorado, and its associated deposit of silver ore, Transactions of the American Institute of Mineralogical Engineers, 30, pp. 227–236

• Siddoway, C.S.; Gehrels, G.E., 2014, Basement-hosted sandstone injectites of Colorado: A vestige of the Neoproterozoic revealed through detrital zircon provenance analysis, Lithosphere, 6, pp. 403–408

• Strangeways, W.T.H.F., 1821, Dikes near Great Pulcovca near Saint Petersburg, Russia, Transactions of the Geological Society of London, v. V, pp. 386, 407, 408 and Plates 25–28

• Strickland, H.E., 1838, Calcareous sandstone dikes in Triassic shale at Ethie in Rossshire, Transactions of the Geological Society of London, v. V, 2nd series, pp. 599–600. And Strickland, H.E., 1840, On some remarkable dikes of Calcareous Grit, at Ethie in Ross-shire, Transactions of the Geological Society, Second Series, 5, pp. 599–600

• White, E.E., 1916, Analysis of slate and dike, Engineering & Mining Journal, v. 101, pp. 433–434

• Wicander, R.; Wood, G.D.; Dreimanis, A.; Rappol, M., 1997, Late Wisconsin sub-glacial intrusive sheets along Lake Erie bluffs, at Bradtville, Ontario, Canada, Sedimentary Geology, 111, pp. 225–248

External links

• Sandstone dikes photo gallery