Rip-up clasts
Rip-up clasts (also known as mud chips) are clasts of muddy sediment of variable size that are found within sandstone or conglomerate. As the name suggests, they form when high-energy currents erode pre-existing mud from the bottom of the basin, transporting it as clasts that are later re-deposited. Rip-up clasts form in muddy sediments because mud is impermeable and cohesive, allowing it to remain as compact clasts when it is torn away from the substratum by a current. This sedimentary structure is common in many marine and continental environments where erosion alternates with deposition, for example alluvial plains, deltas, and underwater fans.
Mud chip rip-up clasts producing a localized intraformational breccia in the Indian Cave Sandstone (Pennsylvanian), near Peru, Nebraska, USA. Photo by Michael C. Rygel via wikimedia.org.
Rip-up clast breccia in the Pennsylvanian of Ohio, USA. Photo by James Cheshire via James St. John.
Channel fill in turbiditic sandstone (brown) containing several rip-up clasts of shale (white). Cala del Leone, Quercianella, Italy. Photo Samuele Papeschi/Geology is the Way.
Rip-up clast of shale (black) suspended in graded sandstone. Cala del Leone, Quercianella, Italy. Photo Samuele Papeschi/Geology is the Way.
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- Rip-up clast of shale surrounded by sandstone with turbiditic structures. Oligocene Macigno Sandstone, Cala del Leone, Quercianella (Italy). Photo Samuele Papeschi/Geology is the Way. Note that the shale is easier to erode.
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- Rip-up clast of shale surrounded by sandstone with turbiditic structures. Oligocene Macigno Sandstone, Cala del Leone, Quercianella (Italy). Photo Samuele Papeschi/Geology is the Way.
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- Rip-up clast of shale surrounded by sandstone with turbiditic structures. Oligocene Macigno Sandstone, Cala del Leone, Quercianella (Italy). Photo Samuele Papeschi/Geology is the Way.
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- Rip-up clast of shale surrounded by sandstone with turbiditic structures. Oligocene Macigno Sandstone, Cala del Leone, Quercianella (Italy). Photo Samuele Papeschi/Geology is the Way.
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- Rip-up clast of shale surrounded by sandstone with turbiditic structures. Oligocene Macigno Sandstone, Cala del Leone, Quercianella (Italy). Photo Samuele Papeschi/Geology is the Way.
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- Rip-up clast of shale surrounded by sandstone with turbiditic structures. Oligocene Macigno Sandstone, Cala del Leone, Quercianella (Italy). Photo Samuele Papeschi/Geology is the Way.
References
Henares, S., Arribas, J., Cultrone, G., & Viseras, C. (2016). Muddy and dolomitic rip-up clasts in Triassic fluvial sandstones: Origin and impact on potential reservoir properties (Argana Basin, Morocco). Sedimentary Geology, 339, 218-233.
Ishizawa, T., Goto, K., Yokoyama, Y., Miyairi, Y., Sawada, C., & Takada, K. (2018). Reducing the age range of tsunami deposits by 14C dating of rip-up clasts. Sedimentary Geology, 364, 334-341.
Mackenzie, F. T., & Garrels, R. M. (1971). Evolution of sedimentary rocks. New York: Norton.
Pettijohn, F. J. (1975). Sedimentary rocks (Vol. 3). New York: Harper & Row.
Lucchi, F. R. (1995). Sedimentographica: Photographic atlas of sedimentary structures. Columbia University Press.
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