A piggyback basin (also piggy-back, thrust-sheet-top, detached, or satellite basin) is a minor

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subsidence ...

developed on top of a moving thrust sheet as part of a

foreland basin A foreland basin is a structural basin that develops adjacent and parallel to a mountain belt. Foreland basins form because the immense mass created by crustal thickening associated with the evolution of a mountain belt causes the lithospher ...

system. Piggyback basins form in the wedge-top depositional zone of a foreland basin system as new thrusts in the foreland cut up through the existing

footwall In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

containing the eroded wedge-top basins in the old thrust sheet. The basin is separated from the foredeep by an

anticline In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...

or syndepositional growth structures. The piggyback basin is named after its tendency to be carried passively toward the hinterland with the old thrust sheet in response to the compressive forces of the new thrust sheet. Sedimentary fill for the basin come from the

hanging wall In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

ramp of the older thrust sheet, from the foreland

orogeny Orogeny is a mountain building process. An orogeny is an event that takes place at a convergent plate margin when plate motion compresses the margin. An ''orogenic belt'' or ''orogen'' develops as the compressed plate crumples and is uplifted t ...

or from the sides of the basin. Drainage into the basin may come from highs associated with the thrust sheets or the basin may be filled from longitudinal flows across the basin. The

Po Basin The Po Valley, Po Plain, Plain of the Po, or Padan Plain ( it, Pianura Padana , or ''Val Padana'') is a major geographical feature of Northern Italy. It extends approximately in an east-west direction, with an area of including its Venetic e ...

of Italy and the Ebro Basin of Spain were the example basins used to initially describe the

tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents k ...

s and occurrence of piggyback basins. The Tannheim-Losenstein basin in the Eastern

Alps The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...

is also a piggyback basin system.

References

*Allen, Philip A. and Allen, John R. (2005) Basin Analysis: Principles and Applications, 2nd ed., Blackwell Publishing, 549 pp. *''Encyclopedia of Geomorphology'', Andrew Goudie (Editor), , Routledge, 2013 Basins Sedimentology Tectonics {{Geology-stub

See also

References