Clinoform

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Background & Definition of Clinoforms

John L. Rich (1884 - 1956) is considered the father of clinoforms. John proposed that the depositional settings of sediment accumulation on the shelf, slope, and bottom must be either undaform, clinoform, or fondoform (Described visually in Figure 1 & Figure 2). Specifically, the deeper water overlying the continental slope is the depositional environment for clinoforms.[1] Clinoforms are defined as sloping depositional surfaces.[2] They are deposited free from wave disturbance and where the continental shelf has regressed as sea level falls. Clinoform composition is primarily mud dominant and fossils are non-abundant. Rock properties used in identification of Clinforms are defined as having fine grain size (silt or clay) in order to be carried by suspension, thin and even bedding, and the presence of flow markings and flutings/striations as evidences for gravity flows.[3]

Figure 1. Clinoform Progradation. Animated GIF by C.G.St.C.
Figure 2. Undaform, Clinoform, and Fondoform systematic from John Rich (1951)

Clinoforms in Seismic

Clinoforms often have distinct seismic responses that one can see in seismic data and can be used to define basin, margins, stacking patterns, and shelf edge trajectories.[4] To be identified in reflection seismic data, clinoforms need to have higher relief compared to the data's vertical resolution, beds must be spaced wider than the data's tuning thickness, and need to have acoustic impedance variations within the clinoform as well surrounding layers.[5] Understanding clinoforms in your data are essential for sequence stratigraphy and basin analysis.

Seismic Examples

Clinforms in seismic can be identified using unique geometric configurations of bedding surfaces.[6] Six general classifications have been identified; oblique tangential, oblique parallel, sigmoid, complex sigmoid-oblique, shingled, and hummocky (Seen in Figure 3). Figure 4 shows clinoform packages from offshore India.[7] Figure 5 shows clinoform packes offshore New Zealand in the central Taranaki Basin.[8]

Figure 3. From Mitchum (1997); Clinoform Geometries
Figure 4. Offshore India, Clinoform seismic package from seismic line running west-east through southern Kardivia Channel from Expedition 359; Integrated Ocean Drilling Program (Betzler, C. et al, 2017)
Franzel, M. & Back, S. Int J Earth Sci (Geol Rundsch) (2019) 108: 475. https://doi.org/10.1007/s00531-018-1663-1
Figure 5. Clinoform Package from offshore New Zealand in the central Taranaki Basin (Franzel, M., & Back, S., 2019)

Clinoforms on Mars

NASA's Mars Reconnaissance Orbiter imaged what is thought to be clinoforms on the Martian surface in 2017.[9] Researchers from NASA identified steeply inclined light-toned layers in an image taken of the Melas Basin (Figure 6). They believe these inclined layers had been deposited during delta progradation representing a time of deposition on the floor of a lake or river.

Figure 6. Melas Basin Clinoforms & Other Sedimentary Structures

See also

Important Papers

External links

Categories

Clinoform, sea level regression, continental shelf, ocean deposition, turbidite, oil and gas exploration, marine seismic data

References

  1. Friedman, Gerald M., 2001, John L. Rich (1884–1956): Father of clinoform, undaform, and fondoform," Abstract, Annual meeting of GSA Boston, Paper 24-0 (https://gsa.confex.com/gsa/2001AM/finalprogram/abstract_25503.htm)
  2. Mitchum Jr., R.M., 1977, Seismic stratigraphy and global changes of sea level. Part 11: glossary of terms used in seismic stratigraphy. (http://archives.datapages.com/data/specpubs/seismic1/data/a165/a165/0001/0200/0205.htm)
  3. Rich, J.L., 1951, Three critical environments of deposition and criteria for recognition of rocks deposited in each of them. Geol. Soc. Am. Bull. 62, 1-20
  4. Patruno, S., Helland-Hansen, W., "Clinoforms and clinoform systems: Review and dynamic classification scheme for shorelines, subaqueous deltas, shelf edges, and continental margins.", Earth Science Reviews 185 (2018) pg. 202-233.
  5. Holgate, N.E., Jackson, C.A., Hampson, G.J., Dreyer, T., 2015. Seismic stratigraphic analysis of the Middle Jurassic Krossfjord and Fensfjord formations, Troll oil and gas field, northern North Sea. Mar. Pet. Geol. 68, 352–380.
  6. Cattaneo, A., Trincardi, F., Langone, L., Asioli, A., Puig, P., 2004. Clinoform generation on Mediterranean margins. Oceanography 17, 104–117. doi:10.5670/oceanog.2004.08
  7. Betzler, C., et al. Expedition 359 Summary. International Ocean Discovery Program. 2017
  8. Franzel, M., Back, S., Three-dimensional seismic sedimentology and stratigraphic architecture of prograding clinoforms, central Taranaki Basin, New Zealand, International Journal of Earth Sciences, Vol. 108, Is. 2, 475-496 (2019)
  9. NASA Clinoforms in Melas Chasms 2017 (https://www.nasa.gov/image-feature/jpl/pia21580/clinoforms-in-melas-chasma)

This page is currently being authored by a student at the University of Oklahoma. This page will be complete by December 1, 2019.