Raised fault block bounded by normal faults
In
physical geography
and
geology
, a
horst
is a raised
fault block
bounded by
normal faults
.
[1]
Horsts are typically found together with
grabens
. While a horst is lifted or remains stationary, the grabens on either side
subside
.
[2]
This is often caused by
extensional forces
pulling apart the crust. Horsts may represent features such as plateaus, mountains, or ridges on either side of a valley.
[3]
Horsts can range in size from small fault blocks up to large regions of stable continent that have not been folded or warped by tectonic forces.
[2]
The word
Horst
in
German
means "mass" or "heap" and was first used in the geological sense in 1883 by
Eduard Suess
in
The Face of the Earth.
[4]
[5]
[note 1]
Geomorphology
[
edit
]
Horsts may have either symmetrical or asymmetrical cross-sections. If the normal faults to either side have similar geometry and are moving at the same rate, the horst is likely to be symmetrical and roughly flat on top. If the faults on either side have different rates of vertical motion, the top of the horst will most likely be inclined and the entire profile will be asymmetrical. Erosion also plays a significant role in how symmetrical a horst appears in cross-section.
Horsts and hydrocarbon exploration
[
edit
]
Horsts can form structural
petroleum traps
.
[6]
In many
rift basins
around the world, the vast majority of discovered
hydrocarbons
are found in conventional traps associated with horsts.
[
citation needed
]
For example, much of the petroleum found in the
Sirte Basin
, Libya (of the order of tens of billions of barrels of reserves) are found on large horst blocks
[7]
such as the
Zelten Platform
and the Dahra Platform and on smaller horsts such as the
Gialo High
.
[8]
Examples
[
edit
]
The
Vosges Mountains
in France and
Black Forest
in Germany are examples of horsts, as are the
Table
,
Jura
, the
Dole
mountains and the
Rila
-
Rhodope
Massif
including the well defined horsts of
Belasitsa
(linear horst),
Rila mountain
(vaulted domed shaped horst) and
Pirin mountain
- a horst forming a massive
anticline
situated between the complex
graben
valleys of
Struma
and that of
Mesta
.
[9]
[10]
[11]
Larger areas where the
continent
remains stable with horizontal table-land
stratification
can be considered horsts, such as the
Russian Plain
,
Arabia
,
India
and Central
South Africa
. This is in distinction to folded regions such as some mountain chains of
Eurasia
.
[2]
The
Midcontinent Rift System
in North America is marked by a series of horsts extending from
Lake Superior
to
Kansas
.
[12]
The
Rwenzori Mountains
in the
East African Rift
are an upthrown fault block, and are the highest non-volcanic, non-orogenic mountains in the world.
[13]
[14]
The
Vosges Mountains
in
France
were formed by
isostatic uplift
in response to the opening of the
Rhine Graben
, a major extensional basin.
[15]
See also
[
edit
]
Notes
[
edit
]
- ^
Originally published in 1883 in German as "Das Antlitz der Erde", translated and published in English in 1904
References
[
edit
]
- ^
Fossen H. (2010-07-15).
Structural Geology
. Cambridge University Press. p. 154.
ISBN
9781139488617
.
- ^
a
b
c
One or more of the preceding sentences incorporates text from a publication now in the
public domain
:
Chisholm, Hugh
, ed. (1911). "
Horst
".
Encyclopædia Britannica
. Vol. 13 (11th ed.). Cambridge University Press. p. 740.
- ^
"Horst and Graben"
.
National Park Service
. 2020-04-22.
- ^
"horst"
.
Etymonline
.
- ^
Suess, Edward (1904).
The Face of the Earth
. Translated by Sollas, Hertha B C.
Clarendon Press
.
- ^
"Hydrocarbon Traps"
.
Geology In
. 2014-12-05
. Retrieved
2021-12-13
.
- ^
Parsons, M.G.; Zagaar, A.M.; Curry, J.J. (1980).
"Hydrocarbon occurrences in the Sirte Basin, Libya"
.
Facts and Principles of World Petroleum Occurrence Memoirs
.
6
: 723?732
. Retrieved
28 June
2022
.
- ^
Selley, R. C. (1 January 1997). "Chapter 3 The sirte basin of libya".
Sedimentary Basins of the World
.
3
: 27?37.
doi
:
10.1016/S1874-5997(97)80006-8
.
ISBN
9780444825711
.
- ^
Мичев (Michev), Николай (Nikolay); Михайлов (Mihaylov), Цветко (Tsvetko); Вапцаров (Vaptsarov), Иван (Ivan); Кираджиев (Kiradzhiev), Светлин (Svetlin) (1980).
Географски речник на България
[
Geographic Dictionary of Bulgaria
] (in Bulgarian). Sofia: Наука и култура (Nauka i kultura). p. 368.
- ^
Димитрова (Dimitrova), Людмила (Lyudmila) (2004).
Национален парк "Пирин". План за управление
[
Pirin National Park. Management Plan
] (in Bulgarian). и колектив. Sofia:
Ministry of Environment and Water
, Bulgarian Foundation "Biodiversity". p. 53.
- ^
Дончев (Donchev), Дончо (Doncho); Каракашев (Karakashev), Христо (Hristo) (2004).
Теми по физическа и социално-икономическа география на България
[
Topics on Physical and Social-Economic Geography of Bulgaria
] (in Bulgarian). Sofia: Ciela. pp. 128?129.
ISBN
954-649-717-7
.
- ^
United States Geological Survey (1989).
"Clastic Rocks Associated with the Midcontinent Rift System in Iowa"
(PDF)
.
U.S. Geological Survey Bulletin 1989?I
: 11
. Retrieved
Sep 3,
2018
.
- ^
Ring, Uwe (2008-08-27).
"Extreme uplift of the Rwenzori Mountains in the East African Rift, Uganda: Structural framework and possible role of glaciations"
.
Tectonics
.
27
(4).
Bibcode
:
2008Tecto..27.4018R
.
doi
:
10.1029/2007tc002176
.
ISSN
0278-7407
.
S2CID
129376195
.
- ^
"The Mountains of the Moon"
.
Volcano Cafe
. 20 February 2021.
- ^
"horst and graben"
.
Encyclopædia Britannica
.
External links
[
edit
]
- The dictionary definition of
horst
at Wiktionary