GulfBase - General Facts about the Gulf of Mexico
General Facts about the Gulf of Mexico
From: Gore, 1992; Darnell and Defenbaugh, 1990;      unless otherwise noted.
LOCATION AND SIZE
The Gulf          of Mexico is a Mediterranean-type sea located at the southeastern          corner of North America.  The Gulf is bordered by the United States          to the north (Florida, Alabama, Mississippi, Louisiana, Texas), six          Mexican states  to the west (Quintana Roo, Tamaulipas, Veracruz, Tabasco, Campeche,          Yucatan), and the island of Cuba to the southeast.
The Gulf measures approximately 1,600 kilometers from east to west,          900 kilometers from north to south, and has a surface area of 1.5          million square kilometers.  The marine shoreline from Cape Sable,          Florida to the tip of the Yucatan peninsula extends ~5,700 kilometers,          with another 380 kilometers of shore on the northwest tip of Cuba.           If bays and other inland waters are included, the total shoreline          increases to over 27,000 kilometers in the U.S. alone.
Source: http://earthobservatory.nasa.gov/
Depth gradient throughout the Gulf of Mexico.
Image modified from ESRI Data & Maps (2000).
The Gulf of Mexico basin resembles a large pit with          a broad shallow rim.  Approximately 38% of the Gulf is comprised by          shallow and intertidal areas  (< 20 m deep).  The area of the          continental shelf (< 180 m) and continental slope          (180 - 3,000 m) represent 22% and 20% respectively, and          abyssal areas deeper than 3,000 m comprise the final 20% (Gore,          1992).    The Sigsbee Deep, located in the southwestern quadrant, is the deepest region of the Gulf of Mexico. Its exact maximum depth is controversial, and reports by different authors state maximum depths ranging from 3,750 m to 4,384 m.          Mean (average) water depth of the Gulf is ~1,615 m          (Turner, 1999) and the basin contains a  volume of 2,434,000 cubic          kilometers of water (6.43 * 1017 or 643 quadrillion          gallons).
ORIGINS AND GEOLOGIC HISTORY
From: Gore, 1992; Donnelly, 1975; Martin, 1975; Uchupi, 1975  After Salvador, 1991
The Gulf of Mexico basin is a relatively simple, roughly circular  structural basin approximately 1,500 km in diameter, filled in its  deeper part with 10 to 15 km of sedimentary rocks that range in age  from Late Triassic to Holocene (approximately 230 m.y. to present).   Little is known about the geologic history of the Gulf of Mexico Basin  before Late Triassic time. Since pre-Triassic rocks are known from only  a few widely separated outcrop areas and wells, much of the geologic  history of the basin during Paleozoic time needs to be inferred from  the study of neighboring areas.  Some authors have postulated the  presence of a basin in the area during most of Paleozoic time, but  most evidence seems to indicate that Paleozoic rocks do not underlie  most of the Gulf of Mexico basin and that the area was, at the end of  Paleozoic time, part of the large supercontinent of Pangea,  the result of the collision of several continental plates.  The present  Gulf of Mexico basin, in any case, is believed to have had its origin in  Late Triassic time as the result of rifting within the North American  Plate at the time it began to crack and drift away from the  African and South American plates.  Rifting probably continued through  Early and Middle Jurassic time with the formation of "stretched" or  "transitional" continental crust throughout the central part of the basin.   Intermittent advance of the sea into the continental area from the west  during late Middle Jurassic time resulted in the formation of the  extensive salt deposits known today in the Gulf of Mexico basin.   It appears that the main drifting episode, during which the Yucatan  block moved southward and separated from the North American Plate  and true oceanic crust formed in the central part of the basin, took  place during the early Late Jurassic, after the formation of the  salt deposits.
Since Late Jurassic time, the basin has been a stable geologic  province characterized by the persistent subsidence of its central  part, probably due at first to thermal cooling and later to sediment  loading as the basin filled with thick prograding clastic wedges along  its northwestern and northern margins, particularly during the Cenozoic.   To the east, the stable Florida platform was not covered by the sea  until the latest Jurassic or the beginning of Cretaceous time.  The  Yucatan platform was emergent until the mid-Cretaceous.  After both  platforms were submerged, the formation of carbonates and evaporites  has characterized the geologic history of these two stable areas.  Most  of the basin was rimmed during the Early Cretaceous by carbonate  platforms, and its western flank was involved during the latest  Cretaceous and early Tertiary in a compressive deformation episode,  the Laramide Orogeny, which created the Sierra Madre Oriental of  eastern Mexico.
GEOLOGY
Today, the Gulf of Mexico is a small oceanic basin surrounded  by continental land masses.  Due to their physical structure, the  Gulf and the Caribbean Sea are sometimes combined and referred to  as the 'American Mediterranean'.  Uchupi (1975) divides the Gulf  into two distinct geographical provinces (Terrigenous and Carbonate)  while Antoine (1972) recognizes seven. The scheme proposed by Antoine  is presented here, with additional information derived from other sources.
1) Gulf of Mexico Basin
This portion of the Gulf of Mexico contains the Sigsbee Deep and  can be further divided into the continental rise, the Sigsbee Abyssal  Plain, and the Mississippi Cone.  Located between the Sigsbee  escarpment and the Sigsbee Abyssal Plain, the continental rise is  composed of sediments transported to the area from the north.  The  Sigsbee Abyssal Plain is a deep, flat portion of the Gulf bottom  located northwest of Campeche Bank.  In this relatively uniform  area of the Gulf bottom, the Sigsbee Knolls and other small diapiric  (salt) domes represent the only major topographical features.  The  Mississippi Cone is composed of soft sediment and extends southeast  from the Mississippi Trough, eventually merging with other sediments  of the central basin.  The cone is bordered by the DeSoto Canyon to  the east and the Mississippi Trough to the west, and has been  described in detail by Ewing et al. (1958).
2) Northeast Gulf of Mexico
Extending from just east of the Mississippi Delta near Biloxi to the  eastern side of Apalachee Bay, this region of the Gulf bottom is  characterized by soft sediments.  To the west of the DeSoto Canyon,  terrigenous (land-derived) sediments are thick and fill the remnants  of the Gulf basin.  In the eastern portion of the region,  Mississippi-derived sediments cover the western edge of the  Florida Carbonate Platform and a transition towards carbonate  sediments begins.  The Florida Escarpment separates the Florida  Platform from the Gulf Basin and also forms the southeastern side  of the DeSoto Canyon.  In a region characterized by sediment deposition,  the presence of the DeSoto Canyon is poorly understood.  Some  theories suggest that the canyon is the result of erosion caused by  oceanic currents, possibly the Loop Current (Nowlin, 1971).
3) South Florida Continental Shelf and Slope
A submerged portion of the larger emergent Florida Peninsula, this  region of the Gulf of Mexico extends along the coast from Apalachee  Bay to the Straits of Florida and includes the Florida Keys and Dry  Tortugas.  A generalized progression towards carbonate sediments  occurs from north to south ending in the thick carbonate sediments  of the Florida Basin.  Evidence suggests that this basin was at one  time enclosed by a barrier reef system (Ewing et al., 1966;  Sheridan et al., 1966; Oglesby et al., 1965; Antoine and Ewing, 1963).   In the Straits of Florida the Jordan Knoll appears to be composed of  remnants from this ancient reef system.  Evidence suggests that this  reef may have once extended across the straits, adjoining the Florida  reefs with those of northern Cuba.
4) Campeche Bank
Campeche Bank is an extensive carbonate bank located to the  north of the Yucatan Peninsula (Ordonez, 1936).  The bank extends  from the Yucatan Straits in the east to the Tabasco-Campeche Basin  in the west and includes Arrecife Alacran.  The region shows many  similarities to the south Florida platform and some evidence suggests  that the two ancient reef systems may have been continuous  (Antoine and Ewing, 1963; Uchupi and Emery, 1968).  Continental  drift and erosional processes are both theorized to have played a  role in the separation of the two geologically similar carbonate platforms.
5) Bay of Campeche
The Bay of Campeche is an isthmian embayment extending from the  western edge of Campeche Bank to the offshore regions just east of  Veracruz (~96 degrees W).  The Sierra Madre Oriental forms the  south-southwestern border, and the associated coastal plain is  similar to the Texas-Louisiana coast in the northern Gulf.   The bottom topography is characterized by long ridges parallel to  the exterior of the basin.  Salt domes are prevalent in the region,  and the upward migration of salt is theorized to be a cause of the  complex bottom profiles (Worzel et al., 1968).  Similar to the  northern Gulf, large quantities of oil are produced here, and thick  terrigenous sediments predominate.
6) Eastern Mexico Continental Shelf and Slope
Located between Veracruz to the south and the Rio Grande to the north,  this geological province spans the entire eastern shore of Mexico.  The  Gulf bottom of the region is characterized by sediment-covered folds  that parallel the shore.  Apparently created by sediment-covered  evaporites, evidence suggests that the folds have impeded sediment  transport from the Mexican coast to the Gulf Basin (Bryant et al., 1968).   As sediment cover increases from south to north, so does the relative  complexity of the bottom structure.
7) Northern Gulf of Mexico
The northern Gulf of Mexico extends from Alabama to the U.S.-Mexico  border.  North to south, the province extends from 200 miles inland  of the present day shoreline to the Sigsbee escarpment.  Sediments in  the region are generally thick with the greatest sediment load provided  by the Mississippi River.  Widespread salt deposits are present  throughout the region (Murray, 1961; Halbouty, 1967) and these  structures act to create subsurface and emergent topographic features  on the continental slope such as the Flower Garden Banks off the  Texas/Louisiana coast, and the pinnacles region offshore of the  Mississippi/Alabama coast.
CIRCULATION AND CURRENTS
Water enters the Gulf through the Yucatan Strait, circulates as the Loop Current, and exits through the Florida Strait eventually forming the Gulf Stream.  Portions of the Loop Current often break away forming eddies or 'gyres' which affect regional current patterns.  Smaller wind driven and tidal currents are created in nearshore environments.
Drainage into the Gulf of Mexico is extensive and includes 20 major river systems (>150 rivers) covering over 3.8 million square kilometers of the continental United States (Moody, 1967).  Annual freshwater inflow to the Gulf is approximately 10.6x1011 m3 per year (280 trillion gallons).  85% of this flow comes from the United States, with 64% originating from the Mississippi River alone.  Additional freshwater inputs originate in Mexico, the Yucatan Peninsula, and Cuba.
RESOURCES
The Gulf of Mexico ecosystem provides a wide array of valuable resources to the nations on its shores.  Brief summaries of petroleum and fisheries resources can be found below.
Physical / Mineral
It is estimated that 1.4-7.2x108 barrels of petroleum and 4.4-22.3x1010 cubic meters of natural gas are present beneath the seafloor in the northern Gulf (Darnell and Defenbaugh, 1990).  According to the Minerals Management Service, offshore operations in the Gulf produce a quarter of the U.S. domestic natural gas and one-eighth of its oil. In addition, the offshore petroleum industry employs over 55,000 U.S. workers in the Gulf (MMS, 2002).        In Mexico, the Secretariat of Energy (Secretaria de Energia - SENER)    estimated that the daily crude oil and natural gas production from Gulf of    Mexico offshore operations in the years 2000 to 2005 ranged from 2.293 to    2.839 million barrels and 41.4 to 44.8 million cubic meters,    respectively (SENER 2006).
Fisheries
Gulf fisheries are some of the most productive in the world. In 2000, the commercial fish and shellfish harvest from the five U.S. Gulf states was estimated to be 1.7 billion pounds (approximately 772 million kg), which represents almost 1/5 (19.4%) of the total domestic landings in the United States.  In the same year, commercial catches in the Gulf represented approximately 25% of the total U.S. domestic commercial fishing revenue and were valued at over $900 million. The Gulf also supports a productive recreational fishery.  Excluding Texas, U.S. Gulf states accounted for over 40% (>104,000 lbs or >47,000 kg) of the U.S. recreational finfish harvest in 2000 (O'Bannon, 2001).
LITERATURE CITED
Antoine, J.W. 1972. Structure of the Gulf of Mexico. In: Rezak, R. and V.J. Henry (eds.) Texas A&M University Oceanographic Studies, Volume 3: Contributions on the geological and geophysical oceanography of the Gulf of Mexico. Gulf Publishing Company, Houston. 303 p.
Antoine, J.W. and Ewing, J.I. 1963. Seismic refraction measurements on the margins of the Gulf of Mexico. J. Geophys. Res. 68:1975-1996.
Bornhauser, M. 1958. Gulf Coast tectonics. Am. Assoc. Petroleum Geologists Bull. 42:339-370.
Bryant, W.R., Antoine, J.W., Ewing, M. and Jones, B. 1968. Structure of Mexican continental shelf and slope, Gulf of Mexico. Am. Assoc. Petroleum Geologists Bull. 52:1204-1228.
Darnell, R.M. and R.E. Defenbaugh. 1990. Gulf of Mexico: Environmental Overview and History of Environmental Research. American Zoologist 30:3-6.
Donnelly, T.W. 1975. The geological evolution of the Caribbean and Gulf of Mexico, some critical problems and areas. Chapter 3, The age of the Gulf of Mexico. In: Nairn, A.E.M., and Stehli, F.G. (eds.). The ocean basins and margins, vol. 3: The Gulf of Mexico and the Caribbean. Plenum Press, NY, p. 666-668.
Ewing, M., Ericson, D.B. and B.C. Heezen. 1958. Sediments and topography of the Gulf of Mexico. In: E. Weeks (ed.) Habitat of Oil. Am. Assoc. Petroleum Geologists, Tulsa, p. 995-1053.
Ewing, J.I., Ewing, M. and Leyden, R. 1966. Seismic profiler survey of Blake Plateau. Am. Assoc. Petroleum Geologists Bull. 50:1948-1971.
Gore, R.H. 1992. The Gulf of Mexico. Pineapple Press, Inc. Sarasota Florida. 384 p.
Halbouty, M.T. 1967. Salt domes, Gulf region-United States and Mexico. Gulf Publishing, Houston, 425 p.
Hardin, G. 1962. Notes of Cenozoic sedimentation in the Gulf Coast Geosyncline, USA. In: E.H. Rainwater and R.P. Zingula (eds.) Geology of the Gulf Coast and central Texas and guidebook to excursions. Houston Geol. Soc., Houston, p. 1-15.
Martin, R.G. 1975. Geophysical studies in the Gulf of Mexico. Chapt. 5, Origin of the Gulf of Mexico. In: Nairn, A.E.M. and Stehli, F.G. (eds.). The ocean basins and margins, vol. 3: The Gulf of Mexico and the Caribbean. Plenum Press, NY, pp. 97-99.
Meyerhoff, A.A. 1968. Geology of natural gas in south Louisiana. Lafayette and New Orleans Geological Soc. In: B.W. Beebe and B.F. Curtis (eds.) Natural gases of North America.  Am. Assoc. Petroleum Geologists Mem. 9, Tulsa, p. 376-581.
Minerals Management Service (MMS), 2002.  Summary of offshore petroleum operations in the Gulf of Mexico OCS Region.  Located at: http://www.gomr.mms.gov/homepg/whoismms/aboutmms.html
Moody, C.L. 1967. Gulf of Mexico distributive province. AAPG Bulletin, 51(2):179-199.
Murray, G.E. 1961. Geology of the Atlantic and Gulf coastal province of North America. New York: Harper and Bros.
Nowlin, W.D. 1971. Water masses and general circulation of the Gulf of Mexico. Oceanology 5(2):28-33.
O'Bannon, B.K. 2001. Fisheries of the United States 2000. National Marine Fisheries Service, Office of Science and Technology, Fisheries Statistics and Economics Division. U.S. Dept. Commerce. Silver Spring, MD.
Oglesby, W.R. 1965. Folio of South Flordia basin, a preliminary study. Map series No. 19, State Division of Geology, Florida Geological Survey, Tallahassee.
Ordonez, E. 1936. Principal physiogeographic provinces of Mexico. Am. Assoc. Petroleum Geologists Bull. 20:1277-1307.
Salvador, A. 1991. Introduction. In: Salvador, A. (ed.) The Gulf of Mexico Basin. Geological Society of America, The Geology of North America, Boulder, Colorado.
SENER [Secretaria de Energia].  Sistema de Informacion Energetica:    Informacion Estadistica. http://sie.energia.gob.mx/ ,     accessed on July 25, 2006.
Sheridan, R.E., Drake, C.L., Nafe, J.E. and Hennion, J. 1966. Seismic refraction study of continental margin east of Florida. Am. Assoc. Petroleum Geologists Bull. 50:1972-1991.
Turner, R.E. 1999. Inputs and outputs of the Gulf of Mexico. Chapt. 4, In: Kumpf, H., Steidinger, K. and Sherman, K. (eds.) The Gulf of Mexico large marine ecosystem; assessment, sustainability and management. Blackwell Science, Inc. 704 pp.
Uchupi, E. 1975. Physiography of the Gulf of Mexico and Caribbean Sea. In: Nairn, A.E.M. and Stehli, F.G. (eds.) The ocean basins and margins, vol. 3: The Gulf of Mexico and the Caribbean. Plenum Press, NY. 706 p.
Uchupi, E. and Emery, K.O. 1968. Structure of continental margin off Gulf Coast of United States. Am. Assoc. Petroleum Geologists Bull. 52:1162-1193.
Worzel, J.L., Leyden, R. and Ewing, M. 1968. Newly discovered diapirs in Gulf of Mexico. Am. Asso. Petroleum Geologists Bull. 52:1194-1203.
Contribute