Geology of Ecuador

Last updated

The geology of Ecuador includes ancient Precambrian basement rock and a complex tectonic assembly of new sections of crust from formerly separate landmasses, often uplifted as the Andes or transformed into basins.

Contents

Geologic History, Stratigraphy & Tectonics

Much of Ecuador is underlain by Precambrian igneous and metamorphic crystalline basement rocks. The Piedras Group rocks date to the period and outcrop in El Oro Province on the western Andean slope in the southwest of the country and includes greenschist and amphibolite with small intercalations of quartz-sericite schist and quartzite, dated to 743 million years ago in the Proterozoic. These high-grade, polymetamorphic rocks often signs of overprinting and green hornblende with a feather-like texture is found in the amphibolite. [1]

Mesozoic (251-66 million years ago)

Continental and oceanic terranes began to be added to western South America in the Mesozoic. In north-central Ecuador, the Peltetec-Portovelo fault marks the suture between the pre-existing South American craton and the Amotape-Chaucha terrane, which partially subducted beneath a preexisting Mesozoic continental arc system. The Triassic mafic and granitoid rocks of the El Oro metamorphic complex and the component eclogite, blueschist and amphibolite are known as the Raspas metamorphic complex. This section of the terrane was previously subducted but brought to the surface with tectonic activity. [2]

The breakup of the supercontinent Gondwana is recorded in the Triassic in Ecuador with S-type granite plutons, followed by the intrusion of calc-alkaline batholiths in the Jurassic. [3]

Oceanic basalts formed in the Jurassic and Cretaceous were accreted to the edge of the continent as a separate terrane around 130 million years ago, forming a belt of basalt and diabase, together with tuff, metasedimentary and sedimentary rocks running north–south into Ecuador. [4] [5]

Cenozoic (66 million years ago-present)

Following the accretion of new terranes to the Western Cordillera, the Cenozoic brought the extensive uplift of the Andean orogeny. Volcanic rocks vary geochemically between the Western Cordillera and Eastern Cordillera. In the east, they are predominantly rhyolite, andesite and andesitedacite while in the west, they are characteristically andesite and plagidacite. These are inferred to be the result of hydrous partial melting of Basic Igneous Complex garnet amphibolite and amphibolite. [6]

Natural resource geology in Cenozoic rocks

Most mineable deposits in Ecuador are either epithermal gold or porphyry copper hosted in Paleogene rocks, formed from the Eocene to the Miocene. They may have originated from an enriched mid-ocean ridge (MORB) basalt. Compared to other neighboring countries, copper deposits are comparatively small. Explanations have included a lack of development of magma chambers around nine million years ago due to the extent of compression in the Ecuadorian section of the Andes, or perhaps of a lack of exposure of deposits near the surface. [7]

Related Research Articles

Basement (geology) Metamorphic or igneous rocks below a sedimentary platform or cover

In geology, basement and crystalline basement are the rocks below a sedimentary platform or cover, or more generally any rock below sedimentary rocks or sedimentary basins that are metamorphic or igneous in origin. In the same way, the sediments or sedimentary rocks on top of the basement can be called a "cover" or "sedimentary cover".

Franciscan Complex A late Mesozoic terrane of heterogeneous rocks in the California Coast Ranges

The Franciscan Complex or Franciscan Assemblage is a geologic term for a late Mesozoic terrane of heterogeneous rocks found throughout the California Coast Ranges, and particularly on the San Francisco Peninsula. It was named by geologist Andrew Lawson, who also named the San Andreas fault that defines the western extent of the assemblage.

The Cadomian Orogeny was a tectonic event or series of events in the late Neoproterozoic, about 650–550 Ma, which probably included the formation of mountains. This occurred on the margin of the Gondwana continent, involving one or more collisions of island arcs and accretion of other material at a subduction zone. The precise events, and geographical position, are uncertain, but are thought to involve the terranes of Avalonia, Armorica and Iberia. Rocks deformed in the orogeny are found in several areas of Europe, including northern France, the English Midlands, southern Germany, Bohemia, southern Poland and the southwest Iberian Peninsula. The name comes from Cadomus, the Latin name for Caen, northern France. L Bertrand gave the orogeny its name in 1921, naming it after Cadomus the Gaulish name for Caen in Normandy. He defined the end as being marked by Lower Palaeozoic red beds.

Metamorphic core complex

Metamorphic core complexes are exposures of deep crust exhumed in association with largely amagmatic extension. They form, and are exhumed, through relatively fast transport of middle and lower continental crust to the Earth's surface. During this process, high-grade metamorphic rocks are exposed below low-angle detachment faults that show ductile deformation on the lower side (footwall) with amphibolite- to greenschist-facies syndeformational metamorphism, and ductile-brittle to brittle deformation on the upper-side (hanging-wall) with tilted geometries.

Wrangellia Terrane Geological area in northwestern North America

The Wrangellia Terrane is a terrane extending from the south-central part of Alaska and along the Coast of British Columbia in Canada. Some geologists contend that Wrangellia extends southward to Oregon, although this is not generally accepted.

Andean orogeny Ongoing mountain-forming process in South America

The Andean orogeny is an ongoing process of orogeny that began in the Early Jurassic and is responsible for the rise of the Andes mountains. The orogeny is driven by a reactivation of a long-lived subduction system along the western margin of South America. On a continental scale the Cretaceous and Oligocene were periods of re-arrangements in the orogeny. Locally the details of the nature of the orogeny varies depending on the segment and the geological period considered.

Geology of North America Overview of the geology of North America

The geology of North America is a subject of regional geology and covers the North American continent, the third-largest in the world. Geologic units and processes are investigated on a large scale to reach a synthesized picture of the geological development of the continent.

Siletzia Rock formation that forms the basement rock of the southern Pacific Northwest coast

Siletzia is a massive formation of early to middle Eocene epoch marine basalts and interbedded sediments in the forearc of the Cascadia subduction zone, on the west coast of North America. It forms the basement rock under western Oregon and Washington and the southern tip of Vancouver Island. It is now fragmented into the Siletz and Crescent terranes.

High pressure metamorphic terranes along the Bangong-Nujiang Suture Zone

High pressure terranes along the ~1200 km long east-west trending Bangong-Nujiang suture zone (BNS) on the Tibetan Plateau have been extensively mapped and studied. Understanding the geodynamic processes in which these terranes are created is key to understanding the development and subsequent deformation of the BNS and Eurasian deformation as a whole.

The geology of Somalia is built on more than 700 million year old igneous and metamorphic crystalline basement rock, which outcrops at some places in northern Somalia. These ancient units are covered in thick layers of sedimentary rock formed in the last 200 million years and influenced by the rifting apart of the Somali Plate and the Arabian Plate. The geology of Somaliland, the de facto independent country recognized as part of Somalia, is to some degree better studied than that of Somalia as a whole. Instability related to the Somali Civil War and previous political upheaval has limited geologic research in places while heightening the importance of groundwater resources for vulnerable populations.

Geology of Somaliland

The geology of Somaliland is very closely related to the geology of Somalia. Somaliland is a de facto independent country within the boundaries that the international community recognizes as Somalia. Because it encompasses the former territory of British Somaliland, the region is historically better researched than former Italian Somaliland. Somaliland is built on more than 700 million year old igneous and metamorphic crystalline basement rock.. These ancient units are covered in thick layers of sedimentary rock formed in the last 200 million years and influenced by the rifting apart of the Somali Plate and the Arabian Plate.

The geology of Alaska includes Precambrian igneous and metamorphic rocks formed in offshore terranes and added to the western margin of North America from the Paleozoic through modern times. The region was submerged for much of the Paleozoic and Mesozoic and formed extensive oil and gas reserves due to tectonic activity in the Arctic Ocean. Alaska was largely ice free during the Pleistocene, allowing humans to migrate into the Americas.

The geology of Brazil includes very ancient craton basement rock from the Precambrian overlain by sedimentary rocks and intruded by igneous activity, as well as impacted by the rifting of the Atlantic Ocean.

Geology of Peru

The geology of Peru includes ancient Proterozoic rocks, Paleozoic and Mesozoic volcanic and sedimentary rocks, and numerous basins and the Andes Mountains formed in the Cenozoic.

The geology of Panama includes the complex tectonic interplay between the Pacific, Cocos and Nazca plates, the Caribbean Plate and the Panama Microplate.

The geology of Costa Rica is part of the Panama Microplate, which is slowly moving north relative to the stable Caribbean Plate.

The geology of Guatemala encompasses rocks divided into two tectonic blocks. The Maya Block in the north has igneous and metamorphic North American Craton basement rocks, overlain by late Paleozoic metasedimentary rocks, which experienced deformation during the Devonian. Red beds, evaporites and marine limestone from the Mesozoic overlie these rocks. A karst landscape formed in the thick limestone units across the north of the country. During a collisional orogeny, these Paleozoic and Mesozoic rocks were uplifted, thrusted and folded as the Central Guatemalan Cordillera. Paleogene rocks from the early Cenozoic include volcanic and marine clastic rocks, associated with high rates of erosion.

Eastern Block of the North China Craton

The Eastern Block of the North China Craton is one of the Earth's oldest pieces of continent. It is separated from the Western Block by the Trans-North China Orogen. It is situated in northeastern China and North Korea. The Block contains rock exposures older than 2.5 billion years. It serves as an ideal place to study how the crust was formed in the past and the related tectonic settings.

South China Craton

The South China Craton or South China Block is one of the Precambrian continental blocks in China. It is traditionally divided into the Yangtze Block in the NW and the Cathaysia Block in the SE. The Jiangshan–Shaoxing Fault represents the suture boundary between the two sub-blocks. Recent study suggests that the South China Block possibly has one more sub-block which is named the Tolo Terrane. The oldest rocks in the South China Block occur within the Kongling Complex, which yields zircon U–Pb ages of 3.3–2.9 Ga.

Western Block of the North China Craton

The Western Block of the North China Craton is an ancient micro-continental block mainly composed of Neoarchean and Paleoproterozoic rock basement, with some parts overlain by Cambrian to Cenozoic volcanic and sedimentary rocks. It is one of two sub-blocks within the North China Craton, located in east-central China. The boundaries of the Western Block are slightly different among distinct models, but the shapes and areas are similar. There is a broad consensus that the Western Block covers a large part of the east-central China.

References

  1. ↑ Feininger, Tomas (1982). "The metamorphic "basement" of Ecuador". Geological Society of America Bulletin. 93: 87. doi:10.1130/0016-7606(1982)93<87:TMBOE>2.0.CO;2.
  2. ↑ Arculus, R. J.; Lapierre, H.; Jaillard, É. (1999). "Geochemical window into subduction and accretion processes: Raspas metamorphic complex, Ecuador". Geology. 27 (6): 547. doi:10.1130/0091-7613(1999)027<0547:GWISAA>2.3.CO;2.
  3. ↑ Aspden, John A.; Litherland, Martin (1992). "The geology and Mesozoic collisional history of the Cordillera Real, Ecuador". Tectonophysics. 205: 187–204. doi:10.1016/0040-1951(92)90426-7.
  4. ↑ Aspden, J. A.; McCourt, W. J. (1986). "Mesozoic oceanic terrane in the central Andes of Colombia". Geology. 14 (5): 415. doi:10.1130/0091-7613(1986)14<415:MOTITC>2.0.CO;2.
  5. ↑ Feininger, Tomas; Silberman, M.L. (1982). "K-Ar geochronology of basement rocks on the northern flank of the Huancabama deflection, Ecuador". Open-File Report. Open-File Report. doi:10.3133/ofr82206.
  6. ↑ Hörmann, Paul K.; Pichler, Hans (1982). "Geochemistry, petrology and origin of the Cenozoic volcanic rocks of the Northern Andes in Ecuador". Journal of Volcanology and Geothermal Research. 12 (3–4): 259–282. doi:10.1016/0377-0273(82)90029-4.
  7. ↑ Chiaradia, Massimo; Fontboté, Lluís; Beate, Bernardo (2004). "Cenozoic continental arc magmatism and associated mineralization in Ecuador" (PDF). Mineralium Deposita (Submitted manuscript). 39 (2): 204–222. doi:10.1007/s00126-003-0397-5.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.