Punta del Cobre Formation () is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

age cropping out in the interior of Atacama Region, Chile. The formation is of

age. It is made of massive

volcanic rock Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...

s, chiefly

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

, and

volcaniclastic rock Volcaniclastics are geologic materials composed of broken fragments ( clasts) of volcanic rock. These encompass all clastic volcanic materials, regardless of what process fragmented the rock, how it was subsequently transported, what environment it ...

s representing "flows" and

Volcanic breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a varie ...

of basaltic andesitic and

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

ic composition. The rocks of the formation belong to the

calc-alkaline magma series The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic ...

. Rocks show intense

hydrothermal alteration Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a Rock (geology), rock by hydrothermal and other fluids. It is traditionally defined as metamorphism which involves a change in t ...

and hosts significant copper and gold deposits and lesser amounts of

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

and

silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...

. The formation lies in a zone of small-scale mining that supplies the nearby

Fundición Paipote Fundición Hernán Videla Lira better known as Fundicón Paipote, and formerly known as Fundición Nacional Paipote, is a copper smelter plant 8 km southeast of Copiapó in Chile's Atacama Region. It operates with a Teniente Converter smelting ...

copper

smelter Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. It is a form of extractive metallurgy that is used to obtain many metals such as iron, copper, silver, tin, lead and zin ...

. The copper and

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

s of the Dominga prospect are in part emplaced in Punta del Cobre Formation. It was by 1980 considered to be part of Chañarcillo Group but was by 2001 considered to more likely represent the lower member of the

underlying In finance, a derivative is a contract between a buyer and a seller. The derivative can take various forms, depending on the transaction, but every derivative has the following four elements: # an item (the "underlier") that can or must be bou ...

Bandurrias Group. The upper boundary of Punta del Cobre Formation is marked by the appearance of an alternation of beds of carbonate and volcaniclastic rocks belonging to the Abundancia Formation of Chañarcillo Group. The contact is transitional with the first appearance of carbonate beds indicating the beginning of Abundancia Formation. Geologists Rober Marschik and Lluís Fontboté divided the formation in 2001 into two members, the Geraldo-Negro Member and the overlying the Algarrobos Member. The former is contain massive volcanic rocks, and the latter the volcaniclastic rocks.

References

{{Geology of Chile Geologic formations of Chile Lower Cretaceous Series of South America Mesozoic Chile Geology of Atacama Region Cretaceous volcanism Andesite formations Basalt formations Dacite formations