Earth:Arqueros Formation
| Arqueros Formation Stratigraphic range: Hauterivian-Barremian | |
|---|---|
| Type | Geological formation |
| Underlies | Quebrada Marquesa Formation |
| Overlies | La Negra Formation |
| Thickness | 1020 m |
| Lithology | |
| Primary | Porphyritic andesite, limestone, calcareous sandstone, volcanic sandstone |
| Other | Manganese deposits |
| Location | |
| Coordinates | [ ⚑ ] : 24°1′51.70″S 68°11′44.79″W / 24.031028°S 68.195775°W |
| Region | Coquimbo Region |
| Country | Chile |
  Arqueros Formation (Chile) | |
Arqueros Formation (Spanish: Formación Arqueros) is a geological formation composed of alternations of volcanic and volcaniclastic rock layers and limestone of marine origin in inland Coquimbo Region, northern Chile.[1][2] The formation has been dated to the Early Cretaceous,[3] more specifically to the Hauterivian and Barremian.[2] The volcanic rocks of the formation are of andesitic composition.[2] The formation has a stratigraphic thickness of 1020 m.[2] The exposed parts of the formation run as a belt from north to south through the central part of the region.[4][5] There are large outcrops of the formation in mountain plateaux north of Quebrada Marquesa, a tributary of Elqui River.[2] These outcrops are thought to have originated by uplift of the region bounded by one normal fault to the west and one to the east.[2]
The work of Aguirre and Egert (1970) found that five members could be identified in the formation, beginning with porphyritic andesites in the bottom (Ka1)[2], overlaid by cherts, sandstones and limestones (Ka2), again overlain by a layer of porphyritic andesites (Ka3) and then followed by limestones, sandstones and andesites (Ka4). The stratigraphically uppermost layer, Mn1, is made of volcanic sandstones and manto-type volcanic sandstones and manto-type manganese deposits.[2] The manganese-bearing beds of the Mn1 member lie typically 30 m from the roof of the formation, and thus lie close to Quebrada Marquesa Formation that overlies it.[4]
Arqueros Formation is underlaid by La Negra Formation.[5]
References
- ↑ Oyarzun et al. 1998, p. 547.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Oyarzun et al. 1998, p. 549.
- ↑ Aguirre & Mehech 1964, p. 428.
- ↑ 4.0 4.1 Aguirre & Mehech 1964, p. 431.
- ↑ 5.0 5.1 Aguirre & Mehech 1964, p. 432.
- Bibliography
- Aguirre, Luis; Mehech, Sonia (1964). "Stratigraphy and Mineralogy of the Manganese Sedimentary Deposits of Coquimbo Province, Chile". Economic Geology 59 (3): 428–442. doi:10.2113/gsecongeo.59.3.428. Bibcode: 1964EcGeo..59..428A. https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=30a883aec2e794a5f50da56da19cb7cba09b39a3.
- Oyarzun, R.; Ortega, L.; Sierra, J.; Lunar, R.; Oyarzun, J. (1998). "Cu, Mn, and Ag mineralization in the Quebrada Marquesa Quadrangle, Chile: the Talcuna and Arqueros districts". Mineralium Deposita 33 (6): 547–559. doi:10.1007/s001260050171. Bibcode: 1998MinDe..33..547O. https://docta.ucm.es/rest/api/core/bitstreams/aafc094d-8450-42a8-a54e-7db11df07aca/content.
Template:Sedimentary formations and groups in Chile
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