RT Journal Article
T1 Características diferenciales y génesis de los niveles silíceos explotados en el yacimiento arqueológico de Casa Montero (Vicálvaro, Madrid)
T1 Differential features and genesis of silica levels mined in the Casa Montero archaeological site. (Vicálvaro, Madrid)
A1 Bustillo Revuelta, María Ángeles
A1 Pérez Jiménez, José Luis
AB The research during the construction of the M-50 highway has allowed the study of the silica levels thatconstitute the most important Neolithic flint mine in the Iberian Peninsula. A group of more than 3.800extraction pits were realized to obtain cherts and opals that appear among Mg smectites beds (Aragoniandeposits). The description of the nodular and stratiform silica levels and the study of their types anddistribution have been done at geological sections obtained during the archaeological excavations. Threepetrological types of siliceous rocks (chert, opal and opaline chert) are established and defined accordingto their mineralogy and microfacies. Cherts are constituted only by quartz and locally minor amounts ofmoganite. Opals contain opal CT, Mg smectites and minor quartz. Opaline chert is defined when theproportion of quartz is higher than 50%. All the types of siliceous rocks reproduce bioturbation structuresas well as other structures found in the host rocks (grains, intraclasts, brecciation).The silica levels at the base of the columns are constituted only by chert and were formed by the silicificationof nodular and lenticular dolomite levels included in the Mg-smectites beds. The rest of the siliceous levelsare composed of opals and opaline cherts and were formed by silicification of Mg-smectites. The outer partof the opaline chert has a higher content in opal and clay relicts whereas the inner part is mainly microcrystallinequartz. This change is consequence of the recrystallization of the opal (aging) producing a more compactsilica rock. The main silicification occurred under the groundwater table because the structure of the hostrocks is conserved in the silica rocks. A general question is whether the silica that precipites is introduced bygroundwater or it is released from the dissolution of clays during their replacement
PB Sociedad Geológica de España
YR 2005
FD 2005
LK http://hdl.handle.net/10272/8693
UL http://hdl.handle.net/10272/8693
LA spa
DS Repositorio Institucional de la Universidad de Huelva
RD 30 may 2026