http://www.cnr.it/ontology/cnr/individuo/prodotto/ID29126

Two-stage growth of laccoliths at Elba Island, Italy. (Articolo in rivista)

Type

Label

Two-stage growth of laccoliths at Elba Island, Italy. (Articolo in rivista) (literal)

Anno

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi

Alternative label

Rocchi S. (1), Westerman D.S. (2), Dini A. (3), Innocenti F. (1), Tonarini S. (3) (2002)
Two-stage growth of laccoliths at Elba Island, Italy.
in Geology (Boulder Colo.); Geological Society Of America, Inc., Boulder (Stati Uniti d'America)
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

Rocchi S. (1), Westerman D.S. (2), Dini A. (3), Innocenti F. (1), Tonarini S. (3) (literal)

Pagina inizio

Pagina fine

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#altreInformazioni

The emplacement of granitic melts contributes prominently to the processes of mass redistribution in the continental crust, but the way felsic intrusions gain space and grow has been debated throughout the twentieth century. In the last decade, new ideas on magma ascent by dikes, tabular shape of intrusions, and room-generating processes (fault opening, roof lifting and floor depression) have helped to mitigate the space problem, and the process of growth of felsic intrusions has gained renewed interest. This study provides new data for such a debate and shed new lights on the similarr intrusive environment for granite laccoliths and plutons. (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume

Rivista

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#note

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#descrizioneSinteticaDelProdotto

The unique tectonic history of Elba Island allows the direct collection of quantitative fìeld data on several shallow intrusions of similar composition, all emplaced within a short time span in a uniform tectonic setting. Indeed, a shallow-level late Miocene igneous complex has been decapitated with its upper slice translated and tilted by tectonic processes, resulting in serendipitous roof and floor exposures of several intrusive layers that constitute an outstanding example of three Christmas-tree laccoliths nested within each other. The geometric parameters of the laccolith latersare the first reported coherent field data set, and are used to test hypotheses recently outlined for the emplacement of tabular igneous intrusion. New speculatìons are proposed concerning the two-stage growth of shallow-level intrusion, and the relationship between that process and the formation of plutons (generally larger, wider and deeper inrusions than laccoliths). (literal)

Note

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni

(1) Università di Pisa, Dipartimento di Scienze della Terra, Via S. Maria 53,56126, Pisa, Italy (2) Norwich University, Department of Geology, Northfield, Vermont 05663, USA (3) CNR, Istituto Geoscienze e Georisorse-CNR, Via Moruzzi 1,56124, Pisa, Italy (literal)

Titolo

Abstract

At Elba Island (Italy), nine shallow-levei late Miocene granite porphyry layers connected by feeder dikes built up three nested Christmas-tree laccoliths. The intrusive units have been defined and correlated between exposures in western and centrai Elba on the basis of field,petrographic, and geochemical data, along with intrusive relationships. Detailed mapping and reconstuction of tectonic history led to restoration of the originai 5-km-thick sequence and determination of the dimensional parameters of each intrusive layer. Thè laccolith layers were emplaced at depths between 1.9 and 3.7 km, exploiting physical discontinuities that served as crustal magma traps inside a stack of nappes. The intrusive layers are 50-700 m thick, with diameters between 1.6 and 10 km. Length to thickness relationships for individuai laccolith layers show a power-law correlation that does not fìt the known dimensional distribution for laccoliths, but instead fit a line with a slope typical of the theoretical vertical-inflation stage of laccolith development This is interpreted as the first reported natural example of the occurrence of a vertical-inflation stage during laccolith growth. The dimensional data for Elba intrusive layers also suggest that laccoliths and plutons commonly form by amalgamation of smaller sheet-like bodies, while multilayer laccoliths form when coalescence faiis, possibly owing to the large availability of crustal magma traps. (literal)

Editore