thumbnail

Formation of tectonic peperites from alkaline magmas intruded into wet sediments in the Beiya area, western Yunnan, China

Journal of Structural Geology

By:
, , , ,
DOI: 10.1016/j.jsg.2007.04.007

Links

Abstract

Tertiary (3.78 Ma to 3.65 Ma) biotite-K-feldspar porphyritic bodies intrude Tertiary, poorly consolidated lacustrine sedimentary rocks in the Beiya mineral district in southwestern China. The intrusives are characterized by a microcrystalline and vitreous-cryptocrystalline groundmass, by replacement of some tabular K-feldspar phenocrysts with microcrystalline chlorite and calcite, and by Fe-rich rings surrounding biotite phenocrysts. Peculiar structures, such as contemporary contact faults and slickensides, ductile shear zones and flow folds, foliation and lineations, tension fractures, and banded and boudin peperites, are developed along the contact zones of the intrusives. These features are related to the forceful intrusion of the alkaline magmas into the wet Tertiary sediments. The partially consolidated magmas were deformed and flattened by continued forceful magma intrusion that produced boudinaged and banded peperites. These peperites characterized by containing oriented deformation fabrics are classified as tectonic peperites as a new type of peperite, and formation of these tectonic peperites was related to fracturing of magmas caused by forceful intrusion and shear deformation and to contemporary migration and injection of fluidized sediments along fractures that dismembered the porphyritic magma. Emplacement of the magma into the wet sediments in the Beiya area is interpreted to be related to a large pressure difference rather than to the buoyancy force. ?? 2007 Elsevier Ltd. All rights reserved.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Formation of tectonic peperites from alkaline magmas intruded into wet sediments in the Beiya area, western Yunnan, China
Series title:
Journal of Structural Geology
DOI:
10.1016/j.jsg.2007.04.007
Volume
29
Issue:
8
Year Published:
2007
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1400
Last page:
1413
Number of Pages:
14