Primary and tectonic fabric intensities in mudrocks

Author(s): Paterson, Scott R.; Yu, Hao; Oertel, Gerhard
Author Affiliation(s): Primary:
University of Southern California, Department of Earth Sciences, Los Angeles, CA, United States
University of California at Los Angeles, Los Angeles, CA, United States
Volume Title: 30 years of Tectonophysics; a special volume in honour of Gerhard Oertel
Volume Author(s): Engelder, Terry, editor
Source: 30 years of Tectonophysics; a special volume in honour of Gerhard Oertel, edited by Terry Engelder. Tectonophysics, 247(1-4), p.105-119. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0040-1951 CODEN: TCTOAM
Note: In English. 37 refs.; illus., incl. 1 table
Summary: In this paper, we present a summary of quantitative measurements of the preferred orientation of phyllosilicate grains in a variety of tectonically weakly deformed to undeformed, fine-grained, pelitic rocks. We also briefly examine a small amount of data on clay fabrics in deep sea cores, and compare them to fabrics in deformed equivalents from the Mariposa Formation and Calaveras Complex, Sierra Nevada, California. The measured fabric ellipsoids support the following conclusions: (1) a bedding-parallel foliation forms in pelitic rocks during compaction that in our samples is associated with shortening between 3% and 74%; (2) the amount of compaction is in part controlled by the quartz-feldspar content: interbedded sandy layers undergo little to no compaction and do not develop bedding parallel foliations; and (3) it is impossible to determine precisely the amounts of compaction, horizontal shortening, and later tectonic strain in deformed samples because of the variability of initial compactions. Our data, and results presented by others, indicate that strain paths in pelitic rocks always include early compaction, followed by an episode of simultaneous compaction and plane strain in accretionary wedges, and by a variety of other types of strain in other settings.
Year of Publication: 1995
Research Program: ODP Ocean Drilling Program
Key Words: 06 Petrology, Sedimentary; 16 Structural Geology; Canada; Clastic rocks; Compaction; Cores; Deformation; Diagenesis; East Pacific; England; Europe; Fabric; Foliation; Great Britain; Great Valley Sequence; Green River basin; Labrador Trough; Leg 131; Leg 132; Marine sediments; Mesozoic; Mudstone; New York; North Pacific; Northeast Pacific; Northwest Pacific; ODP Site 808; Ocean Drilling Program; Pacific Ocean; Pelitic texture; Petrofabrics; Pigeon Point Formation; Preferred orientation; Sedimentary rocks; Sediments; Sheet silicates; Silicates; Strain; Structural analysis; Textures; United Kingdom; United States; Utah; West Pacific; Western Europe; Yorkshire England
Coordinates: N322105 N322111 E1345646 E1345634
N310326 N322524 E1575045 E1345630
N322105 N322111 E1345646 E1345634
Record ID: 1995066032
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands