Selective destructive demagnetization of breccias from DSDP Leg 83; a microconglomerate test

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doi: 10.1016/0012-821X(86)90070-1
Author(s): Smith, Guy M.
Author Affiliation(s): Primary:
Univ. Minn., Dep. Geol. and Geophys., Minneapolis, MN, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 78(2-3), p.315-321. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 10 refs.; illus. incl. 2 tables
Summary: The magnetization of four breccia samples from the Leg 83 section of DSDP Hole 504B was analysed by selective destructive demagnetization in order to study the origin and stability of hydrothermally altered basalts. The n.r.m. directions of the clasts for three of the four samples are randomly oriented and much more strongly magnetized than the bulk sample. Clasts which were individually demagnetized show two or more components of magnetization, but none are coincident with those of the bulk sample, indicating that n.r.m. was probably acquired prior to the consolidation of the breccia and suggesting that any oveprint can be removed by AF (alternating field) demagnetization to at most 50 Oe. Reflected light microscopy and probe analysis of two samples show that the unexpectedly high n.r.m. of the matrix regions is apparently the result of secondary magnetic phases precipitated from hydrothermal solutions. The bulk magnetic properties of the four breccia samples, and the n.r.m. directions of the various pieces (29 results) after demagnetization, are presented.
Year of Publication: 1986
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; Basalts; Breccia; Clastic rocks; DSDP Site 504; Deep Sea Drilling Project; Demagnetization; Equatorial Pacific; Hydrothermal alteration; IPOD; Igneous rocks; Leg 111; Leg 137; Leg 140; Leg 148; Leg 69; Leg 70; Leg 83; Leg 92; Magnetization; Metasomatism; Natural remanent magnetization; Ocean Drilling Program; Pacific Ocean; Paleomagnetism; Remanent magnetization; Sedimentary rocks; Selective destructive demagnetization; Tectonophysics; Volcanic rocks
Coordinates: N011335 N011338 W0834348 W0834357
N011203 N011400 W0834000 W0834500
N011338 N011338 W0834349 W0834349
N011338 N011338 W0834349 W0834349
N011300 N011340 W0834320 W0834400
N011000 N020000 W0834000 W0835000
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N011337 N011338 W0834348 W0834349
S192706 N011400 W0834349 W1294614
Record ID: 1986073401
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom