Rock Magnetism of Basement Rocks, Deep Sea Drilling Project Site 417

Smith, B.M.; Bleil, Ulrich

doi:10.2973/dsdp.proc.515253.159.1980

Cited by 2 publications

(2 citation statements)

References 17 publications

(28 reference statements)

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“…A few generalizations can be gleaned from the available data. The more viscous samples are associated with the coarse-grained massive flows, whose median destructive fields (MDF) are <100 Oe [Lowrie, 1973;Lowrie and Kent, 1978; Smith and Bleil, 1980]. In many instances the coarse-grained basalts are completely dominated by a viscous component acquired over the Brunhes epoch [Ryall et al, 1977;Johnson, 1979;Levi, 1980].…”

mentioning

confidence: 99%

A comparison of the magnetic properties of synthetic titanomaghemites and some oceanic basalts

Moskowitz¹,

Banerjee²

1981

J. Geophys. Res.

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The variation of some magnetic properties of (1) synthetic titanomaghemites and (2) oceanic basalts from DSDP site 417 D as a function of grain size and oxidation is presented. The synthesis of the initial titanomagnetite (x = 0.6) was carried out, using controlled fugacity and self-buffering techniques. Singlephase titanomaghemites were produced by heating the titanomagnetite in air at low temperatures (<350øC). The magnetic properties studied on the synthetic titanomagnetite (grain size --, 1/•m) show the following variations with increasing degrees of oxidation (0 _< z <_ 0.6): (1) Curie temperature (Tc) increases, (2) saturation magnetization (Js) at room temperature increases, (3) J, measured at 77øK decreases for z •< 0.3 and then increases for 0.3 < z • 0.6, (4) bulk and reinanent coercivities (He and Hr) increase slightly initially (z < 0.2) and then decrease at both room temperature and 77•'K, (5) susceptibility (Xo) decreases for z • 0.3 and then increases, (6) the magnetic viscosity acquisition and decay coefficients (Sa and Sa) increase and (7) the median destructive fields for an anhystretic reinanent magnetization and a viscous reinanent magnetization increase for z •< 0.3 and then decrease. These magnetic data also suggest that the synthetic titanomaghemites are pseudo-single domained (PSD) and with increasing degrees of oxidation these PSD grains become more SD-like. The basalt samples from site 417D are divided into fine-grained pillow basalts and coarse-grained massive flows. Most of the magnetic properties measured are distinctly different between these two groups. The magnetic data indicate that the domain states of these basalts are probably PSD. Although it is difficult to separate the effects of grain size and oxidation on the magnetic properties of these basalts, it appears that grain size effects predominate. A preliminary investigation of the magnetic viscosity of the synthetic and oceanic titanomaghemites suggests that a combination of thermally activated and diffusive magnetic viscosity is responsible for their viscous behavior. Finally, we will discuss the roles of grain size and oxidation variation in oceanic basalts and their separate and combined effects on their magnetic behavior. vasiveness of low-temperature oxidation and its effect on their magnetic properties [Marshall and Cox, 1972; Johnson and Hall, 1978; Marshall, 1978]. A degradation of the magnetic signature of the oceanic crust with distance from the ridge seems to be associated with this low-temperature (lt) oxidation. Stoichiometric titanomagnetite (Fe3_xTixO4) with a restricted range of composition around x --0.6 -0.65 is ubiquitous in almost all young (<1 m.y.) submarine basalts [Johnson and Hall, 1978; Marshall, 1978; Pr•vot et al., 1979]. Subsequent to formation, the titanomagnetite is subjected to various degrees of It oxidation, producing single-phase titanomaghemite [Marshall and Cox, 1972; Ozima et aL, 1974; Marshall, 1978; Pr•vot et al., 1979]. Many studies indicate that oxidation of submarine basalt occurs re...

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confidence: 99%

A comparison of the magnetic properties of synthetic titanomaghemites and some oceanic basalts

Moskowitz¹,

Banerjee²

1981

J. Geophys. Res.

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“…Bleil and Smith (1980a) and Smith and Bleil (1980) discuss paleomagnetic and rock magnetic properties, respectively, of Holes 417A and 417D. and investigated paleomagnetism and rock magnetics of samples from 417D and 418A.…”

Section: Paleomagnetism and Rock Magnetismmentioning

confidence: 99%

Site synthesis report of DSPP sites 417 and 418

Swift¹,

Bolmer²,

Stephen³

1989

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Rock Magnetism of Basement Rocks, Deep Sea Drilling Project Site 417

Cited by 2 publications

References 17 publications

A comparison of the magnetic properties of synthetic titanomaghemites and some oceanic basalts

A comparison of the magnetic properties of synthetic titanomaghemites and some oceanic basalts

Site synthesis report of DSPP sites 417 and 418

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