Not logged in
PANGAEA.
Data Publisher for Earth & Environmental Science

Lagabrielle, Yves; Karpoff, Anne Marie; Cotten, Joseph (1992): Mineralogical and geochemical analyses of serpentines from ODP Hole 125-778A [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.770538, Supplement to: Lagabrielle, Y et al. (1992): Mineralogical and geochemical analyses of sedimentary serpentinites from conical seamount (Hole 788A): implication for the evolution of serpentine seamounts. In: Fryer, P; Pearce, JA; Stokking, LB; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 125, 325-342, https://doi.org/10.2973/odp.proc.sr.125.175.1992

Always quote citation above when using data! You can download the citation in several formats below.

RIS CitationBibTeX CitationShow MapGoogle Earth

Abstract:
Thirty-five samples from Hole 778A were prepared for X-ray diffraction (XRD) mineralogical analyses and for chemical analyses of major and trace elements. Most of the selected samples were silt- and sand-sized sedimentary serpentinites or microbreccias except for a soft clast of mafic rock, a hard clast of massive serpentinized peridotite, and a pebble of consolidated, undeformed serpentine microbreccia that contained planktonic foraminifers. Both mineralogical and geochemical analyses allow discrimination of three groups among the analyzed samples. These groups correspond to three stratigraphic intervals present along the drilled section.
Group A contains the upper samples (lithologic Unit I). These consist of poorly consolidated serpentine muds carrying hard-rock clasts (serpentinized peridotites, metabasalts). They are characterized by the following mineralogical assemblage: serpentine, Fe-oxides and hydroxides, aragonite, and halite. They exhibit variable SiO2, MgO contents, but are characterized by a SiO2/MgO ratio near 1. CaO content is high in relation to development of aragonite. Al2O3 content is low. Relatively high K2O, Na2O, and Sr contents are present, presumably in relation to interactions with seawater.
Group B (30-77 mbsf) contains samples exhibiting very homogeneous chemical and mineralogical compositions. They consist of serpentinite microbreccias exhibiting frequent shear structures. Hard-rock clasts are also present (serpentinized peridotites, metabasalts, one possible chert fragment). The mineralogy of the Group B samples is characterized by the presence of serpentine and authigenic minerals: hydroxycarbonates and hydrogrossular. Calcite and chlorite are also present, but all the samples lack aragonite. Their chemical compositions are remarkably similar to compositions of their parent rocks.
Group C contains silt- and sand-sized serpentine and serpentine microbreccias, which are locally rich in red clasts, probably strongly altered (oxidized?) mafic fragments. Intervals having clasts of more diverse origin than those higher in the section were recovered. Clast lithology includes serpentinized peridotites, metabasalts, metavolcaniclastite, meta-olivine gabbro, and amphibolite sandstone. Mineralogy and geochemistry reflect these compositions. Serpentine content of the samples is less than in previous groups. Correlatively, sepiolite, palygorskite, and chlorite-smectite are mineral phases present in the analyzed samples. Accessory igneous minerals (amphiboles, pyroxenes, hematite) also were found. The chemical compositions of most of Group C samples differ from that of massive serpentinized peridotites. The main differences are (1) higher SiO2, CaO, TiO2 and Al2O3 contents, (2) a SiO2/MgO ratio greater than 1, and (3) a negative correlation between Al2O3, and MgO, Cr, and Ni. These characteristics suggest new constraints relative to the flow structure of the flank of Conical Seamount.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Latitude: 19.499000 * Longitude: 146.666000
Date/Time Start: 1989-02-22T06:30:00 * Date/Time End: 1989-02-24T19:25:00
Event(s):
125-778A * Latitude: 19.499000 * Longitude: 146.666000 * Date/Time Start: 1989-02-22T06:30:00 * Date/Time End: 1989-02-24T19:25:00 * Elevation: -3924.0 m * Penetration: 107.6 m * Recovery: 22.8 m * Location: North Pacific Ocean * Campaign: Leg125 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 13 cores; 107.6 m cored; 0 m drilled; 21.2 % recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
4 datasets

Download Data

Download ZIP file containing all datasets as tab-delimited text — use the following character encoding:

Datasets listed in this publication series

  1. Lagabrielle, Y; Karpoff, AM; Cotten, J (1992): (Table 2) Chemistry of hydrogarnets of ODP Hole 125-778A. https://doi.org/10.1594/PANGAEA.770533
  2. Lagabrielle, Y; Karpoff, AM; Cotten, J (1992): (Table 1) Mineral composition of ODP Hole 125-778A. https://doi.org/10.1594/PANGAEA.770532
  3. Lagabrielle, Y; Karpoff, AM; Cotten, J (1992): (Table 3) Major-element concentrations in serpentine sediments of ODP Hole 125-778A. https://doi.org/10.1594/PANGAEA.770534
  4. Lagabrielle, Y; Karpoff, AM; Cotten, J (1992): (Table 4) Trace-element concentrations in serpentine sediments of ODP Hole 125-778A. https://doi.org/10.1594/PANGAEA.770537