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Composition of dikes and lavas from the Pito Deep Rift

Authors
Publisher
PANGAEA
Publication Date
Identifiers
DOI: 10.1594/pangaea.782597
Keywords
  • 206Pb/204Pb
  • 207Pb/204Pb
  • 208Pb/204Pb
  • Al2O3
  • Al-4075
  • Al-4076
  • Al-4077
  • Al-4078
  • Al-4079
  • Al-4080
  • Al-4081
  • Al-4082
  • Al-4083
  • Al-4084
  • Al-4085
  • Al-4086
  • Aluminium Oxide
  • Amples That Fall Into The Low Feo* Group Are Indicated By An X
  • Area
  • Area/Locality
  • As Cation Mole %[Mg/[Mg+Fe]] Using The Recalculated Values Of Feo* And Mgo
  • At11-23
  • Atlantis Ii
  • Ba
  • Barium
  • Bathy Depth
  • Be
  • Beryllium
  • Caesium
  • Calcium Oxide
  • Calculated
  • Cao
  • Ce
  • Ce/Yb
  • Cerium
  • Cerium/Ytterbium Ratio
  • Chromium
  • Co
  • Cobalt
  • Comment
  • Copper
  • Cr
  • Cs
  • Cu
  • Depth
  • Bathymetric
  • Direct Current Plasma Emission Spectrometry (Dcp)
  • Dy
  • Dysprosium
  • Elements
  • Total
  • Er
  • Erbium
  • Eu
  • Europium
  • Fe2O3
  • Feo
  • Gadolinium
  • Gd
  • Hafnium
  • Hf
  • Ho
  • Holmium
  • Icp-Ms
  • Inductively Coupled Plasma - Mass Spectrometry
  • Iron Oxide
  • Fe2O3
  • Iron Oxide
  • Feo
  • Is Total Fe Recalculated As Feo
  • Refer To Dataset Doi:10
  • 1594/Pangaea
  • 782595 For The Recalculated Major Element Values
  • J2-119-1
  • J2-119-2
  • J2-119-3
  • J2-119-4
  • J2-121-1
  • J2-121-2
  • J2-122-3
  • J2-123-4
  • J2-123-5
  • Jason Transect
  • K2O
  • La
  • La/Sm
  • Label
  • Lanthanum
  • Lanthanum/Samarium Ratio
  • Lead
  • Lead 206/Lead 204 Ratio
  • Lead 207/Lead 204 Ratio
  • Lead 208/Lead 204 Ratio
  • Lithologic Unit/Sequence
  • Loi
  • Loss On Ignition
  • Lu
  • Lutetium
  • Magnesium Number
  • Magnesium Oxide
  • Manganese Oxide
  • Mass Spectrometer Vg Sector 54
  • Measured By Igniting Each Sample For 30 Minutes At 950°C
  • Mg/(Mg + Fe)
  • Mgo
  • Mno
  • Morphology
  • Na2O
  • Nb
  • Nb/Ta
  • Nd
  • Neodymium
  • Ni
  • Nickel
  • Niobium
  • Niobium/Tantalum Ratio
  • No
  • Normalized To Chondrite Values Of Sun And Mcdonough
  • 1989
  • Number
  • P2O5
  • Pb
  • Phosphorus Oxide
  • Potassium Oxide
  • Pr
  • Praseodymium
  • Rb
  • Remote Operated Vehicle Jason Ii
  • Rubidium
  • Samarium
  • Sample Code/Label
  • Sc
  • Scandium
  • Silicon Dioxide
  • Sio2
  • Sm
  • Sodium Oxide
  • Sr
  • Strontium
  • Submersible Alvin
  • Ta
  • Tantalum
  • Tb
  • Terbium
  • Th
  • Thorium
  • Tio2
  • Titanium Oxide
  • Total
  • Total Fe Calculated As Fe2O3
  • U
  • Unit
  • Uranium
  • V
  • Vanadium
  • Western Pacific
  • Y
  • Y/Nb
  • Yb
  • Ytterbium
  • Yttrium
  • Yttrium/Niobium Ratio
  • Zinc
  • Zirconium
  • Zn
  • Zr
Disciplines
  • Chemistry
  • Earth Science

Abstract

The northwest trending walls of the Pito Deep Rift (PDR), a tectonic window in the southeast Pacific, expose in situ oceanic crust generated ?3 Ma at the superfast spreading southern East Pacific Rise (SEPR). Whole rock analyses were performed on over 200 samples of dikes and lavas recovered from two ~8 km**2 study areas. Most of the PDR samples are incompatible-element-depleted normal mid-ocean ridge basalts (NMORB; (La/Sm)N < 1.0) that show typical tholeiitic fractionation trends. Correlated variations in Pb isotope ratios, rare earth element patterns, and ratios of incompatible elements (e.g., (Ce/Yb)N) are best explained by mixing curves between two enriched and one depleted mantle sources. Pb isotope compositions of most PDR NMORB are offset from SEPR data toward higher values of 207Pb/204Pb, suggesting that an enriched component of the mantle was present in this region in the past ?3 Ma but is not evident today. Overall, the PDR crust is highly variable in composition over long and short spatial scales, demonstrating that chemically distinct lavas and dikes can be emplaced within the same segment over short timescales. However, the limited spatial distribution of high 206Pb/204Pb samples and the occurrence of relatively homogeneous MgO compositions (ranging <2.5 wt %) within a few of the individual dive transects (over distances of ~1 km) suggests that the mantle source composition evolved and magmatic temperatures persisted over timescales of tens of thousands of years. The high degree of chemical variability between pairs of adjacent dikes is interpreted as evidence for along-axis transport of magma from chemically distinct portions of the melt lens. Our findings suggest that lateral dike propagation occurs to a significant degree at superfast spreading centers.

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