关键词: 磁性地层, 沉积间断, 南极底流, 磁铁矿, 东太平洋

Abstract:

The piston core WPC1101 collected from western Clarion-Clipperton fracture  zone, Eastern Pacific, was studied by the methods of rock magnetism, magnetostatigraphy and biogeochronology. The results of rock magnetic measurements, which include isothermal remanent magnetization (IRM), IRM acquisition curves and hysteresis loops showed that most of subsamples contain magnetite as the magnetic minerals and only a few subsamples at the bottom of the core contain minor hematite and/or goethite. Buried polymetallic nodule layer between 340-350 cm was the symbol of a sedimentary gap; Species of diatom fossil Cosinodiscus nodulifer in 60-336 cm indicated the stratum was deposited in the Late Pliocene, but the 2r reversal was missed; Species of Pseudoenuotia doliolus, Spongaster tetras were found in the top 60 cm, meanwhile, the uppermost 1 normal epoch was missed. After comparing with previous studies nearby, we inferred that the sedimentary history from Late Oligocene till now was recorded in the core, and there are three sedimentary gaps within the Late Oligocene and Early Pliocene, Late Pliocene and Early Quaternary and the Late Quaternary. Those sedimentary gaps might be related to the formation and enhancement of the Antarctic bottom water, rising of calcite compensation depth and enhancement of the marine floor erosion.

Key words: magnetostratigraphy, sedimentary gap, Antarctic bottom water, magnetite, Eastern Pacific