Deep melting and sodic metasomatism underneath the highly oblique-spreading Lena Trough (Arctic Ocean)

Computer Science

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

17

Abyssal Peridotite, Partial Melting, Melt-Rock Reaction, Metasomatism, Secondary Ion Mass Spectrometry

Scientific paper

Abyssal peridotites collected along the highly oblique-spreading Lena Trough north of Greenland and Spitsbergen have mineral compositions that are similar to residual abyssal peridotites, except for high sodium concentrations in clinopyroxene (cpx). Most samples are lherzolites with light rare earth element (REE)-depleted cpx trace element patterns, but significantly fractionated middle to heavy REE ratios at relatively high heavy REE concentrations. Such characteristics can only be explained by initial melting of a garnet peridotite followed by low degrees of melting in the stability field of spinel peridotite. The residual garnet signature requires either a high potential temperature of the upwelling mantle, or elevated solidus-lowering water contents. The limited spinel field melting suggests a deep cessation of melt extraction, possibly because of the presence of a thick lithospheric cap. This is consistent with the extremely low effective spreading rate and the vicinity to a passive continental margin, which allow conductive cooling to reach deeper levels than commonly estimated for faster mid-ocean ridges. High sodium concentrations in cpx are neither explainable by melt refertilization, nor by a simple diffusion mechanism. The efficient fractionation of sodium from the light REE requires post-melting metasomatism, which is typically restricted to the subcontinental lithosphere. This might imply that the Lena Trough peridotites represent unroofed subcontinental mantle, from which no melt was extracted during the opening of the Lena Trough. It is more likely that sodic metasomatism occurred after partial melting underneath the Lena Trough, and that such an enrichment process is responsible for elevated sodium concentrations in abyssal peridotites elsewhere. Sodium in cpx of residual peridotites can therefore not serve as an indicator of partial melting or melt refertilization.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

Deep melting and sodic metasomatism underneath the highly oblique-spreading Lena Trough (Arctic Ocean) does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Deep melting and sodic metasomatism underneath the highly oblique-spreading Lena Trough (Arctic Ocean), we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Deep melting and sodic metasomatism underneath the highly oblique-spreading Lena Trough (Arctic Ocean) will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-1087962

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.