English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Methane carbon-isotopic compositions (δ C values relative to the PDB standard) at Sites 565, 566, 567, and 569 were lighter (enriched in 1 C) than -60‰, indicating a biogenic origin. In the deeper sections at Sites 568 and 570, δ C values were heavier, approaching 40‰, and therefore suggest a thermogenic source. A significant thermogenic source was discounted, however, because the carbon dioxide δ C values in these sections were also anomalously heavy, suggesting that the methane may have formed biogenically by reduction of the heavy carbon dioxide. δ 1 C values of ethane and higher hydrocarbons were measured in several sections from Sites 566 and 570 that contained sufficient C 2 -C 4 hydrocarbon concentrations. Ethane values in six sections (245-395 m sub-bottom) from Site 570 were fairly uniform, ranging from 24 to 26%o. These values are among the heaviest ethane values reported for natural gases. The isobutane/n-butane and isopentane/«-pentane ratios of the core gases suggested that the C 2 -C 5 hydrocarbons are thermally produced by low-temperature chemical diagenesis of indigenous organic matter. This process apparently generates isotopically heavy C 2 -C 5 hydrocarbons. High gas concentrations in the serpentinite basement rocks at Sites 566 and 570 appear to have resulted from migrated biogenic methane gas containing small amounts of immature C 2-C 5 hydrocarbons.

Isotopic Analysis of Core Gases at Sites 565-570, Deep Sea Drilling Project Leg 84