Open AccessReconstructing the environmental conditions around the Silurian Ireviken Event using the carbon isotope composition of bulk and palynomorph organic matter
Author(s) -
Vandenbroucke Thijs R. A.,
Munnecke Axel,
Leng Melanie J.,
Bickert Torsten,
Hints Olle,
Gelsthorpe David,
Maier Georg,
Servais Thomas
Publication year - 2013
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2012gc004348
Subject(s) - organic matter , geology , acritarch , total organic carbon , δ13c , trophic level , isotopes of carbon , productivity , oceanography , composition (language) , carbon fibers , foraminifera , benthic zone , plankton , paleontology , environmental chemistry , stable isotope ratio , ecology , chemistry , biology , philosophy , materials science , linguistics , composite number , composite material , quantum mechanics , physics , macroeconomics , economics
The carbon isotope composition (δ 13 C) of bulk organic matter and two palynomorph groups (scolecodonts and chitinozoans) from the Llandovery‐Wenlock strata of Gotland (E Sweden) are compared to gain knowledge about carbon cycling in the Silurian (sub)tropical shelf environment. The δ 13 C values of the palynomorphs are mostly lower than the δ 13 C values of the bulk organic matter, and the δ 13 C values of the benthic scolecodonts are lower than those of the planktonic chitinozoans. While the difference between bulk and palynomorph δ 13 C may be in part a function of trophic state, the lower values of the scolecodonts relative to those of chitinozoans, which are assumed to live in the well‐mixed water column, might imply an infaunal mode of life for the polychaetes that carried the scolecodonts. Lower δ 13 C for the scolecodonts in the middle of the section may represent variations in primary marine productivity (supported by acritarch abundance data), oxidation of organic matter in the bottom waters, or genera effects. In general, however, trends between the three data sets are parallel, indicating similarities in the low frequency, environmentally forced controls. The δ 13 C data show a decreasing trend from the base of the section, up to a horizon well below the base of the Upper Visby Formation. At this level, and therefore probably several 10 kyr before the δ 13 C increase in the carbonates, the δ 13 C organic values increase by ~1‰. This perhaps is an expression of a changed composition of the bulk organic matter associated with the extinction events prior to the Llandovery‐Wenlock boundary.