TY - JOUR
T1 - Shallow stratification prevailed for ~1700 to ~1300 Ma ocean
T2 - Evidence from organic carbon isotopes in the North China Craton
AU - Luo, Genming
AU - Junium, Christopher K.
AU - Kump, Lee
AU - Huang, Junhua
AU - Li, Chao
AU - Feng, Qinglai
AU - Shi, Xiaoying
AU - Bai, Xiao
AU - Xie, Shucheng
PY - 2014/8/15
Y1 - 2014/8/15
N2 - The Late Paleoproterozoic to Early Mesoproterozoic (from ~1700 Ma to ~1300 Ma) was highlighted by the assembly of the Nuna supercontinent, expansion of euxinic marine environments and apparent stasis in the diversity of eukaryotes. The isotopic composition of carbonate carbon (δ13Ccarb) was surprisingly constant during this interval, but little is known about the secular variation in the organic carbon isotopic composition (δ13Corg). Here we report δ13Corg data from the latest Paleoproterozoic (>1650 Ma) to Early Mesoproterozoic (~1300 Ma) succession in North China. The δ13Corg values range from -25‰ to -34‰, and are dependent on sedimentary facies. In subtidal and deeper environments δ13Corg values are low and constant, ca. -32‰, but relatively enriched and more variable in shallower intertidal and supratidal environments. We attribute the facies-dependent variation in δ13Corg to the presence of a shallow chemocline. A probable result of a shallow chemocline is that it supported significant contributions of organic matter produced by chemoautotrophic and/or anaerobic photoautotrophic microbes in relatively deep environments from the latest Paleoproterozoic to Early Mesoproterozoic continental shelf of North China.
AB - The Late Paleoproterozoic to Early Mesoproterozoic (from ~1700 Ma to ~1300 Ma) was highlighted by the assembly of the Nuna supercontinent, expansion of euxinic marine environments and apparent stasis in the diversity of eukaryotes. The isotopic composition of carbonate carbon (δ13Ccarb) was surprisingly constant during this interval, but little is known about the secular variation in the organic carbon isotopic composition (δ13Corg). Here we report δ13Corg data from the latest Paleoproterozoic (>1650 Ma) to Early Mesoproterozoic (~1300 Ma) succession in North China. The δ13Corg values range from -25‰ to -34‰, and are dependent on sedimentary facies. In subtidal and deeper environments δ13Corg values are low and constant, ca. -32‰, but relatively enriched and more variable in shallower intertidal and supratidal environments. We attribute the facies-dependent variation in δ13Corg to the presence of a shallow chemocline. A probable result of a shallow chemocline is that it supported significant contributions of organic matter produced by chemoautotrophic and/or anaerobic photoautotrophic microbes in relatively deep environments from the latest Paleoproterozoic to Early Mesoproterozoic continental shelf of North China.
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U2 - 10.1016/j.epsl.2014.05.020
DO - 10.1016/j.epsl.2014.05.020
M3 - Article
AN - SCOPUS:84902154969
VL - 400
SP - 219
EP - 232
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
SN - 0012-821X
ER -