2024-03-29T06:10:03Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1460702020-07-03T12:19:45Zcom_10261_82com_10261_8com_10261_76com_10261_5col_10261_335col_10261_329
00925njm 22002777a 4500
dc
de las Heras, Francesc Xavier C.
author
Grimalt, Joan O.
author
Albaigés Riera, Joan
author
Julià Brugués, Ramón
author
Anadón, Pere
author
1989
A suite of samples from the lacustrine facies of the Cerdanya Basin (Miocene) containing early diagenetic phosphatized sediments in several horizons has been examined for phosphate mineralogy and organic content. The phosphates consisted of anapaite and farifeldite occurring as veins, spaherulite beds and septarian-like nodules. The hydrocarbon and fatty acid distributions of the samples studied show that terrestrial inputs were generally predominant throughout the sedimentary record. Furthermore, the good correlation of higher molecular weight n-alkanes and n-alkanoic acids with total organic carbon (TOC) suggests that the productivity of the lake was determined to a large extent by the amounts of detrital organic matter entering into the system. Thus, the phosphate accumulations studied here are different from those of marine origin usually described in the literature. However, several common characteristics are found when comparing these terrestrial phosphate deposits with those of marine origin, namely an intermediate TOC content (0.5-1.3%) and important microbial inputs, suggesting that phosphatogenesis occurred at rather mild oxidizing/reducing conditions and was mediated by intense microbial degradation. Furthermore, the results presented here extend previous observations from marine phosphate basin studies in the sense that phosphate generation seems to be a phenomenon much more dependent on the environmental conditions of deposition and early diagenetic processes rather than on a specific type of sediment or organic matter source. © 1989.
Organic Geochemistry 14: 667- 677 (1989)
http://hdl.handle.net/10261/146070
10.1016/0146-6380(89)90046-6
fatty acids
hopanes
n-alkanes
phosphatogenesis
lacustrine phosporites
Origin and diagenesis of the organic matter in Miocene freshwater lacustrine phosphates (Cerdanya Basin, Eastern Pyrenees)