Publications by authors named "Fernando J Gomez"

3 Publications

  • Page 1 of 1

Mineralized microbialites as archives of environmental evolution, Laguna Negra, Catamarca Province, Argentina.

Geobiology 2019 03 13;17(2):199-222. Epub 2018 Dec 13.

Department of Earth & Planetary Sciences, The University of Tennessee, Knoxville, Tennessee.

Environmental fluctuations are recorded in a variety of sedimentary archives of lacustrine depositional systems. Geochemical signals recovered from bottom sediments in closed-basin lakes are among the most sensitive paleoenvironmental indicators and are commonly used in reconstructing lake evolution. Microbialites (i.e., organosedimentary deposits accreted through microbial trapping and binding of detrital sediment or in situ mineral precipitation on organics [Palaios, 2, 1987, 241]), however, have been largely overlooked as paleoenvironmental repositories. Here, we investigate concentrically laminated mineralized microbialites from Laguna Negra, a high-altitude (4,100 m above sea level) hypersaline, closed-basin lake in northwestern Argentina, and explore the potential for recovery of environmental signals from these unique sedimentary archives. Spatial heterogeneity in hydrological regime helps define zones inside Laguna Negra, each with their own morphologically distinct microbialite type. Most notably, platey microbialites (in Zone 3A) are precipitated by evaporative concentration processes, while discoidal oncolites (in Zone 3C) are interpreted result from fluid mixing and biologically mediated nucleation. This spatial heterogeneity is reflected in petrographically distinct carbonate fabrics: micritic, botryoidal, and isopachous. Fabric type is interpreted to reflect a combination of physical and biological influences during mineralization, and paired C-isotope measurement of carbonate and organic matter supports ecological differences as a dominant control on C-isotopic evolution between zones. Laminae of Laguna Negra microbialites preserve a range of δ C from +5.75‰ to +18.25‰ and δ O from -2.04‰ to +9.28‰. Temporal trends of lower carbon and oxygen isotopic compositions suggest that the influence of CO degassing associated with evaporation has decreased over time. Combined, these results indicate that microbialite archives can provide data that aid in interpretation of both lake paleohydrology and paleoenvironmental change.
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http://dx.doi.org/10.1111/gbi.12327DOI Listing
March 2019

Ring opening metathesis polymerization on non-covalently functionalized single-walled carbon nanotubes.

Chem Commun (Camb) 2003 Jan(2):190-1

Department of Chemistry, Stanford University, Stanford, California, USA.

Norbornene polymerization has been initiated selectively on the surface of single-walled carbon nanotubes (SWNTs) via a specifically adsorbed pyrene-linked ROMP initiator, resulting in a homogeneous non-covalent poly(norbornene) coating.
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http://dx.doi.org/10.1039/b211194bDOI Listing
January 2003

Polymer synthesis. Catalysts rise to the challenge.

Science 2002 Jan;295(5555):635-6

Department of Chemistry, Stanford University, Stanford, CA 94305, USA.

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http://dx.doi.org/10.1126/science.1067919DOI Listing
January 2002
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