Paleoenvironmental and Carbon-Oxygen Isotope Record of Middle Cambrian Carbonates (La Laja Formation) in the Argentine Precordillera

Gómez, Fernando J.; Ogle, Neil; Astini, Ricardo A.; Kalin, Robert M.

doi:10.2110/jsr.2007.079

Cited by 21 publications

(23 citation statements)

References 99 publications

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“…However, frequently it is noted in passing that in addition to the shallowing-upward of the facies in a parasequence, there is an increase in bed thickness leading up to the exposure surface at the top of the cycle. For an example see Figure 21 of a parasequence from the Cambrian of the Argentine Precordillera (Gomez et al, 2007). Now this increasing bed-thickness cannot simply be the result of shallowing and decreasing accommodation.…”

Section: Beds As Cycles In the Sedimentary Recordmentioning

confidence: 99%

Are beds in shelf carbonates millennial-scale cycles? An example from the mid-Carboniferous of northern England…

Tucker

Gallagher

Leng

2009

Sedimentary Geology

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The mid-Carboniferous strata of northern England are characterised by mixed clastic-carbonate cycles (Yoredale cyclothems), attributed here to the short eccentricity Milankovitch rhythm. In a typical cycle, transgressive normal-marine shelf carbonates are succeeded by marine shales, then highstand prodelta mudstones and delta front-delta top sandstones with local coals. A detailed study of one cycle, the Great Limestone Cyclothem of the northern Pennines (Alston Block), reveals that within the transgressive carbonates, the beds, averaging 75 cm in thickness and defined by mm-shale partings or cm-mudrock layers, form two thinning-upward to thickening-upward bed-sets. Individual beds and the bed-sets can be correlated across the region. Oxygen isotope and strontium trace element data also reveal patterns of increasing and decreasing values through the limestone, which broadly correspond to the bed-thickness cycles.The beds are interpreted as millennial-scale cycles, the result of highfrequency, arid-humid climatic fluctuations. The bed-sets are interpreted as the response to a longer term arid-humid climate and sea-level cycle, driven by the precession rhythm.It is postulated that millennial-scale climatic changes, which are a well-known feature of the Quaternary and are here inferred for the Carboniferous, were responsible for the deposition of the beds that are a characteristic feature of many marine sedimentary successions in the geological record. The most likely over-riding control is fluctuations in solar output.

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Section: Beds As Cycles In the Sedimentary Recordmentioning

confidence: 99%

Are beds in shelf carbonates millennial-scale cycles? An example from the mid-Carboniferous of northern England…

Tucker

Gallagher

Leng

2009

Sedimentary Geology

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“…To study the La Laja chemostratigraphic information collected during this and previous studies (see Gomez and Astini, 2006;Gomez et al, 2007;and Gomez, 2008) as well as the biostratigraphic information available from the literature (see Bordonaro, 2003a-b;andFoglia andVaccari, 2010 andFoglia, 2011 and references therein).…”

Section: Methodsmentioning

confidence: 99%

“…In Figure 3, the C-isotope curve for La Laja Fm., with three positive isotopic excursions and used by Gomez et al, (2007) and Gomez (2008) for regional and global correlation is shown.…”

Section: Methodsmentioning

confidence: 99%

“…The chemostratigraphic curve carried out by Gomez et al, (2007) has been more precisely adjusted according to new trilobite biostratigraphy findings (see for example Bordonaro et al, 2008;Foglia and Vaccari, 2010;Foglia, 2011) (Fig. 3).…”

mentioning

confidence: 99%

“…For correlation purposes, the stable isotope study only focused on the sequence boundary between the Soldano and Rivadavia Members, within the La Laja Formation (Gomez et al, 2007;Gomez, 2008). This interval coincides with a positive isotope excursion known as obvious secondary fabrics (like fractures, bioturbations, replacements, recrystallized zones) were avoided (see Gomez et al, 2007 for more details).…”

mentioning

confidence: 99%

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Sedimentology and sequence stratigraphy from a mixed (carbonate–siliciclastic) rift to passive margin transition: The Early to Middle Cambrian of the Argentine Precordillera

Gómez

Astini

2015

Sedimentary Geology

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Systematic, morphometric and palaeobiogeographic study of Blainia gregaria Walcott, 1916 (Trilobita, Ptychopariida), Middle Cambrian of the Precordillera of western Argentina

2012

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The ptychoparioid trilobite Blainia gregaria Walcott, 1916 is described for the first time from the late middle Cambrian (Series 3) of the Argentine Precordillera. It occurs commonly in the upper part of La Laja Formation, a carbonate platform succession that crops out in the Precordillera Oriental of San Juan where it reaches a thickness of some 600 m. Sections were sampled on cerro Tres Marías in Sierra de Marquesado and in quebrada de Zonda at the northern termination of Sierra Chica de Zonda. More than 1200 specimens were recovered from 22 stratigraphic levels over a thickness of 155 m, located in the uppermost 15 m of the Soldano Member, the approximately 100 m thick Rivadavia Member, and in the lower 40 m of the Juan Pobre Member. Our biometric study dealt with 205 cranidia and 365 pygidia from cerro Tres Marías. Measured dimensions of a subset of this collection provide bivariate datasets that in some characters show broad scatter plots and relatively low linear correlation coefficients, indicative of rather wide intraspecific morphological variation. Six morphotypes (three cranidial and three pygidial), recognized mainly on the basis of shape, occur together in the same collections. This evidence for an unusually high degree of variability leads to a proposed synonymy of some 30 previously named species in North America belonging to two genera, Blainia Walcott, 1916 and Glyphaspis Poulsen, 1927, the latter considered a junior synonym. The biogeographic distribution of B. gregaria, as redefined here, shows that it was an endemic Laurentian species that inhabited the inner parts of the carbonate platform that rimmed the craton and mantled portions of its interior. Its presence in western Argentina is further evidence for the very close faunal relationship between the Precordilleran terrane, known as Cuyania, and Laurentia during the Cambrian.

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Paleoenvironmental and Carbon-Oxygen Isotope Record of Middle Cambrian Carbonates (La Laja Formation) in the Argentine Precordillera

Cited by 21 publications

References 99 publications

Are beds in shelf carbonates millennial-scale cycles? An example from the mid-Carboniferous of northern England…

Are beds in shelf carbonates millennial-scale cycles? An example from the mid-Carboniferous of northern England…

Sedimentology and sequence stratigraphy from a mixed (carbonate–siliciclastic) rift to passive margin transition: The Early to Middle Cambrian of the Argentine Precordillera

Systematic, morphometric and palaeobiogeographic study of Blainia gregaria Walcott, 1916 (Trilobita, Ptychopariida), Middle Cambrian of the Precordillera of western Argentina

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