Abstract
The late Guadalupian Lamar Limestone Member of the Bell Canyon Formation, Delaware Basin, west Texas, records dramatic fluctuations in radiolarian faunal composition that are interpreted to record basin-scale changes in hydrography. Samples taken across one of these intervals of fluctuation show a change from a sparse, nearly monospecific fauna dominated by Follicucullus ventricosus to a more radiolarian-rich interval dominated by spongy spumellarians of the Copicyntrinae and Spongodiscidae. Carbonate stable isotope and organic biomarker geochemical data from this same interval support a strong terrestrial- freshwater influence on the spumellarian-dominated beds. Specifically, biomarker data show lower C 22/C 27 ratios and n-alkane distributions indicative of terrestrial organic matter sources in the spumellarian-dominated beds. In the whole-rock carbonate fraction, δ 18O and δ 13C show a shift to more negative values, consistent with increased meteoric water influence in the spumellarian-dominated interval. Lithologically, the spumellarian-dominated beds are siltier; however, they lack any increase in shallow water allochems, such as sponge spicules, that might indicate the spumellarians and associated terrestrial signature are a function of transporting a shallower radiolarian fauna into the basin via turbidity flows. Faunal changes more likely represent a stimulatory response to increased runoff by in situ spumellarians in the surface waters of the basin.
| Original language | English |
|---|---|
| Pages (from-to) | 180-186 |
| Number of pages | 7 |
| Journal | Palaios |
| Volume | 26 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Mar 1 2011 |
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All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics
- Palaeontology
Cite this
Paleohydrographic influences on permian radiolarians in the Lamar Limestone, Guadalupe Mountains, west Texas, elucidated by organic biomarker and stable isotope geochemistry. / Noble, Paula J.; Naraoka, Hiroshi; Poulson, Simon R.; Fukui, Eri; Jin, Yuxi; O'Connor, Sarah.
In: Palaios, Vol. 26, No. 3, 01.03.2011, p. 180-186.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Paleohydrographic influences on permian radiolarians in the Lamar Limestone, Guadalupe Mountains, west Texas, elucidated by organic biomarker and stable isotope geochemistry
AU - Noble, Paula J.
AU - Naraoka, Hiroshi
AU - Poulson, Simon R.
AU - Fukui, Eri
AU - Jin, Yuxi
AU - O'Connor, Sarah
PY - 2011/3/1
Y1 - 2011/3/1
N2 - The late Guadalupian Lamar Limestone Member of the Bell Canyon Formation, Delaware Basin, west Texas, records dramatic fluctuations in radiolarian faunal composition that are interpreted to record basin-scale changes in hydrography. Samples taken across one of these intervals of fluctuation show a change from a sparse, nearly monospecific fauna dominated by Follicucullus ventricosus to a more radiolarian-rich interval dominated by spongy spumellarians of the Copicyntrinae and Spongodiscidae. Carbonate stable isotope and organic biomarker geochemical data from this same interval support a strong terrestrial- freshwater influence on the spumellarian-dominated beds. Specifically, biomarker data show lower C 22/C 27 ratios and n-alkane distributions indicative of terrestrial organic matter sources in the spumellarian-dominated beds. In the whole-rock carbonate fraction, δ 18O and δ 13C show a shift to more negative values, consistent with increased meteoric water influence in the spumellarian-dominated interval. Lithologically, the spumellarian-dominated beds are siltier; however, they lack any increase in shallow water allochems, such as sponge spicules, that might indicate the spumellarians and associated terrestrial signature are a function of transporting a shallower radiolarian fauna into the basin via turbidity flows. Faunal changes more likely represent a stimulatory response to increased runoff by in situ spumellarians in the surface waters of the basin.
AB - The late Guadalupian Lamar Limestone Member of the Bell Canyon Formation, Delaware Basin, west Texas, records dramatic fluctuations in radiolarian faunal composition that are interpreted to record basin-scale changes in hydrography. Samples taken across one of these intervals of fluctuation show a change from a sparse, nearly monospecific fauna dominated by Follicucullus ventricosus to a more radiolarian-rich interval dominated by spongy spumellarians of the Copicyntrinae and Spongodiscidae. Carbonate stable isotope and organic biomarker geochemical data from this same interval support a strong terrestrial- freshwater influence on the spumellarian-dominated beds. Specifically, biomarker data show lower C 22/C 27 ratios and n-alkane distributions indicative of terrestrial organic matter sources in the spumellarian-dominated beds. In the whole-rock carbonate fraction, δ 18O and δ 13C show a shift to more negative values, consistent with increased meteoric water influence in the spumellarian-dominated interval. Lithologically, the spumellarian-dominated beds are siltier; however, they lack any increase in shallow water allochems, such as sponge spicules, that might indicate the spumellarians and associated terrestrial signature are a function of transporting a shallower radiolarian fauna into the basin via turbidity flows. Faunal changes more likely represent a stimulatory response to increased runoff by in situ spumellarians in the surface waters of the basin.
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UR - http://www.scopus.com/inward/citedby.url?scp=82055202111&partnerID=8YFLogxK
U2 - 10.2110/palo.2010.p10-059r
DO - 10.2110/palo.2010.p10-059r
M3 - Article
AN - SCOPUS:82055202111
VL - 26
SP - 180
EP - 186
JO - Palaios
JF - Palaios
SN - 0883-1351
IS - 3
ER -