X-ray fluorescence analysis for the determination of potassium in small quantities of silicate minerals for K–Ar dating

Solé, Jesús; Enrique, P.

doi:10.1016/s0003-2670(01)01060-1

Cited by 28 publications

(10 citation statements)

References 8 publications

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“…We selected the size fraction of 2-0.5 mm for isotopic analysis of the white mica concentrates in order to avoid possible contaminations with the sparse detrital mica that is present in grain sizes >2 mm in the Sierra de los Cuarzos stratigraphic succession. The K-Ar methodology used is a modification of the classical technique, specifically designed to date small amounts of sample (50-100 mg), and was described in Solé and Enrique (2001) and Solé (2009). For potassium analysis we use X-ray fluorescence with high-dilution fused pearls to minimize both the amount of sample (50-100 mg) and the matrix effects (Solé and Enrique, 2001).…”

Section: Methodsmentioning

confidence: 99%

“…The K-Ar methodology used is a modification of the classical technique, specifically designed to date small amounts of sample (50-100 mg), and was described in Solé and Enrique (2001) and Solé (2009). For potassium analysis we use X-ray fluorescence with high-dilution fused pearls to minimize both the amount of sample (50-100 mg) and the matrix effects (Solé and Enrique, 2001). For argon quantification, we used a CO 2 laser system for sample fusion, followed by gas cleaning and measurement in a MM1200B noble gas mass spectrometer (Instituto de Geologia, UNAM).…”

Section: Methodsmentioning

confidence: 99%

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Evidence for two Cretaceous superposed orogenic belts in central Mexico based on paleontologic and K-Ar geochronologic data from the Sierra de los Cuarzos

et al. 2016

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The continental interior of Mexico is characterized by a Late Cretaceous-Eocene fold-thrust belt named the Mexican Fold-Thrust Belt, which shows characteristics of an eastward-tapering orogenic wedge. The juxtaposition of the Guerrero terrane to the west of the Mexican Fold-Thrust Belt has motivated many to propose the accretion of this terrane as the cause for the regional shortening in the Mexican continental interior. The Sierra de los Cuarzos is located in the westernmost Mexican Fold-Thrust Belt, directly to the east of the boundary with the Guerrero terrane. Based on its position, the Sierra de los Cuarzos is key in reconstructing the possible propagation of shortening deformation from the Guerrero terrane suture belt into the Mexican continental interior. Our new paleontologic and K-Ar geochronologic data from the Sierra de los Cuarzos show that shortening in the westernmost Mexican Fold-Thrust Belt started ca. 83 Ma, which is ~30 m.y. later than the late Aptian age of the Guerrero terrane suture boundary. Therefore, the integration of our new paleontologic and geochronologic determinations with previous data suggests that the Guerrero terrane was already accreted and amalgamated with the Mexican continental interior at the time of the formation of the Mexican Fold-Thrust Belt. In light of this, the shortening structures in the western Mexican Fold-Thrust Belt do not show any in-sequence relationship with the adjacent Guerrero terrane suture belt. Therefore, we favor the idea that the Guerrero terrane suture boundary and the Mexican Fold-Thrust Belt are two distinct orogens that mark two distinct stages of tectonic evolution of the North American Pacific margin.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Evidence for two Cretaceous superposed orogenic belts in central Mexico based on paleontologic and K-Ar geochronologic data from the Sierra de los Cuarzos

et al. 2016

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“…For sample Despeñaderos 1-2, the most altered one, we separated also the magnetic fraction for analysis. K was obtained following the method of Solé and Enrique (2001). Briefly, 100 mg of sample were fused with 50% lithium metaborate +50% lithium tetraborate.…”

Section: Rudiments Of Sierra Chica De Córdoba Geology Sampling and Amentioning

confidence: 99%

Early cretaceous absolute geomagnetic paleointensities from Córdoba Province (Argentina)

et al. 2006

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We present here new paleointensity and geochronology results from Early Cretaceous volcanic rocks of Sierra Chica de Cordoba (Argentina). The new K-Ar isotopic ages of 5 samples range from 136 to 122 Ma. Twenty five samples from 7 individual flows yielded acceptable paleointensity estimates. The mean paleointensity values per flow are ranging from 53.0 ± 1.9 to 25.4 ± 2.6 μT and the corresponding Virtual Dipole Moments (VDMs) are ranging from 9.3±1.3 to 4.6±0.5 (10 22 Am 2 ). This corresponds to the mean value of 7.3±1.7×10 22 Am 2 , which is compatible to the present geomagnetic axial dipole. Currently available selected paleointensity data from 80 to 130 Ma suggest that geomagnetic field strength frequently fluctuated before and during the Cretaceous Normal Superchron while the magnetic polarity maintained stable. The mean paleointensities derived from Córdoba lavas agree remarkably well with those obtained from the Paraná Magmatic Province (133-132 Ma). This reinforces the hypothesis about the unreliability of 'Mesozoic Dipole Low'.

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“…Analytical precision on argon measurements was better than 0.5%. Potassium was determined by X‐ray fluorescence analysis following the method described by Solé and Enrique [2001] and a 1% relative error is assumed. The age was calibrated with the international standards LP‐6 and HD‐B1 biotites.…”

Section: Sampling Details and Age Determinationmentioning

confidence: 99%

Absolute geomagnetic paleointensity after the Cretaceous Normal Superchron and just prior to the Cretaceous‐Tertiary transition

et al. 2004

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[1] We report a detailed rock magnetic and Thellier paleointensity study from Autlan volcanic succession in western Mexico. The whole rock K-Ar age obtained for these lavas, 67.4 ± 1.2 Ma, together with the magnetostratigraphy results indicates that the lava flows were erupted during chron 30n just prior to Cretaceous-Tertiary transition. Thirty-nine samples from eight cooling units were preselected for paleointensity experiments on the basis of their low-viscosity index, stable remanent magnetization, and close to reversible continuous thermomagnetic curves. High-quality determinations were obtained for 18 individual samples from four independent lava flows. The mean virtual dipole moment (VDM) obtained in this study is 4.9 ± 0.6 Â 10 22 A m 2 , which is significantly lower than the present geomagnetic field strength but in reasonably good accord with other comparable quality determinations between 35 and 80 Ma. Our data are not significantly different from almost all published paleointensities between 5 and 90 Ma. Moreover, rigorously selected worldwide paleointensity data in the same interval better fit trend 2 of Heller et al. [2002]. A careful examination of high-quality paleointensity data from Cretaceous indicates that there is no simple relation between magnitude of Earth's magnetic field and reversal rate.

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X-ray fluorescence analysis for the determination of potassium in small quantities of silicate minerals for K–Ar dating

Cited by 28 publications

References 8 publications

Evidence for two Cretaceous superposed orogenic belts in central Mexico based on paleontologic and K-Ar geochronologic data from the Sierra de los Cuarzos

Evidence for two Cretaceous superposed orogenic belts in central Mexico based on paleontologic and K-Ar geochronologic data from the Sierra de los Cuarzos

Early cretaceous absolute geomagnetic paleointensities from Córdoba Province (Argentina)

Absolute geomagnetic paleointensity after the Cretaceous Normal Superchron and just prior to the Cretaceous‐Tertiary transition

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