Illite polytype quantification for accurate K-Ar age determination

Ylagan, Robert F.; Kim, Charlie S.; Pevear, David R.; Vrolijk, Peter

doi:10.2138/am-2002-11-1203

Cited by 35 publications

(42 citation statements)

References 21 publications

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“…1 M ? 1M d ) versus apparent K-Ar age, Ar-Ar age, or e kt -1 (where k is the decay constant and t is time) can provide both the protolith (100 %) and authigenic (0 %) ages (Pevear 1999;Van der Pluijm et al 2001Ylagan et al 2002;Haines and van der Pluijm 2010;Solum et al 2010;Duvall et al 2011;Hnat and van der Pluijm 2014).…”

Section: Discussionmentioning

confidence: 99%

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Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

et al. 2015

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The Silltal Fault is the northern brittle continuation of the Brenner Fault Zone, marked by a narrow zone of cataclasis and, in three locations, clay-rich fault gouges. The clay mineral composition of these gouges is dominated by higher temperature 2M 1 polytype illite/muscovite, with no 1M/1M d illite or mixed layer illite/ smectite detected. Smectite is limited to the northern samples from the Stephansbrücke location, whereas chlorite is present in all samples. The K-Ar ages from the different sample size fractions (\0.1, \0.4, \2, 2-6, 6-10 lm, ''whole rock gouge'') show a wide spread, from ca. 115 to 12 Ma, with ages consistently decreasing with grain size. Although the ranges overlap, ages from the northern Stephansbrücke samples are generally older (115-36 Ma) than those from the south near Matrei (55-12 Ma), possibly reflecting increasing regional metamorphic temperatures to the south. The well-defined linear relationship between apparent age and hydrogen stable isotope (dD) values establishes a direct correlation between rejuvenation of the K-Ar system and increased interaction with meteoric water introduced and focussed within the fault zone. The dependence of both apparent age and dD on grain size also indicates that radiogenic and stable isotope exchange was controlled by grain size, reflecting new 2M 1 illite growth, mechanical grinding of protolith muscovite during cataclastic faulting, or both. The results demonstrate the advantages of combining radiogenic and stable isotope analysis in interpretation of K-Ar ages from clay fault gouges. The combined approach was necessary to establish the crucial influence on apparent K-Ar ages of meteoric water influx focussed on the fault zone and its interaction with clay-size-fraction grains.

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Section: Discussionmentioning

confidence: 99%

“…Most clay fault gouges are therefore a mixture of comminuted protolith (''detrital'') clay/mica/chlorite and different authigenic clay-sized minerals and polytypes(Vrolijk and van der Pluijm 1999;Ylagan et al 2002;Zwingmann et al 2010a;Surace et al 2011;Bense et al 2014). However, this is not what is observed in Silltal Fault gouges.…”

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confidence: 99%

Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

et al. 2015

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“…In recent years, autogenetic illite K-Ar dating has been widely used in China [16][17][18][19][20][21][22][23][24][25] . Overseas, the technique is becoming more mature and being applied to wider fields, such as reservoir diagenesis and evolutionary age dating [26] , metamorphic temperature and age dating [27] , timing of hydrocarbon fluid migration [28,29] , age dating of multi-stage charging of ancient fluids in fractures of different periods, etc. [30] 1 Geological setting…”

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confidence: 99%

Reservoir-forming age and its exploration significance to stratigraphic reservoirs in southern Songliao Basin

2007

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Despite many studies concerning the forming age, evolution characteristics and the age of petroleum charging in the Fuxin upheaval of southern Songliao Basin, no consensus has been reached so far. This paper presents the first K-Ar dating of autogenetic illite from stratigraphic petroleum reservoirs in the Fuyu oil layer of the Fuxin upheaval belt. Isotopic test and age calculation were carried out based on the separation and purification of illite mineral, X-diffraction analysis and the detection of scanning electron microscopy. The evolution characteristics of structure, sedimentation, reservoir-forming about the Fuxin upheaval belt were interpreted in terms of the synthetical analysis of "six-type geological history" evolution in southern Songliao Basin. The geologic background of petroleum evolution and reservoir formation are similar in the entire central depression region of southern Songliao Basin. The Changling sag and the Fuxin upheaval belt brought about obvious upheaval-sag separation after the hydrocarbon-generation peak of K 2 qn 1 and the main reservoir-forming period of the Fuyu oil layer, namely reservoir-forming happened before the Fuxin upheaval belt extensively raised. The reservoirs have three characteristics: the hydrocarbon source rock above the reservoir, the oil source in the locality, and the vertical migration. The geological cognition is corrected, that is, oil source came from the Changling sag and migrated from the side direction. The bulk process of petroleum charging in the stratigraphic hydrocarbon reservoirs in the Fuxin upheaval belt of southern Songliao Basin is determined according to the isotopic age of autogenetic illite in combination with the method of fluid inclusions. The cognition is helpful to exactly evaluate the resource potential and exploration direction in the Fuxin upheaval belt, Changling sag and their peripheral areas. The present results indicate that the combination of the two methods (the K-Ar dating of autogenetic illite and fluid inclusions) is an effective way to lay bare petroleum charging history and ascertain reservoir age.

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“…Dating of gouge thus tended to overestimate the age of faulting, as later work showed that some detrital material remains present in even very fine size fractions [ Pevear , 1992; Grathoff et al , 2001]. Subsequent applications of geochronological methods to date fault gouge [ van der Pluijm et al , 2001, 2006; Ylagan et al , 2002; Solum et al , 2005; Haines and van der Pluijm , 2008] have resolved the problem of detrital contamination by separating the gouge into several size fractions, each having a separate ratio of detrital and authigenic material, and iteratively modeling XRD patterns of the various size fractions to determine the percentage of authigenic and detrital material in each prior to vacuum‐encapsulated Ar‐Ar dating. Using an approach known as Illite Age Analysis, the percentage of detrital illite in each of the size fractions is plotted against its apparent Ar‐Ar total gas ages and then extrapolated to 0% and 100% to find the end‐member ages.…”

Section: Clay Mineralogy Terminology and Fault Gouge Datingmentioning

confidence: 99%

Dating the detachment fault system of the Ruby Mountains, Nevada: Significance for the kinematics of low-angle normal faults

Haines

Pluijm

2010

Tectonics

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[1] The mechanics of low-angle normal faulting and metamorphic core complexes continue to be a subject of debate. We investigate the conditions, timing, and kinematics of slip in the late, upper-crustal stages of core complex evolution of the Ruby Mountains detachment fault at the well-exposed Secret Pass locality with an X-ray diffraction (XRD) and Ar-Ar study of clay gouge samples from three separate faults, two from the low-angle detachment system and one from a high-angle normal fault that soles into the main detachment fault system. XRD analysis and modeling of XRD analysis show that authigenic illite-rich illite/ smectite (I/S) in gouge at Secret Pass is distinguishable from clay phases in hanging wall rocks because the I/S in the gouges contains only one-water layer as opposed to the more common two-water I/S phases found in both the hanging wall and footwall. Ar-Ar ages for the monomineralic one-water I/S found in the hanging wall high-angle fault, the main detachment, and a lowangle normal fault structurally above the main detachment are 11.6 ± 0.1 Ma, 12.3 ± 0.1 Ma, and <13.8 ± 0.2 Ma, respectively. The not-quite-flat Ar-Ar spectra indicate the gouge illites grew over some interval of time and not in discrete events. The nearly overlapping ages indicate that gouge formation and thus the last major period of activity on the detachment were at 11-13 Ma and were active coevally as part of a kinematically linked fault system with the main detachment active at dips <45°and possibly as low as 22°.Citation: Haines, S. H., and B. A. van der Pluijm (2010), Dating the detachment fault system of the Ruby Mountains, Nevada: Significance for the kinematics of low-angle normal faults, Tectonics, 29, TC4028,

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Illite polytype quantification for accurate K-Ar age determination

Cited by 35 publications

References 21 publications

Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

Reservoir-forming age and its exploration significance to stratigraphic reservoirs in southern Songliao Basin

Dating the detachment fault system of the Ruby Mountains, Nevada: Significance for the kinematics of low-angle normal faults

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