Direct dating of Eocene reverse faulting in northeastern Tibet using Ar-dating of fault clays and low-temperature thermochronometry

Duvall, Alison R.; Clark, Marin K.; Pluijm, Ben A. van der; Li, Chuanyou

doi:10.1016/j.epsl.2011.02.028

Cited by 229 publications

(176 citation statements)

References 35 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%

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%

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

et al. 2015

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“…The event initially appears at the southern margin of NE Tibet as displacement along the WNW-trending West Qinling fault zone at 45-50 Ma (Clark et al, 2010;Duvall et al, 2011). During this time, the West Qinling fault zone experienced rapid cooling and exhumation (Clark et al, 2010;Duvall et al, 2011).…”

Section: Tectonic Settingsmentioning

confidence: 95%

Lithospheric architecture and deformation of NE Tibet: New insights on the interplay of regional tectonic processes

Guo

Gao

et al. 2016

Earth and Planetary Science Letters

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Editor: P. ShearerKeywords: deep seismic reflection image residual gravity NE Tibet lithospheric architecture deformation pattern GPS measurements indicate rapid lateral extrusion of the NE Tibetan Plateau, which causes active NEdirected crustal shortening and has initiated oblique shearing along the margins of NE Tibet. However, the Tibetan highlands terminate around 103 • E longitude and topographic relief disappears to the northeast. The exact reasons for this drop in elevation remain obscure due to widespread Tertiary sediments and Quaternary loess, which obscure details of the lithospheric structure. This study describes a new 310 kmlong deep seismic reflection line striking NE-SW across the interior of NE Tibet. Integrating its data with a previously described 165 km-long deep seismic profile of the Tibet-Ordos transition zone together, these datasets provide a complete picture of the crustal architecture of the north-easternmost Tibetan Plateau. Gravity anomaly and previous geological evidence also help constrain complex deformation pattern in the region. Interpretations of these patterns indicate the importance of the large-scale sinistral Haiyuan fault zone and inherited vertical variation in mechanical properties of the lithosphere in the overall tectonic evolution of the NE Tibetan Plateau. The overall crustal architecture obtained in this study provides spatial context for the neotectonic evolution of NE Tibet and helps constrain the interplay of geologic and geodynamic processes affecting NE Tibet and adjacent regions.

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“…The closure temperature of coarse-grained (100 µm) musco vite at cooling rates of 10°C/Ma is around 405°C at a pressure of 5 kbar (or 425°C at 10 kbar; Harrison et al, 2009). Based on the same diffusion parameters, Duvall et al (2011) estimated the closure temperature of fine-grained muscovite (2-0.05 µm) to be 250-350°C. This is consistent with empirical studies based on present-day borehole temperatures and estimated palaeotemperatures, which consistently indicate closure temperatures >250°C for illite <2 µm (Hunziker et al, 1986;Wemmer & Ahrendt, 1997).…”

Section: Illite and Temperaturementioning

confidence: 99%

“…Though it contains no illite, its K-concentration is similar to that of the finer fractions, suggesting that most of the potassium might come from the K-feldspar, and the age is essentially a K-feldspar age. Fine-grained K-feldspar has a potentially lower closure temperature (350-150°C; Lovera et al, 1989) than illite/muscovite (425-250°C; Harrison et al, 2009;Duvall et al, 2011) and could therefore be reset at lower temperatures, yielding younger ages. However, this requires fault activity at temperatures exceeding the closure temperature of K-feldspar; the temperatures indicated by the high KI values of the sample (100-200°C) are barely high enough and hostrock temperatures in the Late Jurassic were well below the closure temperature of K-feldspar (Rohrman et al, 1995;Ksienzyk et al, 2014).…”

Section: Palaeozoic Faultsmentioning

confidence: 99%

Post-Caledonian brittle deformation in the Bergen area, West Norway: results from K–Ar illite fault gouge dating

Ksienzyk¹,

Wemmer²,

Jacobs³

et al. 2016

NJG

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Post-Caledonian extension during orogenic collapse and Mesozoic rifting in the West Norway-northern North Sea region was accommodated by the formation and repeated reactivation of ductile shear zones and brittle faults. Offshore, the Late Palaeozoic-Mesozoic rift history is relatively well known; extension occurred mainly during two rift phases in the Permo-Triassic (Phase 1) and Mid-Late Jurassic (Phase 2). Normal faults in the northern North Sea, e.g., on the Horda Platform, in the East Shetland Basin and in the Viking Graben, were initiated or reactivated during both rift phases. Onshore, on the other hand, information on periods of tectonic activity is sparse as faults in crystalline basement rocks are difficult to date. KAr dating of illite that grows synkinematically in fine-grained fault rocks (gouge) can greatly help to determine the time of fault activity, and we apply the method to nine faults from the Bergen area. The K-Ar ages are complemented with X-ray diffraction analyses to determine the mineralogy, illite crystallinity and polytype composition of the samples. Based on these new data, four periods of onshore fault activity could be defined: (1) the earliest growth of fault-related illite in the Late Devonian-Early Carboniferous (>340 Ma) marks the waning stages of orogenic collapse; (2) widespread latest Carboniferous-Mid Permian (305-270 Ma) fault activity is interpreted as the onset of Phase 1 rifting, contemporaneous with rift-related volcanism in the central North Sea and Oslo Rift; (3) a Late Triassic-Early Jurassic (215-180 Ma) period of onshore fault activity postdates Phase 1 rifting and predates Phase 2 rifting and is currently poorly documented in offshore areas; and (4) Early Cretaceous (120-110 Ma) fault reactivation can be linked either to late Phase 2 North Sea rifting or to North Atlantic rifting.

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Direct dating of Eocene reverse faulting in northeastern Tibet using Ar-dating of fault clays and low-temperature thermochronometry

Cited by 229 publications

References 35 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)

Lithospheric architecture and deformation of NE Tibet: New insights on the interplay of regional tectonic processes

Post-Caledonian brittle deformation in the Bergen area, West Norway: results from K–Ar illite fault gouge dating

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