Fluid–rock interactions in seismic faults: Implications from the structures and mineralogical and geochemical compositions of drilling cores from the rupture of the 2008 Wenchuan earthquake, China

Duan, Qingbao; Yang, Xiao‐Song; Ma, Shuping; Chen, Jianye; Chen, Jinyu

doi:10.1016/j.tecto.2015.11.008

Cited by 29 publications

(43 citation statements)

References 112 publications

(164 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Second, our study shows that the PSZ gouge contains abundant partially graphitized amorphous carbon (or low-crystalline graphite, 12 wt %) and small amounts of crystallized graphite [Togo et al, 2011]. TOC analyses of fault gouges collected from other exposures further reveal the widespread presence of carbon along the YX-BC fault, such as Shenxigou [28.3%, Wang et al, 2014], Longci (3.2%), Jinhe (3.1%, Duan et al [2016]), Beichuan (0.9%), Pingxi (2.4%). Previous studies suggest the presence of graphite carbon can dramatically weaken the fault [Kuo et al, 2011;Oohashi et al, 2013].…”

Section: Dynamic Weakening Of the Yingxiu-beichuan Faultmentioning

confidence: 74%

“…TOC analyses of fault gouges collected from other exposures further reveal the widespread presence of carbon along the YX‐BC fault, such as Shenxigou [28.3%, Wang et al ., ], Longci (3.2%), Jinhe (3.1%, Duan et al . []), Beichuan (0.9%), Pingxi (2.4%). Previous studies suggest the presence of graphite carbon can dramatically weaken the fault [ Kuo et al ., 2011; Oohashi et al ., ].…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Hydraulic properties of samples retrieved from the Wenchuan earthquake Fault Scientific Drilling Project Hole‐1 (WFSD‐1) and the surface rupture zone: Implications for coseismic slip weakening and fault healing

Chen

Yang

et al. 2016

Geochem Geophys Geosyst

Self Cite

View full text Add to dashboard Cite

In this study, we report the hydraulic properties of samples recovered from the first borehole of the Wenchuan earthquake Fault Scientific Drilling and from outcrops associated with the surface rupture zone of the 2008 Wenchuan earthquake. Compositional and microstructural analyses have also been performed on selected samples. Using the pore pressure oscillation method, the permeability measurements show that (1) fault gouge samples have low permeabilities, decreasing from 2 3 10 218 m 2 at an effective pressure (P e ) of 10 MPa (equivalent to an in situ depth of 600 m) to 9 3 10 221 m 2 at 155 MPa. (2) Intact and cemented samples are impermeable with permeabilities less than 2 3 10 220 m 2 at 10 MPa. (3) Fractured samples have variable permeabilities, ranging from 3 3 10 215 to 1 3 10 220 m 2 at 10 MPa, and are most insensitive to changes in the effective pressure. (4) Granitic cataclasites have a moderate permeability at low pressure (i.e., 10 216 to 10 217 m 2 at 10 MPa); which decreases rapidly with increasing P e . Hydraulic conduction of the fault is believed to be influenced by the permeability of the fractures developed, which is controlled by the density, aperture, and/or connectivity of the fractures. Microstructural and compositional analyses of the samples indicate that the fault zone heals through chemically mediated fracture closure related to mineral precipitation, possibly assisted by pressure solution of stressed fracture asperities. Although other weakening mechanisms remain possible, our laboratory measurements combined with numerical modeling reveal that thermal/thermochemical pressurization, perhaps leading to gouge fluidization, played an important role in the dynamic weakening of the Wenchuan earthquake, at least in the study area.

show abstract

Section: Dynamic Weakening Of the Yingxiu-beichuan Faultmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Hydraulic properties of samples retrieved from the Wenchuan earthquake Fault Scientific Drilling Project Hole‐1 (WFSD‐1) and the surface rupture zone: Implications for coseismic slip weakening and fault healing

Chen

Yang

et al. 2016

Geochem Geophys Geosyst

Self Cite

View full text Add to dashboard Cite

show abstract

“…Duan et al . [] provide a more detailed description of these drill cores, including microstructural, mineralogical, and geochemical characteristics.…”

Section: Geological Setting and Samplesmentioning

confidence: 99%

“…However, overprinting by extensive fracturing and precipitation of typical alteration minerals suggest that these rock have Geochemistry, Geophysics, Geosystems 10.1002/2015GC006095 undergone a complex history, involving both brittle deformation and pervasive fluid-rock interaction. Duan et al [2016] provide a more detailed description of these drill cores, including microstructural, mineralogical, and geochemical characteristics.…”

Section: Geological Setting and Samplesmentioning

confidence: 99%

“…In order to better understand compositional, physical, and chemical characteristics of the fault zone, two shallow holes (LMFD‐3A and 3B) were drilled at the Jinhe (also called Golden River) locality (site LMFD‐3), at Hongbai Town, Shifang City, Sichuan Province (China) in 2011 (Figures and ). Microstructural, mineralogical, and geochemical analyses of representative drill core samples suggest that fluids have pervasively infiltrated into the fault zone [ Duan et al ., ]. Here we describe rock magnetic properties of selected samples from the two drill holes, and examine their relationship with mineralogical and chemical compositions, in an effort to explore the potential magnetic record of fluid infiltration.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rock magnetic expression of fluid infiltration in the Yingxiu‐Beichuan fault (Longmen Shan thrust belt, China)

Yang

Duan

et al. 2016

Geochem Geophys Geosyst

Self Cite

View full text Add to dashboard Cite

Fluid infiltration within fault zones is an important process in earthquake rupture. Magnetic properties of fault rocks convey essential clues pertaining to physicochemical processes in fault zones. In 2011, two shallow holes (134 and 54 m depth, respectively) were drilled into the Yingxiu-Beichuan fault (Longmen Shan thrust belt, China), which accommodated most of the displacement of the 2008 Mw 7.9 Wenchuan earthquake. Fifty-eight drill core samples, including granitic host rock and various fault rocks, were analyzed rock-magnetically, mineralogically, and geochemically. The magnetic behavior of fault rocks appears to be dominated by paramagnetic clay minerals. Magnetite in trace amounts is identified as the predominant ferrimagnetic fraction in all samples, decreasing from the host rock, via fault breccia to (proto-)cataclasite. Significant mass-losses (10.7-45.6%) are determined for the latter two with the ''isocon'' method. Volatile contents and alteration products (i.e., chlorite) are enriched toward the fault core relative to the host rocks. These observations suggest that magnetite depletion occurred in these fault rocksexhumed from the shallow crust-plumbed by fluid-assisted processes. Chlorite, interpreted to result from hydrothermal activity, occurs throughout almost the entire fault core and shows high coefficients of determination (R 2 > 0.6) with both low and high-field magnetic susceptibility. Close relationships, with R 2 > 0.70, are also observed between both low and high-field magnetic susceptibility and the immobile elements (e.g., TiO 2 , P 2 O 5 , MnO), H 2 O 1 , and the calculated mass-losses of fault rocks. Hence, magnetic properties of fault rocks can serve as proxy indicators of fluid infiltration within shallow fault zones.

show abstract

Mineralogical compositions of fault rocks from surface ruptures of Wenchuan earthquake and implication of mineral transformation during the seismic cycle along Yingxiu-Beichuan fault, Sichuan Province, China

Dang

Zhou

et al. 2017

Miner Petrol

View full text Add to dashboard Cite

Fluid–rock interactions in seismic faults: Implications from the structures and mineralogical and geochemical compositions of drilling cores from the rupture of the 2008 Wenchuan earthquake, China

Cited by 29 publications

References 112 publications

Hydraulic properties of samples retrieved from the Wenchuan earthquake Fault Scientific Drilling Project Hole‐1 (WFSD‐1) and the surface rupture zone: Implications for coseismic slip weakening and fault healing

Hydraulic properties of samples retrieved from the Wenchuan earthquake Fault Scientific Drilling Project Hole‐1 (WFSD‐1) and the surface rupture zone: Implications for coseismic slip weakening and fault healing

Rock magnetic expression of fluid infiltration in the Yingxiu‐Beichuan fault (Longmen Shan thrust belt, China)

Mineralogical compositions of fault rocks from surface ruptures of Wenchuan earthquake and implication of mineral transformation during the seismic cycle along Yingxiu-Beichuan fault, Sichuan Province, China

Contact Info

Product

Resources

About