Episodic Dissolution, Precipitation, and Slip along the Heart Mountain Detachment, Wyoming

نویسندگان

  • Erika Swanson
  • Brian P. Wernicke
  • Thomas A. Hauge
چکیده

The Heart Mountain allochthon is among the largest landslide masses in the rock record. The basal fault, the Heart Mountain detachment, is an archetype for the mechanical enigma of brittle fracture and subsequent frictional slip on low-angle faults, both of which appear to occur at ratios of shear stress to normal stress far below those predicted by laboratory experiments. The location of the detachment near the base of thick cratonic carbonates, rather than within subjacent shales, is particularly enigmatic for frictional slip. A broad array of potential mechanisms for failure on this rootless fault have been proposed, the majority of which invoke single-event, catastrophic emplacement of the allochthon. Here, we present field, petrographic, and geochemical evidence for multiple slip events, including crosscutting clastic dikes and multiple brecciation and veining events. Cataclasites along the fault show abundant evidence of pressure solution creep. Banded grains, which have been cited as evidence for catastrophic emplacement, are associated with stylolitic surfaces and alteration textures that suggest formation through the relatively slow processes of dissolution and chemical alteration rather than dynamic suspension in a fluid. Temperatures of formation of faultrelated rocks, as revealed by clumped isotope thermometry, are low and incompatible with models of catastrophic emplacement. We propose that displacement along the gently dipping detachment was initiated near the base of the carbonates as localized patches of viscous yielding, engendered by pressure solution. This yielding, which occurred at very low ratios of shear stress to normal stress, induced local subhorizontal tractions along the base of the allochthon, raising shear stress levels (i.e., locally rotating the stress field) to the point where brittle failure and subsequent slip occurred along the detachment. Iteration of this process over geological time produced the observed multikilometer displacements. This concept does not require conditions and materials that are commonly invoked to resolve the stress paradox for low-angle faults, such as near-lithostatic fluid pressures or relative weakness of phyllosilicates in the brittle regime. Cyclic interaction of viscous creep (here by pressure solution) and brittle failure may occur under any fluid pressure conditions and within any rock type, and as such it may be an attractive mechanism for slip on “misoriented” fault planes in general.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Effect of detachment levels, thrust and basement strike-slip faults on structural geometry of the Naft anticline in the Lurestan zone, West Iran

The Naft anticline with NW-SE trend is located in north of the Lurestan sub-zone and the Zagros fold and thrust belt. Thrust and basement strike-slip faults and detachment levels play an important role in the structural geometry of the folded structures in this is sub-zone.  In this research, deformational pattern and structural geometry of the Naft anticline hane been studied using constration...

متن کامل

Estimation of Mean Annual Precipitation in Wyoming Using Geostatistical Analysis

Precipitation is a function of many topographical land features as well as geographical locations. Spatial correlations between precipitation and topographical and geographical features can be used to improve estimation of precipitation distributions. In this study, kriging with external drift of topographical information was utilized for determining precipitation spatial distributions in Wyomi...

متن کامل

Seed weight variation of Wyoming sagebrush in northern Nevada.

Seed size is a crucial plant trait that may potentially affect not only immediate seedling success but also the subsequent generation. We examined variation in seed weight of Wyoming sagebrush (Artemisia tridentata ssp. wyomingensis Beetle and Young), an excellent candidate species for rangeland restoration. The working hypothesis was that a major fraction of spatial and temporal variability in...

متن کامل

Investigation of Reversibility of Asphaltene Precipitation and Deposition for an Iranian Crude Oil

In this work, the precipitation and re-dissolution of asphaltenes were studied for an Iranian relatively heavy crude oil. A series of experiments were designed and carried out to quantitatively examine the reversibility of asphaltenes precipitation upon the change in the solvent concentration along with the temperature. n-Heptane was used as the precipitant, and a temperature range of 30 to...

متن کامل

I Nventory of S Ensitive a Nimal S Pecies in the F Erris

The Ferris Mountain Wilderness Study Area (WSA) is one of 42 WSAs in Wyoming managed by the Bureau of Land Management (BLM) as part of the National Landscape Conservation System (NLCS). To date, no WSA in Wyoming has been elevated to Wilderness Area status under the NLCS. Information about the characteristics that make a WSA eligible for Wilderness Area designation is needed during the evaluati...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2016