1 Across contractional orogens, the equivalency between decadal convergence rates from geodetic GPS data and geologic shortening rates at time scales of thousands or millions of years has rarely been documented. Here, we present an example from the northern margin of Chinese Pamir, where the Main Pamir Thrust is tectonically quiescent, and recent deformation is concentrated on the Pamir Frontal Thrust (PFT). Based on dated and faulted fluvial terraces, magnetostratigraphy, and mapping, the horizontal shortening rate of the PFT is ∼6–7 mm/a at time scales of both ∼18.4 ka and ∼0.35 Ma, comparable to the geodetic rate of ∼6–9 mm/a across the same zone, implying that modern geodetic rates are a reasonable proxy for geologic rates since ∼0.35 Ma. Comparing this example with studies in other contractional orogens, we conjecture that a match or mismatch of geologic‐geodetic rates typically depends on the time scale of observation, fault geometry, and fault mechanics. Introduction 2 The proliferation of GPS data on relative velocities across orogens and plate boundaries has provided a far more complete view of the modern patterns of crustal deformation.
Although it is tempting to use these decadal rates as proxies for rates applicable to thousands or millions of years, this equivalency has rarely been tested in contractional orogens. Along some well‐studied strike‐slip faults, such as the southern San Andreas fault where numerous paleoseismic studies define slip rates at time scales of hundreds of years, geologic and geodetic rates appear quite closely matched. Across contractional orogens, however, mismatches are more common than matches. For example, in the Himalaya, geomorphic studies at Holocene time scales clearly show that ∼20 mm/a of slip occurs along the Main Frontal Thrust , whereas geodetic shortening across the same zone is only a few millimeters per year ;. Similar mismatches are observed across the Taiwanese orogen. In contrast, across the Kyrgyz Tian Shan, cumulative late‐Quaternary rates on major faults spanning the range provide a good match to the geodetic rates. When these Kyrgyz geodetic rates are used to estimate the initiation age of mountain building , however, they predict a much younger age than that deduced from thermochronology and magnetostratigraphy ; , implying much slower geologic rates at longer time scales.
3 Here we present shortening rates of the Pamir Frontal Thrust (PFT) along the northern margin of Chinese Pamir. Our new data indicate that shortening rates of the PFT adjacent to the Mayikake basin (∼75 km west of Kashgar) are similar at time scales of both ∼0.35 Ma and ∼18.4 ka and comparable to the decadal geodetic rate across the same zone. Hence, the geodetic rate of the PFT appears to yield a reasonable proxy for the long‐term geologic rate. Comparing this example with previous studies, we investigate the time scale for which the geodetic rates can be reliably extrapolated to represent geologic rates and define factors that may modulate the equivalence of geologic and geodetic rates. (a) Topography of the Pamir and surrounding area with local GPS vectors. Box encloses GPS sites used in Figure 1b. (b) N15°E component of GPS velocities (perpendicular to the PFT trend) across the Main Pamir Thrust (MPT), Pamir Frontal Thrust (PFT) and South Tian Shan Thrust (STST), showing ∼6–9 mm/a of convergence across the PFT.
The gray bar represents mean value and standard error of velocities. Purple field shows predicted geodetic pattern for MPT slip from an elastic half‐space model with a creeping detachment depth of 6–17 km (see).
Locations of the MPT, PFT and STST are not exact due to map projection. (c) GPS vectors projected on an ASTER image of the field area. See Figure 1a for location. Earthquake locations from the USGS seismic catalog for the period 1973–2010. (d) Interpreted seismic line KS99‐610 between the MPT and PFT from. Location in Figure 1c. DKF‐Darvaz‐Karakul Fault, KES‐Kongur Extension System, KYTS‐Kashgar‐Yecheng Transfer System.
GPS velocities relative to Eurasia from. Deformation Along the Northern Margin of Chinese Pamir 4 The Pamir lies in the northwestern region of the Indo‐Asian collision zone. During Cenozoic times, the northern margin of the Pamir has indented northward ∼300 km, as it was accommodated by south‐dipping intracontinental subduction along the Main Pamir Thrust (MPT) and was coupled to strike‐slip faulting on its western and eastern margins. In westernmost China, geologic deformation is concentrated on the MPT along the Pamir's oblique eastern margin, on the PFT along the leading edge of deformation, and on the piggyback basin between them.
5 The MPT, separating domains with contrasting geology and geomorphology, comprises several high‐angle reverse faults involving pre‐Cenozoic basement , with slip initiating sometime between 25–20 Ma. Geologic mapping and rare earthquakes , however, indicate low Holocene activity along the thrust. 6 The 30‐ to 40‐km‐wide piggyback basin north of the MPT exhibits little geomorphic expression of active structures. In the subsurface, however, three seismically imaged imbricate thrusts are interpreted to represent the northward propagation of the MPT.
These faults are overlain by largely undeformed piggyback‐basin Plio‐Quaternary deposits, indicating that slip on these thrusts has apparently ceased and deformation has been transferred to the PFT along a detachment surface localized within Paleogene gypsum. 7 The PFT is a zone of active thrust faulting and folding that can be subdivided into several segments based on different deformation characteristics. For example, in the Mayikake basin, the PFT includes the Biertuokuoyi Frontal Thrust and the Mayikake Thrust , whereas further east, it includes the Tuomuluoan Thrust and thrust‐related Tuomuluoan anticline. Widely distributed active structures and frequent earthquakes, including the 1985 Wuqia M7.4 event , reflect ongoing activity on the PFT and contrast with the quiescent MPT to its south. (a) Geologic map of the Tuomuluoan Thrust (TT) and surrounding area showing a minimum overthrusting width of ∼2.1 km between Paleogene and Pleistocene strata.
WSR‐1985 Wuqia earthquake surface rupture. Location map in. Same legend as. (b) Field photo of the TT outcrop, exposing Paleogene units overthrusting Pleistocene conglomerate.
Outcrop location marked in Figure 3a. (c) Magnetostratigraphy of the Pleistocene conglomerate section as correlated with the time scale of. (d) Thickness as a function of magnetostratigraphic age. Upward extrapolation of the nearly uniform sedimentation rate seen from ∼2.15 to 0.8 Ma implies an age of ∼0.35 Ma for the top of the section. Modern Convergent Rate Along the PFT 8 A swath of 22 GPS sites that is oriented N15°E (perpendicular to the PFT, ) and spans the MPT, PFT and Southern Tian Shan Thrust (STST) serves to constrain the modern convergence rate of the PFT. GPS velocities in the Pamir and those bracketing the MPT are similar, with an average of 20.5 ± 1.0 mm/a relative to stable Eurasia. Across the PFT, velocities abruptly drop to 13.9 ± 1.2 mm/a, and across the STST to the north, velocities average ∼11.2 ± 0.8 mm/a.
Although both slip and elastic strain accumulation are difficult to isolate on individual faults due to sparse GPS sites, elastic half‐space modeling suggests the geodetic data are incompatible with slip on a temporarily “locked” MPT ( and ) and supports slip cessation of the MPT. Whereas the STST may also accumulate elastic strain, low Quaternary slip ; and absence of evidence for significant earthquakes on the STST near the Mayikake basin indicate the geodetic rate accommodated by the STST is very limited, and the major convergence is concentrated on the PFT.
Assuming that elastic strain accumulation on the PFT does not extend over the surface traces of the MPT and the STST, GPS velocities bracketing the PFT yield a minimum convergent rate of 6.6 ± 1.1 mm/a along the PFT. If elastic strain accumulation were assumed to extend beyond surface traces of the MPT and the STST, GPS velocities across this wider zone yield a maximum convergent rate of 9.3±0.9 mm/a.
In either case, the modern convergent rate across the PFT is ∼6–9 mm/a, irrespective of whether or not elastic strain accumulation on the PFT extends over surface traces of the MPT and the STST. 9 The epicenter of the Wuqia M7.4 earthquake in 1985 occurred within the GPS swath. This event could have introduced a component of postseismic relaxation that would influence the geodetic measurements. Such an effect, however, is likely small because the regional contraction is suffici.
Mac OS X’s default media player – Quicktime 10 doesn’t natively support the playback of AVI, MKV & DIVX video files. These formats are widely used to distribute Videos.
Also, the previous solution of playing these files in Quicktime 7 using Perian doesn’t work anymore since the new Mac OS X Mavericks update. So, here’s an easy tutorial which will show you How to Play AVI/MKV Files on Mac OS X using the 3 Best Free Avi Players to Play AVI/MKV/DIVX/MOV/WMV files on Mac OS X.
These Video players are not only free but contain the codecs inbuilt within them to play these files 3 Best Free Media Players to Play Avi, Mkv & DivX Videos on Mac OS X – Player # 1 – VLC Media Player for Mac OS X. VLC for Mac OS X The most popular Media player for Windows – VLC is available for Mac OS X too, and to be frank it really does come in as a saviour! VLC Media player for Mac OS X comes with a host of features such as –. Codecs to Play MKV & AVI & HD Videos. Subtitles.srt files support on Mac OS. Ability to play network streams & rtmp:// protocol.
Plays real media.ram and.rm files too. VLC for Mac is Open-source & thus free of cost. The method to use VLC to play mkv, avi files on mac is Pretty simple –. First of all download VLC Media Player for Mac OS X from the link below –. Now, install the downloaded.dmg file. Now, Open the VLC app - Click on “ File” on the top bar, Select the “ Open” option.
Now simply select the video file (.mkv/.avi /.3gp) which you want to Play. That’s it your Video will start playing on Mac OS X.
Update – ElMedia is another great light-weight media player for Mac OS X which can play all major video file types –. UMPlayer for Mac OS X Installation Another great free alternative to VLC for Mac OS X is UMPlayer. Universal Media Player (UMPlayer) like VLC is an open-source media player which has inbuilt codecs to play.avi,.mkv and can play.webm video on Mac OS. UMPlayer too is free of cost and easy to use as well.
The Installation procedure slightly differs for installation of UmPlayer –. First of all download the UmPlayer for Mac OS X from the link below –. Now, Double-click the downloaded.dmg file & it will open a window with UMPlayer installer icon as shown in the alongside image.
Simply double click on the icon, to start the installation process. Now, click on continue to finish the installation. Now once UmPlayer is installed, launch the UmPlayer app from Applications folder/ Spotlight and use the “ File-Open method as used in VLC to start playing your favorite videos in Mac OS X. Player # 3 – MPlayer OS X Extended. Mplayer OS X Extended Now there was a bit of tussle for the third spot between MPlayer OS X, its lookalike – MPlayerX and 5kPlayer. Now, since 5kPlayer provides a lot of features such as And the MPlayerX installer coming with some toolbars we chose Mplayer OS X extended – as although being an older app, it worked smoothly on Mavericks, Yosemite and even El Capitan too. The Process of using MPlayer OS X extended to play.mov.wmv files on Mac too is same as that of VLC – Install, File – Open.
Here’s a list of formats supported by MPlayer OS X Entended –.wma,.avi,.divx,.ram,.dat,.dv,.vcd,.wmv all popular formats are supported. Do let us know if you face any problems while using any of the above app. Also do let us know of any other such great media player for mac if you know one.