Karakoram Shear Zone from Agham to Pangong Lake, Ladakh, NW India

Looking NE towards the Karakoram Metamorphic Complex from high in the Pangong Range. Notice the presence of marble layers in light tones, absent from the Pangong Metamorphic Complex, dipping moderately away from the viewer to the NE. The Pangong Lake is to the right, Muglib to the left.

 

Satelite image of the Karakoram Lineament, through the Shyok valley and across to Muglib and the Pangong Tso. CLICK ON AREAS to GO TO photographs of the structures. CLICK HERE FOR A MAP WITH STEREONETS.

 

This page documents the main aspects of the Karakoram Shear Zone betweeen Agham (Lomo Yogma) in the NW, and  the Pangong Lake to the SE,  over a distance of 60 km covered by foot. The page is organized from NW to SE, starting at Lomo Yogma where the road currently ends. The satelite image is active: click on different regions to see related photo documentation.   The study focus on the relationships between the upper amphibolite facies Pangong Range comprised by the Pangong Metamorphic Complex, and the lower amphibolite facies Karakoram Metamorphic Complex to the NE. The main findings are:   1. Generally, rocks of the Pangong Metamorphic Complex comprsing the Pangong Range dip SW and rocks of the Karakoram Metamorphic Complex, KMC, dip NE. The two are separated by the Pangong strand of the Karakoram Shear Zone, which is generally vertical in the deeper part of the valleys. We documented the folding of layers from vertical in the valleys, to NE dipping in the KMC in two localities: close to Agham in the Lomo Yogma area, and close to the Pangong Lake.   2. The shear zone is dominantly dextral. Along the Shyok valley, the intense, gently plunging lineation indicates transtension characterized by oblique dextral-normal moevement. This dominant lineation gives way locally to zones of intense steep crenulation lineation, corresponding to zones of folding with E-W axial plane, indicating zones of transpression.    3. Still in the Shyok valley, the main shear zone, and the valley exploits schists and quartzites in between a large calc-alkaline body, comprised mostly of granodiorite, with large areas, such as the Darbuk-Shyok gorge, where it is intensely intruded by leucogranite dykes.   4. The central section of the area studied, between the two NE-trending gorges that cut across the main NW-trending fabric (the Darbuk-Shyok and Tangtse-Muglib gorges) the Pangong Range is a pop-up structure characterized by transpression, being thrust over the Ladakh Range to the SW.   5. Further SE, the Pangong Range is dominated by SW-dipping layers thrust dextrally towards the Karakoram Metamorphic Complex to the NE. This is a zone of transpression.   6. Close to the Pangong Tso (Pangong Lake) the main fabric is folded from its NW-trending orientation to an E-W trend and characterized by sinistral shearing overprinting an earlier dextral event.   7. Greenschist facies shearing overprinted amphibolite facies sheared rocks. These domains are localized and documented within the two shear zone strands bounding the Pangong Range, rather than within the range.

 

a) Lomo Yogma area, 20 km SE of Agham

Figure (1385). Tng195 34  78. Looking  NNW where the Shyok river cuts off the path due to its many curves (bridge under construction). Leucogranite to the SW in intrusive and sheared contact with pelites. Most significantly the foliation folds from steep in the lower part of the  foreground to moderately NE dipping in the background.  Fig. 1386 (right) shows detail of the folding of foliation in the upper part of the mountain in the foreground.

Figure (1386). Detail of 1385 showing folding of foliation from steep NW trending (as in most of the Shyok valley to the SE), to moderately NE-dipping. NOTE: LARGE SCALE FOLD HAS BEEN MAPPED CLOSE TO THE PANGONG LAKE.60 km  TO THE SE

 

Figure (1379). Tng195 Looking  NE towards the leucogranite psammite intrusive and sheared contact. This contact can be seen in an Aster image of the area.	Figure (1358).Same contact as in left (1379) but on the next range Notice an apparent fault trending at a high angle to foliation (oblique from lower central part to the right) separating granite from psammite. Note small blue building for scale.

 

Figure (1383). Mylonitic coarse, mafic granite with mafic enclaves at the wall at the end of the road Tng195.	Figure (1384).Coarse mylonite Tng 195.

 

Figure (1434). Looking NE towards the right side of the Shyok valley, layers dip moderately NE, unlike the left side where layers are dominantly vertical or dipping steelply to moderately SW.	Figure (1432). Detail of right part of 1434 (to the left) showing layer dips to NE.

 

b) Transpression zones along the Shyok valley (34 16' 48.3" 78 03' 24.7"):
These zones are characterized by an intense, steeply plunging crenulation lineation occasionally overprinting the shallow plunging stretching lineation. The strike of bedding and mylonitic lineation trend towards 90 to 100, instead of the regional 140, shear plane parallel orientation.

 

Figure (1419). Tng194 34 ??' 44.1" 78 ??'25.8" Shyok valley: three dimensional outcrop. Horizontal exposure shows section of folds with axial plane trending 100/sv. Vertical wall shows steeply pluging crenulation lineation (65 to W).	Figure (1417). Tng194 34 ??'31.4" 78 ??'36.8".  Crenulation in schist

 

Figure (1422). Tng194 34 ??' 44.1" 78 ??'25.8" Horizontal exposure shows folded rocks cut by fault parallel to axial planar foliation 120/80SW.	Figure (1421). Tng194 34 ??'31.4" 78 ??'36.8".  Same as 1422.

 

Figure (1435). Tng198 34 16' 48.3" 78 03' 24.7" Shyok valley: steep exposure showing two lineations on plane trending 100/65N: a gently plunging stretching lineation and a steep, nearly down-dip crenulation lineation. We found two or three areas along the Shyok valley, between Shyok village and Lomo Yogma, where a strong steep lineation was present. These regions coincide with areas of intense foliding, and bedding/myloniic foliation trending 100 to 90, instead of the regionally dominant 130-140 parallel to the trend of the Karakoram Shear Zone.	Figure (1427). Tng198 34 17'25.0" 78 03'07.2". Vertical exposure parallel to dominant foliation showing dominance of a vertical,crenulation lineation.
Figure (1430).  Tng198 34 17'25.0" 78 03'07.2". Vertical exposure parallel to dominant foliation showing dominance of a vertical,crenulation lineation

 

Figure (1245). Tng188 34 12' 44.1" 78 07'25.8" Shyok valley: steep exposure (above coim), horizontal exposure (below coin).  A gently plunging stretching lineation (310/05) and a steeper crenulation lineation (plunging 55 to NW).	Figure (1352). Tng192 34 16'31.4" 78 03'36.8". Steep wall parallel to the dominant C-plane showing a strong NW plunging lineation (321/16).

 

c) Transtension: Shyok Village (valley up the range to the SW)

Figure (4011). Tng  34 ??" 78 ??" Lateral valley that runs into Shyok village. Normal faulting. In this valley, penetrative foliation attitude is 140/45SW and stretching lineation is generally plunging to the WNW and indicates an oblique (normal with a dextral component).	Figure (4012). Detail of 4011 (right-hand-side).
Figure (4013).Detail of 4011 upper central part. Notice leucocratic band including hornblende porphyroblasts iin the centre is sheared.

 

Figure. Stereonet showing structures related to structures in the Shyok Lungpa. The average C plane strikes 306/49SW, and the average stretching lineation plunges 287/23 defining a normal-dextral oblique shear sense.

 

d) Darbuk - Shyok Gorge

Figure (3935). Tangtse strand of the shear zone at Darbuk (NE of Tangtse) looking N. Biotite psammite (dark) in contact with sheared leucogranite (light brown).

 

Figure. Stereonet showing dominant structures along the Shyok-Darbuk road.

 

Figure (4019). Vertical wall in the Shyok gorge. Sheared leucogranite dykes in biotite-hornblende gneiss in Shyok gorge running NE-SW. Photo looking SE, scale order of 100m in length.	Figure (1166). Same wall.. Scale 50-100m.	Figure (1169). detail of 1166

 

e) Tangtse Gompa: Tangtse strand of Karakoram Shear Zone

Figure (1708). Tangtse Gompa outcrop of mylonitic garnet leucogranite. Looking SE. Planes trend 140, and lineations on those planes plunge 30-40NW. Tangtse strand of Karakoram Shear Zone.	Figure (1698) Tangtse Gompa outcrop of mylonitic garnet leucogranite. Looking NW along the Tangtse valley. Background mountains are comprised of Ladakh calc-alkaline grantoids and related Khardung volcanics.

 

Figure (3647). Rheological contrast between amphibolite to left and marble to right wrapping around the amphibolite blocks.	Figure (3649). Intense rheological contrast between amphibolite, broken up into angular blocks, and easy flowing marble. Notice the folded foliation on the marble along the vertical contact with the amphibolite.	Figure (3639). Folded leucogranite-pegmatite dyke. Fine-grained part to the left is mylonitic, coarse-grained part to the right lacks obvious foliation. Transition between the two is gradual and so is the loss of foliation.

 

Figure .3645, Brittle dextral fault overprinting sheared rocks of the Karakoram Fault.	Figure (3646). Band of calc-silicate with very large garnets embedded in an epidote-rich matrix.

 

f) Pangong strand: outcrop Png10 ( 33 59' 57.1" 78 20'02.6") mylonitic leucogranites

Figure (812). Mylonitic leucogranite (vertical face, dextral shearing).	Figure (803). Mylonitic pegmatite, horizontal surface, dextral shearing, includes S-C-C',	Figure (804). Mylonitic pegmatite, dextral shearing on horizontal surface.

 

Figure (820). Mylonitic petmatite (horizontal face, dextral shearing).	Figure (808). Mylonite.	Figure (809). Mylonitic pegmatite, dextral shearing on horizontal surface.

 

Figure (806). Sheared K-feldspar.	Figure (814 miranda). Shear folds in fine-grained mylonitic leucogranite and in layered amphibolite.

 

Figure (814_miranda2) detail of right-hand-side of photo above.	Figure (814) detail of left-hand-side of photo above.

 

g) Png 12: a few hundred meters East of Png10, biotite-psammite in contact with marble

 

Figure (827). Mylonitic marble on the NE side of the Tangtse valley along the Pangong strand of the shear zone, characterized by fine layering, dipping SE (photo 825).	Figure (826). Strong stretching-scratch lineation plunging gently SW. Vertical exposure.	Figure (825). Mylonitic base of marble layer, characterized by a 1m thick quartz-rich marble forming pods.

 

h) Png40, N 33 59'45.8" E 78 20'23.6":
greenschist facies overprinting amphibolite facies rocks during dextral shearing.

 

Figure (1098). Stretching lineation plunging gently (5-10 degrees)  to SE (right-hand-side), on mylonites.	Figure (1101). Greenschist facies overprint of amphibolites during dextral shearing.	Figure (1105). Dextral shearing on grenschist (chlorite+tremolite).

 

Figure (1110). Dextral shearing, S-C-C' (C' can be seen as a diagonal band from the upper center to the upper right).	Figure (1113). Sinistral fish comprised of amphibole aggregates (exception to the otherwise dominant dextral shearing).	Figure (093). Greenschist facies overprint of sigmoidal amphibolites.

 

Figure (082) Block showing shear folding in banded amphibolite.

 

Figure (864) Interlayered and strongly sheared contact between amphibolite to the left (NE) and marble to the right (SW). Add coordinates.

 

h) Pangong Fold

Figure (P8290173). The "Pangong Fold". Bedding is folded from steep to moderately dipping to the SW (upper part of photo). Simultaneously the strike changes from 140 to 90. View looking ESE from Tangtse valley close to Lukung towards Pangong Tso.		Figure (P8290171).  The "Pangong Fold" where bedding, parallel to a mylonitic foliation turns from dipping to the NE to dipping SW and from striking 140 to 90. View looking ESE from Tangtse valley close to Lukung towards Pangong Tso.

 

Figure (858). View close to Lukung to NW along the main Tangtse valley, parallel to the Karakoram Shear Zone, 320. To the SW (left-hand-side) bedding parallel to mylonitic foliation dips 45SW, whereas the NE (right-hand-side) ditto dips 45 to the NE. The two photos below detail aspects of the right-hand, NE side of the valley. A similar fold was documented at Lomo Yogma, 20km SE of Agham.

 

Figure (P8280146). Looking NW along the NE side of the valley (right-hand-side of  preivous image). In the foreground at the level of the valley,  mylonitic foliation parallel to bedding is vertial. In the background in the higher altitudes limestone and other beds dip moderatly to the NE.	Figure (850). Detail of top right corner of photo to the left. The two lower marble layers (light brown) widen to the right,  where they merge defining an isoclinal fold (hinge zone mapped to the right of the fold). The top marble layer is surrounded by schists and either defines a fold closure or the edge of a thick pod of limestone.

 

i) Giant Fish , Png47, N33 58' 13.0" E78 24' 04.8"

Figure (1071_reworked2). Giant fish of amphibolite blocks in marble in a vertical wall close to the Pangong Lake. The fish indicate an apparent thrusting, but the actual movement is oblique (dominantly dextral with a thrusting component). This is then overprinted by sinistral shearing, but this later straining did not modifiy the fish shape recorded by the competent amphibolite blocks. The presence of thick packages of marble differentiates this sequence known as the Karakoram Metamorphic Complex from the Pangong Metamorphic Complex. Dominant C-plane: N90E/60S and stretching lineation plunges 100/15. The vertical wall trends 150. Photo looking WNW.

Figure (1074_reworked). b) detail of a.

j) Pangong Tso, near Phobrang:
bedding and mylonitic foliation trending E-W, dipping 45-60 S, and sinistral shearing overprinting dextral.
Overprinting relationships in ph 1024.
N33 58'31.8" E78" 24'39.5"

 

Figure (1033). Asymmetric fold indicating, marked by the break up of the more competent marble layer in a pelite. The S- asymmetry is indicative of sinistral shearing. Fold axis at high angle to stretching lineation. Photo down-plunge of fold axis (195/25) and close to parallel to stretching lineation (110/20).	Figure (1024). Asymmetric fold on the left-hand-side indicative of sinistral shearing. On the right a drag fold over-riding a fault indicative of dextral shearing.

 

Figure (1027). Marble with a 0.5cm delta clast (upper right-hand-side), and small fish of quartz (right of the coin), both indicative of sinistral shearing. Bottom right: quartz vein thrust to left. Photograph at high angle to foliation and parallel to lineation.	Figure (1034).Disrupted quartz vein and asymmetric S-fold at the base of the photo indicative of sinistral shearing. Main mylonitic foliation: N77E/45S.

 

Figure (1044). Sinistral asymmetry of pods in marble. Photograph at high angle to foliation and parallel to lineation.

 

Figure (1046). 33 58' 25.0" E78 24'29.3" Dextral slip plane (diagonal plane from upper left to lower centre) separating two pods of a continuous pegmatitic dyke in biotite-psammite. The dextral plane develops as a result of sinistral shearing of a dyke originally trending obliquely across the shear plane. The dextral shear zone accommodates  anticlockwise rotation of the blocks comprising the vein.

Figure (1048) . Detail of 1046. S-C fabric inside the pod is dextral, indicative of an early dextral event.

 

Figure (1051). Same outcrop as 1046-48. Sinistral shearing on pegmatitic rocks, side by side with dextral shearing in photo 1048). Crenulation lineation almost at right angles to stretching lineation. L stretching= 100/10, L cren = 195/46	Figure (1053)  Same outcrop as 1046-48. Dextral shearing in the vicinity of sinistral shearing shown in photo 1051.

 

Figure (1060) . Large scale S-asymmetry indicative of sinistral shearing (?). Fold axis (180/ moderate plunge) at high angle to stretching axis (110/ shallow plunge). Notice road for scale at the bottom of the photo.	Figure (1055). Detail of 1060.

 

Figure. Stereonet showing the dominant C plane= 100 / 60 S with sinistral shearing on gently plunging lineation.