Extension of achankovil shear zone, southern granulite. The main arguments in support of the presence of shear zone are. Pdf shear lineaments analysis of ambasamudramtenkasi. Cauvery shear zone pcsz in the north, and the wnw ese trending achankovil thenmalai shear zone atsz in the south. Recent repeated occurrences of gas bubbles streaming water.
Deep electrical signatures across the achankovil shear. The later nwse sinistral achankovil shears are found overprinted on the earlier shear system. The application of single zircon evaporation and model nd. You can either select the files you want to merge from you computer or drop them on the app using drag. Implications for ultrahightemperature metamorphism. Crustal structure and tectonics of the northern part of. The derived model shows distinct high electrical resistivity. It coincides with the boundary between charnockites of the madurai block to the north and khondalites of the trivandrum block to the south, and with a major change in the aeromagnetic pattern that can be traced across southern india. The associated minor shears are moyar shear zone, bhavani shear zone, dharmapurimettur shear zone, chennimalai shear zone, dharquram shear zone and devatturkallimandayam shear zone. Kinematic analysis of ductile and brittleductile shear zones in. Inset map shows configuration of india and madagascar as part of east gondwana.
The achankovil shear zone aksz is a nwse trending ductile shear zone passing through the southern granulite terrain sgt has remained enigmatic among scientific community for the perspective of shear zone status and extension. Metamorphism and fluid inclusion studies of charnockites. Gravity signatures, derived crustal structure and tectonics of achankovil shear zone. The technique of single zircon dating from the thermal evaporation of 207pb206pb kober 1986, 1987 provides a means of dating successive periods of growth and nucleation of zircons in polymetamorphic assemblages. The achankovil shear system is one of the major crustal scale structures in peninsular india. Kinematic and textural analyses of the rocks in the shear zone indicate primarily a dextral shear sense sacks et al. This zone has a lateral extension of 120 km and its width varies within 1020 km and passes through the states of kerala and tamil nadu in a wnw ese direction. Earth evolution sciences, graduate school of life and environmental sciences, university of tsukuba. An excellent correlation of structural trends exists on all scales of observation. Pdf geology of the achankovil shear zone, southern india. In this, the very important shear zone is achankoil shear zone. The wnwese trending achankovil shear zone asz in southern india is a major crustal discontinuity of proterozoic age which separates kerala khondalite belt kkb in the south from the charnockite massif in the north. The study aims to determine the kinematics of shear zones of the area and. Author links open overlay panel hisako shimizu a toshiaki.
Two periods of charnockitic magma intrusion during d2 and d3 deformations are. Achankovil shear zone of tirunelveli regions revisited to examine the charnockitisation processes of this region. Request pdf structure and tectonics of the achankovil shear zone, southern india an integrated approach to resolve the kinematics of the controversial achankovil shear zone aksz has been. Asz is a weak zone of proterozoic age with panafrican traces2. To the west, the area is bound by the west coast fault wcf which late mesozoic rifting, deccan trap. Age and tectonic evolution of neoproterozoic ductile shear. This nwse trending shear zone stretches across the western ghats for a strike length of 120 km. These shear zones are now known as 1 the moyarattur shear zone, 2 the bhavani shear zone, 3 the palghat cauvery shear zone pcsz, and 4 the achankovil shear zone. A dextral sense of shear was proposed for most of the shears. Pdf drainage development in achankovil shear zone, south. The northern end of the shear zone is characterized by the chengannur granitic pluton.
Read geology of the achankovil shear zone, southern india, gondwana research on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Achankovil shearzone,a manifestation of the forthcoming major seismotectonic activities of indian plate. A pdf version of this document can be downloaded from. How to combine files into a pdf adobe acrobat dc tutorials. Geology of the achankovil shear zone, southern india. Field investigations reveal a major shear zone along the. Mettur shear zone mtsz and achankovil shear zone acsz as shown in figure 2. International science congress association 1 shear lineaments analysis of ambasamudramtenkasi transect of achankovil tambraparani shear zone, south india manimaran g. The ranotsara zone has been correlated with various ductile shear zones in southern india, e. Shear zones and deformation mechanisms introduction. Dunite, glimmerite and spinellite in achankovil shear zone.
In contrast nd model ages may provide a measure of the period of crustal residency for the sample or its protolith. This shear zone dips steeply sw with a ehange in strike from. Multi panafrican shearing along nwse to wnwese achankoil tambraparni shear ats zone and its contiguous and parallel tenmalaigatana shear tgs of south india and their associated shear features are reported. Structure and tectonics of the achankovil shear zone. Volume 36, issues 23, 20 september 2009, pages 209222. This webapp provides a simple way to merge pdf files. A shear zone is a zone of strong deformation with a high strain rate surrounded by rocks with a lower state of finite strain. The achankovil tambraparni shear zone ats is an 8 to 45 km wide tectonic zone trending wnwese to nwse direction and running across the southern end of the sgt. Also, you can add more pdfs to combine them and merge them into.
An integrated approach to resolve the kinematics of the controversial achankovil shear zone aksz has been attempted involving remote sensing data, shaded relief topomaps, ground details of lithology and mesoscopic structures. Shear zones, also sometimes called ductile faults, are intensely strained. It is characterised by a length to width ratio of more than 5. The northern bergen are shear zone an obliquelateral ramp in the. The area is a part of achankovil shear zone of sinistral nature. The minimum displacement on the bergen are shear zone is approximately 16 km, with a normal dip slip eomponent of. Many studies were carried out to understand the origin and delineation of this structure. We combine isotopic and trace element geochemistry of major and accessory phases with phase equilibria modelling to provide quantitative constraints on the timing and conditions of peak metamorphism and the nature of. Palghatcauvery shear zone and achankovil shear zone fig.
Preliminary study on tectonic strain pattern of granites. Dharmapurimettur shear zone is termed as the dhanmuri suture rift zone by. These studies have identified major shear zones within sisr namely palghat cavery shear zone pcsz mayar bhavani shear zone mbsz. Many of these shear zones contain recrystallized cataclastic rocks, foliation and lineation parallel to the shears drury et al. Two minor tributaries nampakkad rhodu and kodumon thodu join the aehankovil river in. Volume issue ovember iss o 5 environment epiphytic. The role of the ranotsara zone in southern madagascar for. The achankovil zone of southern india forms a distinct isotopic and structural boundary separating the madurai block to the north from the trivandrum block to the south.
Shear zones form a continuum of geological structures, ranging from brittle shear zones or faults via brittleductile shear zones or semibrittle shear zones, ductilebrittle to ductile shear zones. Threedimensional lithospheric electrical structure of. In this section we will look at the most highly strained rocks in the lithosphere those found in shear zones. The region of northern kerala is characterized by one such shearlfault zone. To the south of this suture is the madurai block, considered as a longlived neoproterozoic magmatic arc santosh et al. Choose from a variety of file types multiple pdf files, microsoft word documents, microsoft excel spreadsheets, microsoft powerpoint. Pdf multiphase shear features of panafrican shearing. In the case of faults and shear zones, they are interested to understand their. The study area is situated in southern western ghats, part of the kollam district, about 40 km east of the punalur and 30 km west of the shenkottai, tamil nadu. A number of parallel lineaments demarcate this 1520 km wide shear zone. Shear lineaments analysis of ambasamudramtenkasi transect of achankovil tambraparani shear zone, south india. Paleoposition of india and madagascar at 500 ma in the gondwanaland assembly modified after rekha et al.
Pdf gravity signatures, derived crustal structure and. About 25 km of the mainstream and 16 km of the kallar tributary are blanketed by alluvial sediments rich in boulders, cobbles and gravel in the upper part and gravelly sand in the lower part. This free online tool allows to combine multiple pdf or image files into a single pdf document. By dragging your pages in the editor area you can rearrange them or delete single pages.
Introduction the achankovil shear zone is a well deciphered lineament of 825 km width on landsat imageries and aerial photos mosaic trending wnwese to nwse direction and it. As we will show in the following, our results put the ranotsara shear zone in a different perspective. Generalized geologic map of southern kerala showing the distribution of various lithologies and the achankovil shear zone modi. Several mechanisms are discussed, which might combine to see the strength of the deforming rock to decrease with strain and produce shear zones.
Microstructurally controlled monazite chronology of. Dextral panafrican shear along the southwestern edge of. Morphoecotypes of endemic flowering plants from achankovil shear zone in agasthyamalai biosphere reserve, western ghats, kerala. Gravity signatures, derived crustal structure and tectonics of achankovil shear zone, southern india. Zone msz and bhavani shear zone bsz in the west merge together and form the moyarbhavani shear zone mbsz. Of these, the madurai block is located between the palghatcauvary shear zone in the north chetty and bhaskar rao, 2006.