We document the stratigraphy and provenance of the lower Tertiary terrigenous sections in the Zhepure Shan region of the Tethyan Himalaya, southern Tibet, using petrographic and geochemical whole‐rock and single‐grain techniques. The Cretaceous–early Tertiary shelf deposits of shallow marine carbonates and siliciclastics of the former Indian passive margin near the western end of the Zhepure Shan are conformably overlain by lower Tertiary clastic rocks. Sandstones in the Jidula Formation (Paleocene) mostly contain monocrystalline quartz grains of cratonic origin. In contrast, significant amounts of immature framework grains with a distinct ophiolitic and volcanic arc influence are present in the Youxia (Early Eocene) and Shenkeza (post–Early Eocene) formations. Major, trace, and rare earth element concentrations in both sandstones and shales complement the petrographic data and indicate that the source of the Jidula Formation consisted primarily of quartzose basement rocks, probably of Indian continental origin, whereas the sediments of the Youxia Formation were mainly derived from the uplifted Gangdese arc‐trench system associated with the obduction of the Asian subduction complex. The compositions of Cr‐rich spinels in the Youxia and Shenkeza sandstones resemble those from fore‐arc peridotites and were most likely derived from the arc and ophiolite rocks along the developing Yarlung‐Zangbo suture to the north. No spinels have been observed in the Jidula sandstones. Therefore, the early Tertiary detrital clastics in the Zhepure Shan record a marked change in provenance and sediment character and specifically at the time of deposition of the Youxia Formation, which contains a zone P‐8 foram assemblage. This change indicates that the onset of India‐Asia collision and the first development of the foreland basin immediately south of the India‐Asia suture zone occurred at $$50.6\pm 0.2$$ Ma in the both the western (Zanskar) and eastern (this study) Tethyan Himalaya.
Research Article| September 01, 1992 Nyainqentanglha shear zone: A late Miocene extensional detachment in the southern Tibetan Plateau Y. Pan; Y. Pan 1Department of Geological Sciences, State University of New York, Albany, New York 12222 Search for other works by this author on: GSW Google Scholar W.S.F. Kidd W.S.F. Kidd 1Department of Geological Sciences, State University of New York, Albany, New York 12222 Search for other works by this author on: GSW Google Scholar Author and Article Information Y. Pan 1Department of Geological Sciences, State University of New York, Albany, New York 12222 W.S.F. Kidd 1Department of Geological Sciences, State University of New York, Albany, New York 12222 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1992) 20 (9): 775–778. https://doi.org/10.1130/0091-7613(1992)020<0775:NSZALM>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Y. Pan, W.S.F. Kidd; Nyainqentanglha shear zone: A late Miocene extensional detachment in the southern Tibetan Plateau. Geology 1992;; 20 (9): 775–778. doi: https://doi.org/10.1130/0091-7613(1992)020<0775:NSZALM>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract A major low-angle ductile shear zone containing S-C mylonites involves metamorphosed granitic rocks at the southeastern edge of the Nyainqentanglha mountain range, southern Tibet. Prominent triangular facet geomorphology is developed by valley erosion of the detachment surface, defined by the top of the southeast-dipping mylonitec shear zone. Kinematic criteria consistently indicate a top-to-southeast sense of shear. The ductile shearing deformation is inferred, from isotopic cooling ages, to have occurred during the interval 11-5 Ma (late Miocene). We interpret the shear zone as a regional extensional detachment; its development indicates when the extensional tectonics in this area started, which in turn may mark the time when the maximum sustainable surface elevation, and perhaps crustal thickness, was reached in southern Tibet. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
content over the entire stratigraphic limits of the Muncho-McConnell, Stone interval is a meaningless exercise within the context of this discussion -breccias do occur within sandy dolomite beds containing more than 30% by weight of quartz sand and it appears to us that special pleading is required if only the quartz sand-free beds are to be dissolved; (3) corrosion, solution, and resultant insoluble residue or deposits are not ruled out by a fracture mechanism, but the quantity of such lags is expected to be small (as is the case at Robb Lake) and not comparable in quantity, or areal extent with lag deposits associated with well-documented solution-collapse terranes such as those described by Sando (1974); (4) Figures 8 and 9 together with the accompanying discussion (Macqueen and Thompson 1978, pp. 1751-1752) demonstrate large scale geological relations that are not fully explained by a solution-collapse mechanism; (5) we did not make a direct comparison with the work of Phillips (1972) and we do not accept Sangster's (1979) contention that the geological relationships described by Phillips (1972) constitute the necessary and limiting conditions for a fracture mechanism to be operative; and (6) we suggested r? hydraulic fracturing mechanism as a pussihle alternative that meets the criteria set out on p. 1752 (Macqueen and Thompson 1978) as well as providing greater flexibility with regard to the timing of brecciation. We leave Si~ngster with the dilemma of timing: the occurrence of bitumen within the breccia matrix suggests breccia matrices may have been open long after deposition of the
Summary We use the tectonics of Eastern Anatolia to exemplify many of the different aspects of collision tectonics, namely the formation of plateaux, thrust belts, foreland flexures, widespread foreland/hinterland deformation zones and orogenic collapse/distension zones. Eastern Anatolia is a 2 km high plateau bounded to the S by the southward-verging Bitlis Thrust Zone and to the N by the Pontide/Minor Caucasus Zone. It has developed as the surface expression of a zone of progressively thickening crust beginning about 12 Ma in the medial Miocene and has resulted from the squeezing and shortening of Eastern Anatolia between the Arabian and European Plates following the Serravallian demise of the last oceanic or quasioceanic tract between Arabia and Eurasia. Thickening of the crust to about 52 km has been accompanied by major strike-slip faulting on the right-lateral N Anatolian Transform Fault (NATF) and the left-lateral E Anatolian Transform Fault (EATF) which approximately bound an Anatolian Wedge that is being driven westwards to override the oceanic lithosphere of the Mediterranean along subduction zones from Cephalonia to Crete, and Rhodes to Cyprus. This neotectonic regime began about 12 Ma in Late Serravallian times with uplift from wide-spread littoral/neritic marine conditions to open seasonal wooded savanna with colluvial, fluvial and limnic environments, and the deposition of the thick Tortonian Kythrean Flysch in the Eastern Mediterranean. Earthquake hypocentres are scattered throughout the region but large earthquakes are concentrated mainly on the major faults and are mostly shallow, supporting the idea of a brittle elastic lid with hypocentres concentrated towards its base with more ductile deformation in the middle and lower crust. Neotectonic magmatic suites are nepheline-hypersthene normative alkali basalts of mantle origin, and silicic/intermediate/mafic calcalkaline suites, both suites occurring in pull-apart basins in strike-slip regimes and along N-S extensional fissures, and both suites showing a strong change to central activity in the Pliocene. Upper-crustal strains appear to be discontinuous in space and time, with zones of strong shortening representing shoaling of crustal detachment zones flattening between 5 and 10 km. Approximately NW- (dextral) and NE- (sinistral) trending lineaments bound less deformed wedges (low relief seismically ‘dead’ areas) and vary from simple strike-slip faults to complicated braided transform-flake boundaries with pull-apart and compressional segments (N and E Anatolian Transform Faults). Volcanoes lie in grabens on N-S ‘cracks’ that extend into the Arabian Foreland and in transcurrent pull-aparts. Major extensional basins lie at plate (Adana) and flake (Karliova) triple junctions and result from compatibility problems.
Research Article| January 01, 1992 Remnants of an Archean oceanic plateau, Belingwe greenstone belt, Zimbabwe T. M. Kusky; T. M. Kusky 1Department of Geosciences and Allied Geophysical Laboratories, University of Houston, Houston, Texas 77204-5503 Search for other works by this author on: GSW Google Scholar W.S.F. Kidd W.S.F. Kidd 2Department of Geological Sciences, State University of New York at Albany, 1400 Washington Avenue, Albany, New York 12222 Search for other works by this author on: GSW Google Scholar Author and Article Information T. M. Kusky 1Department of Geosciences and Allied Geophysical Laboratories, University of Houston, Houston, Texas 77204-5503 W.S.F. Kidd 2Department of Geological Sciences, State University of New York at Albany, 1400 Washington Avenue, Albany, New York 12222 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1992) 20 (1): 43–46. https://doi.org/10.1130/0091-7613(1992)020<0043:ROAAOP>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation T. M. Kusky, W.S.F. Kidd; Remnants of an Archean oceanic plateau, Belingwe greenstone belt, Zimbabwe. Geology 1992;; 20 (1): 43–46. doi: https://doi.org/10.1130/0091-7613(1992)020<0043:ROAAOP>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Stratigraphic and structural data from the Archean Zimbabwe craton suggest that a major detachment surface exists within the Belingwe greenstone belt. The surface separates ultramafic and mafic magmatic rocks of the upper greenstones in the hanging wall from an ancient gneiss complex, older volcanic-sedimentary rocks, and a shallow-water sedimentary sequence in the footwall. Rocks dated at ca. 2.7 Ga above the detachment surface form the proposed Mberengwa allochthon. The regionally extensive upper greenstone succession represents tectonically emplaced allochthonous sheets, not indigenous magmas erupted within autochthonous continental rifts. Magmatic rocks of the Mberengwa allochthon resemble oceanic plateaus preserved in younger mountain belts. Comparison of the Zimbabwe craton with the Proterozoic Birrimian terranes of west Africa leads us to suggest that Precambrian continental growth may have been characterized by intense structural imbrication related to the difficulty of subduction of buoyant oceanic lithosphere. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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