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Late Cretaceous, Synorogenic, Low-Angle Normal Faulting Along The

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TECTONOPHYSICS ELSEVIER Tectonophysics280 (1997) 261-293 Late Cretaceous,synorogenic, low-angle normal faulting alongthe Schlinig fault (Switzerland,Italy, Austria) and its signiflcancefor the tectonicsof the EasternAlps N. Froitzheim*,P. Contil, M. vanDaalen Geologisch-Palcirttologisches Instttut, Universität Basel, BemoLilistr 32, CH-1056 Basel, Swit:erland Received9 July 1996t accepted10 February 1997 Abstract The Schlinig fault at the western border of the Ötztal nappe (EasternAlps), previously interpretedas a west-directed thrust, actually representsa Late Cretaceous,top-SE to -ESE normal fault, as indicated by sense-of-shearcriteria found within cataclasitesand greenschist-facies'mylonites.Normal faulting postdated and oflset an earlieq Cretacedus-age, west-directedthrust at the baseof the Ötztal nappe. Shapefabric and crystallographicpreferred orientation in completely recrystallizedquarlz layers in a mylonite from the Schlinig fault record a combination of (1) top-easrsoutheastsimple shear during Late Cretaceous normal faulting, and (2) later north-northeast-directedshortening during the Early Tertiary, also recordedby open folds on the outcrop and map scale.Offset of the basalthrust of the Ötztal nappeacross the Schlinig fault indicatesa normal displacementof l7 km. The fault was initiated with a dip angle of 10'to 15" (low-angie normal fault). Domino-style extension of the competentLate Triassic Hauptdolomit in the footwall was kinematically linked to normal faulting. The Schlinig fault belongs to a system of east- to southeast-dippingnormal faults which accommodatedsevere stretchingof the Alpine orogen during the Late Cretaceous.The slip direction of extensionalfaults often parallels the direction of earlier thrusting (top-W to top-NW), only the slip senseis reversedand the normal faults are slightly steeper than the thrusts.In the western Austroalpine nappes,extension stafied at about 80 Ma and was coeval with subduction of Piemont-Ligurian oceanic lithosphere and continental fragments farther west. The extensional episode led to the formation of AustroalpineGosau basins with fluviatile to deep-marinesediments. West-directed rollback of an east-dipping Piemont-Ligurian subductionzone is proposedto have causedthis stretchingin the upperplate. Ket'*-ords:tectonics; synorogenic extension; low-angle normal fault; Alps; Austroalpine 1. Introduction nappeabove and Mesozoic sedimentaryrocks of the Engadinedolomites (S-charl nappe) below (Fig. 1). The Schlinig fault is the shallowly dippingcon- It has gained some fame in the Alpine literature ^. tact between pre-Mesozoic basementoI the (Jtztal becauseit is spectacularlyexposed, shows the su- perposition of basementon sedimentaryrocks in a *Conesponding text-book manner, and has given rise ro different author. Fax: *41 61 267-3613. E-mail: interpretations controversiesamong Alpine ge- froitzheim@ ubaclu.unibas.ch and 'Present address:Drrezione Rilevamento,Via Nuoro 3, 09046 ologists. The kinematics and age of this fault are Srn Vito iCAt. ltaly. not only of local interest but greatly affect the tec- 00.10-1951/97l$17.00O 1997Elsevier Science B.V All riehtsreserved P/1S0040- | 9 5 1( 97)0003 7- 1 t N. FroitzheützeI al./Tectonophysics280 (1997) 267-293 m Valaisbasin, European margin . ] fffi Briangonnais , tl Piemont-Lrguria basrn I ]f] Apulian margin 1oo km LANDECK Brenner -...l Mesozoic .lauernJ// / Steinach window öt zta I ,/ ,/ ,/ I/,/,' Brenner 7- SchlinisJfault S-charl cover I Upper ba sementj Austroalpine schgau Lower Austroalpine ar zone Southern Alps Penninic units Helvetic Ca m p o Tertiary intrusives { \< lertlary normal rault <'--4 ,, G iudicari thrust Adamello {-< Cretaceous normal 1. " thrust O 1O 20 30km ;ig. 1. Tectonic overview of the westernpart of the Eastem Alps. Inset: sketch map of the Alps showing palaeogeographicprovenance of tectonic units. ,4.1H: Meliata-Hallstatt unitsl S : Schlinig fault ZG : Zentralgneiss. tonic interpretation of the westerx part of the Aus- ward thrustingalong the Schlinig fault. Both authors troalpine nappe system. Hammer (1908) and Spitz assumedthat at least the late stagesof thrusting oc- and Dyhrenfurth( 1914) interpretedthe Schlinig fault curred in the Tertiary period, postdating earlier, Late as a W- to WNW-directed thrust of the Ötztal mass Cretaceousdeformation and metamorphism,because over the Engadine dolomites. They were cnticized the Schlinig fault truncatedearly folds of the Enga- by Heim (1922) who postulated that the thrust- dine dolomites and disturbed the zonation of Cre- ing was directed northward. Trümpy (1980) and taceous-agemetamorphism (Thöni, 1980a).Schmid Thöni (1980a). among others, again inferred west- and Haas (1989) studied an east*west-trendingmy- N. Froitzheimet al. /Tectonophlslcs280 (1997) 267 293 ionite zoneat the southernborder ofthe Otztal nappe around SW-NE axes (Domleschgphase, ca.30-25 in the Vinschgau valley, the Vinschgau shear zone Ma; von Blanckenburg,1992), and dissectedby the (Fig. 1), and demonstratedthat it accommodateda Engadine line, an oblique-slip fault which accom- westward transport of the Ötztal nappe relative to modated important block rotations (Figs. I and 2; the underlying Campo nappe,during the Cretaceous. Schmid and Froitzheim, 1993). They assumedthat the Schlinig fault representedthe For this study, the following Austroalpine tectonic continuation of the Vinschgau shear zone towards units are of interest(Figs. I and 2): northwest into shallower levels of the crust. Con- (1) The Ötztal nappe largely consistsof Pre-Per- sequently, they interpreted the Schlinig fault as a mian crystailine basement.Remnants of its Permo- Cretaceous-age,top-west thrust. Mesozoic cover are preserved near the eastern bor- In the following, we will present a kinematic der of the nappe (Brenner Mesozoics). The Permo- study of the Schlinig fault between the Vinschgau Mesozoic rocks of Jaggl, often interpreted as a tec- valley to the south and the Reschenpass to the north, tonic window through the Ötztal nappe(Hess. 1962; and of its southwestwardprolongation, the Gallo Stutz and Walter, 1983),represent, according to our fault (Fig. 2). The result of this study contradictsall results, another remnant of the sedimentary cover of of the aboveinterpretations: the Schlinig fault is not the Ötztal nappe. a thrust, but a Late Cretaceous,top-southeast normal (2) The S-charl nappe. underlying the Ötztal fault postdating earlier nappe imbrication. This has nappe along the Schlinig fault, includes pre-Per- important implications for the tectonic history of the mian basement as well as Permian to Mesozoic Austroalpinenappes. cover rocks. The Permian to Middle Triassic part of the cover was folded and slightly imbricated to- 2. Regional setting getherwith the basement('S-charl-Unterbau'; Spitz and Dyhrenfufih, l9I4), whereas the Upper Trias- The study area belongs to the western Aus- sic Hauptdolomit was detachedfrom the underlying troalpine nappes. These originated from the south- rocks along the evaporite-bearing Raibl Formation, easternmargin of the Mesozoic Tethys ocean.They and deformedindependently ('S-charl-Oberbau' ). were stackedeast-over-west in Late Cretaceoustime (3) The Umbrail-Chavalatsch Schuppenzone and were later, during the Early Tertiary thrust north- (UCS) represents an imbricated stack of crystalline ward as one large thrust mass over the Penninic basementand Mesozoic,mostly Upper Triassic,sed- nappes. The iatter are exposed in the Tauem and imentary rocks (Schmid, 1973). The basementrocks Engadine windows, framed by the overlying Aus- are lithologically identical to ceftain rock types troalpine nappes.The sequenceof deformation in the of the Ötztal nappe. Within the UCS, the base- Austroalpinenappes of Graubündenwas recentlyes- ment/sedimentratio decreaseswestward. Hence, the tablishedas follows (Froitzheim et al., 1994:Fig. 3): whole UCS appearsas a zone of tectonic interfi.nger- Cretaceousdeformation includes west- to northwest- ing of the Ötztal basement, dominating to the east, directed nappe imbrication and associated folding with a stack of sediment thrust sheets to the west. (Trupchunphase, ca. 100-80 Ma), followed by ESE- The largest of these thrust sheetsis the Quattervals directed asymmetric extension of the nappe stack nappe,consisting almost exclusivelyof Upper Trias- (Ducan-Elaphase, ca. 80-67 Ma). Subsequently,in sic carbonates. To the north, the Quattervals nappe the Early Tertiary, the Austroalpine nappe stack was and the UCS overlie the S-charl nappe along the thrust northward over the Penninic nappesand folded southwest- to southeast-dipping Gallo line. In the aroundWNW-ESE axes(Blaisun phase,50-35 Ma, northern part of the study area, the Triassic rocks possibly beginning earlier). This was followed by of Piz Lad near Nauders occupy a similar posi- renewed E-W extension along the Turba mylonite tion as the sedimentary constituentsof the Umbrail- zone located at the base of the Cretaceousnappe Chavalatsch Schuppenzone (Fig. 2). To the north- stack, contemporaneouslywith north-south shorten- east, the Piz Lad sediments rest along a tectonic ing (Turba phase, ca. 35-30 Ma) (Dal Piaz et al., contact on Ötztal basement rocks. To the south, the 1988). Finally, the nappe stack was mildly folded sediments are overlain by the main mass of Ötztal 210 N. hotr:htint et al./Tectottopftr'slcs280 ( lS97) 267-293 10"30'E ötztal nappe " X JAGGL r ! + + + + + +\ nappe+ + + + + + + 10km + + + + + + + + + + + + + +(? + + \<-+L J + i _ + + t. + + + + BORMIO++ +-+ + + t+F<:+ + + + _
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  • Evolving Flexure Recorded in Continental Rift Uplifting Landscapes - Corinth Rift, Greece

    Evolving Flexure Recorded in Continental Rift Uplifting Landscapes - Corinth Rift, Greece

    [Non Peer-Reviewed Earth ArXiv Preprint – Originally submitted to Geology, preparing resubmission to GRL] Evolving flexure recorded in continental rift uplifting landscapes - Corinth Rift, Greece David Fernández-Blanco1, Gino de Gelder1, Sean Gallen2, RoBin Lacassin1 & Rolando Armijo1 1 Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Univ Paris Diderot, UMR 7154 CNRS, F-75005 Paris, France 2 GeoloGical Institute, Swiss Federal Institute of TechnoloGy (ETH), 8092 Zü rich, Switzerland Abstract Elastic flexure of the lithosphere is commonly used to model crustal mechanics, rheoloGy and dynamics. However, accurate characterizations of flexure in nature at the spatiotemporal scale of active continental riftinG (tens of km; 104-106 yr) are scant. We use exceptionally preserved Geomorphic evidence in the asymmetric, younG and fast-extendinG Corinth Rift, central Greece, to document the combined effect of proGressive uplift and footwall flexure throuGhout its upliftinG marGin. Across the rift marGin, footwall lonGitudinal river profiles and topoGraphy define uplift increasinG exponentially towards the boundinG fault. AlonG the rift marGin, geomorphic proxies for fault’s footwall relief, slip rate and uplift rate show parabolic distributions decayinG alonG strike away from the fault center. Conspicuous drainage reversals where the topoGraphic expression of elastic flexure is most prominent similarly suGGest that maximum slip rates occur at the rift center. Overall, the geomorphic evidence for flexure implies disruptive Middle Pleistocene onset of a highly-localized, master fault system of crustal scale controllinG the Growth of the modern Corinth Rift. Similar hiGhly-localized strain and associated elastic flexure of the lithosphere may have occurred elsewhere, includinG old and/or slow-extendinG rifts and areas of intracontinental extension lackinG adequate Geomorphic evidence.
  • Faulted Joints: Kinematics, Displacement±Length Scaling Relations and Criteria for Their Identi®Cation

    Faulted Joints: Kinematics, Displacement±Length Scaling Relations and Criteria for Their Identi®Cation

    Journal of Structural Geology 23 (2001) 315±327 www.elsevier.nl/locate/jstrugeo Faulted joints: kinematics, displacement±length scaling relations and criteria for their identi®cation Scott J. Wilkinsa,*, Michael R. Grossa, Michael Wackera, Yehuda Eyalb, Terry Engelderc aDepartment of Geology, Florida International University, Miami, FL 33199, USA bDepartment of Geology, Ben Gurion University, Beer Sheva 84105, Israel cDepartment of Geosciences, The Pennsylvania State University, University Park, PA 16802, USA Received 6 December 1999; accepted 6 June 2000 Abstract Structural geometries and kinematics based on two sets of joints, pinnate joints and fault striations, reveal that some mesoscale faults at Split Mountain, Utah, originated as joints. Unlike many other types of faults, displacements (D) across faulted joints do not scale with lengths (L) and therefore do not adhere to published fault scaling laws. Rather, fault size corresponds initially to original joint length, which in turn is controlled by bed thickness for bed-con®ned joints. Although faulted joints will grow in length with increasing slip, the total change in length is negligible compared to the original length, leading to an independence of D from L during early stages of joint reactivation. Therefore, attempts to predict fault length, gouge thickness, or hydrologic properties based solely upon D±L scaling laws could yield misleading results for faulted joints. Pinnate joints, distinguishable from wing cracks, developed within the dilational quadrants along faulted joints and help to constrain the kinematics of joint reactivation. q 2001 Elsevier Science Ltd. All rights reserved. 1. Introduction impact of these ªfaulted jointsº on displacement±length scaling relations and fault-slip kinematics.
  • PLANT FOSSILS in the CASSIAN BEDS and OTHER CARNIAN FORMATIONS of the SOUTHERN ALPS (ITALY) Evelyn Kustatscher1, Fabrizio Bizzar

    PLANT FOSSILS in the CASSIAN BEDS and OTHER CARNIAN FORMATIONS of the SOUTHERN ALPS (ITALY) Evelyn Kustatscher1, Fabrizio Bizzar

    ZOBODAT - www.zobodat.at Zoologisch-Botanische Datenbank/Zoological-Botanical Database Digitale Literatur/Digital Literature Zeitschrift/Journal: Geo.Alp Jahr/Year: 2011 Band/Volume: 008 Autor(en)/Author(s): Kustatscher Evelyn, Bizzarini Fabrizio, Roghi Guido Artikel/Article: Plant fossils in the Cassian Beds and other carnian formations of the southern Alps (Italy). 146-155 download unter www.biologiezentrum.at Geo.Alp, Vol. 8, S. 146–155, 2011 PLANT FOSSILS IN THE CASSIAN BEDS AND OTHER CARNIAN FORMATIONS OF THE SOUTHERN ALPS (ITALY) Evelyn Kustatscher1, Fabrizio Bizzarrini2 & Guido Roghi3 Mit 16 Abbildungen und 3 Tabellen 1 Naturmuseum Südtirol, Bindergasse 1, 39100 Bozen, Italy 2 C/o Museo Civico di Rovereto, Borgo S. Caterina 41, I-38068 Rovereto 3 Istituto di Geoscienze e Georisorse-CNR-Sezione di Padova, c/o Dipartimento di Geoscienze, Università degli Studi di Padova, Padova, Italy. Introduction Triassic macrofloras in the Southern Alps are rare, and the majority of literature data is devoted to Ladinian plants. The first plant remain from the Southern Alps, a not better defined “fern fragment”, has been illustrated by Wissmann and Münster (1841). Later, several authors mentioned and figured plant fossils from the so-called “Buchensteiner Schichten”, “Wengener Schichten” and “alpiner Muschelkalk” of the Dolomites (e.g., Mojsisovics, 1879; Ogilvie Gor- don, 1927, 1934; Leonardi, 1953; for an overview see Wachtler & van Konijnenburg-van Cittert, 2000). Only Koken (1913) indicated badly preserved plant remains from the Heiligkreuz Schichten without describing or figuring them. Outside the Dolomites, only two more localities rich in Triassic plant remains were known: the Anisian flora of Re- coaro (e.g., De Zigno, 1862; Schenk, 1868) and the Carnian flora of Raibl/Cave del Predil (e.g., Bronn, 1858; Schenk, 1866-7, Stur, 1868, 1885).