Mandy Hofmann 1, Ulf Linnemann 1 and Thomas Voigt 2. Abstract. 59: Sept 2013

Transkript

1 59: Spt 2013 Snknbrg Gsllshft für Nturforshung, Th Uppr Crtous stion t Shmilk in Sxony (Elbsndstingbirg, Grmny) synttoni sdimnttion nd invrtd ziron g popultions rvld by LA ICP MS U/Pb dt Ds Obrkrid-Profil bi Shmilk in Shsn (Elbsndstingbirg, Dutshlnd) syntktonish Sdimnttion und invrs Zirkon-Altrspopultionn offnglgt durh LA ICP MS U/Pb-Dtn Mndy Hofmnn 1, Ulf Linnmnn 1 nd Thoms Voigt 2 1 Snknbrg Nturhistorish Smmlungn Drsdn, Musum für Minrlogi und Gologi, Sktion Gohronologi, Königsbrükr Lndstrß 159, Drsdn, Grmny; mndy.hofmnn@snknbrg.d 2 Fridrih-Shillr-Univrsität Jn, Institut für Gowissnshftn, Burgwg 11, Jn, Grmny Rvision ptd 19 Jun Publishd onlin t on 10 Sptmbr Abstrt Msozoi sdimnts in Sxony r rprsntd by fw limitd ourrns of Lowr Trissi nd Middl to Uppr Jurssi dposits but minly by Uppr Crtous prdominntly lsti units filling th Elb Zon (Pitzsh 1963, Voigt & Trögr in Nibuhr t l. 2007, Trögr in Pälhn & Wltr 2008). Th lttr ons r onfind by th Lusitz Blok (prt of th Wst-Sudti Islnd) in th NE nd th Erzgbirg (prt of th Mid-Europn islnd) in th SW. Th Uppr Crtous sdimnttion in th r of th Elbsndstingbirg strts with th Uppr Cnomnin mrin trnsgrssion. Sdimnts of th Elbsndstingbirg wr dpositd in mrin nvironmnt in nrrow strit onnting northrn old Borl wtr of N NW Europ with th Tthyn wrm-wtr rs in th S. Th Wst-Sudti Islnd (Lusitz- Krkonosz High) ws th most possibl sour r for th Uppr Crtous sdimnts of th Elb Zon (Voigt 1994, Wilmsn 2011). Composition of sndstons nd onglomrts indit rosion nd rdposition of oldr sdimnts whih ovrd initilly th bsmnt of th Lusitz. W nlysd six smpls rprsnting 400 m thik sndston sussion (Shmilk, Postlwitz nd Shrmmstin formtions) of Erly Turonin to Erly Coniin g from th r round Shmilk (Elbsndstingbirg) rgrding thir U/Pb-gs of dtritl ziron grins. A signifint hng in th g sptr ours from th Uppr Turonin to th Lowr Coniin. W found suddn input of Msond Ploprotrozoi gs in th upprmost prt of th Shmilk stion tht rprsnt typil Blti gs. As th whol rgion of northrn Grmny ws ovrd by mrin Crtous sdimnts, dirt input from Blti (Sndinvi?) is impossibl. Fis distribution nd rnt invstigtions suggst tht during Middl Jurssi mjor prt of sndstons drivd from upliftd prts of Ploprotrozoi nd Msoprotrozoi units of Blti. Thrfor, w intrprt th prsntd Coniin g sptr s signl of rdpositd Middl Jurssi sndstons. Erosion of Jurssi sdimnts strtd not rlir thn Erly Coniin (highr Shrmmstin Formtion, Sndston ). Th limitd mount of. 540 M gs nd prdominn of vrisn gs in ll smpls onfirm ovring of th Cdomin bsmnt units of th Lusitz Blok by Msozoi sdimnts, originlly drivd from th Bohmin mssif during th first dpositionl yl. Th bsmnt roks of th Lusitz Blok wr not vilbl for rosion until t lst Middl to Lt Coniin tim. Furthr, our dt onfirm th invrsion of th Lusitz Blok rltiv to th Elb Zon during Lt Crtous tim s lrdy proposd by Voigt (1994). ISBN ISSN

2 M. Hofmnn t l.: Th Uppr Crtous stion t Shmilk in Sxony (Elbsndstingbirg, Grmny) Kurzfssung Msozoish Sdimnt sind in Shsn durh wnig vrinzlt Vorkommn dr untrn Tris und ds mittlrn bis obrn Jur in dr Umrndung ds Lusitzr Mssivs vrtrtn. Dn Huptntil bildn br di obrkrtzishn vorwignd klstishn Einhitn, wlh in dr Elbtl-Grupp zusmmngfsst sind und ds Elbtl usfülln (Pitzsh 1963, Voigt & Trögr in Nibuhr t l. 2007, Trögr in Pälhn & Wltr 2008). Dis wrdn im NE durh dn Lusitz-Blok (ls Til dr Wstsudtish Insl) und im SW durh ds Erzgbirg (ls Til dr Mittluropäishn Insl) bgrnzt. Di obrkrtzish Sdimnttion im Elbsndstingbirg bginnt mit dr obrnomnn Trnsgrssion. Di hir diskutirtn Sndstin wurdn in inm ngn Mrsrm bglgrt, wlhr ds kältr borl Nordmr mit dr südlihn wärmrn Tthys vrbnd (Wilmsn t l. 2011). Di Wstsudtish Insl (Lusitz-Risngbirg Blok) stllt ds Huptlifrgbit für di obrkrtzishn Sdimnt dr Elbzon dr (Voigt 1994, Wilmsn 2011). Di Zusmmnstzung dr Sndstin und Konglomrt lgt nh, dss dr Lusitz-Blok ls in Til dr Wstsudtishn Insl mit Sdimntn bdkt wr, wlh währnd dr Obrkrid rodirt wurdn. Wir nlysirtn shs Sndstinprobn us dm Gbit um Shmilk (Elbsndstingbirg) hinsihtlih ihrr U/Pb-Altr dtritishr Zirkon. Di tw 400 m mähtig Abfolg (Shmilk-, Postlwitz- und Shrmmstin-Formtion) rpräsntirt ds Untr Turon bis Untr Coni. Es gibt in uffällig Vrändrung dr Altrssprktrn vom spätn Turon bis ins früh Coni. Wir fndn inn plötzlihn Eintrg mso- und pläoprotrozoishr Altr im obrstn Nivu dr Shmilk-Sndstinbfolg. Dis Altr sind typish für in Bltik-Hrkunft. D br gnz Norddutshlnd währnd dr Obrkrid von Mr bdkt wr, ist in dirkt Lifrung von Blti (Skndinvin) usgshlossn. Di Fzisvrtilung und nust Provninzstudin indizirn, dss währnd ds Mittlrn Jur in großr Til dr Sndstin us ghobnn Einhitn Bltiks hrzulitn ist. Dshlb intrprtirn wir ds Altrsspktrum ls Widrufrbitung jurssishr Sndstin. Di Erosion disr Jur-Sdimnt uf dm Lusitz-Blok bgnn rst im Untroni (höhr Shrmmstin- Formtion, Sndstin ). Di gringn Mngn n 540 M ltn Zirkonn in lln Probn und di Vorhrrshft von vriszishn Altrn, di für ds Böhmish Mssiv typish sind, bstätign, dss ds domish Grundgbirg ds Lusitz-Bloks von Sdimntn bdkt wr, di im rstn Ablgrungszyklus vom Böhmishn Mssiv glifrt wurdn. Di Grundgbirgsinhitn stndn niht vor dm untrn Coni (vrmutlih rst spätr) n dr Obrfläh n. Di Untrsuhungn bstätign di Invrsion ds Lusitzr Mssivs in dr spätn Obrkrid (Voigt 1994). 1. Introdution nd gologil stting Aprt from som sttrd ourrns of Lowr Trissi in som shllow synlins nd Zhstin to Uppr Jurssi t th mrgins of th Lusitz Blok, Uppr Crtous sdimnts rprsnt th mjor prt of Msozoi dposits in Sxony. Thy r minly rstritd to th Elb Zon nd rprsnt th subsidn xis of th xtndd Bohmin Crtous bsin whih ovrs th Bohmin Mssif in th Czh Rpublik. In th Elbsndstingbirg sdimnts rng from th Middl Cnomnin to th Lowr Coniin nd wr summrizd s Elbtl Group. Thiknss nd fis distribution indit synttoni dposition in th front of n uplifting sour r (Pitzsh 1963, Voigt 1994, Trögr in Pälhn & Wltr 2008) Msozoi sdimnttion in Sxony Jurssi nd Trissi sdimnts r only known from vry fw lolitis, but ths sttrd rmnnts support th ssumption tht thr hd bn Trissi s wll s Jurssi ovr on th pr-msozoi bsmnt of Sxony (.g. Trögr in Pälhn & Wltr 2008). Trissi sdimnts show th sm hrtristis s th vry uniform bsin-fill of th Trissi Grmni Bsin. Th lowr Trissi tim is hrtrizd by ontinntl rd bds (Buntsndstin). Sdimnts r only known from drill hols in northstrn Sxony (Sprmbrg-Wißwssr, Lusitz Blok) nd from som ourrns in wstrn (Zitz- Shmölln Synlin) nd northrn (Mügln nd Dübn- Mühlbrg Synlin) Sxony (Pitzsh 1963, Frib in Pälhn & Wltr 2008). Additionlly, Lowr Trissi sndstons of limitd thiknss r xposd in th ntrl prt of th Elbzon round Mißn. Jurssi sdimnts in Sxony r vn rrr thn th Trissi ons nd only known from som ourrns long th Lusitz Thrust (Trögr in Pälhn & Wltr 2008), whr thy undrli Uppr Crtous dposits nd got inorportd into th prtly ovrturnd sdimnts long th thrust (Fig. 1). Sdimnttion strtd in th Middl to Lt Jurssi, s t this tim th mrin trnsgrssion rhd th r of tody s Sxony. A gnrl fining trnd is obsrvd in th sdimntry rord, forming sussion tht grds from snd- into silt- nd limstons (ording to Cott 1838 in Pitzsh 1963: 360). Erlir invstigtions proposd nrrow s strit in th Elbzon but plgi limstons nd mrls point to n xtndd shllow bsin t lst during Lt Jurssi. Th Lt Jurssi to Erly Crtous tim is hrtrizd by widsprd nd xtnsiv rosion. This ld to gnrl subsidn nd is ssumd to xplin th trnsgrssion of Cnomnin dposits on th mtmorphi bsmnt of th Erzgbirg nd th Elb Zon (Trögr in Pälhn & Wltr 2008). A first trnsgrssion hppnd during th Erly Cnomnin (Mißn Form- 102

3 GEOLOGICA SAXONICA 59: 2013 tion), but did not rh th r of th Elbsndstingbirg. Aftr fluvil phs nw trnsgrssion during th Lt Cnomnin strongly inflund th whol r inluding ll sdimnts of th Elb Zon (Voigt & Trögr in Nibuhr t l. 2007). Thrfor, sdimnt umultion nd subsidn in th Elbzon strtd not bfor Cnomnin. Th Uppr Crtous sdimnts in th surroundings of th Lusitz Blok r minly rstritd to th northrn mrgin of th Lusitz nd th Elb Zon but ovrd lso th strn Erzgbirg (Trögr in Pälhn & Wltr 2008). Th Mißn Formtion (mrin) ontins th oldst sdimnts of th Elbtl Group. Th fluvil dposits of th Nidrshön Formtion rprsnt th hronologil nxt unit, whih is followd gin by mrin sdimnts du to th Middl to Lt Cnomnin trnsgrssion. During this sond trnsgrssion th sndstons of th Elbsndstingbirg whr dpositd (Obrhäslih, Shmilk, Postlwitz, nd Shrmmstin formtions). Sdimnttion ontinud t lst until th Sntonin in th Bohmin Crtous, but ths youngst dposits wr not prsrvd in Sxony. Sdimnttion ourrd in nrrow s strit onnting th old Borl of N NW Europ with th wrm Tthyn rs in th S. This strit ws onfind by th Mid-Europn Islnd omprising th Bohmin Mssif in th SW nd th Wst-Sudti Islnd inluding th Lusitz Blok in th NE (Trögr 1964, Wilmsn t l. 2011). Thrfor, th Erzgbirg (Bohmin Mssif, prt of th Mid-Europn Islnd) nd th Lusitz Blok (prt of th Wst-Sudti Islnd) r likly sour rs for th Crtous sdimnts in Sxony. Du to ttoni tivity nd th dvlopmnt of th Lusitz Thrust, th r btwn ths two islnds volvd s n symmtri bsin (mrginl trough) dpning towrds th Lusitz Blok (Voigt 1994). Thiknss mps of th Uppr Cnomnin sdimnts show first vidn of diffrntil subsidn du to th ttoni tivity. From Turonin tim onwrds, th sdimnttion ws lrly syn-ttonilly ontrolld by th rltiv uplift of th Lusitz Blok nd nhnd subsidn in n xis running prlll to th rnt Lusitz thrust (Voigt 1994). From th NW to th SE, th Sxon Crtous sdimnts bom mor nd mor siliilsti, hnging from hmiplgi limstons nd mrly domintd units round Mißn nd Drsdn (NW) to mssiv sndstons in th Elbsndstingbirg (SE). Th Shmilk-Großr Wintrbrg stion (Elbsndstingbirg, for lotion s Fig. 2) rprsnts th thikst undisturbd sussion, rnging from th Lowr Turonin Shmilk-Formtion to th Uppr-Turonin/Lowr Coniin Shrmmstin-Formtion. Th totl thiknss of th Uppr Crtous in Sxony is in th ordr of 550 to 650 m (Trögr in Pälhn & Wltr 2008) in th Elbsndstingbirg nd possibly 1000 m in th Zittur Gbirg, whr th Lowr Coniin is rprsntd by thik sndstons of th Wltrsdorf Formtion. Furthr towrds th SE, th sndstons pss ovr into th Uppr Crtous of th Bohmin Bsin (Czh Rpubli) Shmilk stion Th Shmilk Großr Wintrbrg stion is minly hrtrisd by thik mrin sndston pkgs ompris ing omplt 400 m thik sussion of th Lowr to Middl Turonin Shmilk Formtion, th Middl to Uppr Turonin Postlwitz-Formtion nd th Uppr Turonin to Lowr Coniin Shrmmstin For m tion. Th lbitus Sndston mrks th bs of th stion (Shmilk Formtion). Th ovrlying Postlwitz- nd Shrmmstin formtions n b furthr subdividd in distint units whih hv mmbr sttus: Sndstons, b nd ording to Lmprht 1928, 1931 nd 1934 r summrizd s Postlwitz Formtion (Prshr 1981), d nd s Shrmmstin Formtion (Voigt & Trögr 2007) t th top of th Großr Wintrbrg (Fig. 2 nd 3). 2. Smpls nd mthods 2.1. Smpls Th ompltly xposd Shmilk Großr Wintrbrg stion forms th typ lolity of th lithostrtigrphi subdivision of th Crtous in th Elbsndstingbirg. Smpling ovrd th whol sussion within vrtil distn of bout 30 to 70 mtrs btwn th smpl points. Ths smpls rprsnt ll Uppr Crtous sndston units from th Shmilk-, Postlwitz-, nd th Shrmmstin formtions (s Fig. 3). Th sdimnts r rprsntd by fin- to ors grind qurtz sndstons with rltivly low ontnt of fldspr in th Shmilk Formtion nd th Sndstons b nd d, rsptivly; nd highr mount of fldspr in th Snd ston nd. Hvy minrl sptr r minly domintd by tourmlin, ziron, nd rutil. In totl six sndston smpls wr nlysd rgrding thir ziron U/Pb gs. Th smpl lolitis for th sndstons usd for ziron dting r mrkd in figurs 2 nd 3. Smpl oordints r givn in tbl Mthods Ziron onntrts wr sprtd from 1 3 kg smpl mtril t th Snknbrg Nturhistorish Smm lungn Drsdn. Aftr rushing th roks in jw rushr, th mtril ws sivd nd wshd. Th hvy minrl sprtion ws rlizd by using hvy liquid LST (sodium htropolytungstts in wtr) nd Frntz mgnti sprtor. Finl sltion of th ziron grins for U/Pb 103

4 M. Hofmnn t l.: Th Uppr Crtous stion t Shmilk in Sxony (Elbsndstingbirg, Grmny) Fig. 1. Th ross-stion of th Sxonin Crtous Bsin shows th thrusting of th Lusitz Blok on th Msozoi dposits (bsd on Lobst 1993). Th sdimnts r ovrthrustd. Importnt r th Jurssi dposits tht r prsrvd long th fult. Thy r in gnrl bsnt blow th Crtous dposits lswhr in Sxony. Thir ourrn nd fis indit widsprd Jurssi ovr nd th invrsion of Jurssi-Erly Crtous grbn whih ws stblishd in th r of th rnt Lusitz Blok. Abb. 1. Shnitt durh ds sähsish Kridbkn, dr dutlih di Aufshibung ds Lusitz-Bloks uf di msozoishn Sdimnt ds Elbtls zigt. Di Sdimntshihtn wurdn dbi übrkippt. Wihtig ist ds Vorkommn jurssishr Sdimnt im Ligndn dr kridzitlihn Ablgrungn. Si sind nur im Störungsvolumn rhltn gblibn und fhln im Untrgrund ds Sähsishn Kridbkns. Ihr Existnz und ihr Ausbildung lssn uf in hmls wit Vrbritung jurssishr Sdimnt und di Invrsion ins Grbns shlißn, dr ursprünglih uf dm Lusitzr Mssiv nglgt und in dr Obrkrid invrtirt wurd. Fig. 2. Gologil mp of th study r (slightly modifid from Lobst, 1993) showing th Uppr Crtous sndstons tht rprsnt th Shmilk (lbitus Sndston), th Postlwitz (Sndstons ) nd th Shrmmstin formtions (Sndstons d nd ). Smpl points r inditd. Abb. 2. Di gologish Krt ds Untrsuhungsgbits (liht vrändrt nh Lobst 1993) zigt di obrkrtzishn Sndstin dr Shmilk- (lbitus-sndstin), dr Postlwitz- (Sndstin ) und dr Shrmmstin-Formtion (Sndstin d und ). Di Probnhmpunkt sind in gtrgn. dting ws hivd by hnd-piking undr binoulr mirosop. Ziron grins of ll grin sizs nd morphologil typs wr sltd, mountd in rsin bloks nd polishd to hlf thir thiknss. Th ziron grins whr xmind rgrding thir thodoluminsn signl using n EVO 50 Ziss Snning Eltron Mirosop (Sn knbrg Nturhistorish Smmlungn Drsdn) prior to U/Pb nlyss. This hlps to distinguish diffrnt growth nd myb mtmorphi zons within th singl grins. For U/Pb nlyss th lsr spots whr pld in zons with monophs growth pttrns tht show no mtmorphi ovrprint. Zirons wr nlyzd for U, Th, nd Pb isotops by LA-SF ICP-MS thniqus t th Snknbrg Nturhistorish Smmlungn Drsdn (Musum für Minrlogi und Gologi, GoPlsm Lb), using Thrmo-Sintifi Elmnt 2 XR stor fild ICP-MS oupld to Nw Wv UP-193 Eximr Lsr Systm. A trdrop-shpd, low volum lsr ll onstrutd by Bn Jähn (Drsdn, Grmny) nd Axl Grds (Frnkfurt m Min, Grmny) ws usd to nbl squntil smpling of htrognous grins (.g. growth zons) during tim rsolvd dt quisition. Eh nlysis onsistd of 15 s bkground quisition followd by 20 s dt quisition, using lsr spot-siz of 20 to 25 µm, rsptivly. Th signl ws tund for mximum snsitivity for nd. A ommon-pb orrtion bsd on th intrfrn- nd bkgroundorrtd 204 Pb signl nd modl Pb omposition (Sty & Krmrs 1975) ws rrid out if nssry. Th nssity of th orrtion is judgd on whthr th orrtd lis outsid of th intrnl rrors of th msurd rtios. Disordnt nlyss wr lwys intrprtd with r nd disrdd. Th intrfrn of 204 Hg on mss 204 (Pb) ws lultd by using 204 Hg/ 202 Hg rtio of nd msurd 202 Hg. Rw dt wr orrtd for bkground signl, ommon Pb, lsr indud lmntl frtiontion, instrumntl mss disrimintion, nd tim-dpndnt lmntl frtiontion of Pb/ Th nd Pb/U using n Exl sprdsht progrm dvlopd by Axl Grds (Frnkfurt m Min, Grmny). Rportd unrtintis wr propgtd by qudrti ddition of th xtrnl rpro duibility obtind from th stndrd ziron GJ-1 (~0.6% nd 0.5 1% for th 207 Pb/ nd /, rsptivly) during individul nlytil sssions nd th within-run prision of h nlysis. Isoplot digrms (1 σ rror) wr produd using AgDisply (Siromb 2004). Th g 104

5 GEOLOGICA SAXONICA 59: 2013 ws tkn for intrprttion for ll zirons >1.0 G, nd th / gs for youngr grins. For furthr dtils on nlytil protool nd dt prossing s Grds & Zh (2006) nd Fri & Grds (2009). 3. Rsults Th U/Pb ziron gs show vry similr rsults for th first fiv smpls (Sk 6 2, Sk 1s, Sk 5, Sk 4 1, 3 1) rprsnting th sndston units lbitus Sndston (Shmilk Formtion), Sndston, b, (Postlwitz Formtion), nd Sndston d (Shrmmstin Formtion) (Fig. 3). Th youngst onordnt msurmnt for h smpl is givn in th AgDisply digrms in Figur 3. For ll smpls, th g sptr strt t. 300 to 330 M nd go on mor or lss ontinuously until. 800 M. Th youngst singl ziron grin ws found in smpl Sk 5, giving n g of 258 ± 6 M ( rror). Thr r bundnt (for smpls Sk 6 2, Sk 1s, Sk 5, Sk 4 1, Sk 3 1) or mny (smpl Sk 2 2) Mso- nd Ploprotrozoi ziron gs up to to 2100 M. Arhn gs wr only found in th bs of th stion in smpl Sk 6 2 (lbitus Sndston, Shmilk Formtion), rprsntd by on ziron grin with n g of 2969 ± 76 M ( rror). Thr is only on mor grin oldr thn 2100 M found in smpl Sk 4 1 (Sndston, Postlwitz Formtion) giving n g of 2441 ± 34 M ( rror, Fig. 3). Th most importnt rsult is th striking diffrn in bundn nd distribution of g sptr of th Msond Ploprotrozoi ziron in smpl Sk 2 2 (Sndston, Shrmmstin Formtion) omprd to ll othr smpls. Th inrsing numbr of Protrozoi gs in th uppr prt of th stion is ssoitd with drs in Plozoi gs (Figs. 3 nd 4). 4. Intrprttion nd disussion Th rnt gology of th Lusitz Blok is domintd by rly Cmbrin grnodiorits whih intrudd Lt Noprotrozoi grywks. Th g sptr of ths units r wll known nd rprsnt th following gs: Th sdimnttion g of th grywks is ssumd to b. 570 M, givn by youngst dtritl ziron grins nd sh lyrs. In ddition to this, th grywks ontin fw dtritl ziron grins of Arhn gs (up to 3.5 G) nd bundnt zirons of Plo- nd Noprotrozoi/Cdomin gs. Importnt is th lk of dtritl Msoprotrozoi ziron grins in ths sdimnts. Th intruding grnodiorits r summrizd s Lusitz Grnodio rit Suit nd show ziron gs of. 540 M. Only th Rumburg Grnit with. 490 M is youngr. On top of ths Cdomin units li Lowr Ordoviin shllow mrin sdimnts rprsntd by th Dubru Formtion (Trmdo,. 480 M; Linnmnn 2008, Linnmnn t l. 2011). Th gs r diffrnt from obsrvd gs of th Crtous sndstons in th Shmilk-Großr Wintrbrg stion. W did not find prominnt pk of. 540 M old ziron grins, s xptd du to th dirt nighbourhood to th 540 M old grnodiorits of th Lusitz Blok. Ags of this tim wr found in ll smpls, but not with inrsd mounts rltivly to othr g groups. Nvrthlss, this g group ours both in th Vrisn dformd bsmnt of th Bohmin Mssif s wll s in th units of th Lusitz Blok. Thrfor, w onlud tht ths sndstons wr drivd from sdimntry units whih ovrd th invrtd Lusitz Blok during th Crtous nd wr originlly drivd from th Bohmin Mssif. W intrprt th Noprotrozoi to Plozoi gs of ll smpls s th influx of rworkd units of th Avlonin/Armorin nd Vrisn bsmnt units (Hofmnn t l. 2009). Th youngst onordnt U/Pb ziron g of 258 ± 6 M (smpl Sk 1s, sndston, Fig. 3) shows tht thr hd bn mgmti tivity in th upprmost Prmin, myb rprsnting th first brk-up tivitis of Png nd opning of Prmin bsins. Zirons of Trissi, Jurssi nd Crtous sndstons in Grmny indit distint hng in sour r of th Jurssi sdimnts omprd to Trissi nd Crtous sdimnts. Middl Jurssi sndstons (Doggr) show distint g pk in th Mso- nd Ploprotrozoi gs (Hofmnn t l. 2009). Ths gs r rprsnttiv for Blti provnn (Hofmnn t l. 2009) nd orrlt to th rgionl uplift of th North S Dom during th Middl Jurssi whih rsultd in th widsprd rosion nd rsdimnttion of Erly Jurssi nd Trissi sndstons of th Norths Bsin whih wr originlly shd from th Blti shild. Thr is no potntil sour r providing big mounts of ziron gs btwn 900 nd 1900 M in Cntrl Europ. Thrfor it is likly, tht th high mount of Protrozoi gs in th upprmost smpl (Sk 2 2, Sndston, s Fig. 4) drivd from rodd nd rworkd Jurssi siliilsti sdimnts ovring th Lusitz Blok t tht tim. Th smpls Sk 6 2 to Sk 3 1 wr tkn blow Sk 2 2 (Fig. 3) nd do not show this mssiv input of Protrozoi gs. Thy prov tht Middl Jurssi dposits whr not t th surf t tht tim. Probbly, thy hd still bn ovrd by youngr sdimnts (Uppr Jurssi to Lowr Crtous). Th rosion of units with th Mso-/Protrozoi g sptr strtd in th Coniin. Thrfor th bsmnt units of th Lusitz Blok wr not t th surf nd not vilbl to rosion during Turonin Coniin tim (Fig. 5). Aptit ooling gs of th Lusitz Blok (Lng t l. 2008) nd of th Krkonosz Mts. (Dnišik t l. 2010) 105

6 M. Hofmnn t l.: Th Uppr Crtous stion t Shmilk in Sxony (Elbsndstingbirg, Grmny) 106

7 GEOLOGICA SAXONICA 59: 2013 Fig. 4. Digrms showing hng in g lsss (Arhn, Protrozoi nd Plozoi) for ll nlysd sndstons. Not th suddn inrs of Protorzoi gs in th upprmost smpl (Sk 2 2, Sndston, Shrmmstin Formtion) in omprison to th fiv smpls blow. Abb. 4. Drstllung dr Vrändrung dr Altrsklssn für ll nlysirtn Sndstin. Auffällig ist di plötzlih Zunhm protrozoishr Altr in dr obrstn Prob (Sk 2-2) im Vrglih zu dn fünf druntrligndn Probn. prov n normous Lt Crtous uplift of th Lusitz Blok. 50 to 85 M go (Lng t l. 2008). Uplift nd fst ooling hppnd in two stgs lso in th Krkonosz Mts. t M nd t M (Dnišik t l. 2010). This uplift rsultd in th rmovl of bout 3 4 km of ovrburdn (stimtd dnudtion rt of. 100 m/1 M for th Lusitz Blok, Lng t l. 2008). On th bs of pbbl omposition los to th Lusitz Thrust nd ths ooling gs, Voigt (2009) onludd tht rodd units wr initilly rprsntd by thik sdimntry pil of Trissi to Erly Crtous sdimnts whih wr rdpositd in n upsid-down sussion (first youngst, lst oldst). As th upprmost Crtous sndstons show no vidn of grnodioriti sour nd most ooling gs indit Sntonin to Cmpnin uplift, muh thikr primry thiknss of Crtous sdimnts n b ssumd. Trissi sndstons wr ssumd s sour for th highr prts of th Lt Crtous sussion in th Elbsndstingbirg (Voigt 1994). But th prdominn of Blti gs (Mso-Ploprotrozoi) in th highst prsrvd units indits tht thy did not provid signifint mount of snds to th bsin fill until th rly Coniin. W propos ltr rdposition of Trissi snds. This is in grmnt with ooling gs of th Lusitz Blok (Lng t l. 2008) nd th Krkonosz Mts. (Dnišik t l. 2010) nd th omprison with bttr prsrvd bsins, proving Sntonin to Cmpnin pk of invrsion ttonis. Unfortuntly, thr r no youngr Uppr Crtous sdimnts thn Lowr Coniin lft in th study r. Bus of tht, w n only ssum tht th Trissi nd Prmin sdimnts, lying blow th Jurssi dposits, got rodd ltr too, nd, myb, vn prt of th grnodiorit of th Lusitz Blok itslf, in th upprmost Crtous. Ths vidns whr probbly rodd during th big Lt Crtous to Erly Plogn wthring. Additionlly, w ssum rgionl uplift of th Lusitz nd th Bohmin Mssif ftr invrsion, bus most of th Crtous dposits of th Bohmin Crtous Bsin hd bn rmovd bfor th Mion. Fig. 3. Stion of th Elbsndstingbirg round Shmilk (Großr Wintrbrg rgion) bsd on Lmprht (1928), Trögr (in Pälhn & Wltr 2008) nd own fild obsrvtions. On smpl of h sndston unit ws nlysd. Smpl points r inditd. Ag- Disply digrms of ll smpls showing onordnt U/Pb ziron gs (x-xis) vrsus probbility nd frquny (y-xis) ftr Siromb (2004) r bsd on 1 σ rrors. All msurmnts with dgr of onordn btwn 90 nd 110 % wr rgrdd s onordnt nd usd for th digrms. / -rtios wr usd for g lultion of ll gs blow 1000 M. For oldr grins 207 Pb/ -rtios wr usd for g lultion. Youngst onordnt singl ziron g of h smpl is givn with rror. Abb. 3. Gologishr Shnitt durh ds Elbsndstingbirg bi Shmilk (Rgion Großr Wintrbrg) bsirnd uf Lmprht (1928), Trögr (in Pälhn & Wltr 2008) und ignn Gländufnhmn. Pro Sndstininhit wurd in Prob nlysirt. Di Probnhmnivus sind durh wißn Strnhn mrkirt. Ds AgDisply Digrmm jdr Prob zigt di U/Pb-Zirkonltr (x- Ahs) ufgtrgn ggn di Whrshinlihkit und Häufigkit (y-ahs), bsirnd uf inm 1-σ-Fhlr (Siromb 2004). All Mssungn mit inr Konkordnz zwishn 90 und 110% wurdn ls konkordnt ngshn und zur Erstllung disr Digrmm gnutzt. Zur Altrsbrhnung für Altr untr 1000 M wurdn di / -Vrhältniss vrwndt. Für höhr Altr wurd ds 207 Pb/ -Vrhältnis hrngzogn. Ds jüngst konkordnt Einzlzirkonltr für jd Prob ist nggbn (2-σ-Fh lr). 107

8 M. Hofmnn t l.: Th Uppr Crtous stion t Shmilk in Sxony (Elbsndstingbirg, Grmny) 5. Summry Th min rsults of this study n b summrizd in svn points: Th Lusitz Blok ws prt of th Wst-Sudti Islnd nd ovrd with Trissi, Jurssi nd probbly Lowr Crtous sdimnts. It ws th most probbl sour r for th Uppr Crtous sndstons of th Elbtl Group. Th dtrmind ziron gs from th Plozoi to Lt Noprotrozoi r intrprtd s signls of rworkd lol mtril, suh s th Vrisn nd Cdomin bsmnt units nd thir Plozoi ovr squns. Th ziron U/Pb-g sptr show suddn input of Mso- nd Ploprotrozoi gs in th upprmost prt of th Shmilk stion (smpl Sk 2-2, Sndston, Fig. 3), tht n only b intrprtd s rworking of siliilsti Jurssi mtril (Middl Jurssi). Erosion of ths Jurssi sdimnts strtd not rlir thn in th Coniin (Fig. 5). Most ziron grins rprsntd in this study xprind t lst thir sond yl of ryling during th Lt Crtous sdimnttion. Th minor mounts of. 540 M gs in ll smpls onfirm th Msozoi ovr of th Cdomin bsmnt units of th Lusitz Blok. Th lttr ons wr not vil- Fig. 5. Modl of invrsion nd synttoni rdposition of th Msozoi ovr of th Lusitz Blok (bsd on Voigt 2009 nd th rnt study) showing sdimnttion nd ttoni tivity long th Lusitz Thrust during th Msozoi. Uplift of th Lusitz Blok strtd in th lowr Uppr Crtous (Middl Cnomnin). From tht tim on, th Msozoi ovr of th Lusitz Blok ws th min sour r for th sdimnts of th Sxonin Crtous Bsin. Erosion of Middl Jurssi siliilsti sdimnts strtd in th Coniin. Oldr (Trissi) sdimnts nd rly Cmbrin grnodiorits did probbly not ontribut to th formtion of Uppr Crtous dposits in Sxony. Abb. 5. Modl zur Sdimnttion und tktonishn Aktivität ntlng dr Lusitzr Übrshibung währnd ds Msozoikums (bsirnd uf Voigt 2009 und dn Ergbnissn disr Studi). Di Hbung ds Lusitz-Bloks bgnn in dr untrn Obrkrid (mittlrs Cnomn). Di uflgrndn msozoishn Sdimnt ds invrtirtn Lu sitz-bloks wrn di Huptqull für di Sndstin ds Elbsndstingbirgs. Di Abtrgung mittljurssishr siliziklstishr Sdimnt bgnn im Coni. Ältr (trissish) Sdimnt und dr hut in dr Lusitz dominirnd Grnodiorit trugn vrmutlih niht zur Sdimntbildung dr sähsishn Obrkrid bi. 108

9 GEOLOGICA SAXONICA 59: 2013 bl for rosion until t lst Middl to Lt Coniin tims (most probbly vn ltr). Th prsntd stion dos not show rl invrsion with Cdomin gs (minly. 540 nd. 570 M) of th Lusitz Blok on top. Aording to ooling gs nd omprd with bttr prsrvd bsins this invrsion took pl during th Sntonin to Cmpnin, whih is too young for th Shmilk Großr Wintrbrg stion. 6. Aknowldgmnt W would prtiulrly lik to thnk Dr. Jn-Mihl Lng (Snknbrg Nturhistorish Smmlungn Drsdn) for vrious orrtions, dviss, nd rfrns tht hlpd to improv this ppr. 7. Rfrns Dnišik, M.; Migoń, P.; Kuhlmnn, J.; Evns, N.J.; Dunkl, I., Frish, W. (2010): Thrmohronologil onstrints on th longtrm rosionl history of th Krkonosz Mts., Cntrl Europ. Gomorphology, 117: 78 89, Amstrdm. Fri, D.; Grds, A. (2009): Pris nd urt in situ U-Pb dting of ziron with high smpl throughput by utomtd L- SF-ICP-MS. Chmil Gology, 261: , Amstrdm. Grds, A.; Zh, A. (2006): Combind U-Pb nd Hf isotop LA- (MC-)ICP-MS nlysis of dtritl zirons: Comprison with SHRIMP nd nw onstrints for th provnn nd g of n Armorin mtsdimnt in Cntrl Grmny. Erth nd Pln try Sin Lttrs, 249: 47 61, Amstrdm. Hofmnn, M.; Voigt, T.; Linnmnn U. (2009): Th snds of Pn - g U-Pb-LA-ICP-MS gohronology of dtritl ziron grins: s study of th Msozoi of Cntrl Europ. Shriftn rih dr Dutshn Gsllshft für Gowissnshftn, 63: 140, Hnnovr. Lmprht, F. (1928): Shihtnfolg und Obrflähnformn im Wintrbrggbit ds Elbsndstingbirgs. Mittilungn ds Vrins für Erdkund Drsdn, N.F., 1927: 1 48, Drsdn. Lmprht, F. (1931): Di Shihtn ds sähsish-böhmishn Turons rhts dr Elb. Sondrbdruk Nus Jhrbuh für Minrlogi t., Bil.-Bd. 67, Abt. B: Lmprht, F. (1934): Di Shihtlgrung ds Turons im sähsish-böhmishn Elbsndstingbirg. Briht dr mthmtish-physiklishn Klss dr Sähsishn Akdmi dr Wissnshftn zu Lipzig, 86: , Lipzig. Lng, J.-M.; Tonk, C.; Wgnr, G.A. (2008): Aptitspltspurdtn zur postvriszishn thrmotktonishn Entwiklung ds sähsishn Grundgbirgs rst Ergbniss. Zitshrift dr Dutshn Gsllshft für Gowissnshftn, 159: , Stuttgrt. Linnmnn, U. (2008): Di Strukturinhitn ds Sxothuringikums. In: Linnmnn, U. (Ed.): Ds Sxothuringikum Abriss dr präkmbrishn und pläozoishn Gologi von Shsn und Thüringn , Drsdn (Sttlih Ntur his torish Smmlungn Drsdn). Linnmnn, U.; Frnz, C.; Hofmnn, M.; Winklr, R.; Ullrih, B. (2011): Th Dubru Formtion (Lowr Ordoviin, Lusitz Blok) Sdimntry fis, fossil ssmbl, nd U-Pb gs of dtritl zirons from pri-gondwnn old-wtr stion with Wst Afrin ffinity. Fribrgr Forshungshft, C 540: , Fribrg. Lobst, R. (1993): Gologish Krt dr Ntionlprkrgion Sähsish Shwiz 1 : , Gologish Rgionlkrt Aufl., Sähsishs Lndsmt für Umwlt und Gologi, Fribrg. Nibuhr, B.; Hiss, M.; Kpln, U.; Trögr, K.-A.; Voigt, S.; Voigt, T.; Wis, F.; Wilmsn, M. (Eds., 2007): Lithostrtigrphi dr norddutshn Obrkrid. Shriftnrih dr Dutshn Gsllshft für Gowissnshftn, 55: 49 66, Hnnovr. Pälhn, W.; Wltr, H. (Eds., 2008): Gologi von Shsn , Stuttgrt (Shwizrbrt). Pitzsh, K. (1963): Gologi von Shsn , Brlin (VEB Dutshr Vrlg dr Wissnshftn). Prshr, H. (1981): Problm dr Korrltion ds Cnoms und Turons in dr Sähsishn und Böhmishn Krid. Zitshrift für Gologish Wissnshftn, 9: , Brlin. Siromb, K.N. (2004): AgDisply: n Exl workbook to vlut nd disply univrit gohronologil dt using binnd frquny histogrms nd probbility dnsity distributions. Computrs nd Gosins, 30: 21 31, Amstrdm. Sty, J.S.; Krmrs, J.D. (1975): Approximtion of trrstril ld isotop volution by two-stg modl. Erth nd Plntry Sin Lttrs, 26: , Amstrdm. Trögr, K.-A. (1964): Di Ausbildung dr Krid (Cnomn bis Coni) in dr Umrndung ds Lusitzr Mssivs. Gologi, 6: Voigt, T. (1994): Fzisntwiklung und Ablgrungssqunzn m Rnd ins Epikontinntlmrs Di Entwiklungsgshiht dr Sähsishn Shwiz (unpublishd dotorl thsis, Thnish Univrsität Brgkdmi Fribrg). Wltr, R. (2003): Erdgshiht Di Entsthung dr Kontinnt und Ozn , Brlin, Nw York (d Gruytr). Wilmsn, M.; Vodrázk, R.; Nibuhr, B. (2011): Th Uppr C nomnin nd Lowr Turonin of Lokwitz (Drsdn r, Sxony, Grmny): lithofis, strtigrphy nd fun of trnsgrssiv sussion. Fribrgr Forshungshft, C 540: 27 45, Fribrg. 109

10 M. Hofmnn t l.: Th Uppr Crtous stion t Shmilk in Sxony (Elbsndstingbirg, Grmny) Tbl 1. LA SF ICP MS U, Pb, nd Th dt of singl ziron grins from th Uppr Crtous sndstons of th Shmilk stion (Elbsndstingbirg). Nm of th smpl s wll s GPS oordints, gologil formtion, strtigrphi g, mount of msurd ziron grins nd mount of onordnt (within 90 to 110% of onordn) nlyss r givn for h smpl s first lin on top of th dt. Itli/gry: disordnt nlyss (not in th rng of % of dgr of onordn) Tbll 1. LA SF ICP MS U, Pb und Th Dtn von inzlnn Zirkonn dr obrkrtzishn Sndstin ds Shmilk Profils (Elbsndstingbirg). Dr Probnnm, di GPS Koordintn, gologish Formtion, strtigrphishs Altr, Anzhl dr gmssnn Zirkon und Anzhl dr konkordntn (innrhlb inr Konkordnz von 90 bis 110%) Anlysn sind für jd Prob in dr rstn Zil übr dn jwilign Dtn nggbn. Kursiv/gru: diskordnt Anlysn (ußrhlb ds % Brihs dr Konkordnz) Sk 1s (Sndston, Postlwitz Formtion, Middl Turonin) N; E, msurd singl ziron grins: 111, onordnt within % of onordn: 108 Isotop rtios Ags U b Pb b Th/U b / 204 Pb / Rho d / on Numbr [ps] [ppm] [ppm] [%] [%] [%] [M] [M] [M] [M] [M] [M] [%]

11 GEOLOGICA SAXONICA 59: 2013 Tbl 1 Sk 1s (Sndston, Postlwitz Formtion, Middl Turonin) ontinud. Isotop rtios Ags U b Pb b Th/U b / 204 Pb / Rho d / on Numbr [ps] [ppm] [ppm] [%] [%] [%] [M] [M] [M] [M] [M] [M] [%] b b b b b b b b b b b b

12 M. Hofmnn t l.: Th Uppr Crtous stion t Shmilk in Sxony (Elbsndstingbirg, Grmny) Tbl 1 Sk 1s (Sndston, Postlwitz Formtion, Middl Turonin) ontinud. Isotop rtios Ags U b Pb b Th/U b / 204 Pb / Rho d / on Numbr [ps] [ppm] [ppm] [%] [%] [%] [M] [M] [M] [M] [M] [M] [%] b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b

13 GEOLOGICA SAXONICA 59: 2013 Tbl 1 Sk 1s (Sndston, Postlwitz Formtion, Middl Turonin) ontinud. Isotop rtios Ags U b Pb b Th/U b / 204 Pb / Rho d / on Numbr [ps] [ppm] [ppm] [%] [%] [%] [M] [M] [M] [M] [M] [M] [%] b b b b b b b b b Tbl 1 Sk 2-2 (Sndston, Shrmmstin Formtion, Lowr Coniium) N; E, msurd singl ziron grins: 120, onordnt within % of onordn: 59 Isotop rtios Ags U b Pb b Th/U b / 204 Pb / Rho d / on Numbr [ps] [ppm] [ppm] [%] [%] [%] [M] [M] [M] [M] [M] [M] [%]

14 M. Hofmnn t l.: Th Uppr Crtous stion t Shmilk in Sxony (Elbsndstingbirg, Grmny) Tbl 1 Sk 2-2 (Sndston, Shrmmstin Formtion, Lowr Coniium) ontinud. Isotop rtios Ags U b Pb b Th/U b / 204 Pb / Rho d / on Numbr [ps] [ppm] [ppm] [%] [%] [%] [M] [M] [M] [M] [M] [M] [%]

15 GEOLOGICA SAXONICA 59: 2013 Tbl 1 Sk 2-2 (Sndston, Shrmmstin Formtion, Lowr Coniium) ontinud. Isotop rtios Ags U b Pb b Th/U b / 204 Pb / Rho d / on Numbr [ps] [ppm] [ppm] [%] [%] [%] [M] [M] [M] [M] [M] [M] [%] b b b b b b b b b b b b b b b b b b b b b b b b b b b b

16 M. Hofmnn t l.: Th Uppr Crtous stion t Shmilk in Sxony (Elbsndstingbirg, Grmny) Tbl 1 Sk 2-2 (Sndston, Shrmmstin Formtion, Lowr Coniium) ontinud. Isotop rtios Ags U b Pb b Th/U b / 204 Pb / Rho d / on Numbr [ps] [ppm] [ppm] [%] [%] [%] [M] [M] [M] [M] [M] [M] [%] b b