Tectonometamorphic Evolution of an Allocthonous Terrane, Gory Sowie Block, Northeastern Bohemian Massif (Poland)

TECTONOMETAMORPHIC EVOLUTION OF AN ALLOCTHONOUS TERRANE, GORY SOWIE BLOCK, NORTHEASTERN BOHEMIAN MASSIF (POLAND)

A thesis presented to the faculty of the College of Arts and Sciences of Ohio University

In partial fulfillment of the requirements for the degree Master of Science

Stephen J. Zahniser November 2004 This thesis entitled TECTONOMETAMORPHIC EVOLUTION OF AN ALLOCTHONOUS TERRANE, GORY SOWIE BLOCK, NORTHEASTERN BOHEMIAN MASSIF (POLAND) by Stephen J. Zahniser

has been approved for the Department of Geological Sciences and the College of Arts and Sciences by

David A. Schneider Assistant Professor of Geological Sciences

Leslie A. Flemming Dean, College of Arts and Sciences Zahniser, Stephen J. M.S. November 2004. Geological Sciences Tectonometamorphic evolution of an allocthonous terrane , Gory Sowie Block, northeastern Bohemian massif (Poland) (76pp.) Director of Thesis: David Schneider

The Gory Sowie Block (GSB), of SW Poland’s Sudete Mountains, contains numerous ultra-high temperature granulites (UHT) and small relict ultra-high pressure (UHP) eclogites enveloped within amphibolite-facies gneisses and amphibolites. The GSB is bounded by ductile fault zones, bisected by the Sudetic Boundary fault and partially overlies ophiolitic sequences. The GSB experienced a polyphase metamorphic history spanning Caledonian and Variscan accretionary events (440 - 330 Ma) with peak metamorphic conditions of 1000°C and >20 kbar occurring ca. 400 Ma, indicated by U- Pb zircon ages on garnet peridotites and felsic granulites. This project involved 40Ar/39Ar hornblende and mica plateau ages from primarily GSB host gneisses. The results indicate that the western GSB experienced a diachronous cooling event with the northern region cooling from upper amphibolite-facies (sillimanite/kyanite zone) ca. 385 Ma and southern region from middle to lower amphibolite-facies (garnet/biotite zone) ca. 375 Ma with cooling rates ranging from 40 - 25°C m.y.-1. U-Th total-Pb monazite geochronometric results obtained during this study reveal both amphibolite-facies metamorphism at 385 Ma, concordant with the 40Ar/39Ar cooling ages, and homophazation of the gneisses and late-fluid mobilization along tectonic boundaries associated with large scale metamorphism of the surrounding Sudetic terranes at ca. 360 Ma. Additionally, concordant 40Ar/39Ar hornblende and biotite plateau ages obtained along the far eastern margin indicate a regional heating event at 336.8 ± 0.8 Ma., most likely associated with Niemcza shearing,

Approved: David Schneider Assistant Professor of Geological Sciences Acknowledgments My deepest thanks to my friend and advisor Dave Schneider for helping me see this project to completion and giving me the opportunity to broaden my intellectual and scientific horizons through his thoughts and insights. Additional thanks to Maciej Manecki, Damian Nance, Gregory Springer, Matt Heizler, Robert Tracy and Bartek Budzyn for their insights and contributions in the field, lab and review processes. Also, much thanks to Jake Glascock for being a friend, providing significant contributions in the field, and all around keeping me sane. Thanks to Zack Wessel, Scott Dodson and Brent Barley for teaching me the fundamentals of Geology through many late nights of pool. Tricia Piercey, Stacia Gordon and Shelly Rose for their friendship, insights and editing skills. The Douglas’s for being supportive neighbors and helping put the Deere out to pasture. My sincere gratitude to my family for their continued support in every aspect of my life and helping me through the hard times. I would like to extend my prayers to Carol Popovich and the Popovich family. Financial support for this project was provided through the National Research Council. v Table of Contents

Page

Acknowledgments……………………………………………………………….… iii

Abstract……………………………………………………………………………. iv

List of Figures………………………………………………………………………vii

List of Tables………………………………………………………………………. viii

1. Introduction………………………………………………………………………9

2. Geologic Setting………………………………………………………………….12

2.1. Variscides……………………………………………………………12

2.2. Bohemian Massif…………………………………………………… 13

2.3. Sudetes……………………………………………………………… 14

2.4. Gory Sowie Block…………………………………………………...15

3. Previous Tectonometamorphic Chronometry……………………………………19

4. Petrology & Petrography………………………………………………………... 22

4.1. Methods & Approach………………………………………………..22

4.2. Gneisses & Migmatites……………………………………………...22

4.3. Granulites……………………………………………………………25

4.4. Eclogites, Metabasites & Serpentites………………………………..26

5. 40Ar/39Ar Thermochronology…………………………………………………….29

5.1. Analytical Procedures………………………………………………. 30

5.2. 40Ar/39Ar Results…………………………………………………….32

6. U-Th-total-Pb Geochronology…………………………………………………...44

6.1. Analytical Procedures………………………………………………. 44 vi 6.2. Total-Pb Results……………………………………………………..46

7. Discussion………………………………………………………………………..55

7.1. Geochronology……………………………………………………....55

7.2. Tectonic Implications………………………………………………..57

8. Conclusions………………………………………………………………………63

References…………………………………………………………………………..65

Appendix A…………………………………………………………………………72 vii List of Figures

Figure Page

1 Lithostratigraphic units of the Bohemian Massif...…………………………13

2 Geologic map of the Sudete Mountains...…………………………………..16

3 Geologic map of the Gory Sowie Block..…………………………………..18

4 Simplified map of Gory Sowie Block with sample locations..……………..23

5 Field shot and photomicrograph of a typical gneiss outcrop………………. 24

6 Field shot and photomicrograph of a granulite outcrop…………………….25

7 Field shot and photomicrograph of a eclogite (retrogressed?) outcrop……. 27

8 Metamorphic isograd map of the Gory Sowie……………………………...28

9a 40Ar/39Ar age spectra………………………………………………………..33

9b 40Ar/39Ar age spectra..………………………………………………………34

10 Cumulative probability graphs of in situ monazite total-Pb analysis……… 49

11 Y-chemical maps and monazite chrontour diagrams of U-Th total-Pb

analysis……………………………………………………………………...50

12 Thermal history of the Gory Sowie Block………………………………….56

13 P-T-t path for the Gory Sowie Block……………………………………….59 viii List of Tables

Table Page

1 Analytical 40Ar/39Ar isotopic data…………………………………………..35

2 Analytical U-Th total-Pb elemental data…………………………………... 51 9 1. Introduction

Ultrahigh grade metamorphic terranes exposed at the surface represent crustal material that once resided at deep-lithospheric depths (>100 km) due to plate subduction or collision-induced crustal thickening. Conditions at these depths often exceed 25 kbar and 800°C and result in the formation of mineral assemblages that include coesite ± cordierite ± garnet ± clinopyroxene ± kyanite ± sillimanite (O’Brien, 1997a). The presence of eclogite and granulite facies rocks exposed at the surface provides an opportunity to study orogenic roots; moreover, preservation of ultrahigh pressure (UHP) and ultrahigh temperature (UHT) mineral assemblages suggests rapid exhumation, often associated with either return flow along a subduction zone or orogenic collapse.

Unraveling the frequently complex thermal and unroofing histories of UHP and UHT rocks through the use of thermochronological and geochronological analyses, coupled with thermobarometric estimates, is instrumental for the construction of quantitative unroofing models of orogenic systems.

An understanding of crustal deformation, metamorphism and the roots of orogenic systems has largely been gained through the study of exhumed rocks.

Exhumation generally occurs through tectonic (normal faulting, ductile thinning) and erosional denudation. These processes are an important component of the Earth system due to their influence on topography, sedimentation and ultimately mantle dynamics.

Various models have been applied to the exhumation of deep seated rocks, but most researchers agree that a density driven buoyancy gradient is the primary driving force behind the emplacement of eclogites and possibly granulites into the lower and middle crust during the initial unroofing processes. Serpentization occurring at ultrahigh 10 pressures during or after collision typically reduces local mantle rock densities from 3.3 to 2.7 g cm-3, thus amplifying the buoyancy force (Ring et al., 1999). However, eclogite

and granulite sequences typically occur as blocks or lenses within an amphibolite-facies

matrix, suggestive of subsequent forces other than simple buoyancy in controlling final

emplacement and unroofing. Exhumation of ultrahigh grade terranes is thus considered a

multistage process (e.g., Hacker et al., 1995).

Within the northeastern Bohemian massif, the Gory Sowie Block (GSB) of the

Sudetes Mountains (southwestern Poland) contains known UHT and UHP exposures.

The GSB is proposed to have attained peak metamorphic conditions during a Late

Caledonian UHP event followed by localized UHT granulite-facies metamorphism and

later regional (retrograde?) amphibolite-facies metamorphism, during the Variscan

orogeny (Brueckner et al., 1996, O’Brien, 1997b). Peak metamorphism is preserved in

exposures of garnet peridotites, granulites locally containing kyanite with sillimanite

overgrowths, and migmatitic mafic and ultramafic zones contained within the local host

gneisses (O’Brien, 1997a; Kryza & Pin, 2002). Sillimanite-kyanite intergrowth is

indicative of a distinctive high-temperature metamorphic event characterized by near

isothermal decompression, likely during rapid exhumation (O’Brien, 1997a; Platt &

Whitehouse, 1999; Kryza & Pin, 2002).

Unlike adjacent portions of the Sudetes, the GSB contains the only documented

ages implicating a Caledonian component (Zelazniewicz, 1987; Brueckner et al., 1996;

O’Brien et al., 1997; Kroner & Hegner, 1998; Gordon et al., in press). Several decades of research has tried to explain this disparity by offering various emplacement models such as: (1) an unrooted nappe of crystalline basement thrust over hundreds of kilometers 11 (allocthonous block), (2) a metamorphic window formed during orogenic collapse

(autocthonous block), and (3) a separate microplate that remained unaffected by later tectonism which influenced other Sudetic metamorphic complexes. Previous geochronometric investigations have only begun to elucidate this complex polyphase metamorphic history.

Despite significant previous research, exhumational constraints on the timing and mechanism of exhumation remain largely unresolved, therefore it is the focus of this study to further constrain the polyphase metamorphic history of the GSB and determine if a unique Caledonian component is indeed present within the Sudete Mountains. In order to gain a better understanding of the tectonothermal history of the GSB, 40Ar/39Ar

thermochronometric and total-Pb geochronometric results are reported from primarily

amphibolite-facies gneisses and migmatites surrounding both granulite and eclogite

facies rocks. The results of this study suggest the otherwise homogenous gneisses of the

GSB experienced a multi-stage exhumation from mid-crustal depths during the latest

Caledonian and concluding in the early Variscan, thus distinguishing the exhumational

history of the Gory Sowie Block from all other metamorphic complexes within the

Sudete Mountains of the NE Bohemian massif and substantiating claims of Caledonian

preservation within Central Europe (Zelazniewicz, 1987; Brueckner et al., 1996; O’Brien

et al., 1997; Kroner & Hegner, 1998; Gordon et al., in press). 12 2. Geologic Setting

2.1 Variscides

The Bohemian massif is generally considered the easternmost extent of the

European Variscides; a series of crystalline basement units forming an orogenic belt stretching from Spain to Poland. The Variscides resulted from protracted collision between Laurentia-Baltica-Avalonia (LBA) from the Early Devonian through the Late

Carboniferous (van Breemen et al., 1982; Cymerman et al., 1997). Caledonian

orogenesis resulted in the closure of the Tornquist Sea during the Ordovician and

produced the Caledonides, traces of which are rarely found within Central Europe.

Variscan orogenic suturing marks the closure of the Rheic Ocean, as LBA collided with

Gondwana; these collisions were complicated by the presence of Gondwana- and Baltica-

derived microplates and various terranes located in the intervening seaway (Matte et al.,

1990; Matte, 1991; 2001). Amalgamation of the microplates and terranes are now

exhibited as linear zones of varying lithostratigraphic, metamorphic and deformational

units marked by fault and suture contacts, and are exposed as various crystalline

basement blocks (massifs; O’Brien, 1997b, Warr, 2000; Linnemann & Romer, 2002).

The crystalline units of the Bohemian massif formed during the collision of the

Armorican microplate and LBA as the Rheic seaway closed. Paleogeographic position is

debated: some authors believe Armorica remained closer to the Gondwana margin

(Zelazniewicz, 1985; 1990; 1997), while others suggest a more prominent separation,

thus opening a large seaway (Gunia, 1985; Cymerman et al., 1997; Cymerman, 1998;

Matte et al., 1990; Matte, 1991; 2001). Evidence of the Armorican microplate exists in

the form of several distinct lithostratigraphic units separated by oceanic-type sutures 13 underlain by MORB-type eclogites. Two key lithostratigraphic units are the

Saxothuringian and Moldanubian zones of the Armorican microplate, of which the

Bohemian massif is primarily composed (Figure 1; Kossmat, 1927; van Breemen et al.,

1982; Matte et al., 1990; Matte, 1991; 2001; Cymerman et al., 1997)

Figure 1. Major lithostratigraphic units of the Bohemian Massif (modified after Franke & Zelazniewicz, 2000). The boxed area highlights the approximate location of the Sudete Mountains, SW Poland and NW Czech Republic. Note, the Gory Sowie region (triangular shape) lies roughly 50 km NNE of its correlative terrane.

2.2 Bohemian Massif

The Saxothuringian zone (STZ) is composed of Neoproterozoic to Carboniferous

volcano-sedimentary sequences suggesting arc-related subduction during a pre-Variscan

evolution. The STZ is dominated by amphibolite-facies metamorphism and its northern

border represents the Rheic suture between LBA and Armorica (van Breemen et al., 14 1982; Matte, 1991; 2001; Warr, 2000). The majority of the Bohemian massif, however, is comprised of the Moldanubian Zone (MZ), which is primarily composed of pelitic and psammitic, often migmatitic, sillimanite ± K-feldspar ± cordierite gneisses. The MZ contains large thrust nappes of UHP and high-T metamorphic facies represented by relict kyanite ± K-feldspar granulites and eclogites bearing coesite (van Breemen et al., 1982).

The MZ is similar to the STZ in that it is also dominated by amphibolite-facies

metamorphism, often overprinting previously UHP and HT facies rocks (Buttner &

Kruhl, 1997; Houlb et al., 1997; O’Brien, 1997a & b; Kroner & Hegner, 1998). The

Gory Sowie block possesses many signatures typical of both the STZ and MZ; however, petrographic investigations by Zelazniewicz (1985) suggest a Moldanubian origin.

Alternately, Cymerman (1998) believes the GSB is a separate terrane that formed as a magmatic arc on the southern margin of Balitca. This theory is based on the lack of

Paleoproterozoic detrital zircons, typical of the STZ and MZ terranes, and relative abundance of Archean and Neoproterozoic zircons, which Zelazniewicz’s models do not accommodate.

2.3 Sudetes

The Sudete Mountains form the northeastern portion of the Bohemian massif and are composed of the Sudetic and Fore-Sudetic Blocks. The Sudetes are a complex assemblage of fault bounded, pre-Permian basement units outcropping in Austria,

Germany, Poland and the Czech Republic (Figure 2). Amalgamation of the Armorican microplate and associated terranes to Baltica (± East Avalonia) during Variscan collision events resulted in the formation of the Sudete Mountains (O’Brien, 1997b; Matte, 1991;

2001; Franke & Zelazniewicz, 2000; Warr, 2000; Linnemann & Romer, 2002). 15 However, late Caledonian collision events followed by early Variscan large-scale thrusting and shear movements also play a significant role in their formation (Oliver et al., 1993; Steltenpohl et al., 1993; Aleksandrowski et al., 1997; Cymerman, 1998).

These series of events likely resulted in the local tectonic emplacement of granulite and eclogite facies rocks within primarily amphibolite-facies host rocks, now exposed in portions of the GSB.

2.4 Gory Sowie Block

The Gory Sowie Bock preserves primarily amphibolite-facies metamorphism with relict UHP eclogites and more predominately UHT granulites. The triangular-shaped

GSB is located in the central portion of the Sudetes and occupies an area of ca. 650 km2

(Figure 3). The block is bounded on the west by the Intra-Sudetic Fault (ISF), separating

the GSB from the Permo-Carboniferous sequence of the Intra-Sudetic Basin. The NW-

SE trending Sudetic Boundary Fault (SBF) separates the block into a mountainous

region, lying to the south and west, and a relatively flat, covered region to the north and

east. It is in the mountainous regions that relict granulite and eclogite facies rocks are

predominantly located, whereas the flat covered region contains primarily amphibolite

grade gneisses. Unfortunately, Cenozoic glacial deposits cover the majority of this flat

region and therefore a paucity of exposures exist. The Variscan aged Niemcza shear

zone (NSZ) bounds the eastern margin of the block, while the southwestern portion is

bounded and cut by numerous smaller shear zones (Cymerman et al., 1997; Marheine et

al., 2002). 16

16°E 17°E Poland

A MASSIF IZER

SMF

KONOSZE GRANITE KAR ISF GORY SOWIE MASSIF

INTRA-SUDETIC BASIN State Border NIEMCZA SHEAR ZONE Czech Republic Gneiss Mica schist

Mylonites SNIEZNIK Ophiolitic rocks MASSIF Metavolcanics ORLICA MASSIF

Phylites & metavolcanics Variscan granitoids

Cadomian granitoids KEPRNIK NAPPE

DESNA DOME Metabasites & gneisses 50°N Stare Mesto & Velke Vbrno Units: amphibolites & mica schists 20 km Undifferentiated gneisses and schists

Figure 2. Geologic map of major lithologies and structural contacts in the Sudete Mts., ISF: Intra-Sudetic Fault, SBF: Sudetic Boundary Fault (modified after Aleksandrowski et al., 1997). Box inset indicates the location of the Gory Sowie study area.

The GSB is composed of polyphase deformed gneisses and migmatites interpreted to have greywacke or pelitic-psammitic protoliths, possibly formed in a volcanic arc setting, evidenced by I-type granites and zircons demonstrating igneous morphologies

(van Breemen et al., 1988; O’Brien et al., 1997; Kroner & Hegner, 1998). Detrital zircon ages (1.8-1.4 Ga) obtained using U-Pb geochronometry (O’Brien, 1997a; Brocker et al.,

1998; Kroner & Hegner, 1998) show Archean, Neoproterozoic and Early Ordovician 17 populations, thus confirming Gondwanan or Baltica origins for the GSB. The Late

Ordovician ages have been interpreted to record granitoid crystallization corresponding to arc formation (Kroner & Hegner, 1998). Additionally, the GSB is partially underlain by a series of ophiolitic sequences (Kossmat, 1927; Oliver et al., 1993) outcropping as the

Sleza complex to the north, and the Nova Ruda complex to the south and southwest

(Figure 3; Kroner & Hegner, 1998). The Sm-Nd whole rock crystallization ages of 353 ±

21 Ma and 351 ± 16 Ma (Sleza and Nova Ruda ophiolite massifs, respectively; Pin et al.,

+20 1988) and an U-Pb zircon age of 420 -2 Ma (Oliver et al., 1993) constrain the timing of tectonism in the GSB. Furthermore, the unmetamorphosed Frasnian to Tournaisian deposits of the Swiebodzice Depression contain Nova Ruda, Sleza and Gory Sowie massif detritus indicating surficial exposure by this time interval (Zakowa, 1963,

Porebski, 1981). 18

Figure 3. Geologic map of the Gory Sowie Block and Niemcza Shear Zone illustrating major lithogical and structural features (modified after Brocker et al., 1998). Note the block is divided into the mountainous, well exposed western region and poorly exposed flat-lying eastern region by the Sudetic Boundary Fault (SBF). 19 3. Previous Tectonometamorphic Chronometry

Previous geo- and thermochronologic investigations of the GSB have loosely constrained several tectonic events occurring between ca. 500 Ma and 320 Ma.

Crystallization ages of Ordovician granitoids, constrained to 480 and 460 Ma based on

Pb/Pb single zircon ages of gneisses (Kroner & Hegner, 1998) are interpreted to date emplacement within an existing Proterozoic basement. Oliver et al’s. (1993, 1998) U-Pb zircon data from a cross-cutting synmetamorphic granite sheet revealed an upper intercept age of 460 Ma, interpreted as the onset of Caledonian collision-related metamorphism. Peak metamorphic conditions occurred ca. 400 Ma as recorded in tectonic lenses of garnet-pyroxene metabasites and quartzo-feldspathic granulites:

O’Brien et al. (1997) obtained U-Pb and Pb/Pb metamorphic zircon ages of 401 ± 10 Ma

(15 - 20 kbar, 900 - 1000°C) and 402 ± 1 Ma (27 kbar, 1030°C), respectively, for high pressure felsic granulites. A similar age of 402 ± 3 Ma was obtained by Brueckner et al.

(1996) using Sm-Nd systematics on a mantle-derived garnet peridotite. Additional

thermobarometric analysis of garnet indicates peak pressures between 20 and 27 kbar and

temperatures exceeding 1000°C on garnet cores, however rim analysis reveals an

amphibolite-facies overprint of 6.5 - 8.5 kbar and 775 - 910°C (Brueckner et al., 1996).

Furthermore, this exhumational metamorphism has recently been constrained through

garnet-biotite thermobarometric studies on the host gneisses and amphibolite lenses that

revealed equilibration conditions of 6.0 kbar and 600°C (Budzyn et al., 2004).

Thermobarometric results have led researchers to conclude that exhumation of the

granulitic and eclogitic rocks to mid crustal depths occurred coevally with amphibolite-

facies metamorphism of the surrounding gneisses and migmatites (Zelazniewicz, 1985; 20 Brueckner et al., 1996; O’Brien et al., 1997; Cymerman et al., 1997; Cymerman, 1998;

Kroner & Hegner, 1998).

Exhumation of the Gory Sowie Complex under the aforementioned conditions has been constrained to the Late Devonian on the basis of lower intercept and nearly concordant U-Pb monazite ages ca. 380 Ma (van Breemen et al., 1988; Brocker et al.,

1998). These ages are supported by nearly identical Rb-Sr mica model ages of 380 - 360

Ma and concordant xenotime ages of 384 - 380 Ma from an augen gneiss (Brocker et al’s., 1998). Additionally, Timmermann et al. (2000) revealed xenotime ages of 378 ± 2

Ma and 383 - 370 Ma for anatectic granite and pegmatite, respectively; prolific melting of the gneiss and migmatite sequences at this time suggests either increased heat flow or, more likely, decompressional melting associated with unroofing events. Gordon et al. (in press) obtained Th-Pb monazite ages which suggest this may have been a protracted tectonothermal event lasting from ca. 385 to 370 Ma. Furthermore, Marheine et al.

(2002) has published preliminary 40Ar/39Ar mica ages from gneisses abutting the south- western shear zone, indicating early Variscan cooling ca. at 360 Ma.

Markedly younger 40Ar/39Ar fusion ages of 330 - 320 Ma (Oliver & Kelley, 1993) and an U-Pb monazite age of 334 ± 2 Ma (Kroner & Hegner, 1998) on Gory Sowie derived granitoid bodies located adjacent to and within the NSZ indicate a late Variscan exhumational-component to the far-eastern portions of the GSB, analogous with the unroofing events of the Orilca Snieznik Dome and adjacent portions of the Sudetes

(Figure 2; Steltenpohl et al., 1993; Maluski et al., 1995; Glascock et al., 2004; Gordon et al., in press). Moreover, recently obtained geochronometric data indicates the NSZ was 21 active over a period of approximately 100 m.y. (380 - 280 Ma; Gordon et al., in press), which spans the entire tectonic evolution of the Sudetes.

This study attempts to further constrain the timing of unroofing events occurring during the amphibolite-facies metamorphic overprinting event, suggested to have occurred between 380 Ma and 360 Ma, through the use of 40Ar/39Ar thermochronology.

Complimentary U-Th total-Pb geochronometry is then used to link amphibolite-facies events to the mid-crustal emplacement of granulitic and eclogitic lenses during peak metamorphic conditions. Gory Sowie-derived clastics found in adjacent sedimentary basins place lower limits on the unroofing history of between 360 Ma and 340 Ma. 22 4. Petrology & Petrography

4.1 Methods & Approach

In order to further define the tectonometamorphic history of the Gory Sowie

Block, a detailed petrographic analysis was performed on thirty-one rock specimens, collected along three northeast-southwest transects traversing the northern, central and southern portions of the GSB (Figure 4). Transects targeted previously investigated granulite facies localities, but incorporated many new localities to determine if a metamorphic trend exists across the massif. Sample localities along transects were primarily determined on the basis of geographic distribution, accessibility and presumption of metamorphic mineral assemblages. Detailed petrologic and petrographic descriptions of each collected sample are given in appendix A, but the major rock units of the GSB are summarized below.

4.2 Gneisses & Migmatites

The Gory Sowie gneiss/migmatite sequences commonly exhibit mid- to upper amphibolite-facies metamorphism and less frequently granulite-facies metamorphism, which is restricted to northern (primarily northwestern) localities. Common mineral assemblages include quartz + plagioclase + biotite ± garnet ± muscovite ± potassium feldspar ± cordierite ± sillimanite (as fibrolite) ± kyanite. The majority of the gneisses demonstrate moderately to strongly developed foliation fabrics and occasional strain preserved as undulose extinction and elongation of quartz grains into ribbons. More commonly quartz grains demonstrate sub-grain boundaries and triple-point structures.

Garnet is preferentially included in biotite foliation planes (Figure 5). Metamorphic mineral assemblages vary from upper amphibolite/lower granulite facies (kyanite - 23 sillimanite zone) in the northern portions to middle/lower amphibolite facies (garnet - biotite zone) in the southern portions of the block (Figure 6). The homogenous nature of the gneisses requires the application of Zelazniewicz’s (1985) textural terms for their field identification (flaser, scaly, augen and laminated).

Figure 4. Sample location map for the Gory Sowie Block overlayed on a terrane outline. Filled symbols represent localities investigated for Ar-Ar thermochronometry (black ovals) and total-Pb geochronometry (gray ovals), while open symbols (white ovals) represent localities of petrographic investigations only. 24

Figure 5. (a) Photograph (close up) of a typical gneiss outcrop (locality GS-8), 1 km northeast of Lasocin, displaying well developed foliation. Note lens cap in upper right for scale. (b) Photomicrograph (crossed polar) of sillimanite-mica gneiss (sample GS-1). Note biotite-sillimanite reaction zones and well developed foliation planes. FOV: 2 mm. 25

Figure 6. Simplified outline of Gory Sowie Block indicating the general trend of metamorphic zones. The north-west margins contain primarily sillimanite zone metamorphism and rapidly decrease to garnet/ biotite grade metamorphism in the south- central and southern margins. Small outcrops of higher grade rocks appear in the north- central GSB, but a lack of exposure limits complete mapping east of the SBF. Note the lack of Staurolite zone assemblages.

4.3 Granulites

Felsic granulites occur as tectonic lenses, often in conjunction with meta- or ultrabasites, surrounded by amphibolite-facies gneisses, and are restricted to the northern portions of the GSB, the majority within the Bystrzyckie Lake region. These are typically fine to medium grained rocks comprising HP mineral assemblages including quartz + plagioclase + potassium feldspar ± garnet ± kyanite ± cordierite (as a retrogression product) and accessory minerals (rutile, apatite, zircon and metal-oxides). Granulites exhibit banding due to alternating garnet-biotite and quartzo-feldspathic layers or, more commonly, to well developed quartz ribbons and directionally arranged kyanite. Relict kyanite, often rimmed with white mica, is indicative of previously high temperatures and 26 pressures. Quartz grains typically demonstrate an elongate granoblastic texture, while feldspars occasionally exhibit antiperthitic characteristics (Figure7).

4.4 Eclogites, Metabasites, and Serpentites

Amphibolite sequences outcrop as lenses, tens to hundreds of meters wide, located throughout the GSB. These units typically display either a strong foliation and mineral lineations or no fabric at all. Foliated amphibolites have been interpreted to be primary intercalation of marl or volcanoclastic units, and non-foliated amphibolites to be mantle derivatives (Zelazniewicz, 1990). Common mineral assemblages include quartz + hornblende + garnet + pyroxene + plagioclase + biotite ± microcline ± chlorite.

Hornblende and garnet porphryoblasts are typically poikiloblastic in nature. Additionally, garnets are anhedral and contain numerous poikiloblasts of quartz, feldspars and rare biotite and kyanite. Rare eclogites exhibit a distinct high temperature overprint as a prevailing kelyphitic texture as well as symplectic intergrowths of plagioclase, hornblende, pyroxene and occasional garnet (Figure 8). 27

Figure 7. (a) Photograph of kyanite-bearing granulite outcrop (locality GS-3), western Bystrzyckie Lake. Note rock hammer in lower right for scale. (b) Photomicrograph (crossed polar) of granulite (sample GS-19) displaying garnet porphyoblast wrapped in (recrystallized?) quartz ribbons. FOV: 2 mm. 28

Figure 8. (a) Photograph of eclogite outcrop (retrogressed?; locality GS-17a), small road cut just northwest of Kiettice. Note rock hammer for scale. (b) Photomicrograph (crossed polar) of eclogite (retrogressed; GS-17b), displaying high temperature overprinting as significant kelyphitic and symplectic intergrowths of pyroxene, garnet, olivine and hornblende. FOV: 2 mm. 29 5. 40Ar/39Ar Thermochronology

The 40Ar/39Ar thermochronology technique is an effective tool in the determination of the tectonic evolution of metamorphic terranes by providing quantitative data on the rate and timing of thermal events. The main advantage of the argon technique is the ability to obtain multiple cooling ages from the same rock given the presence of a suite of potassium-bearing minerals. Potassium-argon thermochronology is based on radiogenic decay of potassium and diffusivity potential of the daughter product at specific temperatures. More specifically, the continual decay of 40K into 40Ar creates a gradual accumulation of the daughter product within the mineral provided thermal conditions favor retention over diffusion (McDougall & Harrison, 1999). Diffusion theory dictates the loss of radiogenic Ar readily occurs when temperatures are in excess of the minerals closure temperature (Tc; Dodson 1973); however, cooling through the Tc allows the accumulation of 40Ar, thus activating the radiometric clock. Perturbations of the

geotherm after crystallization and cooling result in elevated ambient temperatures;

temperatures exceeding a mineral’s Tc will result in the diffusional loss of argon, thereby

“resetting” the radiogenic clock. As the system cools again, partial or complete recrystallization result in the retention of argon, thus subsequent 40Ar retention records post-deformational cooling as apparent ages rather than crystallization ages (Zeitler,

1989; McDougall & Harrison, 1999).

Variations in closure temperatures among minerals allow for the collection of multiple cooling ages from a single rock given the abundance of any K-bearing, rock- forming mineral, such as hornblende, muscovite, biotite and potassium-feldspar.

Hornblende’s Tc of 500 ± 25°C precludes the diffusion of radiogenic argon during most 30 deformational events, as resetting occurs only during significant and prolonged amphibolite-facies reheating. Biotite and muscovite posses much lower closure temperatures, 300 ± 25 and 350 ± 25°C respectively, permitting less significant reheating events to be recorded (McDougall & Harrison, 1999). Moreover, closure temperatures are dependent on both the thermal equilibrium (cooling) rate of the tectonic system and the mineral’s grain size. Therefore, a higher Tc is expected for rocks experiencing rapid cooling rates (e.g., UHP terranes). The use of 40Ar/39Ar cooling ages from several

different minerals allows the construction of Temperature-time (T-t) paths from which

exhumation rates can be determined. The T-t path illustrates the relative cooling rates as

recorded by the rock; therefore, rapid cooling would dictate a narrow age distribution of

Ar-Ar dates across a range of Tc.

5.1 Analytical Procedures

Samples were chosen for analysis based on the presence of target minerals

(hornblende, biotite and white mica) and mineral integrity. Hornblende and mica were

separated from metamorphic rocks of the Sudete Mountains for 40Ar/39Ar age spectrum

analysis. Size fractions of 200-300 mesh of the target mineral were obtained using

standard crushing, heavy liquids, a Frantz magnetic separator, and careful handpicking to

insure 99% purity. All samples were ultrasonically cleaned for five to ten minutes, rinsed

in acetone, and dried at ~100°C. Mineral separates were loaded into machined Al discs

and irradiated with flux monitor Fish Canyon Tuff sanidine (27.84 Ma; Deino and Potts,

1990) for 100 hours in the L-67 position at the 2 MW Ford Reactor at the University of

Michigan. 31 Isotopic analyses were conducted at New Mexico Tech using a MAP 215-50 mass spectrometer on line with an automated all-metal extraction system. The flux monitor crystals were placed in a copper planchet within an ultrahigh vacuum argon extraction system and fused with a 10W Synrad CO2 continuous laser. Evolved gases were purified

for two minutes using a SAES GP-50 getter operated at ~450°C. J-factors, dimensionless

irradiation parameters relating the production of 39Ar from 40Ar during the irradiation process, were determined to a precision of 0.1% (2
) by analyzing a minimum of four single crystal aliquots from each of 3-4 radial positions around the irradiation sample trays (McDougall & Harrison, 1999). The unknown minerals were step-heated in a double-vacuum Mo resistance furnace; hornblende was heated for nine minutes and micas were heated for eight minutes. The gas was scrubbed of reactive species during heating with a SAES GP-50 getter for six to eight minutes at 450°C. Following heating, the sample gas was further cleaned with another GP-50 for three minutes for micas and eight minutes for hornblende. Argon isotopic compositions for both the samples and monitors were determined using the MAP 215-50 equipped with an electron multiplier with an overall sensitivity of 2.66 x 10-16 moles/pA.

Extraction system and mass spectrometer blanks and backgrounds were measured numerous times throughout the course of the analyses. Typical blanks (including mass spectrometer backgrounds) were 1400, 18, 0.3, 2.7, and 4.8 x 10-17 moles at masses 40,

39, 38, 37, and 36, respectively, for furnace temperatures below 1300°C. Correction

factors for interfering nuclear reactions were determined using K-glass and CaF2 and are

40 39 36 37 as follows: ( Ar/ Ar) K = 0.0256 ± 0.0015; ( Ar/ Ar) Ca = 0.00027 ± 0.00001; and

39 37 ( Ar/ Ar) Ca = 0.00070 ± 0.00005). All errors are reported at the 2
confidence level and 32 the decay constants and isotopic abundance are those suggested by Steiger and Jäger

(1977). Age spectra can be found in Figures 9a&b, while corresponding isotopic data are found in Table 1.

5.2 40Ar/39Ar Results

Incremental heating experiments were performed on twelve samples from five

localities across the Gory Sowie Block based on geographic location, petrology and

metamorphic grade; of the twelve analyzed samples, eleven returned well defined plateau

ages. Optimal age plateaus/preferred ages contained three or more contiguous heating

increments and a minimum of 50% of the total gas released.

A subset of four samples were analyzed from the northern transect. Sample GS-

2c, an upper sillimanite zone, micaceous gneiss adjacent to amphibolite and granulite

lenses, produced a well defined biotite age plateau. Incremental heating resulted in the

first two increments demonstrating a gradual increase in age from 132 Ma to 352 Ma

before reaching a plateau of 382.1 ± 1.0 Ma (MSWD: 12.59) over the final nine

increments (90% of the total gas).

Sample GS-6 contained co-existing biotite and hornblende from a garnet-

cordierite amphibolite within the upper garnet zone. Analysis of biotite failed to produce

a well defined plateau over eleven increments, although increments eight and nine

produced an age of 383.0 ± 10 Ma (MSWD: 2.80) constituting 35% of the total gas. All

eleven increments yield a total gas age of 373.2 ± 0.5 Ma. Investigation of the

hornblende revealed initially old ages (six increments) gradually decreasing from 405 Ma

(increments three and four) to 395 Ma (increments five and six). The final six heating 33 steps resulted in a plateau age of 389.9 ± 1.7 Ma (MSWD: 9.23) constituting 65% of the total gas released, relatively concordant with the biotite cooling age.

Figure 9a. 40Ar/39Ar age spectra from the Gory Sowie Block. 34

Figure 9b. 40Ar/39Ar age spectra from the Gory Sowie Block. 35

Table 1: 40Ar/39Ar analytical isotopic data

40 39 37 39 36 39 39 40 39 ID Power Ar/ Ar Ar/ Ar Ar/ Ar ArK K/Ca Ar* Ar Age ±1
(Watts) (x 10-3) (x 10-15 mol) (%) (%) (Ma) (Ma) GS-2C biotite, 0.82 mg, J=0.0161537 A 650 6.30 0.0102 5.265 5.1 50 75.2 1.1 132.5 1.6 B 750 13.66 0.0025 0.901 30.5 202 98.0 7.8 352.7 1.0 C 850 14.51 0.0009 0.128 69.6 580 99.7 22.9 378.3 1.2 D 920 14.52 0.0009 0.118 47.8 568 99.8 33.4 378.8 0.8 E 1000 14.76 0.0014 0.177 34.9 376 99.6 41.0 383.9 0.6 F 1075 14.94 0.0013 0.131 53.2 398 99.7 52.5 388.5 0.9 G 1110 14.76 0.0009 0.157 65.1 553 99.7 66.7 384.2 1.0 H 1180 14.62 0.0007 0.154 79.4 723 99.7 84.0 380.8 0.6 I 1210 14.57 0.0006 0.052 42.9 876 99.9 93.4 380.4 0.6 J 1250 14.64 0.0004 -0.057 27.2 1375 100.1 99.3 382.8 1.2 K 1300 14.81 -0.0016 0.044 3.3 - 99.9 100.0 386.0 2.3 Integrated age ± 1
n=11 458.8 K2O=13.31 % 377.5 0.5 Plateau ± 1
steps C-K n=9 MSWD=12.59 92.2 382.1 1.0

GS-6 biotite, 0.49 mg, J=0.0161099 A 650 4.22 0.2818 7.071 18.6 1.8 50.8 4.6 60.9 1.1 B 750 13.13 0.0590 2.946 30.3 8.6 93.4 12.0 324.8 0.8 C 850 14.59 0.0368 1.154 34.7 13.9 97.7 20.6 372.3 0.8 D 920 15.18 0.0309 0.827 33.1 16.5 98.4 28.8 388.3 0.6 E 1000 15.69 0.0656 0.980 32.7 7.8 98.2 36.8 399.4 0.7 F 1075 16.20 0.1137 0.639 71.0 4.5 98.9 54.3 413.6 0.5 G 1110 15.66 0.1072 0.519 36.2 4.8 99.1 63.2 401.9 0.9 H 1180 14.87 0.0707 0.371 99.3 7.2 99.3 87.7 384.4 0.7 I 1210 14.73 0.0859 0.148 38.5 5.9 99.7 97.2 382.7 0.6 J 1250 14.41 0.1334 0.910 8.1 3.8 98.2 99.2 369.9 1.3 K 1300 15.84 0.1221 3.063 3.2 4.2 94.3 100.0 388.5 2.5 Integrated age ± 1
n=11 405.8 K2O=19.74 % 373.2 0.5 Plateau ± 1
MSWD=N/A N/A N/A N/A 36

Table 1: Cont. 40 39 37 39 36 39 39 40 39 ID Power Ar/ Ar Ar/ Ar Ar/ Ar Ar K K/Ca Ar* Ar Age ±1
(Watts) (x 10 -3) (x 10-15 mol) (%) (%) (Ma) (Ma) GS-6 hornblende , 5.34 mg, J=0.0160577 A 800 44.11 2.6391 38.752 1.9 0.19 74.5 0.8 765.2 6.7 B 900 35.29 3.1815 31.042 1.0 0.16 74.7 1.2 637.8 8.2 C 1000 19.79 5.8213 7.257 1.8 0.09 91.5 1.9 461.7 4.7 D 1030 17.04 5.2772 6.330 1.6 0.10 91.5 2.6 403.8 4.5 E 1060 15.79 5.4233 2.489 13.4 0.09 98.1 8.0 401.4 1.2 F 1090 15.46 4.9477 1.691 67.2 0.10 99.3 35.1 398.2 0.7 G 1120 14.82 4.6575 1.399 82.0 0.11 99.7 68.2 384.6 1.1 H 1170 15.45 5.5418 2.447 15.7 0.09 98.2 74.6 394.0 1.3 I 1200 15.19 5.2261 1.855 52.8 0.10 99.1 96.0 391.3 0.8 J 1250 14.18 5.4627 -1.539 0.6 0.09 106.3 96.2 391.7 9.8 JJ 1250 14.96 5.2953 1.671 9.4 0.10 99.5 100.0 387.5 1.8 Integrated age ± 1
n=11 247.5 K2O=1.11 % 396.4 0.7 Plateau ± 1
steps G-JJ n=5 MSWD=9.23 64.9 389.9 1.7

GS-10 biotite , 1.19 mg, J=0.0160556 A 650 11.50 0.0120 4.746 6.5 42 87.8 1.1 270.4 1.7 B 750 14.97 0.0023 0.960 36.1 221 98.1 7.4 381.4 0.8 C 850 14.51 0.0007 0.183 132.7 756 99.6 30.4 375.8 0.5 D 920 14.56 0.0005 0.162 69.4 1077 99.7 42.5 377.3 1.0 E 1000 14.80 0.0011 0.401 40.8 465 99.2 49.5 381.2 0.7 F 1075 14.80 0.0011 0.350 76.9 459 99.3 62.9 381.6 0.7 G 1110 14.69 0.0005 0.195 60.0 1064 99.6 73.3 380.2 0.9 H 1180 14.58 0.0004 0.259 93.2 1390 99.5 89.5 377.1 0.6 I 1210 14.62 0.0004 0.200 42.2 1323 99.6 96.8 378.4 0.5 J 1250 14.72 0.0015 0.233 16.5 334 99.5 99.6 380.6 0.9 K 1300 15.13 0.0145 1.193 2.0 35 97.7 100.0 383.4 3.1 Integrated age ± 1
n=11 576.3 K2O=11.59 % 377.4 0.5 Plateau ± 1
steps B-K n=10 MSWD=10.58 98.9 378.9 0.7 37

Table 1: Cont. 40 39 37 39 36 39 39 40 39 ID Power Ar/ Ar Ar/ Ar Ar/ Ar Ar K K/Ca Ar* Ar Age ±1
(Watts) (x 10 -3) (x 10-15 mol) (%) (%) (Ma) (Ma) GS-12 biotite , 1.79 mg, J=0.0160803 A 650 7.69 0.0119 5.653 15.0 43 78.2 1.9 166.0 1.0 B 750 14.74 0.0097 1.496 57.6 53 97.0 8.9 372.8 1.4 C 850 14.46 0.0011 0.434 171.9 478 99.1 30.1 373.6 1.2 D 920 14.50 0.0011 0.260 82.7 480 99.5 40.3 375.6 0.7 E 1000 14.65 0.0015 0.465 65.1 345 99.1 48.3 377.8 0.7 F 1075 14.66 0.0014 0.298 165.3 354 99.4 68.6 379.1 0.7 G 1110 14.63 0.0011 0.301 81.5 449 99.4 78.7 378.5 0.8 H 1180 14.59 0.0009 0.302 122.4 538 99.4 93.7 377.6 1.0 I 1210 14.57 0.0013 0.175 43.8 384 99.6 99.1 378.0 0.7 J 1250 14.79 0.0148 0.289 7.2 34 99.4 100.0 382.5 1.4 Integrated age ± 1
n=10 812.6 K2O=10.84 % 373.0 0.6 Plateau ± 1
steps E-I n=5 MSWD=0.65 58.8 378.3 0.7

GS-12 muscovite , 0.48 g, J=0.0160824 C 700 16.05 0.0027 3.780 4.4 189 93.0 0.5 387.7 2.1 D 750 15.93 0.0021 3.201 10.1 240 94.1 1.6 388.8 1.5 E 800 15.62 0.0014 3.016 18.7 359 94.3 3.6 382.9 1.1 F 840 15.04 0.0007 1.766 29.3 727 96.5 6.7 377.9 1.3 G 880 14.94 0.0004 1.888 56.6 1238 96.3 12.9 374.9 1.0 H 920 14.39 0.0002 0.504 182.5 2878 99.0 32.6 371.4 0.6 I 960 14.56 0.0003 0.515 55.0 1994 99.0 38.5 375.3 0.6 J 1000 14.68 0.0003 0.691 41.2 1696 98.6 43.0 376.9 0.6 K 1040 14.53 0.0000 0.435 38.3 - 99.1 47.1 375.3 1.1 L 1080 14.51 0.0002 0.525 52.7 2827 98.9 52.8 374.1 0.9 M 1120 14.43 0.0001 0.536 74.2 3492 98.9 60.8 372.1 0.8 N 1160 14.54 0.0002 0.595 77.2 2886 98.8 69.1 374.3 0.7 O 1200 14.43 0.0002 0.204 80.2 2642 99.6 77.8 374.6 0.7 P 1250 14.45 0.0001 0.163 80.2 5047 99.7 86.5 375.3 1.0 Q 1350 14.28 0.0002 0.163 72.7 2894 99.7 94.3 371.2 1.2 R 1650 15.26 0.0001 3.228 52.7 6192 93.7 100.0 372.9 1.3 Integrated age ± 1
n=16 925.9 374.1 0.5 Plateau ± 1
steps H-R n=11 MSWD=5.94 87.1 374.1 0.7 38

Table 1: Cont. 40 39 37 39 36 39 39 40 39 ID Power Ar/ Ar Ar/ Ar Ar/ Ar Ar K K/Ca Ar* Ar Age ±1
(Watts) (x 10 -3) (x 10-15 mol) (%) (%) (Ma) (Ma) GS-16A hornblende , 5.78 mg, J=0.016084 A 800 80.57 28.1421 207.364 0.4 0.02 26.7 0.5 545.4 32.2 B 900 18.96 30.6652 23.063 0.3 0.02 76.9 0.9 387.2 16.6 C 1000 13.69 10.5463 11.378 1.4 0.05 81.6 2.7 299.5 7.4 D 1030 13.62 12.6098 5.266 0.6 0.04 96.0 3.5 346.4 9.6 E 1060 15.69 16.9031 8.617 2.4 0.03 92.4 6.6 381.4 3.8 F 1090 14.72 17.6780 5.682 38.4 0.03 98.2 56.4 380.6 1.5 G 1120 14.83 18.2878 6.729 9.0 0.03 96.4 68.1 377.2 2.5 H 1170 15.72 18.4690 13.790 1.6 0.03 83.4 70.2 348.9 6.6 I 1200 14.88 17.8542 5.779 12.4 0.03 98.1 86.2 384.2 1.7 J 1250 14.97 18.2245 6.550 10.6 0.03 96.8 100.0 381.8 2.1 Integrated age ± 1
n=10 77.1 K2O=0.32 % 379.5 1.5 Plateau ± 1
steps E-G n=3 MSWD=0.78 64.6 379.9 1.3

GS-16B biotite , 1.85 mg, J=0.01615 A 650 8.93 0.0934 9.631 6.9 5 68.1 0.8 168.7 1.8 B 750 14.47 0.0067 1.325 78.2 76 97.3 9.9 369.1 0.6 C 850 14.23 0.0015 0.180 118.9 337 99.6 23.7 371.2 0.6 D 920 14.26 0.0016 0.121 143.4 322 99.7 40.4 372.4 0.6 E 1000 14.38 0.0034 0.150 57.0 148 99.7 47.0 375.1 0.8 F 1075 14.44 0.0069 0.137 114.6 74 99.7 60.3 376.6 0.6 G 1110 14.24 0.0050 0.081 113.7 102 99.8 73.5 372.3 0.8 H 1180 14.28 0.0085 0.161 94.8 60 99.7 84.5 372.6 0.6 I 1210 14.19 0.0030 0.082 85.9 169 99.8 94.5 371.1 0.6 J 1250 14.32 0.0029 0.138 41.1 175 99.7 99.3 373.7 0.7 K 1300 14.50 0.0020 0.174 6.1 262 99.6 100.0 377.8 1.6 Integrated age ± 1
n=11 860.6 K2O=11.06 % 371.1 0.5 Plateau ± 1
steps C-K n=9 MSWD=8.59 90.1 373.0 0.8 39

Table 1: Cont. 40 39 37 39 36 39 39 40 39 ID Power Ar/ Ar Ar/ Ar Ar/ Ar ArK K/Ca Ar* Ar Age ±1
(Watts) (x 10 -3) (x 10-15 mol) (%) (%) (Ma) (Ma) GS-16B muscovite , 0.14g, J=0.0163863 A 600 33.64 0.6348 107.333 0.7 1 5.8 0.5 56.8 23.2 B 650 15.90 0.3564 23.483 0.4 1 56.5 0.8 247.3 15.1 C 700 15.62 0.2007 7.126 0.4 3 86.6 1.0 360.7 14.1 D 750 15.98 0.0665 0.181 1.3 8 99.7 1.9 417.8 5.5 E 800 15.03 0.0108 1.465 2.0 47 97.1 3.2 386.3 3.9 F 840 14.59 0.0088 1.548 2.7 58 96.9 4.9 375.3 2.8 G 880 14.27 0.0021 0.582 5.8 239 98.8 8.7 374.2 1.9 H 920 14.21 0.0009 0.361 28.1 555 99.2 27.0 374.6 0.9 I 960 13.89 0.0016 0.368 24.1 325 99.2 42.8 366.7 1.1 J 1000 13.83 0.0023 0.402 14.5 223 99.1 52.3 364.9 1.2 K 1040 14.06 0.0040 0.720 6.8 127 98.5 56.7 368.2 1.5 L 1080 14.29 0.0058 0.975 7.1 88 98.0 61.4 372.0 1.4 M 1120 14.28 0.0049 0.732 6.8 104 98.5 65.8 373.6 1.2 N 1160 14.47 0.0034 1.349 10.9 152 97.2 72.9 373.8 1.0 O 1200 14.38 0.0028 0.597 16.1 182 98.8 83.4 376.9 0.9 P 1250 14.48 0.0024 0.610 10.1 210 98.8 90.0 379.2 1.3 Q 1350 14.90 0.0006 2.425 5.4 829 95.2 93.5 376.3 1.9 R 1650 16.17 0.0001 7.129 9.9 4845 86.9 100.0 373.4 1.7 Integrated age ± 1
n=18 153.1 371.2 0.6 Plateau ± 1
steps L-R n=7 MSWD=2.7 43.3 375.0 1.5 40

Table 1: Cont. 40 39 37 39 36 39 39 40 39 ID Power Ar/ Ar Ar/ Ar Ar/ Ar Ar K K/Ca Ar* Ar Age ±1
(Watts) (x 10-3) (x 10-15 mol) (%) (%) (Ma) (Ma) GS-18 biotite , 0.66 mg, J=0.0161784 A 650 10.91 0.0275 20.751 1.9 19 43.7 0.5 133.7 6.8 B 750 11.98 0.0118 4.952 10.0 43 87.8 3.1 282.9 1.4 C 850 12.84 0.0047 1.028 37.7 108 97.6 12.8 332.6 0.7 D 920 12.92 0.0046 0.435 51.7 112 99.0 26.0 338.6 0.6 E 1000 12.93 0.0080 0.795 33.6 63 98.2 34.7 336.3 0.6 F 1075 12.96 0.0125 0.866 42.4 41 98.0 45.6 336.7 0.7 G 1110 12.85 0.0228 0.899 28.7 22 97.9 53.0 333.8 0.7 H 1180 12.86 0.0189 1.026 50.7 27 97.7 66.0 333.2 0.6 I 1210 12.89 0.0169 0.556 42.3 30 98.7 76.9 337.2 0.7 J 1250 12.87 0.0479 0.192 64.9 11 99.6 93.6 339.3 0.6 K 1300 12.90 0.1047 0.341 17.6 5 99.3 98.1 339.1 0.9 L 1650 14.52 0.0345 5.474 7.5 15 88.9 100.0 341.6 1.5 Integrated age ± 1
n=12 389.0 K2O=13.99 % 334.3 0.5 Plateau ± 1
steps D-L n=9 MSWD=12.73 87.2 336.8 0.9

GS-18 hornblende , 5.73 mg, J=0.0161763 A 800 13.53 0.3444 5.546 11.5 1.48 88.1 3.2 317.4 1.6 B 900 12.08 0.5088 1.812 13.3 1.00 95.9 6.9 309.5 1.3 C 1000 11.82 1.8135 1.977 11.0 0.28 96.3 10.1 304.6 1.5 D 1030 12.42 2.1164 2.784 7.1 0.24 94.7 12.2 314.1 2.3 E 1060 12.61 3.0973 1.986 10.1 0.16 97.3 15.2 326.7 1.6 F 1090 12.81 4.6594 1.902 44.9 0.11 98.5 29.3 335.4 0.7 G 1120 12.76 4.4159 1.567 97.6 0.12 99.1 64.5 336.3 1.3 H 1170 12.83 3.6705 1.714 19.9 0.14 98.3 72.5 335.2 1.1 I 1200 12.86 4.0726 1.709 13.2 0.13 98.6 78.0 337.0 1.3 J 1250 12.92 4.9075 1.869 48.1 0.10 98.8 99.6 338.9 0.7 K 1300 15.50 4.9327 10.442 0.9 0.10 82.6 100.0 340.1 16.4 Integrated age ± 1
n=11 277.6 K2O=1.15 % 332.4 0.7 Plateau ± 1
steps F-K n=6 MSWD=2.87 84.8 336.8 0.8 41

Table 1: Cont. 40 39 37 39 36 39 39 40 39 ID Power Ar/ Ar Ar/ Ar Ar/ Ar ArK K/Ca Ar* Ar Age ±1
(Watts) (x 10-3) (x 10 -15 mol) (%) (%) (Ma) (Ma) GS-21 biotite , 0.98 mg, J=0.0161079 A 650 5.20 0.0094 5.112 14.8 54 70.8 4.4 103.6 1.1 B 750 9.96 0.0030 2.610 38.2 169 92.2 15.7 248.4 1.0 C 850 10.53 0.0019 0.989 61.8 272 97.2 33.9 274.8 0.5 D 920 10.84 0.0024 1.147 28.6 213 96.9 42.3 281.2 0.7 E 1000 10.66 0.0033 1.556 36.0 156 95.7 52.9 273.7 0.6 F 1075 10.66 0.0021 1.609 69.6 245 95.5 73.5 273.5 0.8 G 1110 10.42 0.0018 1.569 29.5 282 95.5 82.2 267.6 0.7 H 1180 10.57 0.0017 1.331 50.2 308 96.3 97.0 273.3 0.8 I 1210 11.18 0.0031 0.717 10.2 167 98.1 100.0 293.0 0.9 Integrated age ± 1
n=9 338.9 K2O=8.25 % 264.6 0.4 Plateau ± 1
steps C-H n=6 MSWD=39.52 81.3 274.3 1.7

Notes: Isotopic ratios corrected for blank, radioactive decay, and mass discrimination, not corrected for interferring reactions. Ages calculated ralative to FC-1 Fish Canyon Tuff sanidine interlaboratory standard at 27.84 Ma. Errors quoted for individual analyses include analytical error only, without interferring reaction or J uncertainties. Integrated age calculated by recombining isotopic measurements of all steps. Integrated age error calculated by recombining errors of isotopic measurements of all steps. Plateau age is inverse-variance-weighted mean of selected steps. Plateau age error is inverse-variance-weighted mean error (Taylor, 1982) times root MSWD where MSWD>1. Plateau and integrated ages incorporate uncertainties in interfering reaction corrections and J factors. Bold print represent those values used in plateau age determination Decay constants and isotopic abundances after Steiger and Jaeger (1977). Discrimination = 1.00484 ± 0.00092 Correction factors: 39 37 ( Ar/ Ar)Ca = 0.0007 ± 5e-05 36 37 ( Ar/ Ar)Ca = 0.00027 ± 1e-05 38 39 ( Ar/ Ar)K = 0.01077 40 39 ( Ar/ Ar)K = 0.02559 ± 0.001487 42 From the north-central massif across the SBF, biotite was analyzed from sample

GS - 21, a micaceous gneiss in the lower amphibolite facies. An age plateau exists for increments three through ten (85% of the total gas), and yields an age of 274.3 ± 1.7 Ma

(MSWD: 39.52), albeit with an extremely high MSWD. It is important to note, this sample contained strongly retrogressed garnets and serecite alteration of plagioclase which forms about 25% of the mode.

Three samples were selected for thermochronology from the central transect.

Sample GS-10, a sillimanite-garnet gneiss of the upper sillimanite zone, was processed for biotite analysis. Ten of the eleven heating increments (99% of the total gas) produced an age plateau of 378.9 ± 0.8 Ma (MSWD: 10.58). Co-existing biotite and muscovite were analyzed from GS-12, a micaceous gneiss of the upper garnet zone. Analysis of biotite revealed a fairly uniform distribution of increments, though only increments five through nine contributed to a plateau age of 378.3 ± 0.7 Ma (MSWD: 0.65) with 60% of the total gas released. Muscovite analysis was conducted over sixteen heating increments with the first five increments showing a gradual decrease in age from 388 Ma to a plateau age of 374.2 ± 0.7 Ma (MSWD: 5.94) comprising 85% of the total gas.

The final five samples were collected along the southern transect of the GSB.

Sample GS-16 was collected from two localities, roughly 50 m apart. Hornblende was separated from location A (an amphibolite lens), and co-existing muscovite and biotite from location B (a garnetiferous gneiss). Analysis of GS-16A hornblende from a coarse- grained amphibolite in the garnet zone, yielded a plateau age of 379.9 ± 1.3 (MSWD:

0.78) for increments five through seven with over 65% of the total gas contributing.

Increment eight shows a markedly younger age, thus excluding the remaining heating 43 increments from the plateau age. Incremental heating of muscovite from GS-16B, a garnetiferous gneiss in the lower sillimanite zone, yields initially older ages before attaining a plateau age of 375.0 ± 1.5 Ma (MSWD: 2.70) for increments twelve through eighteen with 55% of the total gas contributing. Biotite from sample GS-16B, in concordance with the muscovite age, yields a uniform plateau age of 372.4 ± 0.8

(MSWD: 12.60) with approximately 99% of the total gas contribution.

Sample GS-18, a garnet zone foliated amphibolite located adjacent to the

Niemcza shear zone, was sampled for both biotite and hornblende. Incremental heating of the hornblende revealed a gradual increase in age over the first five steps before reaching a plateau age of 336.8 ± 0.8 Ma (MSWD: 2.87) over the remaining six steps

(85% of the total gas). Analysis of biotite also produced a gradual increase in ages before attaining an identical plateau age of 336.8 ± 0.9 Ma (MSWD: 12.73) with 85% of the total gas released. 44 6. U-Th total-Pb Geochronology

To further constrain the metamorphic evolution of the GSB terrane, quantitative chemical analysis of monazite was performed through in situ U-Th-total Pb geochronology using an electron microprobe. Monazite, a REE-phosphate mineral commonly found as an accessory mineral in a variety of igneous and metamorphic rocks, is an ideal mineral for the geochronologic investigation of the GSB. Notably, monazite typically contains high concentrations of U and Th, which decay to radiogenic Pb, and low concentrations of common Pb, increasing analytical precision. It is an ideal mineral used in geochronology due to a very high closure temperature (~ 800oC) and remarkably slow diffusion of radiogenic Pb (Catlos et al., 2002). Hence, only high-temperature deformational events are able to “reset” the radiogenic clock. Additionally, monazite is able to grow over a wide temperature range (~300 - 800oC), thus preserving polyphase thermal histories as discrete elemental zoning patterns within the grain (Parrish, 1990;

Catlos et al., 2002; Foster et al., 2002). Therefore, in situ U-Th-total Pb spot analyses of these intercrystalline zones/domains can yield multiple ages from a single crystal, making it possible to constrain the timing of younger thermal events (Williams et al., 1999).

Furthermore, monazite is typically found within other minerals such as garnets, which armor the monazite and aid in the slow diffusion rate (Catlos et al., 2002), and thus allow age constraints to be placed on metamorphic minerals as well.

6.1 Analytical Procedures

In recent years, the advent of electron microprobe analysis of monazite allows for the rapid and reliable collection of multiple spot ages from single grains. Electron microprobe geochronologic investigations of the GSB involved two procedures: high- 45 resolution compositional mapping to aid in the identification of probable intracrystalline age domains, and quantitative elemental analysis of U, Th, Y, and Pb. Matrix corrections, based on a standard monazite major-element matrix, were completed using the PAP method defined by Pouchou and Pichoir (1984, 1985). Analyses were carried out using the Cameca SX-50 electron microprobe analyzer at Virginia Polytechnic

Institute and State University.

Monazite grains were identified through manual rock thin section scanning noting high Ce peaks, in addition to using energy dispersion spectras (EDS). Furthermore, U,

Th, Y and Ca chemical maps were obtained for suitable grains using a high sample current (~200 nA), 15kv accelerating voltage and 50 msec per pixel (resolution of 512 x

512 pixels). Elemental maps were analyzed for distinct chemical domains to determine optimal beam placement for age determinations. Analyses were carried out in two steps: major elements were first determined and then hand entered for trace-element analysis using the Cameca trace-element routine. It is important to note, a single major-element analysis was used for multiple age determinations and trace-element analysis was performed during every sample change operation (three samples per change).

Background intensities were acquired using high-resolution wavelength scans around the peaks of interest, allowing a selection of wavelength regions to use in curve fitting, using appropriate polynomial or exponential models, and calculation of the net intensity to be subtracted from the peak. Quantitative trace-element analyses were performed using counting times of 700 or 900 seconds (based on qualitative EDS, U & Th concentrations).

Once concentrations of U, Th, and Pb were obtained, the age equation of Montel et al.

(1996) was solved by iteration based on calculated Pb. Lead concentration was corrected 46 for Y interference on the Pb M-alpha line by estimation using the empirical approach of

Amlie and Griffen (1975), in this case based on analysis of a synthetic laser-grade YAG

(Y3Al5O12 garnet) from the Harvard Mineral museum. This estimate was then modified

based on the major compositional differences between YAG and monazite to estimate the

shift in relative line intensities due to matrix properties. Similarly, U concentrations were

corrected based on empirical overlap of Th M-gamma on U M-beta, as suggested by

Sherrer et al. (2000). Chemical ages and errors reported were calculated using the standard error equation based on the number of analyses for each domain and results may only reflect analytical precision. Weighted-mean ages are presented as relative probability graphs with errors reported at the 2 level. Complete elemental data tables of

GSB samples can be found in Table 2.

6.2 Total-Pb Results

To further constrain the exhumational history of the Gory Sowie, potential total-

Pb monazite samples were selected to supplement 40Ar/39Ar thermochronometric data

based on geographic location, petrology and previous geochronology. Three samples

were chosen: a granulite from the northern GSB and two gneisses from the central

transect, with a total of six monazite grains analyzed (two per sample) with 220 spot

analyses. The SPSS (v. 11.5) statistical package was used to perform K-means clustering

of the total-Pb spot analysis data (
: 5) and revealed a total of four age domains (359 Ma

n = 31, 382 Ma n = 59, 403 Ma n = 36 and 416 Ma n = 33) consisting of 159 data points. Older

domains were also revealed, though these domains are interpreted to represent initial

crystallization/ emplacement events rather than the a metamorphic/exhumational episode. 47 Sample GS-19 is a kyanite zone micaceous granulite located in the northeastern portion of the GSB. Monazite grains were typically located near, or enclosed within, biotite, with the majority of grains measuring > 20
m in diameter. Monazite #3, a subhedral grain displaying three elemental zones including a well defined core, is approximately 75 x 35
m and located along a biotite grain boundary. A total of twenty-

six spot analyses were conducted over three transects; transect design was based on Y, U

and Th elemental maps. Three distinct age domains were determined based on

cumulative probability peaks: 355 ± 8 Ma, 383 ± 7 Ma and 404 ± 14 Ma (Figure 10).

The 383 ± 7 and 404 ± 14 age domains occur off peak, interpreting the high 390 Ma peak

as binary mixing between the aforementioned age domains. Elemental images reveal a

well defined old core with progressively younger age zones toward the monazite’s edges

(Figure 11a). Monazite #6, a subhedral elongate grain displaying distinct core-rim

elemental zonation, is approximately 35 x 65
m and was also located adjacent to a biotite grain. Two transects with a total of seventeen spot analyses revealed three similar age domains: 357 ± 14 Ma, 382 ± 6 Ma and 404 ± 10 Ma (Figure 10). Chemical maps exhibit a small, old core near the margin of the grain with a large young domain dominating the central half. The large embayment morphology of the domains is characteristic of monazite that has undergone reprecipitation (Figure 11b).

Sample GS-11 is a sillimanite zone scaly-micaceous gneiss located in the west- central GSB. Monazite grains were typically found as inclusions within biotite. The majority of these grains measured 20
m in diameter; ideal grains were > 30
m in diameter. Monazite #17 is a subhedral crystal, approximately 40 x 30
m, located along a biotite grain boundary and displays three distinct chemical zones (a strong Y-low core 48 is clearly defined). Cumulative probability curves reveal age domains of 358 ± 14 Ma,

383 ± 7 Ma and 418 ± 14 Ma (Figure 10). Elemental maps indicate a reverse age zonation pattern with the youngest domains occurring in the center of the grain (Figure

11c). Monazite #21, a subhedral grain approximately 40 x 20
m, was located within biotite and demonstrates similar chemical zoning to that of monazite #17 including the Y- low core. Cumulative probability analysis revealed one age domain coincident with monazite #17 (418 ± 8 Ma) and two more containing significantly older ages: 447 ± 7 Ma and 467 ± 9 Ma (Figure 10). Chemical mapping again demonstrates a reverse core-rim relationship with the youngest ages occurring within the center of the grain (Figure 11d).

Sample GS-8, a garnet zone layered gneiss was collected from the central portion of the GSB. Monazite grains are typically large (often exceeding 60
m in diameter) and occur almost exclusively as rim overgrowths on a range of metamorphic minerals (most commonly garnet, apatite and biotite). Monazite #2, a sub- to anhedral grain, is approximately 70 x 100
m and located between two apatite grains. Chemical maps reveal two discrete Y zones and cracks near the edge of the crystal. Cumulative probability curves define three age domains: 360 ± 5 Ma, 382 ± 4 Ma and 404 ± 5 Ma

(Figure 10). Elemental maps define an old core domain with successively younger domains towards the grain margins (Figure 11e). Monazite #14 is a large grain that wraps around an apatite grain (resembling a rim growth) and measures approximately

110
m in length by an average of 25
m in width. Three age domains revealed through cumulative probability curves are coincident with monazite #2: 360 ± 7 Ma, 382 ± 7 Ma and 402 ± 5 Ma (Figure 10). Chemical mapping revealed two distinct zones with a clear overgrowth rim surrounding 80% of the grain (Figure 11f). The unusual grain geometry 49 and age domain pattern is likely the result of complex apatite to monazite metamorphic mineral reactions (Simpson et al., 2000). It is important to note, core-rim relationships

are often complex and these images only represent a two-dimensional surface of a three-

dimensional grain.

Sample GS-19 Sample GS-11 447 ± 7Ma MSWD = 0.34 Monazite #6 Monazite #21 n = 7 355 ± 8 Ma 404 ± 10 Ma MSWD = 0.48 467 ± 9 Ma n = 6 MSWD = 0.41 413 ± 8 Ma n = 4 MSWD = 0.14 MSWD = 0.36 n = 14 383 ± 7 Ma n = 6 MSWD = 0.95 n = 7

430 ± 14 Ma MSWD = 0.05 n = 2 418 ± 14 Ma MSWD = 0.54 n = 23

382 ± 6 Ma MSWD = 0.4 n = 10 Relative Probability Monazite #3 Monazite #17 383 ± 7 Ma MSWD = 0.24 n = 8 358 ± 14 Ma 404 ± 10 Ma MSWD = 0.02 MSWD = 0.56 n = 2 n = 4 357 ± 14 Ma 420 ± 10 Ma 466 ± 10 Ma MSWD = 0.14 MSWD = 0.14 MSWD = 0.20 n = 2 n = 4 n = 4

320 340 360 380 400 420 440 460 480 500 340 360 380 400 420 440 460 480 500 U-Th total-Pb Age (Ma) U-Th total-Pb Age (Ma)

Sample GS-8

402 ± 5 Ma MSWD = 0.28 Monazite #14 n = 13

382 ± 7 Ma MSWD = 0.19 n = 8

360 ± 7 Ma MSWD = 0.33 n = 8 382 ± 4 Ma MSWD = 0.23 n = 26

Relative Probability 404 ± 5 Ma 360 ± 5 Ma MSWD = 0.20 MSWD = 0.22 n = 15 Monazite #2 n = 13

340 360 380 400 420 440 460 U-Th total-Pb Age (Ma)

Figure 10. Cumulative probability graphs of in situ monazite U-Th total-Pb geochronometric analyses from the Gory Sowie Block. Each graph illustrates the age results from two grains and is comprised of single spot ages at the 2
confidence level. 50

A. GS - 19 Monazite 3 B. GS - 19 Monazite 6 T1

T2 T1

360 Ma 385 Ma 405 Ma T2 > 405 Ma

360 Ma 25 µm 385 Ma 405 Ma T3 > 405 Ma

30 µm

T1 T5 C. GS - 11 Monazite 17 D. GS - 11 Monazite 21 T2 T5 T1

T4 T2

T4 T3 405 Ma 360 Ma 440 Ma 385 Ma 460 Ma 405 Ma T3 480 Ma > 405 Ma 20 µm F. GS - 8 Monazite 14 20 µm I-04 E. GS - 8 Monazite 2 I-05 T3 I-03 I-02

T2 T2T2 T1 I-01 T2 T1

360 Ma 385 Ma I-12 T4 405 Ma 360 Ma > 405 Ma 385 Ma 80 µm I-11 405 Ma I-10 I-06 > 405 Ma I-09 I-07 I-08 40 µm

Figure 11. Monazite chrontour maps of U-Th total-Pb geochronometry based on single spot analyses and elemental mineral zonation from corresponding Y-chemical maps (smaller images). Age bins were defined based on K-means clustering (
: 5) with constant bins of 360 Ma, 385 Ma, 405 Ma and > 405 Ma for figures a,b,c,e and f. Figure d contained significantly older ages outside the defined bins, therefore age bins were assigned using a separate K-means cluster analysis resulting in bins of 405 Ma, 440 Ma, 460 Ma and 480 Ma. Transects (T1, T2,…)and individual spots (I1,I2,…) are labeled accordingly and arrows represent direction of transect analysis. Table 2 contains associated elemental data. 51

Table 2: Analytical U-Th total-Pb Isotopic Data Elemental Concentration (ppm) Elemental Concentration (ppm) Analysis # † Th U Pb Y Age (Ma) Analysis # † Th U Pb Y Age (Ma) GS-8 Monazite 14 I - 06 13648 3975 504 10221 409

T1 - 01 29574 2699 697 2962 403 I - 07 17913 3528 571 7773 423

T1 - 02 33939 2498 746 1971 394 I - 08 13485 3201 561 7607 509

T1 - 03 34688 2728 780 2074 398 I - 09 13369 3361 468 7430 418

T1 - 04 33845 2643 680 2001 356 I - 10 18805 3493 606 7869 438

T1 - 05 35705 2547 788 1999 398 I - 11 19488 3076 557 7036 412

T1 - 06 36477 2594 776 1970 384 I - 12 22087 3274 582 7001 389

T1 - 07 45039 2673 958 2015 397 GS-8 Monazite 2

T1 - 08 40829 2739 822 2062 368 T1 - 01 28247 2492 692 1387 424

T1 - 09 34759 2731 781 2156 398 T1 - 02 35000 2795 708 1682 358

T1 - 10 27613 2585 614 2819 378 T1 - 03 34549 2681 694 1655 358

T1 - 11 27614 2788 658 3270 398 T1 - 04 34583 2774 754 1660 385

T1 - 12 21512 3269 592 6723 403 T1 - 05 35347 2727 809 1602 407

T2 - 01 19175 3538 559 7770 397 T1 - 06 35064 2825 780 1699 393

T2 - 02 28425 3475 738 5401 410 T1 - 07 34500 2859 719 1645 366

T2 - 03 29837 2981 686 3478 385 T1 - 08 34038 2750 825 1663 427

T2 - 04 30447 2845 775 2978 433 T1 - 09 34425 2813 737 1712 377

T2 - 05 30393 2779 673 2794 379 T1 - 10 34266 3072 815 1732 410

T2 - 06 27597 2343 566 2526 357 T1 - 11 37213 3490 866 1911 397

T2 - 07 31461 2546 638 2766 357 T1 - 12 40250 4179 937 2164 388

T2 - 08 32267 2577 692 2762 378 T1 - 13 39714 4087 961 2162 404 T2 - 09 31986 2549 663 2923 366 T1 - 14 39111 4008 873 2190 373 T2 - 10 32606 2512 709 2667 386 T1 - 15 39458 4073 862 2175 406 T2 - 11 31151 2622 676 3413 378 T1 - 16 39185 4018 855 2152 365 T2 - 12 22942 2931 597 5453 404 T1 - 17 39186 4000 936 2176 399 T2 - 13 18532 3189 564 7080 426 T1 - 18 39081 3906 902 2132 388 I - 01 22698 3643 633 7146 401 T1 - 19 38080 3596 893 2002 399 I - 02 22864 3843 575 4962 359 T1 - 20 37930 3928 917 2138 403 I - 03 20901 3353 527 5696 364 T1 - 21 36998 3866 851 2180 382 I - 04 9901 4067 377 8074 351 T1 - 22 35589 3832 817 2198 379 I - 05 13891 3697 547 9294 456 T1 - 23 35469 3812 831 2218 387 52

Table 2: cont. Elemental Concentration (ppm) Elemental Concentration (ppm) Analysis # † Th U Pb Y Age (Ma) Analysis # † Th U Pb Y Age (Ma) GS-8 Monazite 2 GS-8 Monazite 2 T1 - 24 35690 3796 801 2160 372 T4 - 04 33620 2653 741 1623 405 T1 - 25 36180 3824 820 2165 376 T4 - 05 32146 2440 741 1583 388 T2 - 01 20248 2663 461 3374 353 T4 - 06 33043 2507 741 1590 377 T2 - 02 32206 2684 674 2361 366 T4 - 07 32965 2553 741 1607 376 T2 - 03 30515 2773 627 2349 353 T4 - 08 32802 2494 741 1604 363 T2 - 04 30191 2714 675 2646 384 T4 - 09 32537 2450 741 1600 371 T2 - 05 28919 2779 651 2814 381 T4 - 10 32869 2530 741 1584 371 T2 - 06 29087 2741 644 2808 376 T4 - 11 32997 2618 741 1607 387 T2 - 07 25779 2637 590 3425 380 T4 - 12 32589 2436 741 1703 375 T2 - 08 24925 2557 580 4100 386 T4 - 13 31967 2465 741 1676 387 T3 - 01 33406 2689 727 1971 384 T4 - 14 31435 2434 741 1647 359 T3 - 02 34916 2725 760 1667 387 T4 - 15 31195 2372 741 1728 372 T3 - 03 35030 2776 767 1651 388 T4 - 16 27272 2140 741 1679 384 T3 - 04 34701 2660 712 1641 366 T4 - 17 30590 2343 741 2023 386 T3 - 05 34448 2650 782 1735 404 T4 - 18 16206 1276 741 853 416 T3 - 06 34395 2652 757 1643 392 GS-11 Monazite 17 T3 - 07 35030 2668 788 1659 401 T1 - 01 23862 7688 1603 12830 709 T3 - 08 35620 2776 783 1654 391 T1 - 02 29512 7974 1191 14102 469 T3 - 09 36449 2869 741 1624 361 T1 - 03 29673 7758 1055 13359 420 T3 - 10 36070 2864 741 1650 360 T1 - 04 27592 5930 881 5501 415 T3 - 11 35177 2947 741 1682 398 T1 - 05 29676 5419 905 2210 426 T3 - 12 35093 2876 741 1669 377 T1 - 06 31155 5950 928 2995 409 T3 - 13 31831 2401 741 1555 348 T1 - 07 25923 4998 795 2275 419 T3 - 14 34416 2698 741 1660 377 T1 - 08 27503 5992 876 8474 410 T3 - 15 35339 2631 741 1715 410 T1 - 09 29366 6928 1058 14362 444 T3 - 16 36936 2931 741 1841 404 T2 - 01 20372 5940 1115 1552 618 T3 - 17 25935 2773 741 2187 436 T2 - 02 22810 6499 1120 16600 550 T4 - 01 31083 2712 741 1908 356 T2 - 03 25813 7510 1073 20711 460 T4 - 02 33590 2628 741 1710 411 T2 - 04 26437 7391 1087 22380 463 T4 - 03 33485 2629 741 1626 372 T2 - 05 25682 7214 986 22124 430 53

Table 2: cont. Elemental Concentration (ppm) Elemental Concentration (ppm) Analysis # † Th U Pb Y Age (Ma) Analysis # † Th U Pb Y Age (Ma) GS-11 Monazite 17 GS-11 Monazite 21 T2 - 06 23929 7316 1052 23826 471 T3 - 01 14060 4220 690 14641 530 T3 - 01 30724 7914 1109 17275 427 T3 - 02 23401 6508 1021 23061 489 T3 - 02 29195 5877 927 4937 425 T3 - 03 26637 7389 1105 22684 468 T3 - 03 30465 5576 910 1966 417 T3 - 04 26401 7107 1074 20448 467 T3 - 04 28282 6958 1022 11744 439 T4 - 01 23448 6185 918 18267 453 T4 - 01 24882 6629 901 12233 423 T4 - 02 26736 7383 986 17883 420 T4 - 02 27491 6689 964 11097 428 T4 - 03 28701 7531 1019 17193 415 T4 - 03 30805 7459 1077 14543 426 T4 - 04 27661 7637 1097 20502 450 T4 - 04 31442 8120 1110 16951 417 T4 - 05 26091 7355 1102 24730 471 T4 - 05 30029 7219 1018 13968 415 T5 - 01 17766 4346 483 10150 328 T4 - 06 29584 6610 951 11001 408 T5 - 02 29604 7429 1059 13875 429 T4 - 07 30673 7172 1035 14479 418 T5 - 03 27967 6974 1055 15305 452 T4 - 08 31214 6965 1009 14763 408 T5 - 04 26849 6983 1002 14436 440 T5 - 01 17149 6844 597 7421 333 T5 - 05 24293 6208 753 4601 375 T5 - 02 29432 6646 946 7879 408 T5 - 06 26967 6500 883 4288 407 T5 - 03 32373 6006 952 2440 408 T5 - 07 27480 6971 940 7435 413 T5 - 04 33547 6201 940 1960 390 T5 - 08 27341 7046 928 10877 404 T5 - 05 29998 5372 809 2126 380 T5 - 09 19712 5201 708 14374 416 T5 - 06 25147 4868 693 2295 377 GS-19 Monazite 3 T5 - 07 25641 4857 749 3215 401 T1 - 01 29713 1445 631 575 409 T5 - 08 28171 5916 887 9405 410 T1 - 02 29124 1780 544 1866 347 T5 - 09 29411 7515 1047 15793 423 T1 - 03 30003 1731 632 2057 394 GS-11 Monazite 21 T1 - 04 29764 1330 635 1174 415 T1 - 01 9102 0 0 3478 -15 T1 - 05 29573 1149 612 4030 406 T1 - 02 29190 7254 1080 14319 446 T1 - 06 28799 1246 628 4888 421 T2 - 01 29063 7760 1073 16255 429 T1 - 07 31012 1411 632 469 396 T2 - 02 28679 7339 1059 15539 438 T1 - 08 32166 1450 701 519 424 T2 - 03 26913 7032 1058 15148 461 T1 - 09 33657 1347 812 750 475 T2 - 04 23619 6321 953 12574 469 T1 - 10 30862 1298 718 641 456 T2 - 05 14451 3450 529 6501 449 T1 - 11 30323 1302 589 436 380 54

Table 2: cont. Elemental Concentration (ppm) Elemental Concentration (ppm) Analysis # † Th U Pb Y Age (Ma) Analysis # † Th U Pb Y Age (Ma) GS-19 Monazite 3 GS-19 Monazite 6 T1 - 12 30323 1430 690 520 440 T1 - 10 28624 1088 543 356 377 T1 - 13 30070 1199 563 397 370 T1 - 11 28544 1220 512 326 352 T1 - 14 29860 1143 514 372 342 T1 - 12 28265 1330 527 471 361 T1 - 15 28152 2203 655 3757 410 T1 - 13 21244 1941 540 3248 432 T2 - 01 25048 1720 579 3336 418 T1 - 14 18138 1534 488 4461 463 T2 - 02 28994 1547 541 434 355 T2 - 01 20886 2382 534 3443 412 T2 - 03 26798 1369 487 357 348 T2 - 02 22710 2189 549 1650 409 T2 - 04 27866 1392 543 405 374 T2 - 03 30629 1775 639 912 391 T2 - 05 29667 1237 550 422 365 T2 - 04 36443 1684 709 489 378 T2 - 06 31247 1192 689 550 437 T2 - 05 34400 2082 730 499 396 T2 - 07 31906 1406 639 398 391 T2 - 06 36537 2646 766 678 379 T2 - 08 32330 1368 671 541 407 T2 - 09 29662 1108 709 1224 474 † Notes: T3 - 01 34064 1891 827 1077 458 T # reflects transect T3 - 02 34165 1784 636 435 356 I # refelcts individual spot analysis T3 - 03 36012 1539 661 417 360 See Figure 10 for transect locations T3 - 04 31743 1284 678 403 421 T3 - 05 31140 1097 612 403 393 T3 - 06 31341 1039 640 431 411 T3 - 07 31249 1279 600 444 378 GS-19 Monazite 6 T1 - 01 30995 1488 609 801 379 T1 - 02 35484 1726 706 523 384 T1 - 03 34899 1769 628 439 345 T1 - 04 32149 2114 747 210 427 T1 - 05 52103 3932 1131 187 390 T1 - 06 51167 3852 1100 183 386 T1 - 07 39252 2791 835 188 386 T1 - 08 28000 1537 548 256 371 T1 - 09 27765 1096 562 365 400 55 7. Discussion

7.1 Geochronology

The tectonometamorphic history of the Gory Sowie block has been proven both complex and unique to the Sudete Mountains. Most notably, the GSB is believed to have experienced and preserved a polyphase metamorphic history spanning both Caledonian and Variscan tectonism. Previous investigations have provided scattered results, but strongly focusing on the granulites in the northwestern portions of the massif. The new geochronometric data presented here will help elucidate the thermal evolution of the

Gory Sowie Block and assist in understanding the unresolved questions regarding the timing and rate of its exhumation.

Previous geochronometric investigation conducted on tectonic lenses of granulitic and eclogitic rocks of the GSB revealed peak metamorphic conditions occurring at ca.

400 Ma with conditions exceeding 20 kbar and 1000°C (Brueckner et al., 1996; O’Brien et al., 1997). Subsequent HT-MP conditions of 6.5 - 8.5 kbar and 775 - 910°C

(Brueckner et al., 1996) mark regional amphibolite-facies overprinting in the granulites, while recent thermobarometric studies of the country rocks reveal conditions of 5.5 - 6.0 kbar and 600°C (Budzyn et al., 2004). The data collected for this investigation has provided a tectonothermal history of the GSB through the thermal interval 800 - 300°C, thus documenting the final exhumation of the block (Figure 12). It is important to recognize that the results of this study only refer to events affecting the GSB and cannot be extrapolated across the Western Sudetes since the GSB is bounded by high angle faults and ductile shear zones and, therefore, its original position is not known. 56

1200

1000 Pegamititic Intrusives 800 Western GSB Niemcza Grantoid Intrusives ? ? 600 40-25°C my-1 Eastern GSB North South 400 ~27°C my-1 Temperature (°C) Temperature

200 ?

Shearing Overstepping Clastics Units ? Niemcza 0 310 320 330 340 350 360 370 380 390 400 410 Age (Ma)

Figure 12. Thermal history of the Gory Sowie Block based on previously published geochronometry and amended with results from this study. Ovals represent ages attributed to known temperatures and their associated errors based on common geochronometers: 1000°C = U-Pb zircon, 800°C = U-Pb monazite, 750°C = Sm-Nd, 600°C = U-Pb titanite, 500°C = Ar-Ar hornblende, 350°C = Ar-Ar muscovite, 300°C = Ar-Ar biotite. Note differences in cooling histories between the western and eastern GSB.

Thermochronometry employed on mineral separates of hornblende and mica constrains both the timing and rate of unroofing; the results clearly suggesting rapid cooling during early Variscan collision at 385 Ma. Furthermore, the mountainous portion of the GSB appears to have experienced a diachronous cooling history, beginning at 385

Ma in the northern portion and at 375 Ma in the central and southern portions. These results are broadly consistent with U-Pb monazite ages of ca. 380 Ma (van Breemen et al., 1988; Brocker et al., 1998, Oliver et al., 1998) and U-Pb xenotime ages of 380 - 370

Ma from anatectic granites and pegmatites (Timmermann et al., 2000). Recently published 40Ar/39Ar data of Marheine et al. (2002) also indicates rapid cooling coincident 57 with homophazation and shearing along the southwestern margin until 360 Ma.

Moreover, U-Th-total-Pb monazite age domains (405 Ma, 385 Ma and 360 Ma) revealed in this study elucidate this protracted thermal history from peak ultrahigh grade conditions at 400 Ma to HT-MP amphibolite-facies overprinting between 390 and 375

Ma followed by rapid cooling until 360 Ma.

This preserved ca. 360 Ma thermal event in the GSB is coeval with the blueschist metamorphism of the Ruchory Mountains in the adjacent Karkonosze massif to the west

(Figure 2; Maluski & Patocka, 1997; Marheine et al., 2002) and ultrahigh grade metamorphism of the Orilca Snieznik Dome to the south (Steltenpohl et al., 1993;

Maluski et al., 1995; Glascock et al., 2003; Gordon et al., in press). In marked contrast, the eastern portion of the GSB may have experienced a distinct peak Variscan thermal pulse at 337 Ma coincident with wholesale exhumation of the Orlica Snieznik Dome and punctuated Niemcza shear zone events as evidenced by both metamorphic and cooling ages (Steltenpohl et al., 1993; Maluski et al., 1995; Glascock et al., 2003; Gordon et al., in press).

7.2 Tectonic Implications

Several models for the structural and tectonic development of the Gory Sowie

Block have been proposed over the past two decades. Zelazniewicz (1985; 1987; 1990;

1997) has suggested the GSB to be an autocthonous terrane having experienced five discrete deformational and metamorphic episodes spanning Caledonian and Variscan accretionary events. Alternatively, Cymerman et al. (1997; 1998) believe the GSB to represent a magmatic arc that formed on the southern margin of Baltica during the early

Paleozoic. Evidence of ophiolitic complexes of a known age (420 - 400 Ma; Oliver et 58 al., 1993), located on the massif’s margins, record the Late Caledonian closure of the

Tornquist Sea that may have aided the southward-directed thrusting of the GSB into its current position. Additionally, the ophiolitic complexes have been proven to partially underlie the GSB (Kossmat, 1927), leading most researchers to advocate significant displacement of the GSB during obduction of the oceanic crust (Znosko, 1981; Pin et al.,

1988; Matte et al., 1990; Matte, 1991; 2001; Brocker et al., 1998; Cymerman 1998;

Kroner & Hegner, 1998; Marheine et al., 2002). In any event, both models propose polyphase metamorphism of the GSB beginning with initial granitoid crystallization/emplacement at ca. 480 Ma and ending with final exhumation at ca. 350

Ma (Figure 13).

Previous geochronometric and thermobarometric studies in the GSB constrain peak metamorphism at ca. 400 Ma, through U-Pb zircon and Sm-Nd geochronometry on felsic granulites and garnet peridotites, respectively (Brueckner et al., 1996, O’Brien et al., 1997). Although these workers suggest these data represent peak ultrahigh grade metamorphic conditions, a word of caution must be noted. Research on the Austrian portion of the Bohemian massif has shown that zircon growth in granulites was controlled by their exhumation to shallower crustal levels where medium pressures dominated. Therefore, peak conditions may predate granulite zircon ages (Roberts &

Finger, 1997). 59

Figure 13. P-T-t path for the Gory Sowie Block based on previously published thermobarometry, geochronometry, and results of this study complimented by thermobarometry of Budzyn et al. (2004). Note convergence of the Gory Sowie gneisses and UHT and UHP lenses at midcrustal conditions.

Field observations indicate lower density migmatite, ultrabasite and/or serpentinitic zones commonly envelope granulitic and eclogitic rocks of the GSB, likely aiding in their initial emplacement to mid-crustal levels. Guillot et al. (2000) suggests the serpentinization of mantle rocks through eclogite dehydration and decompressional melting forms an envelope around the ultrahigh-grade rock suites. The resulting disparity in buoyancy (~0.6 g cm-3) likely facilitated exhumation of UHP and UHT massifs to shallower, mid-crustal levels. 60 The lower temperatures and pressures of the mid-crust bring about retrograde metamorphism of the partially exhumed ultrahigh grade assemblages and, in the case of the GSB, this most likely occurred coevally with (prograde?) amphibolite-facies metamorphism of the mid-crustal gneissic complex (Figure 13; Zelazniewicz, 1985;

1990; 1997). Post peak equilibration under HT-MP conditions is evidenced by overprinting of earlier deformational fabrics, obscuring Caledonian signatures and metamorphic assemblages, including relict kyanite, poikiloblastic garnets and hornblende/Ca-plagioclase enclosed within garnet ± pyroxene coronas; a typical high temperature solid solution reaction. Continued residence at mid-crustal levels resulted in the transformation of biotite into sillimanite (fibrolite), also a common reaction in high temperature regimes.

O’Brien et al’s. (1997) work on felsic granulites indicates HT-MP amphibolite-

facies overprinting, while thermobarometric investigation of the host gneisses and

amphibolite lenses revealed cooler, shallower conditions of 600°C and 6.0 kbar for this

HT-MP event (Budyzn et al., 2004). This amphibolite-facies metamorphism occurred at

ca. 385 Ma, as indicated by the suite of Ar-Ar and total-Pb ages reported here for the

western half of the GSB. Additionally, regional anatexis, most likely a result of

decompressional melting during rapid unroofing, gave rise to numerous granitic and

pegmatitic lenses as well as leucosomal segregations along fold axial planes, all of which

yielded ages of ca. 380 Ma (Brocker et al., 1998; Timmermann et al., 2000) and are

coincident with the regional Ar-Ar ages obtained in this study. Mineralogic reactions

resulting in the formation of cordierite in felsic gneiss and gedrite in mafic amphibolites

also indicates rapid, near isothermal unroofing. 61 Notably, the mountainous regions of the GSB, west of the Sudetic Boundary fault, reveals a diachronous cooling history with the northern portions cooling from upper amphibolite-facies metamorphism after 385 Ma while the southern portion cooled from mid- to lower amphibolite facies metamorphism after ca. 375 Ma (Figure 12). Despite the 10 m.y. difference, this study indicates cooling rates on the order of 40 - 25°C m.y.-1. for both the northern and southern portions of the GSB during final unroofing. Marheine et al’s. (2002) 40Ar/39Ar results and the total-Pb data presented here indicate a weak late

orogenic event, involving reactivation of shear zones and fluid infiltration at ca. 360 Ma

resulting in the homophazation of the gneisses and migmatites. Final unroofing is

corroborated by clastic sequences that overstep the GSB, and which are loosely

constrained to have been deposited between the Tournaisian and Visean times (360 - 330

Ma; Zakowa, 1963; Porebski, 1981). This sequence is partially composed of Gory

Sowie-derived gneissic detritus indicating surficial exposure and erosion. The coeval

termination of blueschist-facies metamorphism of adjacent sedimentary basins further

confirms relative tectonic quiescence and exhumation of the mountainous portions of the

GSB (Maluski & Patocka, 1997; Marheine et al., 2002).

In contrast to the western GSB, concordant 40Ar/39Ar hornblende and biotite ages obtained from gneisses adjacent to the NSZ (Figures 3 & 4) reveal a distinct Late

Variscan tectonic component at 337 Ma. Recent work on mylonites within the NSZ indicate protracted displacement spanning 100 m.y., with major thermal episodes occurring at ca. 370 and 345 Ma, both of which coincide with significant tectonism in the

Sudetes (Gordon et al., in press). The 370 Ma date is concordant with the Ar-Ar and

total-Pb ages presented here for the western GSB and there are some indications that the 62 eastern half of the GSB also experienced this HT-MP event at 385 - 375 Ma. However, significant retrogression, younger thermal overprinting and extensive cover hamper the ability to reach definitive conclusions. The 345 Ma event also coincides with the Ar-Ar ages for Gory Sowie gneisses and granitoids found adjacent to and within the NSZ, suggesting that sinstral movement along this shear zone may have acted as a final exhumation mechanism for the eastern GSB or, more likely, instigated shear heating and incorporation of hydrothermal fluids into the gneisses resulting in the resetting of isotopic systems. Niemcza shearing at 345 Ma is also consistent with the timing of exhumation of adjacent portions of the Sudetes, most notably the final unroofing of the Orlica Snieznik

Dome, roughly 50 km to the south, inviting a strong correlation (Figure 2; Steltenpohl et al., 1993; Maluski et al., 1995; Glascock et al., 2003; Gordon et al., in press) 63 8. Conclusions

I. The Gory Sowie Block of southwest Poland has experienced a protracted thermal

history, beginning with ultrahigh grade metamorphism during the Late

Caledonian and concluding with final unroofing during Early Variscan tectonism.

II. The block is bounded on all sides by high angle brittle faults and shear zones and

is partially underlain by ophiolite sequences, suggesting an allochthonous origin.

Additionally, the Sudetic Boundary Fault separates the GSB into two distinct

topographic regions: the mountainous western region and the relatively flat,

covered eastern region.

III. Geochronology indicates the GSB experienced ultrahigh grade metamorphism at

400 Ma at granulite and eclogite facies-conditions. Subsequent uplift and

amphibolite-facies overprinting of the ultrahigh grade suites occurred coevally

with the HT - MP metamorphism of the pelitic-psammitic/ greywacke country

rock.

IV. Thermochronometric 40Ar/39Ar ages presented here reveal diachronous uplift of

the northern and southern regions of the western massif with: (1) cooling from

upper amphibolite-facies metamorphism conditions in the north at 385 Ma, and

(2) cooling from mid to lower amphibolite-facies metamorphism in the south at

375 Ma. 64 V. Reactivation of shear zones along the southwestern border of the GSB at 360 Ma

is believed to be responsible for the homophazation and thermal reheating of the

southern margins. This was followed by final surface exposure of the GSB

indicated by detrital Gory Sowie gneisses in the adjacent and overstepping

Tournaisian and Visean aged sedimentary basins (360 - 330 Ma).

VI. The eastern portion of the GSB may have experienced a separate younger thermal

event at 337 Ma as indicated by concordant 40Ar/39Ar ages on hornblende and

biotite. This event is clearly linked to major displacement within the adjoining

Niemcza shear zone and associated with the exhumation of the Orlica-Snieznik

Dome to the south.

VII. The entire massif experienced cooling rates of 40 - 25ºC m.y.-1, aided by the

serpentization of ultrahigh grade assemblages, thus suggesting the disparity in

buoyancy controlled at least the initial stages of exhumation. 65 References

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GS 1 Mylonitic-biotite gneiss Kyanite ± Sillimanite ± Garnet ± Biotite ± Muscovite ± Chlorite ± Quartz ± K-feldspar ± Plagioclase ± Cordierite Dark gray, medium grained, strongly foliated and folded mylonitic-biotite gneiss containing leucosomal bands 1 to 5mm thick consisting of primarily quartz. Fibrous sillimanite occurs along biotite foliation planes. Biotite typically contains rutile and less commonly is altered to chlorite. Quartz and plagioclase ribbons demonstrate sutured grain boundaries and minor poikilolitic textures. Kyanite as an accessory mineral, commonly surrounded by serecitic coronas. Plagioclase altered to serecite. Location: Jugowice, north of bridge

GS 2a Two-mica gneiss Sillimanite ± Garnet ± Biotite ± Muscovite ± Chlorite ± Quartz ± K-feldspar ± Plagioclase Dark gray, medium to coarse-grained, foliated two-mica gneiss, locally amphibolitic. Fibrous sillimanite replacing early garnets. Quartz grains demonstrate zonation and strain, occasionally as pokioblasts in plagioclase. Decussate texture in micas. Muscovite replacing fibrous sillimanite. Plagioclase altered to serecite. Some chloritzation present. Location: Southern shore of Byrtryzyckie Lake

GS 2b Biotite gneiss Garnet ± Biotite ± Andalusite ± Quartz ± Plagioclase ± Chlorite Light gray, medium to coarse grained, foliated-biotite gneiss. Subhedral garnets commonly exhibit serecite coronas. Biotite contains significant chloritization. Sereticized plagioclase and quartz planes reveal significant strain as undulose extinction and recrystallized grain boundaries. Sphene and illmentite as accessory minerals. Location: Along road on southern shore of Byrtryzyckie Lake

GS 2c Micaceous gneiss Kyanite ± Sillimanite ± Garnet ± Biotite ± Muscovite ± Quartz ± K-feldspar ± Plagioclase Medium gray flecked, medium to coarse grained, strongly foliated micaceous gneiss. Fibrous sillimanite abundant along biotite foliation planes. Subhedral garnets exhibit slight rotation as deflection fabrics in sillimanite and biotite. Undulose quartz contain sutured grain boundaries and commonly poikiloblastic inclusions. Significant seretization of plagioclase. Minor muscovite and kyanite as pokioblasts in garnet. Location: Further west of GS 2a & 2b along road on the south shore of Byrtryzyckie Lake.

GS 2d Schistostic-biotite gneiss Sillimanite ± Garnet ± Biotite ± Chlorite ± Quartz ± Plagioclase Medium to dark gray flecked, fine to medium-grained, well foliated schistostic-biotite gneiss. Fibrous sillimanite occurs primarily as overgrowths on biotite and occasionally replaces early garnets. Biotite occasionally altered to chlorite. Zoned quartz and plagioclase exhibit a polygonal to subhedral recrystallization fabric. Plagioclase altered to serecite. Zircon and titanite common as accessory minerals. Location: Further west of GS 2a, 2b & 2c along road on the south shore of Byrtryzyckie Lake.

GS 3 Granulite Kyanite ± Garnet ± Biotite ± Andalusite ± Quartz ± Plagioclase ± Cordierite Light gray, fine to medium grained, strongly foliated granulite. Large poikioblastic garnets and two-phase plagioclase common. Biotite grains most common around garnet. Kyanite typically posses serecite coronas. Pervasive polygonal quartz grains in matrix. Rutile exists as an accessory mineral. Location: Across from the Friegata Restaurant parking area, western Byrtryzyckie Lake.

GS 4a No Sample 73

GS 4b Micaceous gneiss Kyanite ± Sillimanite ± Garnet ± Biotite ± Quartz ± K-feldspar ± Plagioclase ± Cordierite Medium to dark gray, coarse grained, foliated micaceous gneiss. Kyanite and fibrous sillimanite found along biotite foliation planes. Intergrowths of sillimanite & biotite and cordierite & plagioclase common. Strain is represented as significant suturing and undulation of quartz grains. Serecite exists as coronas surrounding kyanite and as an alteration product in plagioclase. Accessory minerals include rutile and zircon. Location: Across dam on Byrtryzyckie Lake, opposite GS 3.

GS 5a Non-foliated amphibolite Garnet ± Hornblende ± Chlorite ± Quartz ± Plagioclase Dark gray, non-foliated amphibolite. Large porphyoblasts of subhedral to anhedral garnet occasionally rimmed by chlorite, more commonly rimmed with a mymercitic intergrowth of hornblende, quartz and or plagioclase. Presence of chlorite or glaucophane as an anomalous blue tinting. Matrix is fine grained containing quartz, plagioclase and serecite. Location: Old railstation 1 km south of Burkatow.

GS 5b Serpentite Dark gray, fine grained sepentite. Enitre sample is composed of serpentine. Location: Old railstation 1 km south of Burkatow

GS 5c Non-foliated amphibolite Garnet ± Biotite ± Chlorite ± Quartz ± Plagioclase Dark gray, non-foliated amphibolite. Large porphyoblasts of garnet and plagioclase in a predominately fine grained quartz, plagioclase and biotite matrix. Garnet contains very fine poikiloblasts of quartz as cores. Serecite alteration of plagioclase and chloritization of biotite common. Accessory minerals include zircon and rutile Location: Old railstation 1 km south of Burkatow

GS 6 Non-foliated amphibolite Garnet ± Hornblende ± Biotite ± Chlorite ± Quartz ± Microcline ± Plagioclase ± Cordierite Dark gray, non-foliated amphibolite with small leucosomal bands. Anhedral-pokioblastic garnet comprises the majority of the slide with fine to medium grained inclusions. Coarse hornblende intergrown with slightly chloritzed biotite. Location: 1 km northeast of Podole

GS 7 Biotite gneiss Sillimanite ± Garnet ± Biotite ± Quartz ± Plagioclase ± Cordierite Medium to dark gray, medium to coarse, slightly folded biotite gneiss with prominent leucosomal banding. Foliation evident as tabular biotite near large, subhedral, poikiloblastic-garnets. Fine quartz inclusions near garnet core common. Matrix consists of seretcized plagioclase, cordierite and some zoned quartz. Accessory minerals include various ferrous oxides and zircon. Location: Small road-cut in Lasocin

GS 8 Mylonitic-gneiss Garnet ± Biotite ± Quartz ± Plagioclase ± Cordierite Light gray, medium to coarse grained, strongly foliated mylonitic-gneiss. Foliation bands consist of either large pokioblastic feldspars with quartz inclusions or tabular biotite and poikiloblastic garnets with fine grained quartz, plagioclase and biotite inclusions. Garnets commonly appear as overgrowths on large quartz or plagioclase grains. Some biotite altered to muscovite. Accessory minerals include various ferrous oxides and zircon. Location: 1 km northeast of Lasocin

GS 9 No Sample-Similar to GS 8 Location: 0.5 km north of Potoczek 74

GS 10a Micaceous granite Sillimanite ± Garnet ± Biotite ± Muscovite ± Quartz ± Plagioclase Light gray, very coarse grained, non-foliated micaceous granite. Large, decussate, tabular biotite and muscovite within a coarse primarily undulose quartz and plagioclase matrix; some altered to serecite. Fe- oxide staining common along grain boundaries. Abundant radiation halos around zircon with biotite grains. Fibrous sillimanite limited to muscovite. Zircon abundant as an accessory mineral. Location: Sharp bend in 383 in Potoczek

GS 10b Micaceous gneiss Sillimanite ± Garnet ± Biotite ± Muscovite ± Quartz ± Plagioclase Light gray, medium to fine grained, well foliated micaceous gneiss. Decussate, tabular biotite and muscovite within a medium-fine subhedral matrix of undulose quartz and plagioclase. Fibrous sillimanite pervasive throughout slide. Similar to GS 10a with exception to sillimanite content. Location: Sharp bend in 383 in Potoczek

GS 11a Micaceous gneiss Garnet ± Biotite ± Quartz ± Plagioclase ± Cordierite Medium brown-gray, fine to medium grained, foliated micaceous gneiss containing large leucosomal bands (>1cm) and occasional boudins. Recrystallization of quartz and plagioclase matrix (polygonal grain boundaries) demonstrates strain (pervasive undulatory extinction patterns). Garnet present as sub- to anhedral grains occasionally possessing very fine quartz cores. Zircon as an accessory mineral. Location: Parking area at sharp turn near Dawnej

GS 11b Micaceous gneiss Sillimanite ± Garnet ± Biotite ± Quartz ± Plagioclase Medium brown-gray, foliated micaceous gneiss. Grain size varies from fine to medium grained in biotite foliation planes to coarse grained in the quartzo-feldspathic foliation planes. Garnet and fibrous sillimanite forming at biotites expense. Abundant radiation halos in biotite from accessory zircon. Sample possess an overall mosaic texture. Location: Parking area at sharp turn near Dawnej

GS 12 Schistostic gneiss Garnet ± Biotite ± Muscovite ± Quartz ± Orthocase ± Plagioclase Silvery, coarse grained, schistostic gneiss. Garnets rims commonly degraded with foliation planes best defined in quartz and mica planes. Strong element of strain evidenced in most minerals. Quartz grains are elongated and contain numerous fine, sub-grain boundaries. Serecite alteration of plagioclase. Location: 1 km north of Sokolec under powerlines.

GS 13 Mica-gneiss Biotite ± Muscovite ± Chlorite ± Quartz ± Plagioclase Reddish-brown, gray, coarse grained foliated mica gneiss possessing macrofolds and local quartz and feldspar onclaves. Elongated quartz and mica grains demonstrate strain as undulose extinction and subgrain boundaries in quartz. Biotite grains have been strongly chloritized. Serecite alteration of plagioclase frequent. Calcite occurs as a void filler. Location: Near sharp bend in Sokolec

GS 14a Micaceous gneiss Garnet ± Biotite ± Muscovite ± Chlorite ± Quartz ± Plagioclase ± Cordierite Dark gray, medium to coarse-grained, well foliated micaceous gneiss containing leucosomal bands commonly 1 to 2 cm thick and locally rich in white micas. Biotite has reddish hue and intergrowths of white mica and or chlorite are patchy. Minor subhedral garnet grains located near or within biotite foliation planes. Groundmass contains zoned-sutured quartz, plagioclase and occasional cordierite. Plagioclase exhibits significant serecitic alteration. Location: ~1 km NE of Wolibroz. 75

GS 14b Pegmatite Staurolite ± Garnet ± Biotite ± Muscovite ± Quartz ± Plagioclase Dark brown-gray, coarse grained, poorly foliated pegmatite. Biotite demonstrates a syntectonic deformational texture. Muscovite grains frequently greater than 1cm. Chlorite present as alteration product. Location: ~1 km NE of Wolibroz

GS 15 Micaceous gneiss Biotite ± Muscovite ± Chlorite ± Quartz ± Plagioclase Medium gray, coarse grained, poorly foliated micaceous gneiss. Micas display a dessucate alignment with strain evident in > 90% of the minerals primarily as undulose extinction, but intergrain suturing of quartz also present. Plagioclase contain small quartz inclusions and some serecitization. Additionally, garnet is present as fine grained, subhedral grains. Location: Parking area at sharp turn, Czarcia Gora (709m)

GS 16a Foliated amphibolite Hornblende ± Magnetite ± Quartz ± Plagioclase Dark gray, medium grained, foliated amphibolite with large porphyoblasts of quartz and plagioclase within a fine grained serecitic matrix. Quartz grains appear elongated and occasionally appear as mono-mineralic veins. Abundant magnetite, commonly exhibits textbook crystal growth. Accessory minerals include titanite and epidote. Location: 0.5 km west of Jodlownik, parking area at blue bridge

GS 16b Garnetiferous gneiss Sillimanite ± Garnet ± Biotite ± Muscovite ± Quartz ± Microcline ± Plagioclase Light tan, red-brown, medium grained, foliated garniteferous mica gneiss; lecosomal veins in excess of 10 cm wide common. Medium grained garnets exhibit anhedral to euhedral characteristics, often found in biotite foliation planes. Intergrowths of biotite, fibrous sillimanite and quartz occasionally altered to muscovite. Plagioclase contains small quartz inclusions and serecitic alteration. Quartz grains have intergrain sutures and undulatory extinction strain patterns. Accessory minerals include zircon and rutile. Location: 50m west of GS 16a

GS 17a Amphibolite Garnet ± Hornblende ± Biotite ± Chlorite ± Gedrite ± Quartz ± Cordierite Dark gray amphibolite exhibiting significant symplectic intergrowth of nearly all minerals with the exception of garnet. Anhedral garnets are surrounded by mymercitic zones of hornblende and plagioclase. Some garnets are altered to chlorite. Location: Small road cut just northwest of Kiettice

GS 17b Amphibolite Garnet ± Hornblende ± Chlorite ± Quartz ± Microcline ± Plagioclase Dark gray, coarse grained, amphibolite. Significant straining of quartz, biotite, plagioclase and cordierite evidenced by undulaose extinction. Subhedral garnets and larger plagioclase grains commonly contain fine grained quartz cores. Biotite occasionally has chlorite alteration typically along grain boundaries. Accessory minerals include; mymercitic magnetite, allanite and calcite. Location: Small road cut just northwest of Kiettice, approximately 5 m north of GS 17a

GS 17c Amphibolite Garnet ± Biotite ± Gedrite ± Quartz ± Microcline ± Cordierite Similar to GS 17b noting an overall increase in biotite content, foliation and number of garnet porphyoblasts. Recrystallization exhibited as euhdral grain boundaries (garnets and triple point qtz) and intergrain suturing of elongated quartz grains. Location: Small road cut just northwest of Kiettice, approximately 3 m north of GS 17b 76

GS 18 Amphibolite Garnet ± Hornblende ± Biotite ± Quartz ± Plagioclase ± Cordierite Dark gray, medium to fine grained, foliated amphibolite containing oriented-leucosomal boudins. Numerous small euhedral garnets accompany hornblende and biotite foliation planes. Sympletic intergrowths of quartz and plagioclase as well as hornblende and biotite common. Additionally, quartz grains are strained and often contain sub-grain boundaries. Titanite and magnetite present as accessory minerals. Location: Approximately 1 km north of Bradziszow

GS 19 Granulite Kyanite ± Garnet ± Biotite ± Muscovite ± Quartz ± Plagioclase ± Cordierite Reddish-brown, gray, fine to medium grained, foliated micaceous granulite with fine-grained mafic and pegmatitic lithologies found in close proximity. Subhedral, fine grained garnets found through slide, though most common in biotite foliation planes. Kyanite grains commonly surrounded by serecite, possibly as retrograde rim reaction. Serecitic alteration prevalent in most minerals. Sub-grain and sutured boundaries common in quartz and plagioclase. Additionally, quartz grains are generally medium to coarse grained. Accessory minerals include rutile and titanite. Location: Road cut in Debowa Gora

GS 20 Micaceous gneiss Garnet ± Biotite ± Quartz ± Plagioclase ± Microcline Reddish-brown, gray, fine to medium grained, foliated micaceous gneiss (similar to GS 19). Porphyoblasts of fragmented garnet strongly degraded to serecite and or epidote. Strain evidenced as undulatory, sutured quartz often containing sub-grain boundaries. Coarse perthitic feldspars occur sporadically. Location: Road cut north of Sieniawka

GS 21 Micaceous gneiss Biotite ± Muscovite ± Chlorite ± Quartz ± Orthoclase ± Plagioclase Dark red-gray, medium to coarse grained, strongly foliated micaceous gneiss. Significant degradation of minerals to chlorite or serecite prevalent. Sub to eudral garnets found periodically throughout slide. Quartz grains frequently contain sutured and or sub-grain boundaries. Antiperthic plagioclase occasionally contains fine quartz inclusions. Location: East of Grodziszcze (topographic high)