Fluid History of the Western Maryland Piedmont

FLUID HISTORY OF THE WESTERN MARYLAND PIEDMONT

Christopher J. LaFonte

A Thesis

Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE

August 2015

Committee:

Charles M. Onasch, Advisor

John R. Farver

Kurt S. Panter ii

ABSTRACT

Charles M. Onasch, Advisor

Regional fluid migrations associated with orogenic events have a number of significant

geologic consequences in the continental interior, such as the emplacement of hydrocarbons, mineralization, and diagenesis. It is currently believed that fluids associated with the Alleghanian

orogeny in the central Appalachians where sourced from the eastern portion of the Piedmont,

migrated westward, passing below the Blue Ridge, into the Valley and Ridge region, and finally into the craton. Previous studies have provided details about fluids across much of the central

Appalachians, but one gap remains: the western portion of the Piedmont. Using fluid inclusion microthermometry on vein samples throughout the western Piedmont, the trapping conditions

and fluid composition were found and used to compare the fluid history of this region with that

of other regions to determine if the Piedmont was part of the westward fluid migration.

The fluids of the western Piedmont were found to be very uniform in terms of trapping

conditions and fluid composition regardless of vein type, rock unit and lithology, and sample

location. All inclusions were two-phase (L+V) and were found to consist of a low salinity

H2O+NaCl brine with a large majority of them having homogenization temperatures between

140 and 200°C.

The age of the veins and fluids cannot be well constrained. While most veins are

probably associated with early phases of deformation and metamorphism during the late

Ordovician Taconic orogeny and/or the early Silurian Cherokee orogeny, the fluid inclusions in

them may be younger and related to recrystallization and/or reequilibration during younger

events, such as the late Paleozoic Alleghanian orogeny. Considering the regionally uniform iii microthermometric properties of the inclusions, their relatively low trapping temperatures and pressures, low salinity fluid composition, the lack of reequilibration textures, and the lack of evidence for significant Alleghanian deformation in the region, the most likely scenario is that the veins trapped the fluids shortly after this region reached peak metamorphic conditions during the Cherokee orogeny in the early Silurian. This timing, along with the significant differences in fluid history with adjacent regions, indicates that the western Piedmont does not record the effects of a late Paleozoic orogen-wide fluid event.

ACKNOWLEDGEMENTS

First I would like to give a big thank you to my advisor Dr. Charles Onasch for his guidance and devotion towards this project. I want to thank my committee members Dr. John

Farver and Dr. Kurt Panter for giving me their insight and providing me with different perspectives. I would also like to thank my parents for the encouragement and support. Without them, this project would not have been completed. Financial support for the field and lab work was made possible thanks to the Furman Economic Geology Research Scholarship, and the

Bowling Green State University Department of Geology.

TABLE OF CONTENTS Page

INTRODUCTION ...... 1

GEOLOGIC SETTING ...... 3

Study Area ...... 3

Stratigraphy ...... 3

Structure ...... 6

Vein Types ...... 8

METHODOLOGY ...... 12

Field Methods ...... 12

Laboratory Methods ...... 12

Fluid Inclusion Microthermometry ...... 13

MICROTHERMOMETRY RESULTS ...... 15

DISCUSSION ...... 19

Fluid History ...... 19

Vein type ...... 19

Structural location ...... 21

Rock type ...... 25

Trapping Conditions ...... 25

Paleohydrology and the age of fluids of the western Piedmont ...... 28

Regional Fluid Migration ...... 33 vi

CONCLUSIONS...... 36

REFERENCES ...... 37

APPENDIX A: MICROTHERMOMETRY MEASUREMENTS ...... 41

APPENDIX B: HOMOGENIZATION TEMPERATURE HISTOGRAMS ...... 42

APPENDIX C: SAMPLE INFORMATION/NOTES ...... 42

vii

LIST OF FIGURES

Figure Page

1 Terrane map showing the location of the Westminster terrane where most of the

samples were collected...... 6

2 Geologic map of the western Piedmont province modified from USGS 30’ x 60’

quadrangle (Southworth et. al., 2007) with sample locations...... 9

3 Cross section (modified from Southworth et. al., 2006) of line A-A’ in Figure 2...... 10

4 Quartz veins in the Ijamsville Phyllite and their relationships to S1 and each other...... 11

5 Cathodoluminescence and plane polarized light images of typical vein quartz sample...... 14

6 Histogram of final ice melting temperature (Tm) for all primary and

secondary inclusions measured...... 16

7 Histogram of homogenization temperature (Th) for all primary and

secondary inclusions measured...... 17

8 Th vs. Tm plot for all fluid inclusions measured...... 18

9 Comparing folded veins to cleavage parallel veins...... 20

10 Th vs. Tm plot separating the Martic thrust and Grove Formation samples

from the rest of the inclusions measured...... 21

11 Homogenization temperatures for the Ijamsville Phyllite,

Urbana Formation, and Sugarloaf Mountain Quartzite samples

separated by eastern and western limbs of the Sugarloaf Mountain

anticlinorium (see text for explanation)...... 23

viii

12 Final ice melt temperatures of the Ijamsville Phyllite,

Urbana Formation, and Sugarloaf Mountain Quartzite samples

separated eastern and western limbs of the Sugarloaf Mountain

anticlinorium (see text for explanation)...... 24

13 Th vs. Tm for inclusions in the Ijamsville Phyllite, Urbana Formation,

and Sugarloaf Mountain Quartzite samples separated by eastern

(lower Th, higher Tm) and western (higher Th, lower Tm) limbs of the

Sugarloaf Mountain anticlinorium...... 25

14 Estimation for trapping pressure and temperature for the two

fluid types (eastern and western limbs of the Sugarloaf Mountain

anticlinorium) with lithostatic and hydrostatic pressure conditions

and with 30°C/km and 50°C/km geothermal gradients...... 27

15 Estimated homogenization temperatures for a peak metamorphic

temperature of 350°C in the western portion of the Westminster terrane...... 32

LIST OF TABLES

Table Page

1 Fluid characteristics separated by eastern and western limbs

of the Sugarloaf Mountain anticlinorium...... 22

2 Trapping conditions for eastern and western limb fluids using

two geothermal gradients...... 27

3 Fluid characteristics across the Appalachians...... 34

INTRODUCTION

Large magnitude, regional fluid migrations are known to be associated with a variety of

orogenic processes. Great quantities of mass and heat can be transported over vast distances

within these large scale fluid migrations (Ge and Garven, 1992). Diagenetic alteration (Hearn et

al., 1987; Schedl et al., 1992), and the emplacement of hydrocarbons and ore deposits (Bethke

and Marshak, 1990) are a few examples of geologic consequences of these large fluid migration

events. While tectonism often provides the first-order driving mechanism (e.g., Bethke, 1986;

Oliver, 1986; Bethke and Marshak, 1990; Ge and Garven, 1992), non-tectonic causes such as

topography (Deming and Nunn, 1991), fluid density differences (Stanislavsky and Gvirtzman,

1999), and compaction (Jackson and Beales, 1967) can also result in the movement of fluids over

long distances (Chen et al., 2001). In the Appalachians, which is perhaps the best studied

example of large scale fluid migrations, thrust loading coupled with topographic differences are

believed to have been the driving mechanism that caused the fluids to be expelled from the

hinterland some 1000 km into the craton (Oliver, 1986).

In the Appalachians, large volumes of fluid are thought to have moved across the orogen

during the Late Paleozoic Alleghanian orogeny and are responsible for features on the craton

such as hydrocarbon emplacement, mineralization, potassic alteration, and diagenesis (Bethke

and Marshak, 1990). Thrust loading and tectonic compression drove warm fluids from the

hinterland to the foreland (Oliver, 1986). The source of the fluids is thought to be a combination

of metamorphic fluids (Schedl et al., 1992) and basinal brines (Evans and Battles, 1999). Recent

work by Chandonais and Onasch (2014) showed that the Blue Ridge province, which lies in the

path of this regional migration, behaved as an isolated paleohydrologic system. If westward- 2

migrating fluids were sourced in the Piedmont province to the east, as has been proposed by a number of workers (e.g., O’Hara et al., 1995), they must have bypassed the Blue Ridge possibly by moving along one or more detachments underneath. Alternatively, the source of the fluids may have been beneath the Blue Ridge itself (Schedl et al., 1992) from where they moved westward into the Valley and Ridge province and beyond. Key to understanding the source and migration path is the western portion of the Piedmont province that lies just east of the Blue

Ridge. Comparison of its fluid history to that of the eastern Piedmont, Blue Ridge, and Valley and Ridge could help resolve the source and path taken by regionally migrating fluids during the late Paleozoic.

The objective of this research is to use fluid inclusion microthermometry to obtain a complete fluid history for the western Piedmont province of Maryland in the context of its structural history. This study, along with the results of previous studies, will help complete an orogen-wide picture of the flow of fluids in the Appalachians during the Alleghanian orogeny.

Specifically, the hypothesis to be tested is that the fluids that were present during the orogeny were sourced in the eastern Piedmont, migrated westward through the western Piedmont, bypassed the Blue Ridge possibly through underlying thrust faults, and moved on into the Valley and Ridge and beyond. Therefore, the region was part of the westward regional fluid flow event

first proposed by Oliver (1986). An alternative hypothesis is that the fluids in the western

Piedmont are unlike those in the eastern Piedmont, Blue Ridge, or Valley and Ridge; therefore, no simple orogen-wide fluid system existed during the Alleghanian orogeny.

GEOLOGIC SETTING

Study Area

The location of this study is in the western portion of the Piedmont province of Maryland.

Samples were collected primarily from Westminster terrane (Fig. 1) of the Piedmont, which

consists mostly of greenschist and sub-greenschist facies metamorphic rocks (Jonas and Stose,

1938; Kunk et al., 2004). Other samples were collected from the Sugarloaf Mountain anticlinorium and Frederick Valley synclinorium, which were overthrusted by the Westminster terrane during the Taconic orogeny and later metamorphosed in the early Silurian (Southworth et al., 2006).

Stratigraphy

The Westminster terrane (Fig. 1) consists of the Prettyboy Schist, Marburg Formation,

Ijamsville Phyllite, Sams Creek Formation, and Wakefield Marble (Fig. 2) (Southworth et al.,

2006; Southworth et al., 2007). These rocks are interpreted to be metamorphosed deep water sediments from an accretionary wedge that was deposited during the Neoproterozoic and Lower

Cambrian on the continental margin, slope, and rise (Southworth et al., 2007). The timing for metamorphism in the Westminster terrane varies from east to west. The rocks west of the

Hyattstown thrust reached peak metamorphism 430 Ma; approximately 60 million years prior to the rocks east of the Hyattstown thrust (Kunk et al., 2004; Wintsch et al., 2010). This early

Silurian metamorphism is due to thrust loading from the accretion of the Carolinia terrane in the southern Appalachians during the Cherokee orogeny (Hibbard et al., 2012;Wintsch et al., 2010)

The rocks of the Westminster terrane all show a pervasive transposition foliation crosscut by 4

younger foliations (Southworth et al., 2007). A recent study done by Wintsch et al. (2010) found that there were at least three generations of foliation in the western portion of the Westminster

terrane. The first generation is Taconic in age and can only be seen in thin section, the second,

and most dominant of the three foliations, is early Silurian (Cherokee), and the third is a discrete

foliation that has been constrained to be late Devonian.

This study focused on the Ijamsville Phyllite, found primary in the western region of the

Westminster terrane (Fig. 2), and which consists mostly of blue, green, and purple phyllitic slate

(Jonas and Stose, 1938; Southworth, 1994). There are eight lithologic units that make up the

Ijamsville Phyllite: phyllite, metabasalt, quartzite, marble, metalimestone, phyllitic

conglomerate, conglomeratic metagreywacke, and chloritic phyllite (Southworth et. al., 2007).

The most abundant lithologic unit is the phyllite, which is a muscovite-chlorite-paragonite-

chloritoid phyllite (Southworth et al., 2007). The Ijamsville Phyllite was found through 40Ar/39Ar

dating of white micas to be metamorphosed to lower greenschist facies with peak metamorphic

temperatures of 320‒350°C between 426 and 431 Ma ago (Wintsch et al., 2010). Since the

initial deformation, the Ijamsville has seen multiple generations of cleavage form due to

reactivations of the Martic thrust throughout the Paleozoic orogenic events, including the late

Paleozoic Alleghanian orogeny (Kunk et al., 2004; Southworth et al., 2007).

Samples were also collected from the Urbana Formation and Sugarloaf Mountain

Quartzite within the Sugarloaf Mountain anticlinorium, and from a quarry within the Grove

Formation found in the Frederick Valley synclinorium (Figs. 1 & 2). These two regions were

also found to be metamorphosed around 430 Ma ago with the Westminster terrane based on

40Ar/39Ar dating (Wintsch et al., 2010). The two formations found within the Sugarloaf Mountain anticlinorium consist primarily of Lower Cambrian clastic metasedimentary rocks that were 5

originally deposited as continental margin strata (Southworth, 1996). The Sugarloaf Mountain

Quartzite is medium to coarse grained quartzite characterized by its retained sedimentary

structures (Jonas and Stose, 1938). The Urbana Formation overlies the Sugarloaf Mountain

Quartzite conformably and consists of a variety of clastic metasedimentary rocks (Southworth et.

al., 2006). Both of these rocks that make up the Sugarloaf Mountain anticlinorium were metamorphosed to lower greenschist facies during in the early Silurian. The Grove Formation is

an interval of carbonate rock at the core of the Frederick Valley synclinorium. These carbonates

were deposited on the shelf edge as a sand wave complex in the lower Grove Formation and as a

peritidial environment in the upper Grove Formation during the upper Cambrian to lower

Ordovician (Jonas and Stose, 1938; Southworth et al., 2007). The Ijamsville Phyllite, along with

the rest of the Westminster terrane, was emplaced directly on the Urbana Formation by the

Martic thrust during the Taconic orogeny in the Ordovician, but it was likely active during all

three Paleozoic orogenies (Southworth et al., 2006).

Figure 1. Terrane map showing the location of the Westminster terrane where most of the samples were collected.

Structure

Each of the lithotectonic terranes within the western Piedmont is fault-bounded. In Figure

2, the Ijamsville Phyllite, Sams Creek Formation, Marburg Formation can be seen to make up the

Westminster terrane. The Sugarloaf Mountain anticlinorium is comprised of the Urbana

Formation and Sugarloaf Mountain Quartzite. The Frederick Valley synclinorium contains the

Grove, Frederick, and Araby formations (Fig. 2). In the late Ordovician, during the Taconic orogeny, the Westminster terrane was thrust westward along the Martic thrust over Cambrian 7

and Ordovician continental margin strata, which now make up the Frederick Valley synclinorium

and Sugarloaf Mountain anticlinorium (Southworth at al., 2007; Wintsch et al., 2010). The rocks

of the Westminster terrane are comprised of imbricated thrust sheets parallel to the Martic thrust

fault (Fig. 2 & 3) (Southworth, 1994). East of the Westminster terrane is the Potomac terrane,

which was thrust over the Westminster terrane along the Pleasant Grove thrust (Figs. 2). Both

thrusting events occurred during the Taconic orogeny and may have been reactivated in the late

Paleozoic during the Alleghanian orogeny (Valentino et al., 2004). During the Silurian

(Cherokee), the rocks of the Sugarloaf anticlinorium and Frederick Valley synclinorium, along

with the Martic thrust, were folded into large recumbent folds (Wintsch et al., 2010). It was during this time in the Silurian when the rocks of the western Piedmont reached their peak metamorphic conditions due to the overburden related to folding and imbricate thrusting in the

hinterland as the Carolinia terrane was accreted to Laurentia (Wintsch et al., 2010). The

Sugarloaf Mountain Quartzite and Urbana Formation, which make up the core of the Sugarloaf

Mountain anticlinorium, have since been exposed in the Bush Creek window through the

Westminster thrust sheet (Southworth et. al., 2007) (Fig. 2 & 3). Figure 3 shows the imbrication of the rocks within the Westminster terrane and the extent of the Martic fault within the study area.

The Ijamsville Phyllite, with its many thoroughgoing thrust faults, lies is in contact with

the Urbana Formation along both sides of the Bush Creek window (Fig. 2). It’s characterized by

composite foliations that are overprinted by a phyllonitic foliation and several younger cleavages

(Southworth et. al., 2006; Southworth et. al., 2007). Quartz veins are abundant throughout the

Ijamsville Phyllite. They range from planar-tabular to isoclinally folded and/or sheared 8

(Southworth et. al., 2007) indicating that they were emplaced at different stages in the structural

history of the unit.

Vein Types

The Ijamsville Phyllite was chosen as the focus of this study due to the abundance of veins. Veins are also abundant in Sugarloaf Mountain Quartzite, but are rare within the Urbana

Formation. Veins were classified into five groups based on their relationship to the pervasive

phyllonitic foliation in the region, which is mostly early Silurian with possible overprinting

during the Alleghanian (Wintsch et al., 2010; Southworth pers. comm.) (Fig. 4): (1) folded,

which are typically isoclinally folded with S1 parallel to the axial plane of the folds and are most

likely pre-cleavage (Fig. 4a); (2) cleavage-parallel, which are parallel to S1 and are possibly syn- cleavage (Fig. 4b, c); (3) cross-cutting, which clearly cross-cut S1 and are post-cleavage (Fig 4c);

(4) float, which were samples collected from a particular location without knowing the relationship to the dominant foliation; and, (5) fault zone, which were found along the Martic thrust. Most commonly observed in the Ijamsville were the cleavage-parallel veins. Almost all veins observed were filled with quartz. The exceptions were the fault zone veins and those in the

Frederick Valley synclinorium both of which were filled with calcite and/or dolomite as well as

minor quartz. 9

Figure 2. Geologic map of the western Piedmont province modified from USGS 30’ x 60’ quadrangle (Southworth et al., 2007) with sample locations. Dashed line represents the axial trace of the Sugarloaf Mountain anticlinorium, which was later used in this study to separate fluid types. 10

Figure 3. Cross section (modified from Southworth et al., 2006) of line A-A’ in Figure 2.

Figure 4. Quartz veins in the Ijamsville Phyllite and their relationships to S1 and each other. (a) Folded vein with S1 parallel to the axial plane. (b) cleavage- parallel vein. Pod shape is common of this type (c) cleavage-parallel and crosscutting veins. Vein B shows pinch and swell geometry typical of cleavage-parallel veins. Both vein B and S1 are crosscut by the younger, vein A.

METHODOLOGY

Field Methods

Approximately 70 samples were collected for fluid inclusion analysis, mostly from the

Ijamsville Phyllite due to its abundance of quartz veins and structural location above the Martic

thrust. For each site within the study area, the orientation of structural features and their relationship to veins were recorded. Timing relationships between the veins and structures associated with different stages of deformation were noted and photographed or sketched.

Laboratory Methods

Thin sections were initially prepared from all samples to determine the inclusion types, vein mineral paragenesis, and degree of vein mineral deformation. Samples suitable for fluid inclusion analysis had inclusions >5 µm in size and a minimal amount of recrystallization and subgrain formation. Samples which satisfied these criteria were then prepared into 50-200 µm- thick, doubly-polished plates from the same billets that were used for the thin sections. Care was taken during this process to not exceed 50°C so as not cause stretching or decrepitation of any low temperature inclusions that might be present.

Of the original 70 samples, 25 were determined to be suitable for fluid inclusion analysis.

From these, 12 spatially well-distributed samples were chosen for microthermometric analysis.

Of the 12 samples, one was from a folded vein, eight from cleavage-parallel veins, two from float samples, and one from the Martic fault zone. No samples from the cross-cutting veins (Fig.

4c) were used due to the large degree of recrystallization and/or small inclusion sizes. Because growth zoning is useful in determining the mineral paragenesis and in the identification of 13

inclusions as primary, each sample was examined in cathodoluminescence with a Technosyn

cold cathode microscope. None contained any form of zoning (Fig. 5).

Fluid Inclusion Microthermometry

Microthermometric measurements were made using a modified USGS-type

heating/cooling stage manufactured by Fluid Inc. housed in the Geology Department, BGSU.

The stage was calibrated at -56.6°C using synthetic CO2 inclusions from SYNFLINC, Inc., at

0.0°C using an ice bath, and at 100.0°C using boiling deionized water. Inclusions were first

separated into primary and secondary using the criteria in Roedder (1984). Primary inclusions

were noted by their larger size, isolated occurrence, and regular shape. Primary fluid inclusion

assemblages (FIA) were identified by the criteria given in Goldstein (2001). Secondary and

pseudosecondary inclusions were identified by their occurrence along planes that form from healed microfractures. Secondary and pseudosecondary inclusions were difficult to separate unequivocally in the absence of any growth zoning, so were grouped together. Very few secondary/pseudosecondary inclusions were measured due to their small size (<2 µm). In the two samples were measurements could be made, their density was so high that it was impossible to distinguish them from any primary inclusions that might have been present.

Because all veins show at least some recrystallization and subgrain formation and

because recrystallization may reset the microthermometric properties (Schmatz and Urai, 2011),

only grains showing minimal effects of recrystallization were used for fluid inclusion analysis.

By avoiding samples or regions in samples that have undergone recrystallization, it was hoped that the inclusions measured would yield the original trapping conditions and fluid compositions.

Given the likelihood of changes in P/T conditions during the complex structural and 14

metamorphic history of the veins studied, there is also a possibility that reequilibration of the

original inclusions may have taken place. Textures characteristic of reequilibration, such as

secondary inclusion halos, annular inclusions, and fracture arrays as described by Vityk and

Bodnar (1995) and Bodnar (2003), were not present, so it was assumed that the inclusions record

the trapping conditions under which they formed.

All inclusions found were two-phase aqueous (L+V) inclusions. The measurements made

for theses inclusions were: homogenization (Th), last ice melting (Tm), and eutectic (Te)

temperatures. Wherever possible, heating/cooling runs were made on a single inclusion or

multiple inclusions in an FIA, sequentially so that Th, Tm, and Te data could be grouped by the

inclusion in which they were measured. Precision, as determined from repeated measurements of

the same inclusions, was ±0.3°C for Tm and ±1.0°C for Th. Because of the very low salinities and

small inclusion sizes, Te measurements could only be estimated. All measurements were routinely made twice to ensure reproducibility. Data were then entered in a spreadsheet from which histograms were constructed and statistics calculated.

a b

Figure 5. Cathodoluminescence and plane polarized light images of typical vein quartz sample. (a) Plane polarized light image of large quartz grain. (b) Cathodoluminescence image of same grain showing no zoning, which was typical of all samples examined. Scale bar is 200µm.

MICROTHERMOMETRY RESULTS

The Th and Tm values fell in narrow ranges, both for individual samples and for the entire sample dataset. All Tm samples measured were between -8.0° and 0.0°C with the majority

of temperatures between -4.0° and -1.0°C (Fig. 6). This corresponds to a salinity range of 1.7 to

6.4 wt. % NaCl equivalent as determined using FLINCOR (Brown, 1989). The Th measurements

for all 12 samples ranged from just over 100°C to 280°C with a majority of the measurements

falling between 140°C and 200°C (Fig. 7). A plot of Th vs. Tm shows a fairly tight grouping (Fig.

8). Given that the first ice melting was difficult to observe in all samples, only a few Te

measurements were made, all of which were around -20°C indicating that the fluid in these

samples is most likely a NaCl brine.

Figure 6. Histogram of final ice melting temperature (Tm) for all primary and secondary inclusions measured. 17

Figure 7. Histogram of homogenization temperature (Th) for all primary and secondary inclusions measured.

Homogenization Temperature (°C)

50 100 150 200 250 300 0

2 C) -° 3

5 Final Ice Melting Temperature (

Figure 8. Th vs. Tm plot for all inclusions measured.

DISCUSSION

The objective of this study is to determine if the western Piedmont was part of Oliver’s

(1986) westward fluid migration event during the Alleghanian orogeny. To test this, the fluid

history in the study area must be determined and compared to those in neighboring regions in the

central Appalachians. The fluid history is determined by identifying different fluids on the basis

of their microthermometric properties and the trapping P/T conditions determined from them,

geographic and structural locations of the samples, and host rock unit lithology. These different

fluids are then integrated with the structural history to yield a picture of how fluids evolved

spatially and temporally throughout the tectono/thermal evolution of the area.

Fluid History

When viewed as a whole, the entire dataset shows little to no separation by Th, Tm, or Th

vs. Tm (Figs. 6-8). Although the entire dataset may show no significant separation in terms of

microthermometric properties, parsing it by vein type, structural location, and/or host rock type may reveal the presence of different fluids.

Vein type – Separating the veins by their relationship to cleavage (folded, cleavage-

parallel, or cross-cutting) (Figs. 4b, c) provided no separation of the data (Fig. 9). 20

A. C.

B. D.

Figure 9. Comparing folded veins to cleavage-parallel veins. (A) Tm values from folded vein over (B) Tm histogram of veins classified as cleavage parallel. (C) Th histograms for folded vein above (D) Th histogram for cleavage parallel veins. (E) Plot of Tm vs. Th for folded and cleavage-parallel veins. 21

Structural location – When separated by structural location, there does appear to be some

separation in the dataset. The one sample from the Martic thrust zone has lower Tm values and somewhat lower Th values than most of the samples measured elsewhere (Fig. 10). This

difference could be attributed to fluid-rock interaction with the carbonate footwall rocks or a

unique fluid that was channeled through the fault zone. Given the protracted history of the fault

(Kunk et al., 2004), it is reasonable to think that it was a fluid pathway during the Taconic,

Cherokee, and/or Alleghanian orogenies and hence, could have been exposed to more or

different fluids than the adjacent rocks.

Homogenization Temperature (°C) 0 50 100 150 200 250 300 0

Martic Thrust 1 C) ° - 2 Grove Formation

3 Ijamsville Phyllite and Sugarloaf Mountain Anticlinorium Samples 4

5 Final Ice Melting Temperature (

7 Figure 10. Th vs. Tm plot separating the Martic thrust and Grove Formation samples from the rest of the inclusions measured.

A second possible separation of the data by structural location occurs across the

Sugarloaf Mountain anticlinorium. The fluid inclusion data from the Ijamsville Phyllite,

Sugarloaf Mountain Quartzite, and Urbana Formation show a small separation by the sample 22

location relative to the axial trace of the anticlinorium (Fig. 2). The histogram for Th shows a

difference of ~10°C in modal temperature for the two groups (Fig. 11) (Table 1). The eastern

limb samples have a higher Th mode of 175°C compared to the samples from the western limb,

which have a mode of 165°C. The two groups also have slightly different mean Tm, but a modal

temperature difference is not readily distinguishable on the Tm histogram (Fig. 12) (Table 1).

Using the modal values, both limbs have a salinity of 4.0 wt. % NaCl equivalent. The liquid-

vapor ratio is also similar between the two limbs ranging from 90:10 to 80:20. The separation by

limb is also visible on the plot of Th vs. Tm (Fig. 13). Both the Th and Tm differences are

statistically significant at the 95% level of confidence as determined by a T-test. Therefore, it

appears that two fluids can be recognized; low Th/high Tm fluids on the eastern limb of the

Sugarloaf Mountain anticlinorium and a high Th/low Tm fluid on the western limb (Fig. 13).

One possible explanation for the different Th between the eastern and western limbs of

the anticlinorium could be due to the timing of vein mineralization in relation to the progression

of deformation phases. Figure 3 shows that the Sugarloaf anticlinorium is a nearly overturned antiform (Scotford, 1951; Southworth et al., 2007). If the veins in these three formations in this area formed syn- or post-deformation then the western limb would have been at a deeper level;

hence, the slightly higher Th values.

Table 1. Fluid characteristics separated by eastern and western limbs of the Sugarloaf Mountain anticlinorium.

Limb Th Range Modal Th Mean Th Tm Range Modal Tm Mean Tm Salinity % (°C) (°C) (°C) (°C) (°C) (°C) (wt% NaCl) Vapor East 150 ‒ 180 165 169.4 -4.5 ‒ 0.0 -2.5 -2.2 4% 10‒20 West 170 ‒ 190 175 177.1 -7.0 ‒ -1.0 -2.5 -2.8 4% 10‒20 23

Eastern Limb

Western Limb

Figure 11. Homogenization temperatures for the Ijamsville Phyllite, Urbana Formation, and Sugarloaf Mountain Quartzite samples separated by eastern and western limbs of the Sugarloaf Mountain anticlinorium (see text for explanation). Blue line represents the mode for the eastern limb; the red line is the mode for the western limb. 24

Eastern Limb

Western Limb

Figure 12. Final ice melt temperatures of the Ijamsville Phyllite, Urbana Formation, and Sugarloaf Mountain Quartzite samples separated eastern and western limbs of the Sugarloaf Mountain anticlinorium (see text for explanation). Vertical line represents the modal temperature for both limbs. 25

Homogenization Temperature (°C) 0 50 100 150 200 250 300 0

1 C)

-° 2

Final Ice Melting Temperature ( Western Limb

6 Eastern Limb

Figure 13. Th vs. Tm for inclusions in the Ijamsville Phyllite, Urbana Formation, and Sugarloaf Mountain Quartzite samples separated by eastern (lower Th, higher Tm) and western (higher Th, lower Tm) limbs of the Sugarloaf Mountain anticlinorium.

Rock type – Samples from the Grove Formation in the Frederick Valley synclinorium have lower Tm values than other rock types in the study area (Fig. 10) yielding a modal salinity of 7.0 weight % NaCl equivalent with Te values around -20°C. The Grove Formation is a limestone and dolomite, while the other rocks in the study area are low-grade pelitic and quartzose metamorphic rocks. The higher salinities in the Grove Formation inclusions could reflect fluid-rock interactions with the carbonate-rich lithologies.

Trapping Conditions

The trapping conditions can be used to identify when vein mineralization took place during the deformational history. This is also useful when comparing the fluids identified here to 26

those in other areas of the Appalachians. No other gases (e.g., CO2 or CH4) or immiscible fluids were present in any of the samples collected, so the entrapment pressures and temperatures

cannot be well constrained. Consequently, trapping conditions were determined using isochores,

along with possible geothermal gradients and fluid pressure conditions. Figure 14 shows the

ranges of entrapment conditions for lithostatic and hydrostatic fluid pressure conditions. These conditions were estimated using isochores determined from the modal homogenization temperatures and fluid salinity (Roedder and Bodnar, 1980). The program FLINCOR (Brown,

1989) was used to determine the isochores for both the eastern and western limb samples by using the modal Tm and Th values and fluid composition. The lithostatic and hydrostatic pressure gradients were plotted using elevated geothermal gradients of 30°C/km and 50°C/km (Fig. 14) is

typical of metamorphic terranes. Evans and Battles (1999) found elevated geothermal gradients

of 20−25°C/km in the Valley and Ridge province were due to orogenic thickening. Using a

30°C/km geothermal gradient and a lithostatic and hydrostatic pressure gradients of 26.5MPa/km

and 9.8MPa/km, respectively, the eastern limb samples yield trapping pressures corresponding to a depth between 5 and 10 km. For the same conditions, the western limb samples have trapping

pressures corresponding to a depth between 6 and 11 km. For geothermal gradients greater than

30°C/km, the entrapments depths will be shallower (Table 1). 27

400 Western Limb 350 Eastern Limb

300

250

200

Pressure (MPa) 150

100

0 0 50 100 150 200 250 300 350 400 450 500 Temperature (°C) Figure 14. Estimation for trapping pressure and temperature for the two fluid types (eastern and western limbs of the Sugarloaf Mountain anticlinorium) with lithostatic and hydrostatic pressure conditions and with 30°C/km and 50°C/km geothermal gradient s. Red line is the western limb modal isochore; blue line is eastern limb modal isochore.

Table 2. Trapping conditions for eastern and western limb fluids using two geothermal gradients. Pressures for lithostatic (PtL) and hydrostatic (PtH) were calculated using FLINCOR (Brown, 1989).

Fluid Th Mode PtH TtH PtL TtL Depth (°C) (MPa) (°C) (MPa) (°C) (km)

East 165 50 195 270 320 5 to 10 (30°C/km)

West 175 60 210 300 350 6 to 11 (30°C/km)

East 165 25 180 95 220 2.6 to 3.6 (50°C/km)

West 175 35 190 105 235 3.6 to 4.0 (50°C/km) 28

Paleohydrology and the age of fluids of the western Piedmont

Despite the complex structural and metamorphic history of the study area, the fluid

inclusion data are remarkably uniform. Th, Tm, and Te all show little to no variation over the area

despite coming from veins of obviously different ages and in different rock types. Furthermore,

there is no difference in the data from primary and secondary inclusions. Taken together, these

suggest that the inclusions record a late event that reset all preexisting inclusions to a single set

of conditions. Also consistent with that conclusion is the low salinity of the fluids suggesting a

meteoric origin that differs from the fluids more typical of metamorphic terranes in which CO2

and CH4 are common components (Roedder, 1984). Despite the apparent simplicity implied by

the data, the lack of evidence for reequilibration of the fluid inclusions or complete

recrystallization of host grains, suggests that a late resetting of earlier inclusions may not be the

case. Coupled with the lack of unequivocal evidence for an absolute age of the fluid or age relative to specific deformational/metamorphic events, a number of possible timing scenarios should be considered.

Four potential fluid histories are proposed to explain these observations: (1) the fluids

are Taconic in age and formed during the development of the original foliation; (2) the fluids and

veins are Silurian in age and were trapped just before or just after the region reached peak

metamorphic conditions during the Cherokee orogeny; (3) the fluids are Alleghanian in age and

either the veins formed during the Alleghanian or formed earlier and were recrystallized and/or

reequilibrated during the Alleghanian; or, (4) the fluids are associated with post-orogenic

Mesozoic continental extension and unroofing and the veins either formed or were reequilibrated

at that time. 29

If the fluids are Taconic in age, then the veins are associated with the first generation of

foliation as describe by Wintsch et al. (2010), which is the earliest foliation found in the western

region of the Westminster terrane. This generation of foliation can only be identified in thin

section and would have formed during the main displacement along the Martic thrust in the late

Ordovician. The temperatures of formation for this foliation are between 250 and 300°C

(Wintsch et al., 2010), which is within the inclusion trapping temperature range using a 30°C/km

geothermal gradient (Fig. 14 and Table 2).

If the fluids are Silurian in age they would have formed shortly after the Cherokee

orogeny when the region reached peak metamorphic conditions. During the Cherokee orogeny,

the Carolinia terrane was accreted to Laurentia in the southern Appalachians as described by

Hibbard et al. (2012). Wintsch et al. (2010) found the peak metamorphic temperatures to be

between 320 and 350°C during the thrust loading that resulted from the accretion of the Carolinia

terrane. This is above most of the trapping temperatures that were calculated using the modal Th

values with the exceptions being at lithostatic fluid pressure in 30°C/km geothermal gradient

(Fig. 14 and Table 2). Figure 16 shows what the homogenization temperatures for inclusions with the same salinity would be if they were trapped at peak metamorphic conditions (350°C)

using FLINCOR (Brown, 1989). At hydrostatic pressure with a 30°C/km gradient,

homogenization temperatures would need to be around 270°C. For a 50°C/km geothermal

gradient, homogenization temperatures would be 235°C at lithostatic and 300°C at hydrostatic

pressures (Fig. 15). These projected homogenization temperatures are higher than those

recorded, indicating that the inclusions were not trapped at those high temperatures; hence, they

are unlikey to be associated with the peak of metamorphism in the Cherokee orogeny. 30

If the fluids are Alleghanian in age then it is possible that the veins formed from the

deformation associated with the reactivation of the Martic thrust. The dominant foliation in the

Ijamsville is a combination of the original foliation from the Taconic orogeny in the Silurian and reactivation during the Alleghanian (Southworth, pers. comm.). The veins that are cleavage- parallel could have formed or were recrystallized/reequilibrated during the Alleghanian reactivation of the Martic thrust. It is more likely that the veins predate the Alleghanian and were recrystallized/reequilibrated since the impact of the Alleghanian was regionally small although any strain would be localized in the preexisting quartz veins (Wintsch, pers. comm.). The folded veins would also be pre-Alleghanian.

The final possibility is that the fluids are associated with the Mesozoic extension and

unroofing. This could explain why the Th and Tm data for all of the samples are so similar. In the southeastern Piedmont, Evans and Bartholomew (2010) found post-orogenic veins and secondary inclusions within older vein sets that had a narrow range of homogenization temperatures and very low salinity. These younger vein sets and secondary inclusion planes were

interpreted to have formed as a result of fracture opening and meteoric water circulation

following unroofing during Mesozoic rifting.

None of the fluid history scenarios described above offer a completely satisfactorily explanation of the data and observations in the western Piedmont. Looking at the data as a whole, they fall in a narrow range of Th and Tm values. Although there may be small differences

related to the position on the Sugarloaf Mountain anticlinorium or along the Martic thrust, the

data still do not vary much across the area. The salinity also remains very low across the

Sugarloaf Mountain anticlinorium; only rising slightly in the Frederick Valley synclinorium.

Also significant is that no reequilibration textures were observed suggesting that the 31

microthermometric data are related to the initial trapping of the inclusions, not subsequent

modification. A Taconic age for the fluids suffers from the observation that all inclusions,

regardless of age relative to the various generations of veins, yield the same data. For this to be

true, the P/T conditions and fluid composition would have had to remain unchanged for several

phases of the progressive deformation across a broad region. Also, fluids other than meteoric

would be expected during metamorphism (Roedder, 1984). The homogenization temperatures

found in all samples are lower than what would be expected if they formed during the peak lower greenschist facies temperatures (320‒350°C) for this region (Fig. 15) (Wintsch et al., 2010) unless the fluid pressure was lithostatic and the geothermal gradient was 30°C/km or lower

(Table 2). This would seem to rule out a syn-tectonic Silurian age. If the fluids are syn-tectonic

Silurian in age, then the inclusions would have had to all be reequilibrated to cooler, post- tectonic conditions in order to explain the lower Th values and the uniformity of the data.

However, no reequilibration textures were noted, nor was the spread of data typical of

reequilibrated inclusions (Bodnar, 2003). Wintsch et al. (2010) found that the western

Westminster terrane, Frederick Valley synclinorium, and Sugarloaf Mountain anticlinorium

reached a thermal equilibrium shortly after these units, along with the Martic thrust, were folded

into large recumbent folds essentially locking these terranes together. This thermal equalibrium

across the these three terranes could explain their similar homogenization temperatures, but it

would have involved reequlibration of existing inclusions, the textural evidence for which is

lacking. An Alleghanian age for all veins is unlikely because the pre-cleavage and cleavage-

parallel veins are associated with the S1 cleavage and metamorphism, both of which pre-date the

Alleghanian (Wintsch et al., 2010). A small impact on this region during the Alleghanian could

have recrystallized/reequilibrated preexisting veins, but again, no reequilibration textures were 32 found in any of the samples. The post orogenic unroofing and meteoric circulation could possibly explain the similar homogenization temperatures and low salinity, but the vein samples analyzed are not from a younger, post-orogenic set.

Given the above considerations, the most probable history for this region would be that the fluids were trapped sometime after peak metamorphism in the Silurian. The uniform data could be due to the region being in thermal equilibrium after being locked together by the folding events of the Silurian. The lack of reequilibration textures would suggest that there would have been no widespread thermal reequilibration from the later Alleghanian and Mesozoic events. An exception might be the sample from the Martic thrust zone, which may have trapped fluids during Alleghanian reactivation.

400

Western Limb 350

Eastern Limb 300

250

200

Pressure (MPa) 150

100

0 0 50 100 150 200 250 300 350 400 450 500 Temperature (°C) Figure 15. Estimated homogenization temperatures for a peak metamorphic temperature of 350°C in the western portion of the Westminster terrane. Isochores

were calculated with FLINCOR (Brown, 1989). 33

Regional Fluid Migration

The original hypothesis being tested is the fluids that were present in the western

Piedmont during the Alleghanian orogeny were sourced in the eastern Piedmont, migrated westward through the western Piedmont, bypassed the Blue Ridge by moving along one or more

detachments below, and moved on into the Valley and Ridge and beyond. Therefore, they were

part of the westward regional fluid flow event first proposed by Oliver (1986). If this holds true,

then the fluids found here in the western Piedmont should be related to those found to the east

and in the Valley and Ridge province to the west. The alternative hypothesis is that the fluids in

the western Piedmont are unlike those in the eastern Piedmont or the Valley and Ridge;

therefore, no simple orogen-wide fluid system existed during the Alleghanian orogeny. If this

alternative hypothesis holds true then fluids within the western Piedmont may be totally unique or resemble what Chandonais and Onasch (2014) found in the Blue Ridge province where they concluded the Blue Ridge was an independent hydrologic system during the Alleghanian. It is also possible that these fluids are not Alleghanian, but rather Taconic, Silurian, or even

Mesozoic,d an hence, are unrelated to an Alleghanian regional flow event.

Table 3 shows the general characteristics of the fluids in the different provinces across

the Appalachians. The western and eastern Piedmont have similar Tm values and uniform data,

but differ due to the presence of CO2, which is absent in the western Piedmont. The western

Piedmont and Valley and Ridge show few similarities. The salinity and the dominant salt differ

and the Valley and Ridge contains inclusions with CO2 and CH4, both of which are absent in the

western Piedmont. Also, several fluid types were found in the Valley and Ridge province, but

there appears to have been only one fluid in the western Piedmont. The Blue Ridge, which is

independent of the regionally migrating fluids (Chandonais and Onasch, 2014), lacks CO2 and 34

CH4 much like the western Piedmont, but differs due to the dominant salt and large variation of fluids found in this region.

Table 3. Fluid characteristics across the Appalachians.

Region Fluids Final Ice Salinity Trapping Melting Temperatures Temperatures

Eastern CO2+H2O+NaCl±CH4 -3.5 − -0.5°C 1.0 wt. % NaCl 250−300°C Piedmont (Markham, 2009)

Western H2O+NaCl -8.0 − 0.0°C 1.7 to 6.4 wt. % 195−350°C Piedmont NaCl (This study)

Blue Ridge H2O+CaCl2±NaCl±Mg -17.6 − -1.7°C 0.0 to over 30.0 wt. 220−387°C (Chandonais Cl2 % NaCl; Majority: and Onasch, 3.0 to 21.0 wt. % 2014) NaCl

Valley and CH4+NaCl+CaCl2 -20.0 − -6.0°C 8.5 to 19.0 wt. % 160 − >220°C Ridge Brine containing CO2 NaCl (Evans and and some HHC (Higher Battles, 1999) Hydrocarbons)

The western Piedmont’s fluid history is not consistent with a single westward fluid migration from the hinterland to foreland. The western Piedmont is not part of the Alleghanian fluid migration because fluids appear to be older and do not have characteristics consistent with being derived from the eastern Piedmont or being the source of fluids in the Valley and Ridge province. This is due primarily to the absence of CO2, which is a common fluid found in metamorphic terranes and a common fluid found in the eastern Piedmont. The lack of CH4 in the western Piedmont can be accounted for since in previous studies CH4 was found to be sourced from the Ordovician black shales (Ryder et al., 1998), which are not present within the Piedmont 35

province. Since the western portion of the Piedmont does not fit in with the western migration of

fluids during the Alleghanian, it would suggest that these fluids may not be Alleghanian in age. It

could be possible that the western Piedmont was an independent fluid system if the fluids found

here are Alleghanian in age or the strain from the Alleghanian orogeny could have recrystallized and/or reequilibrated preexisting inclusions.

CONCLUSIONS

The western Piedmont has a complex, protracted deformational history that extends

throughout much of the Paleozoic starting with its initial metamorphism during the Taconic

orogeny. The fluids found here were all low salinity aqueous brines (H2O+NaCl) trapped in

inclusions in quartz, and less commonly, carbonate veins. These fluids are consistent in their

character across the entire western Piedmont with modal Th of 175°C along the western limb of

the Sugarloaf Mountain anticlinorium and 165°C along the eastern limb. Tm values range from -

8.0° and 0.0°C, with a mode of 2.5°C. The age of the mineralization and fluids is not well constrained due to lack of good age control on the deformation and metamorphism. The most likely scenario that explains the fluid history of the western Piedmont is the formation of veins

and trapping of fluids shortly after this region reached peak metamorphic conditions from the

Cherokee orogeny in the early Silurian. During this time the formation of large scale folds had locked the terranes of the western Piedmont together causing the region to be in a thermal

equilibrium. This would explain the similarities in Th across the different formations. This could

also explain the slight difference in modal Th values along the eastern and western limbs of the

Sugarloaf anticlinorium. Since this feature was formed during this time, it would have a greater difference in overburden across from east to west than an earlier scenario. However, the one sample collected from the Martic thrust with lower Th values may be Alleghanian due to possible

reactivation of the thrust. 37

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APPENDIX A: MICROTHERMOMETRY MEASUREMENTS

BUC-2 BUC-03B P or S Te Tm Th %V P or S Te Tm Th %V P -6.7 127.6 10 S -3.3 P -5.6 172 20 P -3.2 P -5.1 20 P -3.1 P -5 160.6 30 P -3.0 P -24.5 -5 213.5 30 S -2.5 198.3 15 P -4.8 169.7 20 P -2.4 P -4.6 179.4 15 P -2.3 217.5 20 P -4.2 170.9 10 P -2.2 231.0 P -4.1 174.4 20 P -2.2 173.1 P -4.1 10 P -2.2 P -4.1 20 P -2.1 191.0 P -3.8 163.3 20 P -1.9 192.0 20 P -3.7 175.4 20 P -1.8 168.7 15 P -3.7 192 10 P -1.8 P -3.6 P -1.6 197.6 15 P -3.5 20 P -1.4 180.1 20 P -3.4 119.2 10 P -1.1 144.5 25 P -3.4 179.4 20 P -0.3 170.1 25 P -3.3 20 P 0.0 139.7 10 P -3.2 172.5 15 P 282.4 P -3 190.9 10 P 122.1 15 P -2.9 173.3 20 P 159.4 10 P -2.9 174.4 20 P 163.3 15 P -2.9 174.6 20 P 189.8 15 P -2.9 20 P 182.7 15 P -2.9 20 P 161.0 20 P -2.8 175.3 20 P 162.2 20 P -2.7 P 167.8 15 P -2.6 170.6 P 151.5 10 P -2.6 174.9 P 227.8 15 P -2.6 180.8 P 164.5 10 P -2.5 147.7 15 P 155.2 10 P -2.5 147.7 10 P 170.4 10 P -2.5 P 168.0 15 P -2.2 10 P 190.8 P -2.1 10 P 167.1 P -2 193.3 10 P 193.7 P -1.9 P 152.9 42

P -1.4 172.8 20 P 159.4 P 127.9 P or S 172.8 10 P 134.5 15 P or S 181.5 15 P 140.3 P or S 153.3 10 P 140.6 20 S 152.3 10 P 144.7 20 S 150.8 15 P 151.3 15 P 147.1 P 159.2 15 P 148.8 P 163.8 P 131.8 P 165 P 167.2 P 171.2 P 154.3 P 172.2 P 167.6 P 172.4 15 P 133.0 P 173.2 P 134.7 P 173.5 20 P 139.6 P 175.5 P 160.4 P 178.7 20 P 158.9 P 179.1 20 P 148.2 P 179.1 20 P 162.2 P 179.5 P 154.2 P 179.8 25 P 156.5 P 181.6 20 P 161.6 P 182.3 20 P 137.0 P 182.3 20 P 162.2 P 182.9 20 P 162.8 P 183.5 20 P 192.5 15 P 193.2 P 194.9 P 197.5 15 P 207.8 20 P 209.8 15

POL-01 WLK-24 P or S Te Tm Th %V P or S Te Tm Th %V P -2.9 165.0 P -3.8 174.3 P -2.6 171.0 P -3.0 186.0 P -2.6 P -2.9 180.5 P -2.6 P -2.8 152.8 P -2.3 P -2.5 163.5 P -2.3 P -2.5 P -2.2 P -2.4 175.9 P -2.1 159.0 P -2.4 182.0 P -2.0 162.6 P -2.4 182.1 P -2.0 175.0 S -2.3 178.8 P -1.9 165.0 P -2.3 180.0 P -1.8 159.2 P -2.3 181.4 P -1.8 164.8 P -2.3 183.7 P -1.8 179.0 S -2.3 P -1.7 160.1 S -2.3 P or S -1.7 166.8 S -2.3 P -1.6 168.3 P -2.2 176.1 P -1.4 154.4 P -2.2 181.2 P -1.3 172.4 P -2.0 178.2 P -1.3 186.2 P -2.0 179.0 P -1.1 171.2 P -2.0 P -1.1 172.2 P -1.9 169.8 P -1.0 165.3 P -1.9 175.7 P -0.6 171.6 P -1.9 176.7 P -0.6 177.3 P -1.9 179.7 P -0.4 154.6 P -1.9 181.6 P 140.9 20 P -1.9 182.2 P 152.4 S -1.9 187.7 P 152.9 15 S -1.9 188.6 P 154.7 S -1.8 181.6 P 157.7 15 P -1.7 179.2 P 157.9 10 P -1.7 182.2 P 160.8 P -1.7 185.5 P 162.6 15 S -1.4 196.0 P 162.9 20 S -1.3 P 163.2 20 P 173.1 15 P 163.4 15 P or S 174.2 15 P 164.2 10 S 174.2 15 P 164.9 10 P 178.8 15 P 165.0 20 P 178.9 20 P 165.3 20 P 179.2 15 44

S 170.1 P 180.0 15 S 170.1 P 180.1 15 P 173.3 20 P 180.9 15 P 174.7 20 P 181.0 20 P 175.6 10 P 181.1 15 P 176.3 10 P 181.1 15 P 181.4 15 P 181.3 15 P 182.2 P 182.2 15 P 183.8 15 P 182.3 20 S 189.5 S 182.4 15 P 195.6 20 P 182.6 10 P or S 201.2 20 P 184.7 15 P or S 203.8 25 P 203.8 20 P 207.8 30 P 212.2 P 226.4 P 235.6 20 P 254.4 30 P -21.5 P -22.0 P -19.6 P -19.8 P -22.4

URB-04B URB-42 P or S Te Tm Th %V P or S Te Tm Th %V P 91.3 P 133.8 P 120.4 10 S 137.6 P 122.4 P 138.0 P 136.6 P 139.3 P -17 -2.6 137.7 P 144.8 P -3.8 147.0 S 148.5 P 149.4 P 151.0 P -1.9 151.8 P 152.0 P 152.0 S 152.1 P 153.1 S 152.8 P 153.3 P 155.5 P -2.0 153.7 S 156.6 P 153.8 P 157.4 P -1.6 154.0 P 157.6 P -2.2 158.9 P 158.0 P 158.9 P 158.2 P 161.6 P 158.4 P -2.6 163.9 S 158.9 P 165.9 15 P 159.5 P -1.8 167.6 15 S 159.5 P 168.8 P 160.2 P -2.0 169.8 P 160.7 P 170.4 P 161.3 P 174.5 P 161.6 P -1.6 174.8 P 164.5 P 174.8 P 164.9 P 176.9 P 165.2 P -2.6 177.1 P 167.2 P -2.6 177.1 P 167.8 P 179.1 P 168.7 P 179.9 P 169.0 S -18 -3.2 181.3 P 169.1 S -2.5 181.3 P 170.0 P -1.8 181.3 P 170.3 P -2.0 202.6 P 170.8 P 215.8 P 171.6 P -21 -1.6 216.8 S 172.1 P 218.8 S 172.1 P 219.4 P 173.1 P 221.1 P 173.1 P 223.2 P 173.7 46

P -1.2 240.5 P 174.1 P -2.1 246.5 20 P 175.2 P -1.6 261.5 30 P 176.4 P -3.7 P 176.7 P -3.7 P 177.1 P -20 -3.6 P 177.8 P -3.4 P 179.0 P -3.4 P 180.0 P -3.3 P 180.7 P -3.3 P -3.5 183.3 P -3.3 P 185.2 S -2.2 P 187.1 S -2.2 P 210.3 P -2.0 P 219.6 P -2.0 P -3.9 P -1.9 P -20.0 -2.2 P -1.9 P -1.9 P -1.8 P -3.6 P -1.8 P -4.0 P -1.7 P -3.1 P -1.6 P -2.5 P -1.3 P -4.4 P -1.3 P -2.5 P -1.2

BUC-61B BUC-3F P or S Te Tm Th %V P or S Te Tm Th %V P 144.8 P 185.4 P 153.8 P 173.7 P 155.4 P 165.4 P 155.6 P 206.3 P 155.9 P 159.8 P 158.7 P 167.4 P 158.7 P 159.8 P 158.8 P 167.4 P 159.1 P 170.4 P 160.2 P 181.8 P 161 P 186.0 P 161.9 P 161.9 P 162.2 P 162.5 P 163.1 P 163.4 P 164.7 P 165.1 P 165.8 P -2.3 170.5 P -2.5 171.8 P 172.3 P 174.5 P 175.2 P 175.4 P 175.7 P -2.5 P -2.4 P -2.4 P -2.6 P -2.6 P -2.2

BUC-21 WLK-31 P or S Te Tm Th %V P or S Te Tm Th %V P 200.0 P -2.5 133.1 P 202.3 P -2.5 148.8 P 170.0 P -2.1 141.6 P 185.7 P -2.5 152.8 P 218.7 P -3.0 147.7 P 185.2 P -1.9 213.4 P 185.3 P -3.0 167.7 P 217.2 P -2.4 163.0 P 188.4 P -2.8 164.0 P 185.4 P -2.8 164.0 P 188.5 P -2.8 164.0 P 177.5 P -2.8 164.0 P 176.5 P 181.9

QRY BUC-9 P or S Te Tm Th %V P or S Te Tm Th %V P -6.4 159.3 P 171.8 10 - 20 P -6.6 158.5 P 180.0 10 - 20 P -4.9 159.3 P 170.8 10 - 20 P -7.0 P 169.3 10 - 20 P -2.4 211.0 P -23 -5.0 138.2 10 - 20 P -5.6 159.4 P -5.3 138.2 10 - 20 P -5.6 162.4 P -5.9 136.6 10 - 20 P -2.0 166.8 P -5.4 135.2 10 - 20 P -1.7 163.0 P -4.7 10 - 20 P -1.6 159.7 P -4.8 132.7 10 - 20 P 158.5 P -4.6 136.9 10 - 20 P -1.6 P -5.4 125.0 10 - 20 P -1.6 P -3.8 126.4 10 - 20 P -1.2 166.8 P 136.6 10 - 20 P -1.2 159.9 P -4.6 127.2 10 - 20 P -8.1 P -5.7 10 - 20 P 177.9 P -3.7 127.8 10 - 20 P 191.1 P 147.3 10 - 20 P 0.0 166.6 P 154.7 10 - 20 P -20 -4.0 152.6 P 156.0 10 - 20 P -20 -4.6 151.0 P -6.0 155.8 10 - 20 P -20 -5.0 154.0 P -5.1 10 - 20 P 161.1 P -5.1 10 - 20 P -3.2 P 127.6 10 - 20 P -20 -4.0 160.5 P 263.2 40 P -4.0 P 165.0 10 - 20 P -4.4 P 138.1 10 - 20 P 163.6 P -23 -4.4 169.4 10 - 20 P 163.6 P 165.9 10 - 20 P 160.2 P 162.0 10 - 20 P -23 -2.5 165.0 P -5.2 140.0 10 - 20 P -4.4 167.2 P -5.2 155.0 10 - 20 P -23 -4.6 P -5.2 140.6 10 - 20 P 133.2 10 - 20 P 191.6 10 - 20 P 101.3 10 - 20 P -4.3 129.9 10 - 20 P -25 -5.1 143.0 10 - 20 P -4 145.9 10 - 20 P -5.5 148.6 10 - 20 P -4 145.3 10 - 20 50

P -5.2 150.0 10 - 20 P -6 127.9 10 - 20 P -6 131.4 10 - 20 P -5.2 141.3 10 - 20 P -5.2 124.9 10 - 20 P 173.9 10 - 20 P 149.8 10 - 20 P 144.1 10 - 20 P 146.1 10 - 20 P 169.6 10 - 20 P 149.4 10 - 20 P 143.8 10 - 20 P 157.6 10 - 20 P 161.6 10 - 20 P 161.4 10 - 20 P or S 175.6 10 - 20 P 157.9 10 - 20 P 146.1 10 - 20 P 152.9 10 - 20 P 147.3 10 - 20 P 155.8 10 - 20 P 160.0 10 - 20 P -5.5 235.9 40 P 151.3 10 - 20

51 APPENDIX B: HOMOGENIZATION TEMPERATURE HISTOGRAMS

62 63

APPENDIX C: SAMPLE INFORMATION/NOTES

Sample Formation East or West of Fold Axis UTM (Grid) BUC-61B Sugarloaf Mountain East 18S 293539 4347953 Quartzite BUC-21 Sugarloaf Mountain West 18S 292939 4350575 Quartzite BUC-3F Urbana Quartzite West 18S 292446 4352133

POL-01 Ijamsville Phyllite East 18S 291474 4339547

URB-42 Ijamsville Phyllite East 18S 297785 4348635

WLK-24 Ijamsville Phyllite West 18S 301749 4372104

URB-03B Ijamsville Phyllite East 18S 298155 4350443

URB-04B Ijamsville Phyllite East 18S 298155 4350443

WLK-31 Ijamsville Phyllite East 18S 301503 4363986

BUC-2 Ijamsville Phyllite West 18S 291825 4354113

QRY Grove Formation West 18S 301105 4380311

BUC-9 Ijamsville Phyllite – West 18S 291825 4354113 Frederick Formation

Sample Description

Buc-61B Vein set; Vein set - 217°, 60° NW

BUC-21 Vein; Vein - 263°, 55°NE (So - 035°, 48°SE)

BUC-3F Float Sample

POL-01 Pod Vein

URB-42 Vein set parallel to S1 or pod in S1; S1 - 025°, 76°SE

WLK-24 Vein or pod parallel to S1; S1 - 019°, 58°SE

URB-03B Folded Vein

URB-04B Vein; Vein - 012°, 60°SE

WLK-31 Vein parallel to S1; S1 – 166°, 84°SW

BUC-2 Pod of quartz found in S1 plane; S1 – 020°, 74°SE

QRY Collected from quarry in Grove Formation.

BUC-9 Collected from Martic thrust zone that separates the Ijamsville Phyllite from the Frederick Formation.