Deformation and Fluid History of Late Proterozoic and Early Cambrian Rocks of the Central Appalachian Blue Ridge

DEFORMATION AND FLUID HISTORY OF LATE PROTEROZOIC AND EARLY CAMBRIAN ROCKS OF THE CENTRAL APPALACHIAN BLUE RIDGE

Daniel R. Chandonais

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 2012

Committee:

Charles Onasch, Advisor

John Farver

Kurt Panter

ABSTRACT

Charles M. Onasch, Advisor

The Blue Ridge province of the Appalachians is an allochthonous structural unit, which has been deformed into an anticlinorium that is overturned to the northwest. Folding and development of a pervasive southeast-dipping cleavage are attributed to the northwest transport of both crystalline and sedimentary thrust sheets during the late Paleozoic Alleghanian orogeny. Phyllites and schists in the late

Proterozoic Catoctin Formation and in the Cambrian Harpers Formation have abundant evidence for multiple phases of deformation, though the timing and importance of these structures is still unclear.

Fluid inclusion microthermometry along with detailed structural analyses of

Late Proterozoic and Early Cambrian rocks in the Blue Ridge were completed to construct a fluid history of the region. The combination of these methods allows for characterization of deformation phases and estimation of pressure/temperature conditions, which provide a more comprehensive picture of the tectonic evolution of the region.

Structural analysis established the geometry and timing of three deformation phases in relation to the pervasive Alleghanian cleavage. Microthermometry identified at least four fluids from primary, pseudosecondary, and secondary inclusions in quartz veins. Two-phase aqueous inclusions were used to characterize fluid populations on the basis of homogenization temperature and composition. Pre-cleavage veins are characterized by high temperature (Th ≥ 210°C) fluids with moderate salinities (approximately

5-15 wt. % NaCl equivalent). Syn-cleavage fluids occur at moderate temperatures (Th = 150-205 °C) and variable salinities (approximately 5-25 wt. % NaCl equivalent). Post-cleavage fluids are characterized by low temperatures (Th <150 °C) and low salinities (approximately 2-10 wt. % NaCl equivalent). Eutectic temperatures indicate both simple and complex mixtures of Na, Ca, and Mg brines in successive vein generations.

Migrating, orogenic fluids found in the adjacent Valley and Ridge and Piedmont provinces are rich in CH4 and CO2; however, neither of these fluids was observed in the Blue Ridge. Instead, fluids associated with deformation of the Blue Ridge anticlinorium appear to have a local source and show iii

evidence for stratigraphic partitioning and a general trend of decreasing temperatures from hinterland to foreland.

ACKNOWLEGEMENTS

My thesis research project was an achievement I could not have completed without the support of my family, advisor, committee members and friends. I am grateful to have had such an exemplary advisor, Dr. Charles Onasch. Professor Onasch recruited me to attend Bowling Green State University, sparked my interest in Appalachian geology and asked thought provoking questions during our research meetings. I am also thankful to my committee members who challenged me during my proposal defense and showed genuine interested in my research. Dr. John Farver provided me with excellent research articles and comic relief during stressful moments. Dr. Kurt Panter pushed me to pay attention to the details of my project and emphasized diligence during my presentations. I would also like to express my gratitude for my family and their encouragement while in graduate school. Specifically, I am thankful for my mother, Catherine Chall, who instilled an appreciation for higher education and reinforced positive thoughts along the way. Also, thank you to my brother, Michael Chandonais, who consistently asked me about my progress and feigned interested during my explanations. Financial assistance was provided by the Furman Economic Scholarship through the geology department which was vital to the project’s success. Many thanks are also in order for Dr. Sven Morgan for encouraging me as student of structural geology and pushing me to obtain a graduate degree in geology. And finally, a special thanks to Lisa

Tromley for her countless hours of support and for her patience in our relationship.

TABLE OF CONTENTS

Page

INTRODUCTION ...... 1

GEOLOGIC BACKGROUND ...... 3

METHODS ...... 10

FLUID HISTORY ...... 17

DISCUSSION ...... 26

CONCLUSIONS...... 35

REFERENCES ...... 36

APPENDIX ...... 40

LIST OF FIGURES

Figure Page

1 Generalized stratigraphic column of the Blue Ridge province ...... 3

2 Cross section of physiographic units in Maryland ...... 6

3 Geologic map of study area ...... 7

4 Field photographs of vein generations in Catoctin Formation ...... 8

5 Photomicrographs of vein mineral textures ...... 11

6 Plot of homogenization temperature vs. final ice-melt temperature ...... 14

7 Histograms of fluid inclusion data...... 16

8 Plot of homogenization temperature vs. eutectic temperature for

vein generations in the Catoctin Formation ...... 18

9 Summary plots of fluid inclusion data separated by stratigraphic location ...... 21

10 Summary plots of fluid inclusion data separated by vein

generation and geographic location...... 28

11 Pressure-temperature diagram ...... 30

vii

LIST OF TABLES

TABLE Page

1 Primary fluid inclusion data by rock formation and vein phase ...... 15

2 Characterization of fluid events with calculated pressure and

temperature trapping conditions...... 31

3 Summary of fluid inclusion composition and salinity by rock

formation, structural position and vein generation...... 31

INTRODUCTION

At low-metamorphic grades, mass-transfer in fluids is a major mechanism for the development of foliations in rocks (Durney, 1974). The solution transfer process may be viewed as a continuous process, which occurs throughout the development of a cleavage or as a transient process, which occurs in a number of short-lived stages. Vein formation is common in greenschist-grade metamorphic rocks which have been subjected to fluctuations in fluid pressure. Fluctuations between lithostatic and hydrostatic fluid pressures can be a result of seismic pumping (Sibson et al., 1977, Sibson, 1990) which can result in vein formation via the crack-seal mechanism. In this model, elevated fluid pressures drive pore fluid into dilational fractures and are sealed by minerals precipitated from solution due to a pressure decrease

(Ramsay, 1980). During metamorphism, high fluid pressure may be the result of devolatilization reactions and dilations can occur at various scales. At the outcrop scale, minerals precipitated in dilations during regional metamorphism produce veins, which represent the fluid present during cleavage development. In multiply deformed regions, veins of different generations can be matched with appropriate cleavages (if present) to provide a history of the fluids present throughout the structural evolution of the region.

Several authors have combined structural analysis and fluid histories to solve complex geologic problems and interpret tectonic histories (e.g., Crispini and Frezzotti, 1998; Kenis et al., 2000; Fischer et al., 2009). A similar study by Evans and Battles (1999) characterized the migration of orogenic fluids during the late Paleozoic in the Valley and Ridge province. The source of these fluids is presumed to be metamorphic, originating from the Appalachian hinterland (Dorobek, 1988; Schedl et al., 1992; Evans and Battles, 1999). This hypothesis is supported by fluid inclusion and isotopic studies in the surrounding region, but the presence of high temperature, metamorphic fluids has yet to be documented in the intervening structural unit: the Blue Ridge province.

Our partial understanding of the source of these orogenic fluids and the path of migration symbolizes a fundamental missing piece in the puzzling geologic history of the Appalachians. For instance, most of the economic deposits located in the continental interior are speculated to be either 2

related to or the inevitable result of this migration (Oliver, 1986). Also, the timing and relevance of deformation phases in the Blue Ridge province have been disputed throughout most of the past century

(Whitaker, 1955; Nickelsen, 1956; and Onasch, 1986). If orogenic fluids were sourced from the hinterland, as is assumed, and transmitted laterally into the foreland, evidence of their existence should be apparent in fluid inclusions from veins in the Blue Ridge, which lies between the hinterland and the foreland. Also, if unique phases of deformation have produced the multiple fabrics observed in the Blue

Ridge today, fluid inclusions from veins associated with each fabric generation should be able to fingerprint different fluids by noting changes in chemistry and/or trapping conditions. The goal of this study, then, is to describe the fluid history of the Blue Ridge province in the central Appalachians relative to Alleghanian structures and to identify its role in the broad migration of late Paleozoic orogenic fluids.

GEOLOGIC BACKGROUND

Stratigraphy

The stratigraphy in the study area consists of Lower Cambrian metasedimentary sequences, which overlie metamorphosed Precambrian igneous and sedimentary sequences that represent the basal units of

the Appalachian foreland basin (Nickelsen,

1956). Mesoproterozoic (1.1-1.0 Ga) Grenville-

age gneiss (Burton and Southworth, 1996) make

up the basement rocks of the Blue Ridge

mountain belt at this latitude. To the northeast,

the Blue Ridge is cored by the Precambrian

Swift Run and Catoctin Formations, and

overlain by Cambrian Loudoun, Weverton and

Harpers formations (from oldest to youngest)

collectively referred to as the Chilhowee Group

(Espenshade, 1970) (Figure 1).

The Catoctin Formation was emplaced at

the base of a Neoproterozoic rift basin

(Bloomer, 1950) and is composed

predominantly of massive, tholeiitic basalts.

Whole-rock Rb-Sr age dating of greenstones in

the Catoctin Formation yield an age of 570 ± 36

Ma (Badger and Sinha, 1988). The upper

portion of the unit is intercalated with clastic

Figure 1. Generalized stratigraphic column of the Blue sedimentary rocks interpreted by Dilliard (1999) Ridge province. Figure was conceptualized from Nickelsen’s (1956) rock descriptions. See text for details. as incised channel fills from a fluvial 4

depositional setting. In the study area, the occurrence of primary igneous or sedimentary structures is rare because the Catoctin Formation has been overprinted by secondary tectonic fabrics.

The Chilhowee Group is a sequence of Cambrian siliciclastic rocks, which overly the Catoctin

Formation (Bloomer, 1950; Whitaker, 1955). It is estimated to be 450-2,300 m thick and is exposed at the boundary between the Blue Ridge and the Valley and Ridge Provinces (Schwab, 1971). In the study area, only the Weverton Formation and Harpers Formation are exposed. The Weverton Formation is composed of three quartzite members with intermittent green-white phyllite horizons (Nickelsen, 1956). The upper unit of the Weverton Formation grades into the Harpers Formation as noted by a gradual increase in phyllite (Whitaker, 1955). The Harpers Formation was deposited as a sequence of silts, clays and calcareous mud; now phyllite and quartzite units (Schwab, 1971). The Harpers Formation is interpreted to be a sequence of deep water turbidites in an offshore marine depositional setting (Schwab, 1971).

Regional Tectonics and Geologic Structure

The central region of the Appalachians consists of four physiographic and tectonic provinces: the

Alleghanian Plateau, the Valley and Ridge (including the Great Valley), the Blue Ridge, and the

Piedmont (Figure 2). The Alleghanian Plateau is a gently deformed unit composed of Paleozoic sedimentary rocks; the Valley and Ridge is a fold-and-thrust belt composed of deformed Paleozoic sedimentary rocks; the Blue Ridge contains moderately deformed Precambrian crystalline rocks and relatively low-grade, regionally metamorphosed late Proterozoic-Cambrian igneous rocks; and the

Piedmont is composed of extensively deformed Precambrian and Early Paleozoic crystalline rocks. The

Blue Ridge tectonostratigraphic unit was transported northwestward approximately 200 km over lower

Paleozoic sedimentary rocks of the foreland basin during the Alleghanian orogeny (Schedl et al., 1992).

The study area is located within the allochthonous Blue Ridge structural unit, which at this latitude consists of a northeast-plunging, asymmetric anticlinorium, locally overturned to the northwest

(Cloos, 1971) (Figure 3). The core of the anticlinorium is Grenville-aged granodiorite and gneiss, which is unconformably overlain by Late Precambrian Swift Run and Catoctin formations and lower portions of the Chilhowee Group (King, 1951). A review of the complex structural geology of the Blue Ridge in the 5

central Appalachians can be found in Nickelsen (1956), Cloos (1971), Onasch (1986), Mitra (1987) and

Faill (1998).

The abundance of phyllite in the Blue Ridge makes it an ideal location for analysis of the structural evolution. Due to their high phyllosilicate content, phyllites are relatively weak rocks, which preserve secondary fabrics such as cleavages and lineations. More massive units, like some of those overlying the Catoctin Formation, do not preserve these fabric elements or have been overprinted during later phases of deformation. The phyllites thus provide a more detailed record of the deformation history of the Blue Ridge than is found in the units overlying the Chilhowee Group or in more massive units

(Onasch, 1986).

Vein systems in the Blue Ridge province

Veins are present in all stratigraphic units in the study area though their abundance, distribution, and morphology vary considerably. All of the veins studied were composed dominantly of quartz (>95%) with minor amounts of chlorite, magnetite, and/or calcite. For the most part, vein mineralogy was extremely consistent in the study area. However, a few veins containing calcite were encountered in the

Harpers and Catoctin formations. Chlorite and magnetite were fairly ubiquitous in small amounts to all veins sampled. Paragenetically, quartz is the oldest vein-forming mineral. Chlorite and magnetite are found in all vein generations and within host rock samples, indicating these minerals formed during or after the final stage of vein mineralization. Veins containing calcite are relatively sparse and exactly where it fits into the paragenetic sequence was not determined.

Cross-cutting relationships were used to determine the relative timing between the pervasive S1 cleavage surface and corresponding vein generations. In doing so, three generations of veins were established: pre-cleavage, syn-cleavage, and post-cleavage. The pervasive cleavage (S1) referred to herein correlates with Nickelsen’s (1956) S2 flow cleavage and Onasch’s (1986) S2 crenulation cleavage.

Across the entire study area, it is most accurately described as a pervasive schistosity or slaty cleavage, which dips moderately to the southeast and is axial planar to the anticlinorium. It is associated with asymmetric folds that plunge gently to the northeast and have an east-over-west shear sense. Vein 6

ng Catoctin ng Catoctin Cross section of physiographic units which make up the Appalachian mountain belt in Maryland. The study areas are located alo located areas are study The Maryland. belt in mountain Appalachian up the which make units physiographic of section Cross Figure 2. Figure 1968). et al., Cleaves from (modified River Potomac along the Mountain near South Park and State Gambrill in Mountain 7 g

nd nd Study 3Area is and relevant cross

2007) - the quadranglesthe are: A’ modifiedis Onasch from (1986). From - Geologicmap modified from correspondin

Figure 3. USGS quadrangles (1987 sections. A northwest to south east Funkstown, Myersville, Shepherdstown, Keedysville, Middletown, Harpers Ferry, and Point of Rocks) Study Area 1 inis Gambrill State Park a across the river Ferryfrom Harpers National Park.

generations have deliberately been generalized in terms of timing because the purpose of this study is to create a framework of the fluids present throughout deformation of the Blue Ridge province.

Pre-cleavage veins. These veins

predate the pervasive cleavage S1 and usually

form massive, ellipsoidal pods or blebs which

are parallel to bedding surface (S0). In mica-

rich horizons, veins from this generation occur

as tight, isoclinal folds, disconnected pinch-

and-swell structures, or both (Figure 4A). Often

refolded, careful inspection of these structures

shows S1 is subparallel to the axial plane of

folded veins, cutting across veins at a low angle

except in the fold hinges where it is at high

angles. Pre-cleavage veins formed parallel to

bedding and were sheared extensively during

development of the pervasive cleavage. They

are frequently observed in the phyllitic units of

the Catoctin Formation, less frequently in the

Harpers Formation, and were not observed in

exposures of the Weverton Formation. In thin

Figure 4. Field photographs of different vein section, quartz in pre-cleavage veins is generations in the Catoctin Formation. A.) Refolded

pre-cleavage vein with axial planar S1 surface subhedral to anhedral and contains zones of drawn in white (pencil for scale). B.) Syn-cleavage

vein folded with S1, note the more open, tabular insoluble residue. Microstructures in these character of these veins (masonry chisel for scale).

C.) Post-cleavage vein cutting across pervasive S1 veins reveal the greatest amount of deformation cleavage (mallet & marker for scale). and recrystallization as noted by extensive 9

undulose extinction, subgrains, grain boundary polygonization and mosaics of strain-free grains (Figure

5). Though samples show a high degree of recrystallization, relict undeformed grains were observed with intact fluid inclusion assemblages.

Syn-clevage veins. These veins are concordant with the S1 surface. Syn-cleavage veins have also been deformed and occur in moderate to tight, generally rounded folds with axial planes sub-parallel to the S1 surface (Figure 4B). When syn-cleavage veins are folded, S1 is also folded. Frequently, these veins are not folded and instead occur as tabular bodies parallel to S1, 10-20 cm thick and are slightly boudinaged. The occurrence of syn-cleavage veins was documented in each of the units studied, but they are least common in the Weverton Formation. In thin section, quartz in syn-cleavage veins ranges from elongate to blocky in texture. Pressure solution is the most significant deformation mechanism operating in these veins as noted by corroded grain boundaries, stylolites, pressure shadows and overgrowths. Other microstructures observed include undulose extinction and subgrains, which shows evidence for crystal plastic deformation and partial recrystallization. Intact fluid inclusion assemblages were observed in grains with no evidence of recrystallization.

Post-cleavage veins. Post-cleavage veins clearly cut across the pervasive S1 cleavage surface

(Figure 4C). Post-cleavage veins are slightly deformed and occur as planar tabular bodies, which are sometimes very gently folded, or brecciated. The quartz in most of these veins has a blocky habit, but, stretched crystal-fiber textures were observed in some veins. Microstructures in these samples include some evidence for partial recrystallization marked by the presence of subgrains. However, the dominant mechanism of deformation appears to be more brittle as evidenced by abundant secondary fluid-inclusion planes and unhealed microfractures. These veins are present in all units, but were more frequently exposed on the overturned limb of the anticlinorium.

METHODS

Field Sampling

The sampling strategy was designed to characterize fluids present throughout the evolution of the

Blue Ridge anticlinorium on the basis of vein generation, lithostratigraphy, and structural position.

Samples were collected along both limbs of the anticlinorium at exposures with multiple vein generations

(Figure 3). Locations generally parallel each other normal to the strike of the anticlinorium limbs, which aid in separating fluid variations due to stratigraphy from those attributable to structural position. Most of the samples collected were from within the Catoctin Formation because this unit hosts all three generations of veins. The best exposures of the Catoctin Formation are located on the eastern limb of the anticlinorium whereas the Weverton and Harpers Formations are best exposed on the western limb.

Because of this, no samples from within the Harpers Formation were collected on the eastern limb while samples from all three units were collected on the western limb. In all, approximately 80 vein samples and 25 host rock samples were collected and studied by thin section.

Microscopy

Veins from each phase have undergone some degree of recrystallization. Using an optical light microscope, the microstructures for each sample were examined and recorded to quantify the extent of recrystallization (Figure 5). Certain samples were near completely recrystallized and were not included in the fluid inclusion analysis. These samples displayed microstructures such as uniform frameworks of polygonal grains, empty inclusions, and abundant subgrains indicative of extensive recrystallization.

Samples with intact “relict” grains from which fluid inclusion assemblages could be classified were instead used for microthermometry. Those selected for microthermometry were also analyzed using cathodoluminescence to identify heterogeneities such as zoning, which must be accounted for in fluid inclusion analysis. All veins studied display a uniform luminescence with no evidence of growth zones or microveins. 11

EXTENT OF RECRYSTALLIZATION

Figure 5. Photomicrographs of vein mineral textures showing variable degrees of recrystallization. A.) Pre- cleavage vein with very large grain size, subgrains and “bulge” recrystallization. B.) Syn-cleavage vein with undulose extinction, mosaic of small strain free grains (extinct) and elongate grains. C.) Post-cleavage vein with fibrous crystal habit and undulose extinction.

Fluid Inclusion Analysis

Along with the field approach to interpreting different vein generations, the primary goal of fluid inclusion analysis was to document the characteristics of fluids that were present during progressive phases of deformation. It was also important to document fluid variations due to stratigraphy, different structural position on the anticlinorium, and relationships to other structural features such as faults.

Inclusions from each sample were classified as primary, pseudosecondary or secondary, by composition and morphology. Primary inclusions were classified by their occurrence as single, isolated inclusions with relatively large diameters. Primary inclusions have semi-irregular shapes, but occur in various morphologies and in grains without microstructures indicative of recrystallization. Secondary inclusions were classified by their occurrence as planar arrays along healed fractures that cut across multiple grain boundaries. Pseudosecondary inclusions were classified by their occurrence as planar or curviplanar arrays which terminate within individual grains and often display negative crystal shapes.

Pseudosecondary inclusion measurements are interpreted to represent primary fluids as they occur along intracrystalline, grain-internal inclusion planes and were found to have homogenization temperatures, salinities, and liquid-vapor (L:V) ratios that are consistent with primary inclusions. Although some vein generations contained quartz and calcite, only inclusions in quartz were analyzed to decrease the probability of error caused by sample decrepitation. 12

Fluid inclusions assemblages (FIAs) were identified and analyzed as outlined by Goldstein and

Reynolds (1994). This method was used because FIAs represent groups of inclusions, which presumably formed at the same time. Each FIA was characterized by similarities in composition, L:V, morphology, and location relative to microstructures. A comparison between inclusions and microstructures was required to ensure inclusions were in lattice positions which were the least susceptible to the effects of recrystallization (Schmatz and Urai, 2011). If grain boundaries have swept across inclusions several times, measurements of homogenization temperature can be skewed as documented in quartz mineral analogues (Schenk and Urai, 2005). This is an important variable to consider during classification of FIAs because all of the effects of recrystallization on fluid inclusion microthermometry have yet to be completely understood.

Microthermometry

A total of 80 vein samples were collected from the five areas identified on Figure 3. From these, a total of 30 vein samples were selected and prepared for fluid inclusions analysis; 16 of which produced usable data. The remaining 14 samples were discarded because an inadequate amount of inclusions were observed, which produced inconsistent measurements, not allowing for proper classification as fluid inclusion assemblages. The dataset includes: 4 samples from pre-cleavage veins, 9 from syn-cleavage veins, and 3 from post-cleavage veins. Post-cleavage veins are concentrated in the Catoctin Formation, while pre-cleavage and syn-cleavage veins are present at all stratigraphic levels.

Samples were prepared as doubly polished, 50 – 200 µm thick wafers as prescribed by Holland et al. (1978). Inclusion measurements were completed using a U.S.G.S-type heating-freezing stage manufactured by FLUID Inc., and calibrated at 0 °C (ice bath), 374.1 °C (critical point of water), and -

56.6 °C (CO2 triple point). The following measurements were recorded for two-phase aqueous inclusions: eutectic temperature (Te), final ice-melting temperature (Tm), and homogenization temperature (Th).

Measurements of eutectic temperature are the most subjective as the author must record a textural change in the inclusion and the cycling technique cannot be used readily. For the equipment used in this study, the error is approximately ±5 °C, establishing the bin size for measurements of eutectic temperature. For 13

the other measurements, the author settled on bin sizes which maintain the approximate distribution for individual fluid types yet are small enough to make distinctions amongst them (e.g. Tm = ±2 °C, and Th =

±10 °C). Salinities were calculated from final-ice melt temperatures and are reported in terms of wt. %

NaCl equivalent, regardless of actual salt composition, as described by Roedder (1984).

Many inclusions had small diameters (<5 µm), which precluded all measurements from being collected for every inclusion. Also, the small diameter of many inclusions required use of the cycling technique to constrain Tm and Th measurements (Goldstein and Reynolds, 1994). For each sample, homogenization temperatures were measured first to reduce the possibility of stretching or sample decrepitation.

Schematic maps were created for each sample to illustrate different fluid inclusion morphologies and populations, and to establish the timing and relation to microstructures (Touret, 2001). Measurements were restricted to a given field view, which allowed for synchronous analysis of multiple FIAs and observation of abrupt changes in L:V caused by inclusion deformation. A sudden jolt in the sample during heating runs was assumed to be caused by decrepitation elsewhere in the sample and resulted in sample disposal. By analyzing FIAs in a given field view and sketching fluid inclusion maps, systematic variations in inclusions could be observed.

A summary of all fluid inclusion data is shown in Figure 6. It is immediately apparent that samples display a large range of homogenization temperatures and salinities. Over 95% of the fluids, however, are characterized by homogenization temperatures of 120–290 °C and salinities of 3–21 wt. %

NaCl equivalent. One anomalous specimen contained a highly saline fluid, which was within the range of observed homogenization temperatures, but displayed final ice-melt temperatures in the range of -30 to -

40 °C. Aside from these inclusions, trends observed the remainder of the dataset can be explained by systematic changes in the vein generation, stratigraphic position, or structural location. To investigate which of these factors were significant during vein formation and deformation of the Blue Ridge, inclusion data were categorized by fluid type. 14

Figure 6. Plot of fluid inclusion dataset with homogenization temperature vs. final ice-melt temperature and inset symbol key.

To discriminate the inclusion dataset into individual fluid types, population distributions for eutectic, final ice-melt, and homogenization temperatures were analyzed (Figure 7). For each histogram, the number of bins was established by either the approximate error for a given measurement or by iterative comparison between samples. Histograms for homogenization temperature indicate three distinct populations. Salinity histograms identify at least four distinct populations and eutectic histograms indicate at least three separate fluid populations. Eutectic, final ice-melt, and homogenization temperatures were combined with relative timing data from observed vein phases and associated rock formations to characterize the fluids that were present during deformation of the Blue Ridge anticlinorium (Table 1).

Model compositions of fluid inclusions were determined from phase diagrams as in Goldstein and

Reynolds (1994). Eutectic temperatures indicate three fluid compositions: NaCl-H2O, NaCl-CaCl2-H2O, 15

and NaCl-MgCl2-CaCl2-H2O. Most pre- and syn-cleavage veins display eutectic temperatures that are consistent with the NaCl-CaCl2-H2O system while post-cleavage vein eutectics are more indicative of the

NaCl-H2O system (Table 1). An example of this is apparent in the Catoctin Formation, which shows the relationship between fluid composition and homogenization temperature in syn-cleavage and post- cleavage veins (Figure 8).

The histogram of primary inclusions for final ice-melt temperature identified four fluid types between 3-21 wt. % NaCl equivalent (Figure 7B). Secondary inclusions show these four fluid types and display another fluid with salinities >28 wt. % NaCl equivalent (Figure 7C). Inclusion populations segmented by salinities are referred to hereafter as: low salinity (0-10 wt. % NaCl equiv.), high salinity

(10-20 wt. % NaCl equiv.), and very high salinity (>20 wt. % NaCl equiv.).

The population histogram for homogenization temperature of primary inclusions identified three fluid types (Figure 7E). The three populations will be referred to as: low-Th inclusions (110-160 °C), moderate-Th inclusions (160-210 °C), and high-Th inclusions (>210 °C). Secondary inclusions are predominately low to moderate homogenization temperature inclusions (Figure 7F). A few very low-Th inclusions (~75 °C) were noted in the secondary inclusion population as well but have not been included in this study.

Table 1. Primary fluid inclusion data by rock formation and vein phase. (*) Indicates subset also contains inclusions with very high salinity, CaCl2 fluid. N.D. = No Data

T T T Salinity Formation e h m Secondary inclusions (°C) (°C) (°C) (wt.% NaCl equivalent) Harpers Formation Pre-cleavage -45 to -58 255 to 280 -11.6 to -15.2 15.6 to 19.0 Syn- and Post-cleavage

Syn-cleavage -32 to -46 165 to 205 -4.5 to -16.1 7.1 to 19.7 Syn- and Post-cleavage Post-cleavage -19 to -40 120 to 140 -3.7 to -10.7 6.1 to 14.8 Post-cleavage Weverton Formation Pre-cleavage N.D. N.D. N.D. N.D.

Syn-cleavage -11 to -56 150 to 180 -5.6 to -15.4 8.6 to 19.2 Syn-, and Post -cleavage Post-cleavage -23 to -51 145 to 160 -5.7 to -7.1 8.9 to 10.5 Post-cleavage Catoctin Formation Pre-cleavage* -38 to -65 210 to 250 -5.5 to -9.6 8.5 to 9.6 Pre-, Syn-,and Post-cleavage

Syn-cleavage -25 to -52 150 to 205 -4.2 to -17.6 6.8 to 20.9 Syn-, and Post-cleavage Post-cleavage -20 to -38 135 to 145 -1.7 to -3.6 3.0 to 5.8 Post-cleavage

Figure 7. Histograms for primary & pseudosecondary and secondary fluid inclusion data. A. and B.) Eutectic temperature (abscissa). C. and D.) Final ice-melt temperature (abscissa). E. and F.) Homogenization temperature (abscissa). Primary & pseudosecondary inclusion data are presented on A., C. and E., while secondary inclusion data is on B., D. and F. Colors represent fluid types: Low-Th (blue), Moderate-Th, low-salinity (red), Moderate-Th, High-

salinity (green), High-Th (orange), and Moderate-Th, very high-salinity (white).

FLUID HISTORY

Fluid Types

Low-Th Inclusions. These are found in veins within the Catoctin Formation through the Harpers

Formation, these inclusions are colorless at 25 °C, range from 2 µm to 50 µm in diameter, have tabular to negative crystal shapes, and L:V of 70:30 to 80:20. They are characterized by homogenization temperatures of 110-160 °C and salinities of 0-10 wt. % NaCl equivalent. Low-Th inclusions occur as both primary and secondary inclusions in Post-cleavage veins and as secondary inclusions in pre- and syn-cleavage veins. Observed eutectic temperatures in both the Catoctin and Harpers formations are generally in the range of -20 to -35 °C, consistent with a NaCl-H20 system. However, most eutectic temperatures within the Weverton Formation are in the range of -35 to -50 °C indicating the fluid composition is more complex and contains CaCl2 or possibly MgCl2.

Moderate-Th, Low Salinity Inclusions. These are found in veins from each of the studied formations, these inclusions are colorless at 25 °C, range from 2 µm to 30 µm in diameter, have tabular to irregular shapes, and L:V of 80:20. Some of these inclusions appear colorless and initially monophase at room temperature. Following freezing runs, however, a vapor bubble nucleates and subsequent measurements indicate they are a metastable subset of Moderate-Th, low salinity inclusions. All inclusions of this type are characterized by homogenization temperatures of 170-205 °C and salinities of 6

-12.0 wt. % NaCl equivalent. They occur as primary and secondary inclusions in syn-cleavage veins and as secondary inclusions in pre-cleavage veins. Moderate-Th, low salinity inclusions within the Weverton

Formation are rarely observed as primary inclusions. The observed eutectic temperature range for most of these inclusions is -35 to -50 °C, indicative of either the NaCl-CaCl2-H2O or the NaCl-MgCl2-H2O system.

Moderate-Th, High Salinity Inclusions. Inclusions of this type were observed within all stratigraphic units in the study area. They are colorless at 25 °C, range from 2 µm to 30 µm in diameter, have tabular to irregular shapes, and L:V ratios of 80:20. Moderate-Th, high salinity inclusions are characterized by homogenization temperatures of 160- 18

Figure 8. Homogenization temperature vs. eutectic temperature for each vein generation in the Catoctin Formation and inset symbol key.

190 °C and salinities of 12-22 wt. % NaCl equivalent. They occur as primary and secondary inclusions in syn-cleavage veins and as secondary inclusions in pre-cleavage veins. Eutectic temperatures are within the range of -35 to -60, indicative of the NaCl-CaCl2-H2O or possibly the NaCl-MgCl2-CaCl2-H2O system.

Moderate-Th, Very High Salinity Inclusions. These inclusions occur in a single vein within a lower unit of the Catoctin Formation. They are colorless at 25 °C, range from 2 µm to 10 µm in diameter, have L:V ratios of 90:10, and range from tabular to irregular in shape. Inclusions are characterized by homogenization temperatures of 150-180 °C and final ice-melt temperatures of -29 to -34 °C. They were observed as secondary inclusion assemblages along subgrain boundaries in a vein that had undergone extensive recrystallization. The mean eutectic temperature of these inclusions is -58 °C which is indicative of the NaCl-CaCl2-MgCl2-H2O system (Crawford, 1981). The range of eutectic temperatures is 19

from -45 to -60 °C, which is also consistent with the NaCl-CaCl2-H2O system. During freezing runs, inclusion bubbles deform to some extent, but remain clear after freezing of the liquid. Also, no hydrohalite was observed as freezing runs were cycled to constrain final ice-melt temperatures, indicative of solutions with a low NaCl/NaCl+CaCl2 wt. ratio (Goldstein and Reynolds, 1994). No daughter crystals were observed in these inclusions during routine heating-cooling runs.

High-Th Inclusions. Inclusions of this type are in veins located within the Catoctin and Harpers formations. These inclusions are colorless at 25 °C, range from 2 µm to 30 µm in diameter, have irregular shapes, and L:V ratios of 80:20 to 90:10. They are characterized by homogenization temperatures of 210-290 °C and salinities of 8-19 wt. % NaCl equivalent. High-Th inclusions are observed as primary inclusions in pre-cleavage veins and rarely as secondary fluids of that vein phase.

These inclusions are fairly rare and were not observed in all pre-cleavage veins. Observed eutectic temperatures are generally in the range of -40 to -55 indicative of the NaCl-CaCl2-H2O system. Inclusions with homogenization temperatures near the upper limit of this range display higher salinities and are located in the Harpers Formation.

Relationship to Stratigraphic Level

Studies in the adjacent Valley and Ridge province found a stratigraphic control on the distribution of paleofluids (Evans and Battles, 1999). In the Blue Ridge, a relationship between fluid inclusion populations and stratigraphic level becomes apparent when fluid inclusion data are simplified as in Figure

9. In the Catoctin and Harpers formations, the relationship is primarily based on inclusion salinity; while in the Weverton Formation the relationship is constrained by homogenization temperature. Figure 9 also highlights the trend observed in each stratigraphic level.

The lowest stratigraphic unit in the study area, the Catoctin Formation, is host to the bulk of the veins sampled and shows evidence for all five fluid types (Figure 9B). However, when separated by vein generation, both pre- and post-cleavage veins show narrow salinity ranges (Table 1). Syn-cleavage veins show more variation in salinity, which may be the result of multiple deformation phases that have been 20

grouped together. Homogenization temperatures occur over a large range (130-250 °C) and do not appear to be unique to the Catoctin Formation.

Veins are relatively scarce in the Weverton Formation as compared to the Catoctin and Harpers formations (Figure 9C). For the most part, low-Th and moderate-Th, high salinity inclusions make up fluid inclusion populations in veins from the Weverton Formation. Fluids within the Weverton Formation are well constrained both by homogenization temperature and salinity. Moderate-Th inclusions in the

Weverton Formation occur within the same salinity range as moderate-Th inclusions from the Catoctin

Formation.

The uppermost stratigraphic unit in the study area,the Harpers Formation, contains all three vein phases. All inclusion types other than moderate-Th, very high salinity inclusions were observed in this unit (Figure 9D). Low-Th and high-Th inclusions occur as primary inclusions, while moderate-Th inclusions are predominantly secondary. Although there is a large amount of variation in homogenization temperatures, there is a relatively small variation in salinity. Nearly all inclusion measurements from veins in the Harpers Formation fall within one of two, salinity ranges: 5.7-11.1 or 12.9-21.0 wt. % NaCl equivalent. These narrow ranges of salinity provide further evidence in support of the interpretation that fluid inclusion salinity is related to stratigraphy in the study area.

The moderate-Th, very high salinity inclusion type is an outlier in this study (Figure 9A). These secondary inclusions have final ice-melt temperatures below -30 °C, which is far more saline than all other inclusions examined. Measurements of eutectic temperature indicate this fluid is a complex aqueous mixture of NaCl, CaCl2, and possibly MgCl2. Several neighboring veins of the same apparent generation were sampled and microthermometry measurements did not identify inclusions of this fluid composition. Some eutectic temperatures from later vein generations indicate a similar complex aqueous mixture, but their occurrence is rare and corresponding final ice-melt temperatures indicate much lower salinities. Also, no inclusions from the anomalous vein contained the low to moderate salinity fluids observed in neighboring veins either. 21

(Caption on p. 2)

. Figure 9 22

Summary plots for fluid inclusion data separated by

Figure 9. stratigraphic location(B-D) and vein phase (E-G). fluidA.) Entire inclusion dataset, B.) Catoctin Formation, C.) Weverton Formation, D.) Harpers Formation,E.) Pre-cleavage, F.) Syn-cleavage,G.) andPost- cleavage. Filled markers are primary pseudosecondaryor inclusions and hollow markers are secondaryinclusions. Symbol in keys are A. andset E. Homogenization temperature plottedis along the abscissa, final ice- melt temperature alongis primary the ordinate plottedand salinity is along the secondary ordinate.

Relationship to Vein Generation

Because the three vein generations formed at different times, it could be expected that trapping conditions, and hence fluid characteristics, would change from one generation to the next. Trends observed in the microthermometry dataset cannot all be explained by changes in stratigraphic position. As mentioned above, post-cleavage veins show evidence of a different fluid composition than older vein generations (Figure 8). A relationship between homogenization temperature and vein generation is also apparent when inclusion measurements are grouped by vein generation (Figures 9E-G). This provides evidence that trapping conditions changed throughout vein-forming deformation phases of the Blue Ridge anticlinorium.

Pre-cleavage veins represent the earliest stage(s) of deformation. Microthermometry data from primary inclusions for each stratigraphic unit have tightly constrained homogenization temperatures and salinities (Figure 9E). In the Catoctin Formation, homogenization temperatures are generally between

220-250 °C and salinities are 9-14 wt. % NaCl equivalent. In the Harpers Formation, homogenization temperatures are generally between 255-275 °C and salinities are 14-19 wt. % NaCl equivalent. Eutectic temperatures for both fluids indicate they are part of the NaCl-CaCl2-H2O aqueous system. Secondary inclusions are abundant in pre-cleavage veins and have a wide range of homogenization temperatures and salinities which are more similar to inclusions observed in syn- and post-cleavage veins.

Syn-cleavage veins record the intermediate stage(s) of deformation associated with the pervasive

Alleghanian structures. The fluid associated with these veins is characterized by primary inclusions with homogenization temperatures of 160-210 °C and salinities of 7.1-19.2 wt. % NaCl equivalent (Figure 9F).

Eutectic temperatures indicate the fluid inclusions in these veins are part of the NaCl-CaCl2-H2O aqueous system. Primary inclusions in syn-cleavage veins of the Catoctin and Weverton formations overlap; indicating fluids of similar salinities were present in both units and trapped at similar conditions. Primary inclusions in syn-cleavage veins of the Harpers Formation are rare. Secondary inclusions were observed in syn-cleavage veins from all three stratigraphic units and occur in various compositions (Figure 9D).

They display homogenization temperatures similar to both syn- and post-cleavage veins. Eutectic 24

temperatures indicate fluid compositions and salinities that are comparable to both syn- and post-cleavage veins.

Post-cleavage veins represent the final stages of deformation. Fluids associated with these veins are generally characterized by primary fluid inclusions with homogenization temperatures <160 °C and salinities <12 wt. % NaCl equivalent (Figure 9G). Eutectic temperatures indicate fluids from primary inclusions in the Catoctin and Harpers formations and secondary inclusions of the Weverton Formation are part of the NaCl-H2O system. Whereas the primary inclusions within the Weverton Formation are part of the NaCl-CaCl2-H2O system. Microthermometry data from post-cleavage veins show little variation in salinity between the Weverton and Harpers formations. However, measurements from primary inclusions in the Catoctin Formation display lower final ice-melt temperatures. Primary inclusions in the Weverton

Formation occur in a narrow salinity range, but at higher homogenization temperatures than those of the

Catoctin and Harpers formations. All inclusions within the Harpers and Catoctin formations and secondary inclusions within the Weverton Formation have similar homogenization temperatures. The lowest salinities measured were observed in these post-cleavage veins from the Catoctin Formation.

Other Relationships

Other variables exist which may be explain variations in microthermometry data and provide information about the fluid evolution of the Blue Ridge anticlinorium. These include proximity to structural discontinuities (i.e., faults) and changes in structural position on the anticlinorium. Due to the location of sampling sites, scarcity of outcrops and variations in the local geology, each of these variables cannot be completely accounted for. However, some additional observations about fluid variation can be made.

Faults are common structures in the allochthonous Blue Ridge province and could play an important role in the fluid history as they provide migratory fluid pathways (O’hara and Haak, 1992).

Several faults occur between Study Area 2 and Study Area 3 (Figure 3). The normal fault just east of the

Blue Ridge is known to be the result of the Cenozoic extension as seismic imaging has identified it cutting down into the Paleozoic basement (Cook et al., 1979). The faults observed along the western limb 25

occur with similar strikes but their movement senses are unclear. Fluid inclusion data on this limb from pre-cleavage veins of the Harpers Formation display the highest homogenization temperatures recorded.

Placement of the warmest fluids on the foreland-side limb of the Blue Ridge anticlinorium is enigmatic and may be related to the faulting observed in this region of the study area. A more detailed microthermometry study of veins and their proximity to these faults would be required to verify this interpretation.

The Blue Ridge anticlinorium is a northeast-plunging, asymmetric fold structure, overturned to the northwest. Because of the greater amount of deformation on the overturned limb (Cloos, 1971), one may expect to find fluid variations relative to structural position. A comparison was made between veins from the eastern limb and the western limb to highlight changes in structural position on the anticlinorium. The dataset was sufficient in size to allow for comparison of structural position for each successive vein generation (Figure 10). Pre-cleavage veins display the highest homogenization temperatures in primary inclusions from samples collected on the western limb of the anticlinorium

(Figure 10A-B). Syn-cleavage veins show the reverse of this trend; a decrease in homogenization temperature from the eastern limb to the western limb during this phase of deformation (Figure 10C-D).

The final generation of veins, post-cleavage, shows the same trend as observed in syn-cleavage veins

(Figure 10E-F). Salinities vary across the anticlinorium as well, but most of these variations can be attributed to stratigraphic position.

DISCUSSION

Regional paleohydrogeology

The Blue Ridge province is situated between the Valley and Ridge province to the west and the

Piedmont province to the east. In addition to detailed structural analysis, regional fluid histories for each of these structural units have been completed in the central Appalachians. Evans and Battles (1999) characterized fluids from multiple vein generations in the Valley and Ridge and concluded that “warm” methane-rich fluids had migrated through the region during the latter phases of Alleghanian deformation.

Evans and Bartholomew (2000) and Markham (2009) produced similar studies in the Piedmont province, which described the fluids during syn- and post-orgenic exhumation. Both fluid histories identified CH4,

CO2, and aqueous fluid inclusions in successive vein phases. Schedl et al. (1992) studied the isotopic signatures of fluids associated with widespread diagenetic alteration from the Piedmont to the Valley and

Ridge using δ18O and δD. They concluded that hot, metamorphic and basinal fluids migrated across the foreland and that they were partially sourced from a detachment zone beneath the Blue Ridge thrust sheet.

This Alleghanian fluid migration is responsible for much of the diagenetic alteration and remagnetization in the Appalachian foreland and midcontinent region (Oliver, 1986).

Fluid History of the Blue Ridge anticlinorium

Five distinct fluid s have been identified in three successive vein phases associated with deformation of the Blue Ridge anticlinorium. The fluids are characterized by changes in composition, salinity, homogenization temperature, and vein generation. Table 3 provides a generalized summary of the fluid history for the Blue Ridge anticlinorium. The first fluid was recorded in pre-cleavage veins from the Catoctin and Harpers formations. It is characterized by a complex aqueous mixture, high homogenization temperatures, and low salinities. The next fluid was preserved in syn-cleavage veins from all rock units and secondary inclusions in pre-cleavage veins of Harpers and Catoctin formations. It is characterized by a complex aqueous mixture of low to high salinity with moderate to high homogenization temperatures. This fluid is also found in post-cleavage veins of the Weverton Formation at low homogenization temperatures. The last fluid was present in all vein generations, but is only 27

primary in post-cleavage veins within the Catoctin and Harpers formations. Its composition is less complex than the other aqueous mixtures and has low homogenization temperatures and low salinities.

An anomalous fluid was also preserved in secondary inclusions of syn-cleavage veins from the Catoctin

Formation. It is characterized by a complex aqueous mixture of very-high salinity with low to moderate homogenization temperatures.

Estimate of entrapment conditions

The entrapment conditions for these events cannot be well constrained from inclusions in this study because multiple immiscible fluids were not identified. However, an estimate of minimum entrapment pressure and temperature can be provided for lithostatic and hydrostatic fluid pressures Fluid event constructed using modal homogenization temperatures and salinities (Figure 11) (Roedder and

Bodnar, 1980). With an elevated geothermal gradient (30 °C/km), calculated entrapment pressures for pre-cleavage veins indicate a range of depths from 9-14 km (Table 2). Elevated geothermal gradients may be expected in orogenic areas of crustal thickening and the gradient used is consistent with similar studies in the Valley and Ridge province (Evans and Battles, 1999; Winter, 2001). Thermochronology by Roden

(1991) from Devonian age units documented a burial depth of 7.6km in the eastern portion of the Valley and Ridge province prior to the Triassic extension event. One would expect calculated depths to be greater than those observed in the Valley and Ridge because the Blue Ridge is in closer proximity to the source of metamorphism. Also, the geothermal gradient applied to the inclusion dataset was established in the Valley and Ridge. Calculations therefore represent maximum depth as the true geothermal gradient may have been greater than 30 °C/km. 28

) on 29p. (caption

Figure 10.

Summaryplots fluidof inclusiondata separated in Figure 10. terms of veingeneration and geographic location. and A. B.) Pre-cleavage veins highestdisplay the homogenization temperatures on the western C. andlimb. Syn-cleavage D.) veins show a decreasemean homogenizationin temperature from east to west. E. and F.) Post-cleavage veins also show a decrease in meanhomogenization temperatures from the eastern limb to the western thoughlimb, are samples limited on the eastern limb.

Figure 11. Pressure-temperature diagram showing fluid inclusion trapping conditions for three identified fluid types. Temperatures were estimated from modal homogenization temperatures of inclusion populations.

Tectonic Evolution

A simple model of uplift and exhumation can be used to explain the trends in the fluid history.

During exhumation, pressures and temperatures would gradually decrease; a trend that is observed in homogenization temperature in inclusions from the three vein generations. Metamorphic reactions would also slow, which could result in a decrease of the amount of dissolved constituents in pore fluids. This trend is observed in the inclusion dataset as salinity generally decreases from pre- to post- cleavage veins.

Furthermore, the least complex aqueous brines were observed in primary inclusions of post-cleavage veins; possibly the result of fewer chemical constituents in solution during vein formation. Each of the trends observed in temperature, salinity and composition are consistent with a first-order comparison to a uplift and exhumation model.

Table 2. Characterization of fluid events with calculated pressure and temperature trapping conditions.

Lithostatic (PtL) and hydrostatic pressures (PtH) were calculated from fluid inclusion isochores as described by Bakker (2003). Densities were calculated using FLINCOR by Brown (1992). Other assumptions: geothermal gradient = 30 °C/km, hydrostatic gradient = 9.8 MPa/km and lithostatic gradient = 26.5 MPa/km.

T Salinity T P T P T Depth Fluid Types e hMODE tH tH tL tL (°C) (wt. % NaCl) (°C) (MPa) (°C) (MPa) (MPa) (km)

Low-Th -35 to -50 6.5 135 45 160 180 220 4.5 to 7

Moderate-Th -35 to -50 9 175 55 210 255 310 6.5 to 10

Moderate-T , h -35 to -50 16 175 60 205 245 295 6.5 to 10 high salinity

Moderate-Th, very high -45 to -65 30 175 65 205 240 280 6.5 to 10 slainity

High-Th -20 to -30 19 235 85 280 360 430 9 to 14

- Table 3. Summary of fluid inclusion - composition and salinity by rock formation, , low , , high , very

h h h

structural position and vein generation. The T T T - - -

h presence of primary inclusions is marked by h T T salinity - - "P". Secondary inclusions are marked by "s". - alinity Low Moderate salinity Moderate s Moderate high High Rock Formation Harpers P s P Weverton s P P Catoctin P P s P

Spatial Structural Position West limb P P P s P East limb P P P P

Vein Generation Pre-cleavage s s s s P Syn-cleavage s P P Temporal Post-cleavage P P

Alleghanian Fluid Migration and Potential Sources

Evidence for fluid migration events in the Valley and Ridge province during the Alleghanian orogeny was presented by Evans and Battles (1999). In that study, two high temperature events were identified from inclusions in quartz and calcite veins that contain of CH4-saturated NaCl-CaCl2 brines.

These fluids are thought to be the result of metamorphic fluids emanating from the hinterland, which mixed with CH4 and CO2 upon infiltration of the foreland basin. This interpretation was supported by

δ18O and δ13C isotopic compositions, which indicated an external fluid source for quartz vein minerals.

Aqueous fluid inclusions from the Blue Ridge have similar homogenization temperatures and salinities as those in the Valley and Ridge province. In general, homogenization temperatures from syn- and post-cleavage veins overlap, though pre-cleavage veins from the Blue Ridge record higher temperatures. No fluid containing CH4 or CO2 was observed in the study area indicating the Blue Ridge may not have been hydrologically connected to the sources of either of these fluids. The source of hydrocarbon in the region is widely recognized to be the Ordovician black shales (Ryder et al., 1998), which are not present in the Blue Ridge allochthon. Also, the Cambrian-Ordovician carbonate units (a potential source for CO2) occur stratigraphically above the lower Cambrian units studied. Another possible sedimentary source for CO2 (and CH4) is the upper Paleozoic sequence beneath the allochthon in the footwall of the Blue Ridge. However, fluid from this source would likely include CH4 and/or CO2 fluids as studies in the Valley and Ridge and Piedmont provinces previously identified.

The absence of CO2 inclusions in the Blue Ridge is perplexing as metamorphic rocks in the

Piedmont to the east contain abundant CO2 (e.g., Markham, 2009) and the trapping conditions in the Blue

Ridge are consistent with low-grade metamorphism. During low grade metamorphism, dehydration and decarbonation reactions are a common mechanism for sourcing of fluids; therefore, one would expect those fluids to contain CO2 (Roedder, 1984). In low- to medium-grade metamorphic rocks, CO2-free fluids may be sourced from: modified ground waters, original interstitial fluid that was CO2-free, the result of dehydration reactions (exclusively), or CO2 present during mineralization was used up in carbonation reactions (Roedder, 1984). Fluid sourced from dehydration reactions exclusively and CO2 33

being chemically exhausted during carbonation reactions can be excluded as no mineralogical data supports either hypothesis. It may then be that CO2-free fluids were sourced from original interstitial fluids of the stratigraphic units. Given the nature of the Catoctin Formation, a thoeliitic basalt sequence of volcanic flows and tuffs, this explanation appears to be plausible. Volcanic tuffs generally have high initial porosities, so the Catoctin Formation has potential to be a large fluid reservoir. Also, some moderate-Th inclusions from pre- and syn-cleavage veins display eutectic temperatures >-50 °C, indicative of a chloride solution enriched with Na, Ca, and Mg. High concentrations of Ca and Mg can form during low-grade metamorphism of basalt (Roedder, 1984). Inclusions in this study are an indication that pore-fluids, possibly from the Catoctin Formation, are the source of vein-forming fluids in the Blue

Ridge anticlinorium.

A local source for the fluids in the Blue Ridge is consistent with a number of trends observed in this study. Figure 10 shows a gradual decrease in homogenization temperatures from the eastern limb to the western limb. This observation is consistent with others studies that have noted changes in deformation style and mechanisms, isotopic signatures from secondary features, and decreases in homogenization temperatures from hinterland to foreland (Mitra, 1987; Schedl et al., 1992; Evans and

Battles, 1999). Each of these studies found that cooler conditions existed toward the foreland. Although the Blue Ridge is at the foreland-hinterland transitional zone, there is no evidence to support the hypothesis that fluids in the study area are sourced from the hinterland interior (i.e. Piedmont province).

Role of faulting

Fluid histories in the Valley and Ridge and Piedmont provinces suggest decollement faulting promoted lateral migration of fluids beneath thrust sheets. If tectonic brines were “squeezed” from the hinterland as Oliver (1986) suggested, it is likely they would have migrated toward the foreland along bedding-parallel faults (flats). Periodically, fluids could then move up-section along ramps where detachment faults permitted. This scenario explains fluid inclusion studies from the adjacent structural units but not the fluid history of the Blue Ridge. The gradual decrease in homogenization temperatures observed in syn- and post-cleavage veins from east to west indicates fluids were migrating toward the 34

foreland. However, fluid inclusion evidence suggests that vein-forming fluids within the Blue Ridge were locally sourced. Therefore, faults are not perceived to have played a significant role in the regional-scale fluid migration.

CONCLUSIONS

Fluid inclusion microthermometry coupled with the kinematic history of various deformation phases present in the Blue Ridge province identified five fluid types, which correlate with at least three different deformation phases. The earliest fluid was identified in pre-cleavage veins from the Catoctin and the Harpers formations. It is a low salinity brine (NaCl±CaCl2±MgCl2) with a modal homogenization temperature of 235 °C. The second deformation phase (syn-cleavage veins) correlates with the

Alleghanian structures and is characterized by a fluid of a similar composition, at variable salinities and has modal homogenization temperature of 175 °C. Syn-cleavage fluids were observed in all stratigraphic units studied and show a decrease in homogenization temperature from the eastern limb to the western limb of the anticlinorium. The third fluid was identified in post-cleavage veins. It is a simple aqueous mixture of low salinity and has a modal homogenization temperature of 135 °C. The lack of CO2 and CH4 in fluid inclusions, which are common in the adjacent Piedmont and Valley and Ridge provinces, indicates that fluids in the Blue Ridge were locally sourced and not part of regional paleohydrologic systems. Within the Blue Ridge, the distribution of fluid types shows evidence for stratigraphic partitioning, a decrease in trapping temperature throughout the progressive deformation, and a general decrease in trapping temperatures from hinterland to foreland. 36

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Appendix A: Microthermometry Measurements GB-1C GB-2 P or S Te Tm Th % Vap P or S Te Tm Th % Vap s 28 4.6 187 20 s 42 4 178.7 50 s 27 5 179.7 20 s 43 6.5 173.4 30 s 24 5.8 174.4 30 s 41 6.5 172.8 20 s 32 4.3 172.6 20 s 38 7.5 159.2 20 s 37 3.4 180.9 30 s 39 7.2 161.3 20 s 44 6 173.1 30 s 40 7.6 160.4 20 s 46 6.6 171.2 30 s 35 8.2 174.4 20 s 35 6.8 171.4 20 s 36 8.4 174.7 30 s 35 6.4 179 40 s 37 8.2 173.2 20 s 30 7 176.7 20 s 36 7 174.4 20 s 29 7.1 130.2 s 37 7.1 170.8 20 s 32 5.5 181 40 s 36 7.2 173.2 30 s 48 9 183.6 20 s 35 6.9 175.1 20 s 38 5.8 168.6 30 s 32 7 173.3 20 s 41 5.8 169.5 20 s 42 6.4 172.3 20 p 30 6.5 169.5 30 s 30 4.2 176.5 40 p 48 6.6 173 40 p 39 4.5 187.6 50 p 35 6.5 168.3 30 p 30 5.2 185.3 30 p 40 6.3 172.5 10 p 31 5 185.2 30 p 43 6.3 175.9 20 p 40 7 175.6 20 p 36 5.9 171.2 30 p 36 8.7 177 20 p 45 5.5 170.3 20 p 39 7.7 202.1 20 p 32 5.2 166.8 20 p 44 7.2 178.8 20 p 34 5.5 167.8 20 p 40 7.4 187.6 20 p 45 8.6 151.4 20 p 38 7.6 186.7 20 p 35 7.6 178.1 30 p 42 7.5 188 20 p 35 7.8 174 30 p 41 7.7 189 20 p 48 8.8 153.4 20 p 43 7.4 188.3 20 p 35 7.1 177.8 20 p 35 6.5 189.3 20 p 34 6.6 178.3 30 p 32 6.4 188.7 20 p 35 7.3 190 25 p 36 6.8 187.8 20 p 43 6.1 161.1 20 p 34 6.7 187.5 20 p 39 7.2 190.5 40 p 27 6.9 180 40 p 45 9.5 171.3 15 p 25 6.8 181.2 30 p 38 6 173.8 30 p 28 7 179.8 30 s 38 6 30 p 25 6.7 181 40 s 35 7.3 20 p 36 6 174.9 30 s 28 7.2 30 p 35 5.9 175 30 s 39 6 30 p 36 6.1 176.1 30 s 44 6.9 20 s 176.5 30 s 25 7.8 30 s 177.4 20 s 40 7.2 30 s 177.1 30 s 32 7.3 20 s 176.8 30 s 35 5.8 20 s 187.5 30 s 33 6.3 20 s 188 20 s 35 7.1 20 s 187.3 30 s 35 7 20 s 187.6 30 s 46 5.7 30 s 185.5 30 s 44 6 40 s 184.8 30 41 s 42 5 30 s 185.9 30 s 40 7.9 30 s 186 30 s 38 7.2 30 s 194 40 s 38 7 30 s 187.4 30 s 42 7.6 30 s 173.2 30 s 28 7.1 40 s 183.4 20 s 25 7.2 30 s 188.5 30 s 25 7.3 30 s 181.8 20 s 28 7.2 30 s 180.7 20 s 27 7.1 20 s 182 20 s 25 7 20 s 181.4 20 s 30 6.6 20 s 192.4 20 s 36 5.8 20 s 185.5 20 s 42 7.1 20 s 187.3 30 s 42 6.2 30 s 186.7 30 s 41 6.5 20 s 180.1 20 s 25 6.8 20 s 182.3 30 s 42 6.8 20 s 181.4 30 s 45 6.4 20 s 183 20 s 28 7.7 20 s 179.9 20 s 49 6.5 20 s 178.8 20 s 42 6.6 20 s 179.2 20 s 41 6.5 10 s 179.8 30 s 34 5.8 20 s 184.4 30 s 39 6.8 20 s 184.3 20 s 43 6.9 40 s 186.8 30 s 47 6.6 30 s 179.9 20 s 43 7.3 20 s 187.3 30 s 25 7.2 20 s 188 20 s 42 5.7 30 s 186.7 20 s 41 5.6 30 s 185 30 s 36 5.9 20 s 193.5 30 s 46 7.8 20 s 174.2 20 s 47 7.9 20 s 179 20 s 42 6.9 10 s 182.2 20 s 46 5.6 30 s 183.5 30 s 41 6.1 20 p 209.5 30 s 30 5.5 20 p 201.5 30 s 34 6.8 30 s 48 7.4 20 s 38 6.3 30 s 42 7 20 s 39 5.6 30 s 42 6.1 20 s 38 5.4 20 s 50 6.6 30 s 47 6.9 30 s 39 6.6 20 s 30 6.4 30 s 45 5.3 30 s 48 6.3 20 s 44 6.2 30 42 s 36 4.8 30 s 41 6.7 30 s 36 5.6 30 s 35 5.4 30 s 42 6 20 s 38 6.6 30 s 36 5.9 20 s 27 4.3 20 s 49 6.3 20 s 40 6.2 20 s 25 6.2 30 s 30 5.8 30 s 32 4.8 20 s 25 8.5 40 s 28 6.6 30 s 34 7.5 20 s 38 7.6 30 s 38 6.5 40 s 41 7.3 40 s 36 7.1 30 s 35 6.6 40 s 25 8.3 30 s 33 6.6 40 s 42 6.9 20 s 47 7.2 20 s 6.9 20 s 5.1 20 s 4.8 30 s 9.1 20 s 6 30 s 5.9 30 s 42 5.7 30 s 41 5.6 30 s 36 5.9 20 s 46 7.8 20 s 47 7.9 20 s 42 6.9 10 s 5.1 20 s 46 5.6 30 s 41 6.1 20 s 4.8 30 s 30 5.5 20 s 34 6.8 30 s 48 7.4 20 s 38 6.3 30 s 42 7 20 s 39 5.6 30 s 9.1 20 s 6 30 s 5.9 30 s 42 6.1 20 s 38 5.4 20 43 s 50 6.6 30 s 47 6.9 30 s 39 6.6 20 s 30 6.4 30 s 45 5.3 30 s 48 6.3 20 s 44 6.2 30 s 36 4.8 30 s 41 6.7 30 s 36 5.6 30 s 35 5.4 30 s 42 6 20 s 38 6.6 30 s 36 5.9 20 s 6.9 20 s 27 4.3 20 s 49 6.3 20 s 40 6.2 20 s 41 6.4 30 s 38 6.1 20 s 32 6.9 30 s 37 6.4 30 s 51 7.2 30 s 39 6.9 20 s 35 5.3 30 s 44 6.8 20 s 37 6.6 20 s 35 6.8 20 s 39 7 30 s 35 6.7 20 s 37 6.4 20 44

Appendix A: Microthermometry Measurements (continued) GB-6 GB-13 P or S Te Tm Th % Vap P or S Te Tm Th % Vap PS 46 11.2 175 20 ps 35 8 171 20 PS 43 12.3 179 30 ps 33 10 172.8 20 PS 48 13.1 180.3 20 ps 44 10.2 175.2 20 PS 42 14 184.1 20 ps 41 8.8 171 20 PS 41 13.8 187 30 ps 48 8.3 182 20 PS 42 12.6 186.2 30 ps 45 9.6 176 20 PS 39 11 173.3 20 ps 42 9.1 175.4 20 PS 38 10.8 173 20 ps 31 7.9 182 30 PS 40 10.9 171.6 30 ps 30 9.7 181 30 PS 45 12 182.4 20 ps 26 4 204 20 PS 46 12.6 180.1 20 ps 31 11.6 178 20 PS 48 13 183.5 20 ps 36 10.4 178.4 20 PS 44 10.8 188.5 30 ps 33 8 171.8 20 PS 46 14.1 176.4 20 ps 35 10 172 20 PS 47 13.5 179.3 30 ps 44 10.2 175.3 20 ps 178.3 10 ps 41 9.3 179.8 20 ps 124.4 20 ps 45 9.8 181.3 30 ps 176.7 10 ps 31 10.8 179.4 20 ps 175 10 ps 30 9.3 176.4 30 ps 176.1 10 ps 26 9.1 178 30 PS 142.3 20 ps 31 9.2 183.2 20 PS 180.8 20 ps 41 9.7 169.9 20 PS 182.1 10 ps 35 10.4 172.4 20 PS 182.3 20 ps 182.8 30 PS 181.8 20 ps 181.7 20 PS 173.4 20 ps 172.4 30 PS 174.4 20 ps 178.6 20 PS 173.8 20 ps 177.9 20 PS 174.6 20 ps 178.2 30 PS 179.5 20 ps 179 30 PS 178.5 20 ps 181.3 20 PS 180.2 20 ps 178 20 PS 173.2 20 ps 179.3 30 PS 170.8 20 ps 177.8 20 PS 171.6 20 ps 179.8 30 ps 170.5 10 ps 172.4 20 ps 169.8 20 ps 177.3 30 ps 168.7 10 ps 176.5 30 ps 180.8 10 ps 177.4 20 ps 170.1 10 ps 178.3 20 ps 169.5 10 ps 179 30 S 37 7.9 174.4 20 ps 183.5 20 S 38 8.3 175 20 ps 204.3 20 S 36 7.2 178 20 ps 179.4 20 S 35 7.5 178.5 20 ps 175.2 20 S 43 7.3 174.7 20 ps 183.2 20 S 42 7.5 172.3 20 ps 174.8 20 S 42 7.4 173.2 20 ps 169.2 20 s 39 8.1 145.2 20 ps 175.4 30 45 s 37 8.2 176.8 30 ps 174.5 20 s 177.6 20 s 185.3 30 s 192.2 20 s 182.2 10 s 181.9 10 s 179.8 10 s 180.1 20 s 192.1 20 s 196.6 20 s 176.7 20 s 177 20 s 110.6 10 s 175.6 10 s 176 10 s 175 10 s 172 10 s 173.4 20 s 173.2 10 s 172.8 10 s 176.8 10 s 175.4 10 46

Appendix A: Microthermometry Measurements (continued) GB-19 PR-3 Chip 1 Te Tm Th % Vap Chip 1 Te Tm Th % Vap P 40 8.1 237.5 30 s 61 33.9 150.2 30 P 57 7.2 229.4 35 s 59 32 74.8 5 P 49 9.6 241.2 40 s 63 33.9 154.2 30 P 39 7.5 238.2 30 s 68 33 152.4 30 P 40 6.9 235.4 20 s 60 34.2 147.7 40 P 48 6.5 233.2 30 s 59 33.8 163.2 30 P 49 9 248 20 s 61 32.6 167.4 30 P 42 7 238 30 s 60 31.4 166.5 10 P 43 7.6 225 35 s 58 32.6 170.3 20 P 42 7.3 249 35 s 60 30.3 165 20 P 45 6.9 220 40 s 59 30.7 159.9 30 P 44 6.9 225 30 s 61 32 167 30 P 47 7.7 183 30 s 60 30.9 163.8 20 P 45 6.2 223.5 35 s 60 33.2 158.5 20 P 50 8.8 209 30 s 64 34 152.4 30 P 50 8.3 241 30 s 58 39.9 156.6 30 P 47 8.4 216 25 s 55 34.3 154.4 20 P 47 8.2 213 30 s 61 31.4 160 20 P 40 8.1 231.5 40 s 67 33.1 163.8 30 P 44 7.9 237 50 s 56 30.1 150.2 35 P 45 8 176 20 s 59 33.9 159.9 20 P 42 7.5 207 20 s 60 34.4 155.8 30 p 47 5.5 225 30 s 60 29.8 159.4 20 S 50 7.5 164 10 s 55 33.1 20 S 49 8.8 160 10 s 58.6 32.1 20 S 56 4.6 161 15 s 52 27.8 20 S 58 7.5 168 20 s 53 30.3 20 S 37 5.5 163.8 20 s 53 10 20 S 42 5 168.2 20 s 56 10.6 20 S 37 5.1 164 20 s 55 27.8 30 S 45 6.1 149 15 s 56 29.3 20 S 47 6.4 164 20 s 60.2 29 40 S 48 6.6 160 20 s 58 30.3 40 S 46 4.2 163 25 s 63.1 26.5 20 S 45 5.4 161 20 s 60 27.9 20 S 50 4.8 160 20 s 58 26.9 20 S 45 7 159.6 20 s 61 27.3 20 S 45 7.1 143.6 20 s 61 36.7 20 S 44 7.3 151.8 10 s 68.7 35 20 S 42 5.6 162.5 20 s 62 34.3 20 S 43 5.2 145 25 s 61 33 20 S 40 5.8 177.8 40 s 60 31.5 30 S 166 30 s 63 32.1 30 s 175 30 s 65 30.9 20 S 180 30 s 56 29.5 20 S 175 30 s 58 33.1 20 S 173 20 s 61 29.5 30 S 172 20 s 54 26.4 30 S 183 20 s 60 28.4 40 47

S 174 20 s 63 30.3 20 S 177 20 s 60 31.5 20 S 175 20 s 66 29.9 5 S 158.5 20 s 60.5 20 S 165 20 s 161.7 20 S 164 20 s 164.9 30 S 167.7 20 s 163.2 20 S 165.8 20 s 165.8 20 S 166.3 20 s 168.8 20 S 160.6 30 s 162 30 S 168.8 20 s 170 20 S 167.8 20 s 177.1 20 S 166.2 20 s 186.3 30 S 168 30 s 185.8 20 S 167.5 20 s 163 20 S 178 20 s 167.7 20 S 175 20 s 210 20 S 163 10 s 174 30 S 164 20 s 178.3 20 S 160 20 s 196 20 S 161 20 s 194.8 20 S 168 20 s 195 30 S 163.8 20 s S 168.2 30 s S 164 30 s S 149 20 s S 164 20 s S 160 10 s S 225 20 s S 161 20 s S 160 20 S 159.6 S 143.6 S 151.8 S 162.5 S 145 S 177.8 48

Appendix A: Microthermometry Measurements (continued) PR-4 HF-2 Chip 1 Te Tm Th % Vap Chip 1 Te Tm Th % Vap ps 31 9.8 171.8 20 s 181.8 ps 32 10.5 170.2 30 s 153.6 ps 30 11.1 168.7 20 s 152.6 ps 28 9.7 165.8 20 s 152.3 ps 30 10.7 160.1 20 s 136.4 ps 29 9.9 163.2 30 s 189.8 ps 36 11.2 158.2 10 p 235.6 ps 29 13.3 153.8 20 p 231.6 ps 27 12.4 163.3 20 s 137.9 ps 30 11.9 160.7 30 p 217.4 ps 45 11.6 154.5 10 p 217.1 ps 37 13.6 165.8 20 p 215.3 ps 36 12.2 166.7 10 p 244.1 ps 38 11.8 160.1 20 p 215.2 ps 35 15.8 160 20 s 172.9 ps 30 13.4 142.6 30 s 199.6 ps 33 12.6 158.3 20 s 209.8 ps 28 13.1 164.5 20 s 123.5 ps 26 10.5 172.6 20 s 126.7 ps 30 14.5 170.4 20 s 148.8 ps 44 17.6 173.2 30 s 176 ps 46 16.6 160.3 20 p 52 15.2 255.6 30 ps 40 13.1 161.5 30 p 54 13.5 259.9 40 ps 170.3 p 59 14.9 278.4 30 ps 171.4 p 56 14.7 268 30 ps 159.5 p 50 12.8 262 40 ps 139.6 p 48 11.6 275 30 ps 152.9 p 49 14.3 280.5 20 ps 153 p 58 14.7 267.3 40 ps 138 s 42 12 165.3 30 ps 135.6 s 41 4.1 126.7 20 ps 208.1 s 56 4.2 183 20 ps 161.2 s 52 9 153.6 10 ps 195.6 s 41 11 152.6 30 ps 151.6 s 48 10.5 136.4 20 ps 150.8 s 45 9.8 189.8 10 ps 145.8 s 32 13.8 137.9 30 ps 164.4 s 47 4 153.6 20 ps 166.1 s 44 11 217.4 30 ps 165.8 s 38 13 215.3 40 ps 201.2 s 51 15.5 123.5 20 ps 155.5 s 43 13.1 172.9 30 ps 163.2 s 41 12.7 199.6 20 ps 161.1 s 45 14.2 209.8 40 ps 193.3 s 41 13.7 148.8 30 ps 188.7 s 55 6.9 176.6 20 ps 162.3 s 55 15.3 181.8 20 ps 181.4 ps 176.7 49 ps 210.6 ps 172.5 ps 203.3 ps 202.5 ps 206.1 ps 174.2 ps 154.1 ps 145.3 ps 168.1 ps 168.3 ps 166.8 ps 172.1 ps 170.9 ps 172.4 ps 179 50

Appendix A: Microthermometry Measurements (continued) HF-5 HF-6 Chip 1 Te Tm Th % Vap Chip 1 Te Tm Th % Vap s 142.8 30 s 190.8 20 s 144.6 30 s 182.7 30 s 142.6 20 p/s 225.5 30 s 141.7 20 s 210 20 s 146.1 30 s 185.7 20 s 199.1 20 s 189.9 30 s 131.1 30 s 192.4 30 s 133.2 30 p/s 171.6 40 s 160.1 30 p/s 155.3 40 s 155.3 30 s 152.6 30 s 151.2 30 s 157.6 30 s 141.7 20 s 177.5 30 s 135.1 20 s 172.8 20 s 150.4 20 s 162.1 20 s 140.6 30 p/s 163.2 30 s 125.4 30 s 167.8 20 s 126.9 30 p/s 153 30 s 137.4 20 s 183.5 30 s 146 30 s 155.6 20 s 148.2 20 s 157.8 20 s 149.9 20 s 155.2 30 s 149.5 30 s 160.4 20 s 160.3 10 s 167.6 30 s 150.2 20 s 147.8 20 s 153.4 30 s 144.2 30 s 161.3 30 s 136.1 20 s 158.8 30 p/s 140.2 10 s 144 30 s 138.9 20 s 151.7 30 s 149.1 30 s 139.6 30 s 149.3 30 s 142.7 30 s 47 9.5 168.8 30 s 135.7 30 s 36 12.6 170 20 s 136.8 30 s 31 6.5 165.7 30 s 154.5 30 s 28 6.8 176.2 20 s 133.7 20 s 37 11.1 162.8 40 s 140.2 20 s 35 6.7 161.4 20 s 139 30 s 37 10.5 158.4 30 s 146.4 30 s 35 11.1 161.2 30 s 149.7 30 s 33 15.4 177.6 50 s 158 20 s 29 10.1 164.6 20 s 159.8 30 s 36 7.9 169.2 30 s 150.6 20 s 25 5.6 168.7 30 s 144.7 30 s 44 9.1 157.8 30 s 136.1 30 s 38 10.3 159.8 20 s 142.8 20 s 39 8.3 151.1 30 s 157.6 20 s 40 8.9 149.5 30 s 137 30 s 41 8.5 163.8 20 s 32 17.2 151.6 20 s 36 9.2 170.2 30 s 26 12.4 146.5 30 s 22 11.7 171.4 30 51 s 29 16.8 145.5 20 s 44 11.9 165.4 20 s 26 9.3 160.2 30 s 35 10.4 150.2 30 s 34 9.1 151.2 30 s 33 10.1 148.4 30 s 30 18 149.8 20 s 45 13.6 142.7 30 s 35 15.3 155 30 s 29 12.5 161.8 30 s 26 10.4 126 20 s 37 18.3 146 30 s 34 17.4 149 30 s 28 15.2 133 30 s 26 12.4 139.8 20 s 30 13.8 156 20 s 29 12.4 149.8 30 s 30 17.4 160.8 30 s 33 16 150.2 30 s 27 10.5 145.9 20 s 25 18.3 156.7 30 s 31 15.5 152.9 20 s 36 17.9 140.2 20 s 31 15.8 136.2 30 s 30 13.8 139 30 s 22 12.2 148.2 30 s 24 15.5 142.8 30 52

Appendix A: Microthermometry Measurements (continued) HF-8 GB-21 Chip 1 Te Tm Th % Vap Chip 1 Te Tm Th % Vap s 141 s 176.9 s 148.7 s 184.4 s 136.5 s 175.2 s 139.1 s 174.8 s 136.2 s 185.6 s 135.4 s 176.7 s 127.4 s 177.9 s 135.3 s 233.9 s 131.9 s 187.5 s 130 s 182.3 s 137.7 s 184.8 s 136.8 s 186.9 s 138.2 s 188.2 s 139 s 183.8 s 143.4 s 184.5 s 137.3 s 176.5 s 123.5 s 183.9 s 128.5 s 182.8 s 131.2 s 184.2 s 118.6 s 178.8 s 128.8 s 177.5 s 136.8 s 176.3 s 143.6 s 179.2 s 141.7 s 179.8 s 134.5 s 181.1 s 132.6 s 174.5 s 138.5 s 183.2 s 134.6 s 172.5 s 29 10.4 136.7 20 s 167.8 s 38 5.4 129.9 20 s 175 s 36 5.3 128.7 20 s 189.5 s 34 6 141.2 20 s 30 7.9 184.2 s 38 5.1 127.8 20 s 41 7.6 189.7 s 29 8.5 131 20 s 43 7.2 176.6 s 42.5 5.8 136.7 20 s 40 7.4 181.4 s 36 6 144.9 20 s 42 7.5 188.7 s 31 7.4 131.2 20 s 40 5 170.4 s 28 5.2 126.1 20 s 36 4.8 171.6 s 37 6.5 119.8 20 s 38 5.9 185.1 s 25 5.8 134.2 20 s 39 5.6 182.3 s 40 8.7 125.7 20 s 37 5.3 180.7 s 42 5.8 130.2 20 s 48 6 177.9 s 20 6.2 118.7 20 s 45 5.8 177.4 s 25 6.3 144.2 30 s 51 6.7 180.6 s 29 6.9 138.7 20 s 38 6.7 183.2 s 36 7.4 132.8 20 s 44 5.7 188.1 s 37 5.9 131.7 20 s 32 7.1 172.5 s 31 6.1 136.5 20 s 39 8.6 179.6 s 29 4.5 141.2 30 p 31 8.6 186.7 53 s 25 4.9 130.8 20 p 44 6.4 181.5 p 40 7.1 129.2 30 p 45 5.2 179.5 p 42 7.6 130.6 20 p 46 4.9 183.6 p 31 6.6 138.2 30 p 38 8 184.2 p 34 6.7 136.2 30 p 45 6.7 183.7 p 33 6 132.2 40 p 40 7.2 185.9 p 35 6.1 135.4 40 p 40 6.1 193.6 p 20 4.2 123.2 30 p 38 6.2 186.2 p 27 6.9 133.7 30 p 44 5.8 185.4 p 33 7.1 131.8 30 p 42 6.5 178.3 p 36 3.7 120.9 20 p 41 5.8 192.4 p 31 3.5 126.4 40 p 39 5.4 182.8 p 40 6.5 135.4 30 p 46 5.2 182.3 p 34 6.9 132.1 30 p 40 6.9 180.6 p 36 6.8 133.9 30 p 41 6.4 191.8 p 30 6.1 138.2 20 p 178.4 p 41.3 6.1 124.3 20 p 189.8 p 36 4.7 140.8 30 p 178.4 p 34 10.2 144.7 40 p 184.6 p 32 10.7 143.5 30 p 184.8 p 158.2 p 183.5 p 142.8 p 181.2 p 134.5 p 198.2 p 154.2 p 175 p 173.7 p 179.4 p 188.6 p 182.5 p 176.4 p 178.2 p 181.2 p 188.2 p 187.5 p 185 p 185.5 54

Appendix A: Microthermometry Measurements (continued) GB-22 HF-12 Chip 1 Te Tm Th % Vap Chip 1 Te Tm Th % Vap s 198.6 20 p 162.8 20 s 215.6 20 p 164.7 20 s 192.6 20 s 132.6 30 s 193.2 20 p 150.4 20 s 203 20 s 146.5 20 s 183.2 20 s 133.5 20 s 213.23 20 s 137.3 20 s 208.7 20 s 138.5 30 s 186.7 20 p 145.9 20 s 187.8 20 p 144.8 30 s 188.4 20 s 143.8 20 s 173.4 20 s 140.7 20 s 235.2 30 s 138.6 10 s 178 20 p 140.7 20 s 184.9 20 s 137.5 30 s 182.7 20 s 144.3 40 s 183.7 20 s 137.2 20 s 180.1 20 s 39 10.8 131.6 20 s 172.2 20 s 40 12.6 132.1 20 s 167.3 20 s 36 14.1 136.2 10 s 172.1 20 s 34 3.8 148.7 20 s 176.1 20 s 45 3.3 144.8 10 s 224.7 20 s 40 6 129.6 20 s 250 40 s 43 8.7 122.8 20 s 232.6 20 s 45 9.3 130.8 30 s 165.5 20 s 40 14.5 127.2 20 s 184.8 30 s 36 12.6 129.8 10 s 186.7 30 s 42 11.7 130.2 20 s 189.5 20 s 41 13 136.8 20 s 162.2 20 s 43 13.2 148.4 10 s 176.1 20 s 37 14.5 141 20 s 191.2 10 s 36 12.6 139.8 20 s 240.4 30 s 39 10.8 128.9 20 s 233.7 30 s 43 14 134.6 30 s 30 5.8 191.4 20 s 41 13.6 139 20 s 32 7.5 193.4 20 p 42 13.2 153.2 20 s 40 7.2 195 30 p 42 14.2 150.2 20 s 28 1.9 182.4 20 p 36 15 158.6 30 s 26 7.8 172.6 20 p 42 11.9 138.1 20 s 35 7.9 178.8 20 p 41 8.7 134.2 20 s 36 8.1 185 30 p 37 9 138.7 20 s 38 8.3 171.2 20 p 33 10.2 140.2 20 s 45 6.2 194.5 30 p 32 11 145.2 20 s 28 7.9 190 30 p 44 12.5 136.8 20 s 25 9 181.2 20 p 39 10.7 143.7 20 s 26 5.8 183.2 20 p 39 13.7 141.2 20 s 41 5.9 162.4 20 p 39 12.9 145.7 30 s 36 6.7 186.6 20 p 40 10.7 140.1 30 s 25 8.3 199.6 20 p 43 9.6 140.6 20 55 p 20 8.8 231 20 p 35 5.8 226.4 30 p 32 5.8 233.8 20 p 33 6.9 241.7 20 p 35 6.9 220.4 20 p 34 7.5 238.6 30 p 32 7.1 225.3 20 p 28 7.9 240 30 56

Appendix A: Microthermometry Measurements (continued) SM-3 CM-10b Chip 1 Te Tm Th % Vap Chip 1 Te Tm Th % Vap p 135.6 p 36 6.3 156 30 p 128.9 p 32 6.8 158.5 10 s 149.4 p 30 7.1 157.3 20 s 135.8 p 29 6.3 163.4 30 p 126.2 p 30 6.7 147.5 30 p 137.3 p 38 6.3 159 20 s 136.4 p 33 6.5 156.4 20 p 130 p 31 6.6 154.6 30 p 132.3 p 36 6.1 141.2 30 s 143.5 p 35 5.7 157.7 30 s 134.2 p 48 6.6 156.5 10 p 136.5 p 45 7 154.8 20 p 128.4 s 42 6.8 135.4 20 p 145.9 s 44 6.3 127.4 20 s 140.8 s 37 6.1 129.3 30 s 131.2 s 37 6.3 139.3 20 s 126.6 s 35 5.6 138 20 s 133.3 s 38 5.4 137.3 20 s 140.2 s 32 6.1 137.6 20 p 28 1.6 140.8 s 43 7.5 135 20 p 25 1.7 142.6 s 36 7.9 130.8 10 p 31 2.1 145.6 s 40 1.4 30 p 20 1.8 142.9 s 25 1.2 10 p 22 1.6 140.7 s 38 0.4 20 p 34 1.6 140.2 p 39 7.1 20 p 37 1.5 139.9 p 38 7.3 20 p 35 2.3 145.6 s 28 4.1 25 p 29 1.6 145.9 p 37 6.2 30 p 33 2.8 146 p 34 6.9 20 p 40 3.6 139.1 p 35 7.2 20 p 38 2.2 140.5 p 33 7 10 s 30 1.5 138.8 p 34 6.9 10 s 29 1.3 140.1 p 49 7 20 s 25 2 135.9 s 31 7.8 10 s 30 1.1 140.2 s 30 5 20 s 36 1.4 142.1 s 39 7.8 20 s 30 3.3 143.5 p 38 6 20 s 34 3.4 141.9 s 41 5.3 20 s 36 1.3 139.9 p 39 7.9 20 s 31 2.4 138.8 p 36 7.8 20 s 33 1.9 133.8 p 29 8.9 40 s 25 1.7 133.7 p 45 8.5 20 s 21 1.4 133.2 p 34 7.5 20 s 38 2 130.7 p 39 7.1 20 s 30 1.6 138.2 s 41 6.3 20 s 29 2.7 137 s 33 8.2 20 s 34 1.5 135.9 s 38 8.6 20 s 33 0.8 136 s 41 8.7 20 s 28 0.9 133.2 s 38 6.9 20 57 s 136.1 10 s 135.2 20 s 134.2 20 s 134.1 10 s 135 10 s 128.2 10 s 134.8 10 s 130.9 5 s 123.3 15 s 132.2 10 s 131.6 10 s 134.2 10 s 130.8 30 s 111.3 10 s 130.8 10 s 132.4 10 s 128.7 10 p 153.4 20 p 160 20 p 184 30 s 131 20 p 162.2 10 p 169.2 20 p 168.3 20 p 170 10 HF-2 (Primary) 4

2 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 58 HF-2 (Secondary) 10

5 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 59 HF-5 14

Frequency 6

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 60 HF-8 (Primary Inclusions) 10

5 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 61 HF-8 (Secondary Inclusions) 9

Frequency 4

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 62 HF-12 16

8 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 63 HF-6 9

Frequency 4

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-C) 64 CM-10B (Primary) 5

Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 65 CM-10B (Secondary) 5

Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 66 GB-1C 50

25 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 67 GB-2 20

10 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 68 GB-6 (Pseudosecondary) 8

4 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 69 GB-6 (Secondary) 6

3 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Tm (-°C) 70 GB-13 10

5 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 71 GB-19 (Primary) 10

5 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 72 GB-19 (Secondary) 9

Frequency 4

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 73 GB-21 (primary) 8

4 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 74 GB-21 (secondary) 9

Frequency 4

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 75 GB-22 (Primary) 6

3 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 76 GB-22 (Secondary) 6

3 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 77 PR-3 30

15 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 78 PR-4 14

Frequency 6

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 79 SM-3 10

5 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Te (-°C) 80 HF-2 (Primary) 6

3 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 81 HF-2 (Secondary) 6

3 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 82 HF-5 8

4 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 83 HF-8 (Primary Inclusions) 14

Frequency 6

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 84 HF-8 (Secondary Inclusions) 14

Frequency 6

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 85 HF-12 12

6 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 86 HF-6 10

5 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 87 CM-10B (Primary) 14

Frequency 6

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 88 CM-10B (Secondary) 8

4 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 89 GB-1C 140

120

100

Frequency 60

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 90 GB-2 35

Frequency 15

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 91 GB-6 (Psuedosecondary) 9

Frequency 4

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 92 Gb-6 (Secondary) 7

Frequency 3

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 93 GB-13 14

Frequency 6

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 94 GB-19 (Primary) 16

8 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 95 Gb-19 (Secondary) 12

6 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 96 GB-21 (primary) 16

8 Frequency

0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Tm (-°C) 97 GB-21 (secondary) 9

Frequency 4

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 98 GB-22 (Primary) 6

3 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Tm (-°C) 99 GB-22 (Secondary) 8

4 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 Tm (-°C) 100 PR-3 16

8 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 Tm (-°C) 101 PR-4 10

5 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 102 Tm (-°C) SM-3 30

15 Frequency

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 Tm (-°C) 103 HF-2 (Primary) 4

2 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 Th (°C) 104 HF-2 (Secondary) 4

2 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 Th (°C) 105 HF-5 35

Frequency 15

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 106 HF-8 (Primary Inclusions) 14

Frequency 6

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (C)° 107 HF-8 (Secondary Inclusions) 30

15 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 108 HF-12 25

Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 109 HF-6 18

Frequency 8

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 110 CM-10B (Primary) 12

6 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 111 CM-10B (Secondary) 8

4 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 112 GB-1C 100

50 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 113 GB-2 50

25 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 114 GB-6 (Pseudosecondary) 25

Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 115 GB-6 (Secondary) 18

Frequency 8

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 116 GB-13 40

20 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 117 GB-19 (Primary) 8

4 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 118 GB-19 (Secondary) 35

Frequency 15

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 119 GB-21 (primary) 25

Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 120 GB-21 (secondary) 30

15 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 121 GB-22 (Primary) 5

Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 122 GB-22 (Secondary) 7

Frequency 3

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 123 PR-3 18

Frequency 8

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 124 PR-4 25

Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 125 Th (°C) SM-3 30

15 Frequency

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Th (°C) 126