ABSTRACT

PALEOFLUID SYSTEM STRUCTURE IN THE MONTERREY SALIENT OF THE SIERRA MADRE ORIENTAL, NORTHEASTERN MEXICO

Joshua W. Zodarecky, MS Department of and Environmental Geosciences Northern Illinois University, 2016 Mark P. Fischer, Director

This project investigates the paleofluid system in a thinly tapering orogenic wedge and assesses paleofluid system heterogeneity using geochemical analyses of veins and host rock. My goal is to determine the characteristics of paleofluids within a -dominated and to use the spatial, structural and stratigraphic distribution of paleofluid types to assess whether the paleofluid system was compartmentalized within individual folds. Regional structural geometry was characterized by combining geologic maps, digital elevation data, aerial photo interpretation, and cross section balancing and restoration to create new cross sections though the Monterrey

Salient. The chemistry, temperature and distribution of paleofluids were documented through petrographic, microthermometric and geochemical analysis of calcite and quartz veins and their corresponding host rock.

Construction and analysis of the new balanced cross sections reveals that the basement is segmented into several and features likely attributed to the opening of the Gulf of

Mexico. During detachment folding, evaporites at the base of the orogenic wedge migrated into cores, sequentially lowering the regional level of adjacent and causing them to become grounded at the basement. Basement structure appears to have influenced the of detachment folds.

Veins throughout the region formed from 130˚C – 250˚C basinal brines, marine and meteoric waters in both open and closed fluid systems. The regional paleofluid system evolved through different stages of fluid distribution as progressed. Initially, paleofluids were separated into upper and lower hydrostratigraphic units (UHU and LHU). At this time, high- temperature and moderate- to high-salinity (15-30 wt% NaCl) fluids in the LHU were separated from lower temperature and lower salinity (0-15 wt% NaCl) fluids in the UHU by an impermeable shale layer. Isotopic analysis suggests that the fractures created during progressive deformation facilitated mixing between the UHU and LHU. Lower δ13C values in later stage veins in the LHU suggest that hydrocarbons migrated through the system. Overall, the regional stratigraphy, rather than individual structures, seems to have been the dominant factor controlling paleofluid distribution.

NORTHERN ILLINOIS UIVERSITY DEKALB, ILLINOIS

DECEMBER 2016

PALEOFLUID SYSTEM STRUCTURE IN THE MONTERREY SALIENT

OF THE SIERRA MADRE ORIENTAL, NORTHEASTERN MEXICO

BY JOSHUA WILLIAM ZODARECKY

A THESIS SUBMITTED TO THE GRADUATE SCHOOL

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS

FOR THE DEGREE

MASTER OF SCIENCE

DEPARTMENT OF GEOLOGY AND ENVIRONMENTAL GEOSCIENCES

Thesis Director: Dr. Mark P. Fischer

ACKNOWLEDGEMENTS

I would like to thank Drs. Mark P. Fischer, Justin P. Dodd, and Ryan M. Pollyea for providing guidance and assistance to develop the ideas and methods used in this thesis. I would like to thank Mark P. Fischer and Adam Smith for their contribution with both field work and sample collection. I would like to thank Dr. Monica Carroll and Liz Olsen for taking their time to help with the stable isotope analyses. Further acknowledgements to Dr. Robert J. Bodnar and Luca

Fedele for help with LA-ICP-MS analyses, along with the Virginia Tech research lab for the use of their analytical equipment. I would also like to thank Northern Illinois University and the

Department of Geology and Environmental Geosciences for the use of laboratory equipment and computer programs used to analyze data for this research project. Acknowledgements are also made to the Geological Society of America for their funding and support of this research. I also received funding from the Goldich Fund of the Department of Geology and Environmental

Geosciences. All financial support awarded to me was used to fund travel and conduct research on the Laser Ablation (LA-ICP-MS) at Virginia Tech and to conduct the SEM, microthermometric, and stable isotopic analyses in this study.

TABLE OF CONTENTS

Page

LIST OF FIGURES……………………………………….….…………….………………...... v

LIST OF APPENDICES…………………………………………………………...………...... viii

Chapter

1. INTRODUCTION…………………………………………………………………….…. 1

Geological Fluid Systems...……………………………………………………………. 1

Orogenic Fluid Systems…………………………………………………………….…. 4

2. REGIONAL-SCALE STRUCTURAL ANALYSIS OF THE MONTERREY SALIENT……………………...…………...... 11

Geologic Setting…………………………………………………………………….... 11

Rationale and Methodology for Building New Cross Sections…………………….... 15

Subsurface Faulting: Abundance, Slip Sense and Geometry…………………….…... 19

Constraining Basement and the Depth to Detachment……………………………...... 24

Synthesis…………………………………………………………………………….... 35

3. PALEOFLUID SYSTEM STRUCTURE IN THE MONTERREY SALIENT………... 39

Introduction…………………………………………………………………….….…. 39

Mesoscopic and Microscopic Characteristics of Fractures and Veins…………….…. 42

Bedding-Parallel Fractures and Veins…………….….…………………………. 42

Strike-Oblique Fractures and Veins……………………………………….….…. 45

Cross-Fold Fractures and Veins……………………………………………….... 48

Fluid Inclusion Microthermometry: Methods and Results…………………………....50 iv Chapter Page

Carbon and Oxygen Isotopic Analyses: Methods and Results………………….….… 57

LA-ICP-MS Elemental Concentration Analyses: Methods and Results…...……….... 66

Integrated Model of the Paleofluid System………………………………….…….…. 71

Origin and Distribution of Fluids…………………………………….….………. 71

Open vs. Closed System Behavior……………...………………………….….… 74

Evolution of the Paleofluid System……………………………………………... 75

Conclusion…………………………………………………………………….….…... 79

4. CONCLUSIONS……………………………………………………………….………. 81

Summary of the Structural Analyses………………….….……………………...... 81

Summary of the Geochemical Analyses……………………………………………... 82

Model of the Paleofluid System Compared to Real-World Orogenic Fluid Systems………………………………………………………….……………...... 82

Critique of Studies...... 83

Future Work...... 85

REFERENCES…………………………………………...... 87

APPENDICES………………………………………………………………………….. 93

LIST OF FIGURES

Figure Page

Chapter 1:

1.1: Generalized illustration of a fluid system structure within an orogenic wedge from Pollyea et al. (2015)……….……………………………………………………………………….…. 3

1.2: Illustration of a doubly vergent orogenic wedge from Pollyea et al. (2015)..…………….…. 5

1.3: Physical models by Costa and Vendeville (2002) that illustrate the differing contractional orogenic wedge geometries and internal structures as a result of rock strength at the detachment…………………………………………………………………………………… 6

1.4: Numerical models by Pollyea et al. (2015) illustrating infiltrating meteoric water saturation for the 2o (α = 1o) and 10o (α = 9o) wedge models at time intervals ranging from 1 k.y. to 20 m.y. ………………………………………………………………………………………….. 8

1.5: Spatial distribution of groundwater residence time in years by Pollyea et al. (2015).….…… 9

Chapter 2:

2.1: Regional geologic setting and geologic map of the Monterrey Salient, Mexico (modified from Padilla Y Sanchez, 1982)………………………………………………….……….…. 12

2.2: Generalized stratigraphic column for the northwestern portion of the Monterrey Salient…. 13

2.3: Cross sections from Padilla y Sanchez (1982)……………………………………………....14

2.4: Image of flatiron structures located in the Monterrey Salient.………………….……….…. 18

2.5: Published regional cross sections through the La Popa Basin and the Monterrey Salient…. 20

2.6: Interpretations for the faulted area in the southern region of the Monterrey Salient along section A-A’………………………………………………………………………………... 21

2.7: Interpretations for the faulted area in the southern region of the Monterrey Salient along section E-E”………………………………………………………………………………… 22

2.8: Comparison of the southern portion of the Monterrey Salient according to Padilla y Sanchez (1982) and the geologic map from the Instituto Nacional de Estadistica Geografia y Informatica (INEGI).……………………………………..…………………… 23

vi Figure Page

2.9: Cross sections and restorations of cover sequences along section lines A, B and C……….. 25

2.10: Cross sections and restorations of cover sequences along section lines D and E…………. 26

2.11: Basic elements involved in the excess area section balancing method of Epard and Groshong (1993)..………………………………….…………..………………………….. 28

2.12: Idealized hinterland inflation and synclinal deflation detachment fold models modified from Wilkerson et al (2007) and Mitra (2003)..……………………………….....……….. 30

2.13: Diagram for determining depth to basement and orientation and location of faults.…...… 31

2.14: 3-D sketch of the basement faults in the Monterrey Salient, Mexico….…...…………..…. 33

2.15: Magnetic map (1:250,000 scale) of the Monterrey Salient edited from the Servicio Geologico Mexicano (SGM)..…………………………...………………………………....34

2.16: Cross sections with underlying salt and depth to basement from section lines A, B and C………………………………………………………………………………………. 36

2.17: Cross sections with underlying salt and depth to basement from section lines D and E….. 37

Chapter 3:

3.1: Geologic map of the Monterrey Salient modified from Padilla y Sanchez (1982).…...... 40

3.2: Geologic map of the Monterrey Salient modified from Padilla y Sanchez (1982) with stereonets representing the of bedding and veins for each station.…………. 41

3.3: Sequential stages of fracturing during the creation of the Monterrey Salient, edited from Fischer et al. (2009)..………………………………………………………….……………. 43

3.4: Representative SEM analysis of veins from the Monterrey Salient.……………………….. 44

3.5: Field photographs and photomicrographs of bedding-parallel veins in the Monterrey Salient at station A003..……………………...... 46

3.6: Field photographs and photomicrographs of strike-oblique veins in the Monterrey Salient at station A010..………………………...... 47

3.7: Field photographs and photomicrographs of cross-fold veins in the Monterrey Salient at stations A0001 and A005.………………………………………………………………….. 49

3.8: Photomicrographs of the three types of inclusions identified in my samples.……………... 51

vii Figure Page

3.9: Box and whisker plots of microthermometric data from 2-phase aqueous inclusions in quartz and calcite veins showing ice melting temperatures and salinity.…………………….……. 55

3.10: Box and whisker plots of microthermometric data from 2-phase aqueous inclusions in quartz and calcite veins showing homogenization temperature.……………..…………… 56

3.11: Isotopic analysis of δ13C and δ18O comparing and host rock values of each vein type….………………………………...…………………………………………………… 59

3.12: Isotopic analysis of δ13C and δ18O comparing vein and host rock values for each lithology.……….……………………..…………………………………………………… 61

3.13: Isotopic analysis separating the three different vein types bedding-parallel, strike- oblique, and cross-fold veins...……………………………………………………………. 62

3.14: Isotopic values of vein and host rocks for all vein types and lithologies, which are separated into groups according to location across the Monterrey Salient.….……...….…. 64

3.15: Isotopic analysis separating the UHU (Tamaulipas-Parras) and LHU (Zuloaga-Cupido) for bedding-parallel, strike-oblique, and cross-fold veins in both the hinterland and foreland.…...... 65

3.16: δ13C and δ18O (‰ PDB) values of calcite veins and their associated host rock...………… 67

3.17: Isotopic analysis separating the UHU (Cupido-Parras) and LHU (Zuloaga-La Casita) for bedding-parallel veins in both the hinterland and foreland.…………………...………….. 68

3.18: Ternary diagrams of relative abundance of Mn, Mg, and Fe elemental concentrations...... 70

18 3.19: Graph combining inferred vein precipitation temperature (Th) and δ O (‰ PDB) to calculate the δ18O (‰ SMOW) of vein-forming fluids…………………………………… 72

3.20: Generalized model of the evolution of the regional-scale paleofluid system within the Monterrey Salient, Mexico.……………………….………..……………………………... 76

3.21: Generalized model of the evolution of the paleofluid system within the Monterrey Salient.………………………….…………………………..……………………………... 77

LIST OF APPENDICES Appendix Page A: STABLE ISOTOPE ANALYSES……………………...……………………………………. 93 B: PHOTOMICROGRAPHS OF LA-ICP-MS SHOT LOCATIONS………………………….. 97 C: ELEMENTAL CONCENTRATIONS………………………………………………………104

CHAPTER 1:

INTRODUCTION

1. Geological Fluid Systems

A geological fluid system comprises a volume of rocks and the fluids that are generated in, contained in, and move through this volume. The generation, movement, and storage of these fluids result from mechanical and chemical interactions within the volume of rock, which are controlled by stratigraphical, lithological, and geochemical factors. These interactions have the ability to alter the physical characteristics of the system over time and when combined with the spatially heterogeneous nature of rocks can create geological fluid systems that exhibit complex spatially and temporally varying behavior and characteristics (Carter et al., 1990).

A geological fluid system can be modern or ancient. A modern fluid system involves fluids that exist in the rocks, such as fluids encountered during petroleum-industry drilling near a salt diapir (Evans et al., 1991) or during International Ocean Drilling Program (IODP) drilling in the

Nankai (Yamano et al., 1992; Saffer and Bekins, 1998), whereas paleofluid systems involve the movement or distribution of fluids that no longer exist or have long since migrated from the region. Both of these geological fluid systems can be described at small scales, where fluid migration and fluid-rock interactions occur over distances of centimeters to decameters, or at large scales, where fluids may migrate kilometers to hundreds of kilometers from the source. In the latter case many of the most important characteristics of the fluid system can be described by what Evans and Fischer (2012) described as the fluid system structure. 2

The fluid system structure is defined by the flow paths, fluid fluxes, and distribution of fluid types throughout a volume of rock (Figure 1.1). Flow paths relate to faults, joints, fractures, and the matrix porosity of rocks; fluid fluxes occur in response to heat and depth/pressure differences, whereas varying fluid types can reflect different fluid origins, such as meteoric, marine, hydrothermal, or formation waters. Various regional mesoscopic structures have the potential to affect fluid transport properties; specifically, folds and networks can act as conduits or barriers to fluid flow and control how fluids move and migrate through the system

(Sibson, 1981, 1996; Travé et al., 2000; Fischer et al., 2009). Fractures have the ability to allow for increased movement of fluids through a non-porous and impermeable layer, acting as pathways for different fluids to mix and create a homogeneous system. It is possible that, rather than conduits, these fractures could be filled with clay or impermeable materials and inhibit fluid movement in an otherwise porous and permeable unit. These barriers can influence fluid migration to the point that the fluids cannot combine with one another, creating heterogeneity within the system. A heterogeneous system has the capability to form separate reservoirs within individual structures that cannot interact with adjacent fluids, which is defined as compartmentalization

(Barclay et al., 2000; Lefticariu et al., 2005; Dewever et al., 2013). It is possible for the structure of a fluid system to change over time as a result of geological processes like burial, diagenesis, and deformation, resulting in an alteration of the fluid and rocks within the system. The fluid system prior to, during, and after these geological processes (e.g., pre-, syn-, and post-deformation) are likely to be different from one another and the study of how these systems evolved over time can be used to relate the fluid system structure to the distribution of fluids.

3

.

from Pollyea et al. (2015) al. et Pollyea from

Generalized illustration of a fluid system structure within an orogenic wedge orogenic an within structure system fluid a of illustration Generalized

igure 1.1: 1.1: igure

F The colors describe different fluid types and the arrows indicate the direction the flow. fluid indicate of arrows the different and fluid describe types colors The 4

Fluid migration is closely tied to exploration and discovery of hydrocarbons (Gussow,

1968), regional dolomitization (Bethke and Marshak, 1990), and ore deposits (Gu et al., 2012). As a result, knowledge of regional subsurface geology and the characteristics of the paleofluid system are necessary when assessing the occurrence of these economically important resources. Specific fluid systems, such as those in orogenic belts, are of significant interest to geologists as they pertain to large-scale migration of the fluids that play an important role in these geologic processes.

2. Orogenic Fluid Systems

A contractional orogenic belt is created in collisional settings where tectonic plates converge with one another. During this contractional event, layers of rock are detached, folded, and faulted, causing massive shortening of the region. The contraction and shortening creates uplift, forming mountain ranges that can exhibit varying internal structures and geometries. The foreland of these orogenic wedges (Figure 1.2A) has been studied extensively and research has been published on how the fluid system is affected by these varying internal structures and geometries (Pollyea et al., 2015).

The geometry of an orogenic wedge is defined by the taper angle, which is the angle of the surface slope (α) plus the angle of the detachment slope (β) (Figure 1.2). Orogenic wedges with small (i.e., < 2˚; Figure 1.2B) or large (i.e., > 4˚; Figure 1.2C) taper angles exhibit different internal structures, which are dependent on the strength of the rock at the detachment (Marrett and Aranda-

Garcia, 2001). Larger taper angles correspond to thick tapering wedges and are formed as a result of stronger rocks at the bottom of the wedge, which creates a -dominated internal structure

(Figure 1.3A). If the rock above the detachment is weak, such as shale or evaporites, then the taper 5

Region Enlarged Below

Figure 1.2: (A) Illustration of a doubly vergent orogenic wedge from Pollyea et al. (2015). Dashed box surrounds the foreland region that comprises the model domain for Figures 1.4 and 1.5. (B) Schematic, simplified 2-dimensional (2-D) geometry for a 2o critically tapering orogenic wedge. (C) Schematic, simplified 2-D geometry for a 10o orogenic wedge. Note that α refers to surface or topographic slope and β denotes the basal detachment slope. Note the extreme vertical

exaggeration. 6

Thinly Thinly tapering wedge

(B)

dominated internal wedge structure structure wedge internal dominated

-

Fault

(A)

dominated dominated internal structure when a good basal décollement is created as a result of weaker

-

etachment.

Physical Physical models by Costa and Vendeville (2002) that illustrate the differing contractional orogenic wedge

ger ger taper angle that is created when the underlying rock at the detachment is stronger.

lithologies at the d the at lithologies Figure Figure 1.3: detachment. the at strength rock of result a as structures internal and geometries with a lar geometry that exhibits a fold 7 angle is small, the wedge is thinly or narrowly tapered, and it has a more fold-dominated internal structure (Figure 1.3B). The geometry and internal structure of an orogenic wedge can play an important role in the distribution of fluids through the system (e.g., Pollyea et al. 2015).

Parameters controlling the magnitude of fluid flux and the pattern of fluid distribution in an orogenic wedge depend on interactions between topography, geothermal gradients, internal structure, and regional tectonic . It has been determined that the dominant factor for large-scale fluid migration is topography (Garven, 1995). Figures 1.4 and 1.5 show a set of models created by Pollyea et al. (2015) that illustrate how meteoric water flows through a fluid-saturated orogenic wedge that exhibits either thin or thick wedge geometry. Meteoric water percolates deeper into the subsurface in a thin tapering wedge (Figure 1.4A) compared to a thick wedge where the meteoric water penetrates very shallowly (Figure 1.4B). The residence time of the groundwater is much longer in the thin wedge compared to the thick wedge geometry (Figure 1.5), which is a result of the topographic relief. The reason for this is that the larger topographic relief in a thick wedge creates a higher hydraulic head gradient and therefore a higher regional-scale horizontal flow rate, whereas fluids in thin wedges have a more localized vertical flow with limited horizontal flow. Although these numerical models provided a better understanding of how regional-scale wedge geometry and topography affect the distribution and movement of fluids, they ignore the potentially significant role of internal wedge structure.

The presence of complex internal structures such as kilometer-scale faults and folds can act as either conduits or barriers that control how fluids are distributed through the region (Sibson,

1981; Hickman et al., 1995; Travé et al., 1997, 2000; Fischer et al., 2009). In thick wedges, the presence of faults creates a network of conduits or barriers that can improve or impede regional- 8

Figure 1.4: Numerical models by Pollyea et al. (2015) illustrating infiltrating meteoric water saturation for the 2o (α = 1o) and 10o (α = 9o) wedge models at time intervals ranging from 1 k.y. to 20 m.y. Models with saturation of 1.0 have all pore spaces completely filled with meteoric water.

9

Figure 1.5: Spatial distribution of groundwater residence time in years by Pollyea et al. (2015). (A) Residence time for 2o critically tapering wedge (α = 1o). (B) For the 10o (α = 9o) wedge. These models represent groundwater residence time after 20 m.y. of simulation time. Note that water flushes relatively rapidly through the upper kilometer of the wedge. 10 scale fluid movement (Fitz-Diaz et al., 2011, 2012). For thinly tapered orogenic wedges, it is known that the lack of regional-scale faults causes the fluids to utilize smaller scale fracture networks as preferred flow pathways (Janssen et al., 2007), but much less is known about the effect of map-scale folds on the pattern of fluid flow and the distribution of fluid. Understanding how the distribution of fluid is affected by the internal structure in an orogenic wedge is important because it impacts our ability to predict the location of ore, mineral, and hydrocarbon accumulations. Because we know very little about the manner in which map-scale folds within a fold-dominated orogenic wedge affects the overall distribution of fluids within such wedges (e.g.,

Fischer et al., 2009; Evans and Fischer, 2012; Pollyea et al., 2015), it is useful to collect data that constrain the first-order fluid system structure in these areas.

The purpose of this thesis is to determine the regional and fluid system characteristics in a narrowly tapering orogenic wedge to test the hypothesis that map-scale folds cause compartmentalization of the fluid system. This hypothesis is tested by completing two sets of research tasks, one of which is to determine the regional-scale structural geometry along a transect across the Monterrey Salient in northeastern Mexico by creating new, balanced cross sections. The second task is to determine the characteristics and distribution of paleofluids across the orogen using geochemical analyses of veins and host rocks. The cross sections provide a better understanding of the regional structural geometry, whereas mineralogical, isotopic, and elemental analyses are used to identify the characteristics of the vein-forming fluids. Compartmentalization of the paleofluid system will be implied by correlations among fluid types and map-scale structures.

CHAPTER 2:

REGIONAL-SCALE STRUCTURAL ANALYSIS OF THE MONTERREY SALIENT

1. Geologic Setting

The Monterrey Salient is located in northeastern Mexico, southwest of the city of

Monterrey (Figure 2.1). The salient is part of the Sierra Madre Oriental (SMO), an orogenic belt created during the Laramide . The SMO contains a 5,000 m thick sequence of upper

Jurassic to early Tertiary carbonates, calcareous shales and sandstones (Figure 2.2) above a unit of evaporates in which the pre-deformation thickness is estimated at ~1,000 m (Goldhammer et al.,

1991). Triassic, Paleozoic, and Precambrian crystalline basement rock underlies this sequence of sedimentary strata and consists of a variety of schists, gneisses, and intrusive rocks (Wilson et al.,

1984; Wilson, 1990; Marrett and Aranda-Garcia, 1999). During the Laramide Orogeny, the compressional stresses applied to this region resulted in a series of detachment folds with wavelengths between 4-8 km and trending in a NW to SE orientation (Figure 2.3). This 80 km fold train is void of any significant regional-scale faults.

As stated in Chapter 1, the strength of the rock at the detachment has an overall effect on the taper angle and internal structure of a contractional orogenic wedge. The weak evaporites at the base serve as an effective basal décollement, creating a thin tapering wedge with minimal faulting. Thick tapering wedges will not only produce more faults but will also allow for more shortening in the region compared to thin tapering wedges. Previous work has constrained the 12

Figure 2.1: Regional geologic setting and geologic map of the Monterrey Salient, Mexico (modified from Padilla y Sanchez, 1982). Lines A and E on the map coincide with cross sections E and D respectively in Figure 2.3. Section lines B, C, and D were used for the new sections that were created and shown in Figures 2.9, 2.10, 2.16 and 2.17. 13

Figure 2.2: Generalized stratigraphic column for the northwestern portion of the Monterrey Salient. Modified from Higuera-Diaz et al. (2005). 14

. . Also, the fault present in this area cutting

is the only is unit the only that is the present between two

anticline

anging anging wall. B) The second problem area where the

cio

Section Section E corresponds to section line A in Figure 2.1 and cross

an unrealistic geometry. The stratigraphy as well as the basement rock is is rock well basement as the as stratigraphy The geometry. unrealistic an

try.

acklimb acklimb of the Mauri

b

s creates s

to to the

anticline anticline

subsurface subsurface geome

lausible

), ), which is the Shale Parras equivalent in (Kpa 2.2),Figure

Cross sections from Padilla y Sanchez (1982).

:

across the Zuloaga and La Casita Formation Casita and La Zuloaga the across Figure Figure 2.3 section D corresponds to section line E. A) Problem 1,area where the thickness of the Cupido Formation is doubled from the forelimb of the San Cristóbal not interpreted in the subsurface, as seen by the empty space in Mendez Shale (Km the h imp an creating faults 15 shallow structural geometry of the Monterrey Salient and the adjacent regions (Padilla y Sanchez,

1982; Johnson et al., 1991; Marrett and Aranda-Garcia, 1999); however, the deeper basement geometry and any potential subsurface faulting have largely been left uninterpreted because of a lack of seismic, well, magnetic or gravity data to constrain it (Figure 2.3). The aim of this chapter is to use modern techniques of cross section balancing and restoration to develop a coherent, model-driven interpretation of this deeper structural geometry. These techniques are commonly referred to as regional-scale “structural analysis.”

2. Rationale and Methodology for Building New Cross Sections

Cross sections provide a valuable view of the subsurface geology, but they must always be recognized as interpretations. Because the subsurface data (magnetics, seismic, gravity, wells, etc.) in the Monterrey Salient are extremely limited, cross sections through the region are highly speculative. This lack of data enables a wide range of geometries/subsurface structures to be constructed, all of which might honor the existing surface constraints provided by published geological maps. Structural analysis is a set of techniques that enable us to limit the number of viable subsurface interpretations that can be made for any given cross section. Cross sections constructed with these techniques are defined as “balanced” sections. In order for a cross section to be considered balanced, it must satisfy two criteria (Marrett and Aranda-Garcia, 1999). The cross section must be (1) admissible, meaning the subsurface structure should have geologic structures and features that are commonly observed within that region, and (2) viable, which means that it must be possible to restore the cross section to an undeformed state that is geologically plausible at all stages of deformation. 16

Padilla y Sanchez (1982) constructed the most extensive and widely cited cross sections through the Monterey Salient (Figure 2.3). However, even a cursory structural analysis of these sections reveals that many of them have aspects that are neither viable nor admissible. Examples of inadmissible features include unlikely thickness changes between fold limbs, unrealistic fault geometries, and inconsistent or missing stratigraphic units. The thickness of many units drastically changes across some sections, and some sections do not accurately reflect the strike and dip data or contacts that appear on the most recent geological maps. An example of the unrealistic thickness change occurs in section D (Figure 2.3B), where fold limbs are dipping near 30o but should be sub-horizontal (~0o). A consequence of this inaccuracy is that stratigraphic thicknesses are locally almost twice what they are reported in the literature (Goldhammer et al., 1991; Fischer et al., 2009).

The faults in these sections are geologically implausible because the faults cut through the folds in a way that would suggest folding occurred substantially before faulting; there is no evidence that this occurred and regional structural histories agree that these structures formed coevally (Rowan,

1997; Fischer et al., 2009). Moreover, according to Mitra (2003), faulting in detachment folds is secondary to folding, which typically activates in order to accommodate local variations in strain.

Additional admissibility and viability problems in the Padilla y Sanchez (1982) sections include the fact that the sections have incomplete subsurface interpretations and the violation of standard kinematic and geometric rules for fold and thrust belts (Chapple, 1978; Hossack, 1995).

In the former case, the bottoms of the sections do not include the basement rock or the salt underlying the carbonate sequence. Some of these sections also fail to include certain stratigraphic units in the subsurface, which creates missing segments when the sections are restored to an undeformed state. Another example of this type of problem is found in Section D (Figure 2.3B), 17 where the unit Km is separated by faults to the north and south. This is implausible for many reasons, the most important of which being that the thickness of Km in this section does not match the stratigraphic thicknesses locally calculated from the geological map or in published stratigraphic columns. An example of the latter problem is that younger rock is locally thrusted over older rock. This geometry not only contradicts the basic “older over younger” faulting kinematics known for fold and thrust belts worldwide but is also only possible if Km is present in the subsurface in the footwall, something that is highly unlikely. To fix the problem areas associated with Padilla y Sanchez’s (1982) cross sections, I edited and revised sections E and D and created three new sections between the two.

My constraints for my structural analysis include the current geologic maps (from 1:50,000 to 1:250,000 scale) created by the Instituto Nacional de Estadistica Geografia y Informatica

(INEGI), the geologic map (1:200,000 scale) and cross sections created by Padilla y Sanchez

(1982), a 90 m digital elevation model (DEM) of the region, and 1 m resolution satellite imagery in Google Earth™. I incorporated strike and dip data from the geologic map, obtained representative thicknesses of each unit from published stratigraphic columns (Higuera-Diaz et al.,

2005), and generated new thickness and orientation data from the satellite imagery and DEM. To determine bedding orientations, I used Google Earth™ to identify flatiron features (Figure 2.4A) and perform classic three-point problems on these structures to calculate strike and dip of the unit forming the flatiron (Figure 2.4B). Flatirons within the Monterrey Salient were scarce and limited to specific units, such as the Cupido Fm. Therefore, the amount of data collected was extremely limited and left a few areas with almost no constraints on unit orientations. Regional gravity and magnetic intensity maps (1:250,000 scale) published by INEGI were used as a first-order check 18

Figure 2.4: A) Image of flatiron structures located in the Monterrey Salient. B) Using a standard three-point problem approach to calculate the local strike and dip along an example flatiron as seen in Google Earth™ imagery (see text for explanation).

19 on the interpreted depth to basement and the thickness of the Minas Viejas evaporates.

3. Subsurface Faulting: Abundance, Slip Sense and Geometry

A lack of mapped faults in the Monterrey Salient, as well as changes in the mapping itself, have led to different interpretations of subsurface faults throughout the region (Figure 2.5). Marrett and Aranda-Garcia (1999) drew a cross section of the Monterrey Salient that showed blind faults coring many of the regional detachment folds (Figure 2.5B). Other cross sections dismiss the idea of such blind faults and interpret the regional folds as box-style detachment folds that lack any such faults (Figure 2.5C; De Cserna, 1956). In the face of limited subsurface constraints, I chose to abide by Occam’s Razor and did not include substantial, blind, subsurface faulting in my cross sections.

Subsurface interpretations of the geometry of mapped faults in my cross sections were straightforward at the foreland, but near the faulted areas in the hinterland, the complexity increased. In the course of dealing with this complexity, I created four different interpretations for this region (Figures 2.6 and 2.7). Interpretation #1 presents geometries derived from Padilla y

Sanchez’s (1982) geologic map and cross section (Figures 2.6A and 2.7A). For interpretation #2,

I altered the dip and sense of slip of some of the faults in order to create a simpler, balanced interpretation that still honors the surface data (Figures 2.6B and 2.7B). According to the regional geologic map from INEGI (Figure 2.8), the unit in between two major faults is interpreted to be the Jurassic La Casita Formation rather than the Cretaceous Parras Shale (Méndez Shale or Km equivalent, as shown in Figure 2.2), so interpretation #3 makes this change and alters the orientation of the faults to correct for this stratigraphic inconsistency (Figure 2.7C). The INEGI geologic map also interprets one fault as a strike-slip fault rather than a reverse fault, so 20

A

C

B

Garcia (1999); C) De Cserna (1956). (1999); De C) Garcia

-

Published regional cross sections through the La Popa Basin (A) and the Monterrey Salient (B&C). Sections (B&C). Salient Monterrey the and (A) Basin Popa La the through sections cross regional Published

Figure 2.5: Figure and Marrett Aranda (2001); al. et Gray B) A) from: 21

Figure 2.6: Interpretations for the faulted area in the southern region of the Monterrey Salient along section A-A’ (see section A-A’ in Figure 2.9 for the location of this region). A) Following the locations, orientations, and styles of the faults from Padilla y Sanchez’s (1982) geologic map. B) Altering the direction and slightly altering the outcrop location of the faults in Padilla y Sanchez’s (1982) geologic map. C) Changing the unit between the two faults from Km to Jlcs according to INEGI’s geologic map (Figure 2.12). Fault numbers in each figure correspond to the faults labeled in Figure 2.10. Note that the restored sections are presented at 1/2 the scale of the deformed sections. The red box in Figure 2.9 represents the area of the faulted region that was interpreted. 22

Figure 2.7: Interpretations for the faulted area in the southern region of the Monterrey Salient along section E-E” (see section E-E” in Figure 2.10 for the location of this region). A) Following the locations, orientations, and styles of the faults from Padilla y Sanchez’s (1982) geologic map. B) Altering the direction and slightly altering the outcrop location of the faults in Padilla y Sanchez’s (1982) geologic map. C) Changing the unit between the two faults from Km to Jlcs according to INEGI’s geologic map (Figure 2.12). Fault numbers in each figure correspond to the faults labeled in Figure 2.10. Note that the restored sections are presented at 1/2 the scale of the deformed sections. 23

the the

gure 2.11. gure

Box 1 in A and B encompasses

alient alient according to A) Padilla y Sanchez (1982) and B) the

the location used for the sections the in Fi location the for used

encompasses

thern portion of the Monterrey S

e 2.10 and and 2.10 e Box 2

the the sou

in Figur in

Comparison of

used for the usedfor sections

geologic geologic map from the Instituto Nacional de Estadistica Geografia y Informatica (INEGI). area Figure 2.8: 24 interpretation #4 changes the style of the fault according to this map (Figure 2.6C). Due to the simplicity and viability of each section, I have chosen interpretation #2 (Figures 2.6B and 2.7B) as my preferred interpretation. The sections created using this interpretation are Figures 2.9 and

2.10, which include Padilla y Sanchez’s revised sections (Section A in Figure 2.9 and Section E in

2.10) and the three new sections between the former two (B, C, and D in Figures 2.9 and 2.10). To emphasize my interpretation of the geometry of folding and minor mapped faulting in the

Monterrey Salient, these figures present only the deformed and restored geometry of rocks above the Minas Viejas evaporites (i.e., the cover sequence). In the following section I discuss how I developed my interpretation of the rocks beneath the cover sequence.

4. Constraining Basement and the Depth to Detachment

The basement in a contractional orogenic belt is that portion of the stratigraphic column above which substantial shortening occurs. The rocks overlying the basement are detached from the underlying rocks, and the position of this detachment is critical to unraveling the geometry of any or fold belt. The few published cross sections through the Monterrey

Salient differ dramatically on the interpreted depth and structure of the basement rock underlying the salt. Some workers interpreted that the basement rock is an irregular, continuous boundary

(Figure 2.5C; De Cserna, 1956); others interpret the top of basement as a subhorizontal surface that locally dip towards the foreland (Figure 2.5B; Marrett and Aranda-Garcia, 1999), and yet others interpret that the regional basement, including that in the adjacent foreland, is divided into a series of horsts and (Figure 2.5A) created during the opening of the Gulf of Mexico, otherwise known as GoM (Gray and Johnson, 1995; Gray et al., 2001; Latta and Anastasio, 2007).

25

ntal ntal and vertical scales are equivalent in

Horizo

section A, and lines 2.1 C (see B for section Figure

of of coversequences along

). Fold names above each section are from Padilla y Sanchez (1982). Note that the the that Note Sanchez (1982). Padilla fromy are section each namesabove Fold ). Area restored in Figure 2.6 Figure in restored Area

2.6. for restored Figure that and interpreted box region the was red represents The

Crosssections restorations and

Figure 2.9: 2.9: Figure symbolsstratigraphic the and locations restored sections are presented at 1/2 the scale of the deformed sections. sections. all

26

ox ox represents the region that was

The The red b

section lines D and E (see Figure 2.1 for section

of cover sequences along

symbols). Fold names above each section are from Padilla y Sanchez (1982). Note that the Sanchez the that Note (1982). Padilla from y section are each names above Fold symbols).

Area restored in Figure 2.7 Figure in restored Area

Cross sections and restorations

0:

Figure Figure 2.1 stratigraphic the and locations restored sections are presented at 1/2 the scale of the 2.7. for restored Figure and interpreted deformed sections.

27

The most current agreed-upon hypothesis interprets that basement is largely subhorizontal but dissected into a series of features that were created during rifting of the GoM and potentially reactivated and inverted as reverse faults during the Laramide orogeny (Gray et al.,

2001). With this conceptual model in mind, it is then necessary to constrain the depth to the top of basement. Doing so will simultaneously constrain the thickness of the evaporates in the Minas

Viejas Formation, identify the depth of the detachment, and suggest the location of faults that offset basement.

Initially, Epard and Groshong’s (1993) method of depth to detachment calculations was used to constrain the elevation of the detachment zone in the study area. This method is based on the fact that there is a relationship between a unit’s original, undeformed height above the detachment (h) and the excess area (S) above that regional level after deformation (Figure 2.11).

In the absence of a known depth to detachment, an arbitrary, horizontal reference line can be drawn. The measurements of elevation can be made from the reference line and combined with the excess area, the result of which is a single line with the equation:

S = Dh + Sa. (1)

If the line intersects the origin (Sa = 0), then the depth of the arbitrary reference level is the location of the detachment (Figure 2.11B), but if the line does not intersect the origin (Figure 2.11D), then the reference level must be either shallower or deeper than the detachment. The precise elevation of the detachment is determined wherever the line in equation (1) intersects the h axis, or where the excess area is zero. The elevation of the true detachment is calculated by finding the distance between the origin and the point of intersection where S = 0. If the line intersects the negative side of the h axis, then the true detachment will be below the arbitrary reference line, but if it intersects

28

Figure 2.11: Basic elements involved in the excess area section balancing method of Epard and Groshong (1993). A) An example cross section that illustrates the relationship between the displacement (D) and excess area (S1 and S2) created when an area-constant anticline is deformed by layer parallel shortening above a horizontal detachment surface. Note that the units comprising the fold are pinned at both ends, meaning that material cannot move through the pin lines and out of the section. The structure is presumed to form under plane strain conditions. B) Excess area diagram: excess area plotted vs. depth to detachment. The slope of the line through the data points is the displacement on the detachment. C) Cross section of excess area balance with an unknown depth to detachment. Depth measurements are made from an arbitrary, horizontal reference level. D) Excess area diagram: the slope of the line through the data points is the displacement of the detachment and the depth of the reference level Sa. The intercept of the h axis (Excess area = 0) is the depth of the true detachment below the reference level.

29 the positive portion of the h axis, the true detachment lies above that reference line.

A problem arises when using the Epard and Groshong (1993) method to calculate the depth to detachment in the Monterrey Salient because it relies on knowledge of where the datum level is before deformation (i.e., what is h for each stratigraphic unit?). As shown by Mitra (2003) and

Wilkerson et al. (2007), in areas with thick evaporites as the detachment horizon, it is possible that as the were being formed, the datum levels underlying adjacent synclines were repositioned as a result of either hinterland inflation, synclinal deflation, or fold rotation (Figure

2.12). The combined effects of each of these processes in the Monterrey Salient are suggested by the fact that standard depth to detachment calculations yield inconsistent geometries between each cross section, produce an implausible amount of displacement at each fault, or generate an implausible amount of salt underneath some parts of the sections (e.g., a 14 km local depth to detachment). As a consequence, I deemed the Epard and Groshong (1993) method unusable in my area and instead chose to constrain the depth to detachment by assuming that the troughs of the synclines are grounded to the top of the basement. This means that as the synclines were forming, the salt was being pushed into the area created by the adjacent anticlines, allowing for the fold to sink; the fold then continued to sink until it reached the top of basement. Numerous studies of salt and seismic lines through salt-detached folds have suggested that this is a viable assumption (Letouzey et al., 1995; Mitra, 2003; Rowan and Vendeville, 2006).

Figure 2.13 shows the steps I used to interpret the basement geometry and structure.

Initially the top of the basement was drawn under the trough of the under the assumption that the synclines were grounded at the basement (Figure 2.13B). These boundaries were drawn horizontally and ended close to the hinges of the adjacent anticlines. Next, a moderately dipping

30

Figure 2.12: Idealized hinterland inflation and synclinal deflation detachment fold models modified from Wilkerson et al. (2007) and Mitra (2003). A) Hinge migration depicting the increased elevation of the hinterland from its original datum level. B) Fold rotation causing both hinterland inflation and foreland deflation. C) Synclinal deflation where the units sink below their regional datum level in order to compensate for the excess area above the anticline that is much higher than the shortened area. Solid arrows represent displacement (D) of each block, which influences the excess area (S) for the inflated and deflated regions. Dashed arrows indicate in which direction the incompetent material migrated during folding.

31

Figure 2.13: Diagram for determining depth to basement and orientation and location of faults. A) Image of Arteaga-S.J.B. and San Lucas anticlines in cross section A-A’. B) Top of basement is placed at the trough of each syncline. C) Basement blocks are connected by a moderately dipping normal fault. The fault locations for each cross section are changed slightly to create a 3-D surface that shows a simple and realistic geometry and orientation (Figure 2.9)

32 normal fault connected these two different basement blocks (Figure 2.13C). There is no direct evidence that suggests any of these faults were reactivated, so only normal displacement is shown.

The faults are interpreted to be normal faults that formed during the rifting of the GoM as suggested by Gray et al. (2001). To create a plausible 3-D interpretation of the entire salient, individual faults in each cross section were extended along strike and connected in a manner that produced plausible along-strike displacement gradients and slip magnitude (Figure 2.14). Because basement steps are well-established nucleation points for salt anticlines (Trudgill, 2011), faults were drawn subparallel to the trend of the overlying folds. The amount of slip for each fault was constrained by the depth of the syncline where the basement was drawn. In some cases, plausible 3-D fault displacements could only be obtained by slightly tilting the basement surface or adjusting the depth of a syncline (e.g., fault 1 in Figure 2.14 decreasing in displacement to the west).

After completing my interpretation of the top of basement and the position and displacement of basement normal faults throughout the salient, there seemed to be a correlation between the fault surface and the vergence of the folds. For each fold in my sections, the vergence of the folds seemed to be in the same direction as the dip of the fault. Interestingly, this characteristic was not purposely built into the sections; it arose organically as a consequence of the balancing constraints and assumptions I employed. It is possible that the geometry of the folds was shaped by the presence of these basement faults, though the validity of the basement fault geometry needs to be confirmed through additional data.

Regional magnetic data provide a useful, independent check on the depth to basement throughout the Monterrey Salient. Figure 2.15 is a portion of a 1:250,000-scale magnetic intensity map, from the Servicio Geologico Mexicano (SGM), that covers the Monterrey Salient. This map

33

location

the in placed is A’ -

D sketch of the basement faults in the Monterrey Salient, Mexico. Cross section A section Cross Mexico. Salient, Monterrey the in faults basement the of sketch D

-

3

Figure 2.14: Figure 2.17. and 2.16 seen Figures in faults the faults basement the by represent Numbers line. section its of

34

Figure 2.15: Magnetic map (1:250,000 scale) of the Monterrey Salient edited from the Servicio Geologico Mexicano (SGM). Units are represented in nanoteslas. Lines represent sections A and E from Figure 2.1. Section lines A-A' and E-E' are respectively shown in Figures 2.16 and 2.17.

35 shows magnetic low values in the southern portion of the region, which can be due to either a lower basement depth compared to adjacent areas or an excess of weakly magnetic material such as salt. According to my cross sections, the low magnetic anomaly on the map coincides with a graben in my sections (Figure 2.14 between faults 2 and 3) that has a deeper depth to detachment and a slightly thicker amount of salt.

5. Synthesis

Figures 2.16 and 2.17 show my preferred, final, balanced sections through the Monterrey

Salient. These sections are an improvement over existing published sections because they are viable and admissible and because they follow Occam’s Razor and include the simplest interpretation that can be made with the available data. Faults in the sections are coeval with folding (Mitra, 2003) rather than post-dating folding. The sections restore to reasonable geometries, actually depict the geometry of the basement, and interpret local thickness changes in the El Chorro and San Antonio anticlines as a result of structural thickening, rather than regional stratigraphical thickening. This means that stratigraphic thicknesses across the region are nearly constant and that the observed, dramatic local thicknesses changes in some units are a result of structural thickening that is concentrated in the highly deformed and overturned limbs of some folds.

Although I have created several interpretations for this area, there are an infinite amount of possibilities that include subsurface faulting, disharmonic folding, and slightly modifying the locations, orientations, and styles of the regional-scale faults. The subsurface geometry of my cross sections are dependent on the surface data at my disposal, so further data could better constrain

36

and C (see Figure 2.1 for for 2.1 Figure andC (see

,

Cross sections with underlying salt and depth to basement from salt to basement depth B A, Crosslines sections section and with underlying

Figure 2.16: Figure section (1982). from each Sanchez Padilla above symbols). Fold are the names y and locations stratigraphic section in the found by be Numbers 2.10. sections faults Figure these in cover the can basement for sequences Restorations 2.14. seen Figure in faults the represent

37

these these sections can be found in Figure 2.10. Numbers by the basement faults

in in

the the cover sequences

Cross sections with underlying salt and depth to basement from section lines D and E (see Figure 2.1 for

:

Figure Figure 2.17 section locations and the stratigraphic symbols). Fold names above Restorations each for section are from Padilla y Sanchez (1982). 2.14. seen Figure in faults the represent

38 the geometry of this orogenic wedge. The overall use of these sections in this thesis is to compare paleofluid characteristics with individual structures to see if deformation played an important role in fluid distribution.

CHAPTER 3:

PALEOFLUID SYSTEM STRUCTURE IN THE MONTERREY SALIENT

1. Introduction

It is well established that mechanical and chemical interactions between fluids and rock can affect the generation, movement, and storage of subsurface fluids (Evans, 2010; Fitz-Diaz et al., 2011; Evans and Fischer, 2012). Over time, these processes have the ability to alter the physical characteristics of the geological fluid system, causing it to exhibit complex, spatially and temporally varying behavior. The objective of this chapter is integrate field observations with regional structural analysis and geochemical analyses of veins and host rocks to characterize the spatial and temporal variation of paleofluids across the Monterrey Salient. Because of the size of this region and the limitations of my data, I focus on regional-scale differences across the entire salient and among different stratigraphic units. Samples and field observations were collected from 28 stations by Mark P. Fischer and Adam P. Smith in 2008 (Figures 3.1 and 3.2). Although these stations are widely and irregularly distributed across the salient, they nevertheless provide a coarse constraint on the characteristics of the regional fracture network and paleofluid system.

Here I present a summary of the unpublished observations of Fischer and Smith as well as my own petrographic, microthermometric and geochemical analyses of calcite and quartz veins and the corresponding host rock samples they collected.

40

). The points on the map represent map the on points The ).

2

ed from Padilla y Sanchez (198 Sanchez y Padilla from ed

fi

alient modi alient

collected for this for collected project.

sampleswere

Geologic map of the Monterrey S Monterrey the of map Geologic

:

stations where stationswhere

Figure 3.1 Figure the

41

Veins

Bedding

with stereonets

)

2

ed ed from Padilla y Sanchez (198

fi

alient modi S

Geologic map of the Monterrey

2:

representing the strike and dip of bedding and veins for each station. each veins for and bedding strike and of dip the representing Figure Figure 3.

42

2. Mesoscopic and Microscopic Characteristics of Fractures and Veins

At each of their 28 field stations, Fischer and Smith described the local lithostratigraphy; the structural and stratigraphic position of the station; and the orientations, dimensions, abundance, and relative timing of veins and unmineralized fractures. They interpreted that fracturing occurred in three stages throughout the region and divided the different stages into groups of bedding- parallel, strike-oblique, cross-fold, and strike fractures (Figure 3.3). This result was compatible with the timing determined by Higuera-Diaz et al. (2005) and Fischer et al. (2009) for the Nuncios

Fold complex in the northwestern part of the Monterrey Salient.

A total of 50 thin sections were made from the host rock samples and veins that were collected by Fischer and Smith. This sample set included veins precipitated in each of the fracture types from the three stages of fracturing in the Monterrey Salient. In each thin section I made petrographic observations to characterize the mineralogy, paragenesis, microstructure, and deformation (kinematics) of the veins. I subsequently used SEM analyses to check my petrographic interpretations (Figure 3.4) and confirmed that calcite is the major vein mineral within each station dominated by carbonate host rock, whereas quartz is the dominant vein mineral in the quartz sandstones of the La Casita Formation. Cloudy, inclusion-rich quartz is a minor component in many of the carbonate-hosted veins, and much of the calcite is extensively twinned

(Figure 3.5B).

2.1 Bedding-Parallel Fractures and Veins

Cross cutting relations with other vein types show that bedding-parallel fractures (Figure

3.3A) are the oldest structures in each outcrop and are interpreted to have formed during early

43

Figure 3.3: Sequential stages of fracturing during the creation of the Monterrey Salient, edited from Fischer et al. (2009). (A) Bedding-parallel fractures formed during early flexural slip. (B) Strike-oblique fractures form as a result of early to intermediate fold shortening accompanied by down-dip extension. Bedding-parallel veins also continue to form during this time. (C) Cross-fold fractures forming during intermediate to late hinge-parallel extension and fold flattening. Faults and zones like those in stage 2 continue to form during this time, and some bedding-parallel fractures are reactivated from shearing.

44

Figure 3.4: Representative SEM analysis of veins from the Monterrey Salient. A) Typical element spectrum taken from the bedding-parallel vein of sample A014.1 showing peaks representing elements comprising the vein crystals. Peaks at the atomic mass of C, O, and Ca confirm that these veins are made of fairly pure calcite. B) Element spectrum taken from the cross-fold vein of sample A005.1 from the La Casita Formation. Peaks at the atomic mass of Si confirm that these veins are made of quartz. Backscatter images with element maps of calcite and quartz crystals for C) A004.1 and D) A018.1 showing the generally uniform concentration of elements for each crystal. Figure 3.1 can be used for the station location of each sample.

45 stages of deformation as a result of flexural slip between layers (Suppe, 1983; Fischer et al., 2009).

Veins that formed in these fracture types were seen in all stratigraphic units except the Zuloaga

Formation. These veins vary in thickness from 1 to 5 cm and can be traced a few meters across the outcrops (Figure 3.5A). These veins have an abundance of sparry calcite and finely crystalline quartz that have blocky textures (Figure 3.5B&C). The SEM analyses confirm that these veins consist of both quartz and calcite, though the abundance of calcite is significantly greater (~80% or more calcite). According to petrographic analyses, calcite grains in these veins can be heavily twinned with either 1 or 2 directions of twinning. Some samples have no significant twinning of the calcite grains (Figure 3.5C), suggesting that multiple generations of precipitation had occurred.

Most vein samples usually contain one or two generations of calcite precipitation. Quartz is uncommon in these vein types, though the abundance ranges from 5-40% throughout individual samples. The quartz is seen to almost always postdate the calcite in every sample (Figure 3.5D), where the quartz is seen to fill within voids or open spaces within the calcite crystals. In some cases, co-precipitation of the quartz and calcite is observed (Figure 3.5C), where the grain boundaries are smooth and straight, indicating these crystals formed at similar times.

2.2 Strike-Oblique Fractures and Veins

Strike-oblique fractures (Figures 3.3B and 3.6) are interpreted to have formed during the intermediate stages of deformation and occasionally formed coeval with stage 3 (i.e., cross-fold) fractures. Fractures during this stage were restricted to more competent rock units such as limestones in the Cupido Formation or sandstones in the La Casita Formation. The veins within these fractures have an aperture of 0.5 – 5 cm, measure 1-3 meters in length, and show sparry

46

Figure 3.5: Field photographs and photomicrographs of bedding-parallel veins in the Monterrey Salient at station A003. A) Field photograph of bedding parallel veins in the Monterrey Salient at station A003 with a coin for scale. B) Photomicrograph of the texture of calcite in bedding parallel veins taken from sample A003.1. C) Photomicrograph of Sample A003.1 that shows twinned and untwinned calcite along with co-precipitation of quartz. D) Photomicrograph of sample A003.2 that shows initial precipitation of calcite followed by quartz. Refer to Figure 3.1 to find the location of station A003.

47

Figure 3.6: Field photographs and photomicrographs of strike-oblique veins in the Monterrey Salient at stations A010. A) Field photograph of strike-oblique veins in the Monterrey Salient at station A010 with a field book for scale. B) Photomicrograph of the texture of twinned and untwinned calcite and quartz in strike-oblique veins taken from sample A010.1. Also note the smooth boundary between the quartz and calcite grains indicating co-precipitation. C) Photomicrograph of a strike-oblique vein, sample A010.1, which shows later stage precipitation of quartz in the voids of the calcite. Refer to Figure 3.1 to find the location of station A010.

48 calcite and finely crystalline quartz with blocky textures (Figure 3.6A&B). The calcite grains are similar to those in the bedding-parallel veins and generally show evidence for the precipitation of the calcite followed by precipitation of quartz (Figure 3.6C). The amount of quartz in these veins is slightly greater compared to bedding-parallel veins, reaching roughly 15-50% of vein volume in some samples. Though samples usually show calcite precipitating earlier, there is some evidence of co-precipitation with the quartz and calcite (Figure 3.6B).

2.3 Cross-Fold Fractures and Veins

Cross-fold fractures (Figure 3.3C) are interpreted to have formed during the later stages of folding and occasionally overlap with strike-oblique fractures. Veins within these fractures are composed of blocky to tabular quartz and calcite and range from 1 to 10 cm in thickness and a few meters in length (Figure 3.7A&B). The composition of these veins correlates with the composition of the corresponding host rock, where samples in the quartzose portion of the La Casita Formation can consist of >85% quartz (Figure 3.7C). Some rare samples (e.g., Sample A005.1) have a small percentage of feldspar (< 5%) in addition to the large amount of quartz (Figure 3.7D). In contrast, samples from the Cupido Formation., Tamaulipas Formation., Zuloaga Formation and Parras Shale are dominantly calcite (>80% calcite; Figure 3.7E). Except for veins that have an abundance of quartz, calcite is precipitated first, followed by minor amounts of quartz, though some co- precipitation of quartz and calcite is seen in a few samples (Figure 3.7F). Samples such as A004

(Figure 3.7E) show the juxtaposition of different generations of calcite crystals, suggesting several stages of opening and closing events leading to multiple precipitation episodes.

49

Figure 3.7: Field photographs and photomicrographs of cross-fold veins in the Monterrey Salient at stations A0001 and A005. A) Field photographs of cross-strike veins in the Monterrey Salient, as exposed in the La Casita Formation at A) station A005 and B) station A001. C) Photomicrograph of quartz grains in cross fold vein sample A005.2 against the host rock of the La Casita Formation. D) Plagioclase feldspar within a cross-fold vein of the La Casita Formation in sample A005.1. E) Example of calcite in a cross-fold vein from the Zuloaga Formation that exhibits multiple stages of precipitation events as seen by the juxtaposition of different generations of calcite crystals. F) Cross-fold vein in the La Casita Formation that exhibits co-precipitation of quartz and calcite. Refer to Figure 3.1 to find the location of station A001 and A005.

50

3. Fluid Inclusion Microthermometry: Methods and Results

I performed microthermometric analyses on fluid inclusions in my vein samples to constrain the paleofluid temperatures and salinities at different stages of vein growth between the hinterland and foreland of the Monterrey Salient. Eleven vein samples were cut and polished into

100-200 µm thick sections and examined for fluid inclusions on a Linkam THMSG600 heating- freezing stage connected to a Meiji MT9900 polarizing microscope.

For each sample, I first identified groups of fluid inclusions that were formed at the same time (i.e., fluid inclusion assemblages; Goldstein and Reynolds, 1994) and then classified the assemblages by their type, geometry, morphology, and host mineral. I identified and analyzed three different assemblage types: primary, secondary, and pseudosecondary. Within these assemblages, three types of fluid inclusions were distinguished: single-phase aqueous inclusions containing an aqueous fluid, two-phase aqueous inclusions containing an aqueous fluid and vapor bubble, and three-phase aqueous inclusions containing a halite cube in addition to an aqueous fluid and vapor bubble (Figure 3.8). Single- and two-phase aqueous inclusions were readily found in almost all vein samples. The single-phase aqueous inclusions (Figure 3.8A) are colorless to gray, contain no vapor bubble at room temperature, and range from 2 - 5 µm in size. Two-phase aqueous inclusions (Figure 3.8B) are less abundant than single-phase inclusions in some samples but are typically the most abundant inclusion type, are colorless to gray, range from 2 - 10 µm in size, and have estimated liquid to vapor ratios of 85:15 to 95:5. Three-phase aqueous inclusions (Figure

3.8C) were by far the rarest and were only observed in samples A010.2 and A001.4. These inclusions are colorless to gray, 4 - 8 µm in size, have estimated liquid to vapor ratios of 75:25 to

90:10, and contain halite cubes approximately 1 µm to 3 µm.

51

Figure 3.8: Photomicrographs of the three types of inclusions identified in my samples. (A) Undifferentiated 1-phase aqueous inclusions from quartz vein sample (A008.2) of the Zuloaga Formation. (B) Primary assemblage of 2-phase aqueous inclusions from quartz vein sample (A001.4) of the La Casita Formation. (C) Primary assemblage of 3-phase aqueous inclusions with halite cubes from calcite vein sample (A010.1) of the Cupido Formation. Note the 2-phase aqueous inclusions in the same field of view. All inclusions were photographed at 25-30°C. Refer to Figure 3.1 for the station location of each sample.

52

Homogenization temperatures and fluid salinities of the fluid inclusions were collected through heating and cooling runs. The homogenization temperature (Th) is determined from heating two- and three-phase aqueous inclusions until the vapor bubble disappears or homogenizes into the liquid phase. Additionally, for three-phase aqueous inclusions, the melting temperature of the halite cube is recorded as the temperature at which the last bit of halite dissolves into the liquid phase. After heating, I froze the inclusions by reducing the temperature to a minimum of -100oC and slowly warmed them to observe the changes from ice to liquid phases. I recorded the eutectic melting (Te) and final ice melting (Tm) temperatures as the ice completely melted into its liquid phase. Using a phase diagram of the NaCl – H2O system, I was able to convert the ice melting temperatures into NaCl weight % (Crawford, 1981; Shepard et al., 1985). This diagram calculates the salinity of the fluid based on the phase changes that occurred at specific temperatures within the inclusions. Additionally, Bodnar (1993) developed an equation:

Salinity wt % = 1.78θ – 0.0442θ + 0.000557θ (1) that can be used to quickly convert ice melting temperature (θ) to wt % NaCl. The eutectic melting temperature is identified by the characteristic "orange peel" texture that develops in the inclusion, signifying that all three phases are present (Goldstein and Reynolds, 1994).

Analysis of inclusions occurred in both quartz and calcite crystals, though the majority of calcite in my samples has been heavily deformed. This not only weakens the sample, causing the inclusions to stretch and decrepitate much easier, but also increases the chance that the inclusions have been re-equilibrated, making it represent characteristics of fluids that did not initially precipitate the minerals. In undeformed calcite, the majority of inclusions are scarce and those that were found were either isolated inclusions that could not be tied to an assemblage or inclusions

53 that were too small to reliably analyze. Because the calcite that did have usable inclusion assemblages was extremely rare, I conducted most of my microthermometric analyses on quartz.

These samples produced reliable and reproducible results over multiple, repeated heating and cooling runs.

Heating of inclusions in calcite caused the vapor bubble to increase in size or completely burst, showing that the inclusions stretched or decrepitated. My use of Th in calcite-hosted inclusions is therefore minimal. Due to the unreliability of inclusions in calcite during heating, the procedure was to first cool and then warm the inclusions to receive an accurate ice melting temperature. Across all samples, heating of the two-phase and three-phase aqueous inclusions resulted in homogenization of the vapor bubble to occur between 140-250°C and the melting of the halite cube occurred between 160-225°C. After the halite cube had melted, it would only reappear after freezing the inclusion. In rare instances, two-phase aqueous inclusions gained a halite cube once cooled. Freezing of single-phase aqueous inclusions did not cause a vapor bubble to form, suggesting no methane is present in these inclusions. Most of the inclusions were too small to accurately document any observable changes when cooled to -100oC, causing most of the final ice melting temperatures to not be recorded. Cooling of the two- and three-phase aqueous inclusions resulted in vapor bubbles becoming smaller or disappearing; Tm in these samples occurred between -20°C and 0°C. The eutectic melting temperature in the majority of the inclusions ranged between -22°C and -28°C, indicating a brine composition in the NaCl-H2O system. The inclusions from station A002 (strike-oblique box plot in the La Casita Formation from

Figure 3.9) have Te between -36°C and -55°C, indicating a different brine composition of NaCl ±

MgCl ± CaCl ± H2O. The amount of data collected for the Te was not enough to constrain the salt

54 well, but the few measurements that were collected suggested that there was more than simply

NaCl in the system. The range of my temperatures uses the average temperatures of inclusions irrespective of host mineral. The calcite and quartz values in the same samples were very similar, making it acceptable to group them together in Figures 3.9 and 3.10.

The salinity data (Figure 3.9) illustrates that there is a separation of high salinity (>15 wt%

NaCl equivalent) fluids below the La Peña Shale and low salinity (<10 wt% NaCl equivalent) fluids above the La Peña Shale. Homogenization temperatures (Figure 3.10) show high- temperature fluids (190-250˚C) in the La Casita, Cupido, and Tamaulipas Formations. Thermal and thermochronological data from Gray et al. (2001) determined that the basin had reached temperatures of ~170 ˚C under 5-7 km of burial. This can be considered the in situ temperature for fluids that have thermally equilibrated with their host rocks. Fluids with temperatures significantly different from these in situ values can be interpreted to have been in thermal disequilibrium with their host rocks. If the fluids are less than the temperature indicated by Gray et al. (2001), then the fluids could have originated from cooler surface fluids that percolated deeper into the subsurface, but if the Th indicates higher temperature fluids, then that can be attributed to fluids that originated from deeper in the subsurface. High-temperature fluids are found in strike-oblique veins in the

Cupido Formation, but this unit also has lower temperature fluids (100-130˚C) in bedding-parallel veins. This segregation of homogenization temperatures according to stratigraphic position and vein type implies the early presence of a stratigraphic seal at the Taraises Formation and at the La

Peña Shale during the later stages of deformation. This result is compatible with the results of

Fischer et al. (2009) who identified a separation of high-temperature (170-250oC) fluids and lower temperature fluids (< 170oC) across the Taraises Formation.

55

n

phase aqueous inclusions in quartz and calcite

-

ty. ty. Each box plot is located adjacent to its corresponding lithology.

Box and whisker plots of microthermometric data from 2

Figure Figure 3.9: veins showing ice melting temperatures and salini stations. data in all observed across veins all of were number the individualinclusions that represents

56

represents

and and calcite

n n

phase phase aqueous inclusions in quartz

-

2

Box and whisker plots of microthermometric data from

Figure Figure 3.10: lithology. corresponding its to adjacent located is plot box Each temperature. homogenization showing veins individual observed. of number the were inclusionsthat

57

On a regional-scale, the results from microthermometric analysis of fluid inclusions suggests there are two different fluid types, a warmer, saline fluid that is located in the lower units

(Zuloaga Formation-Cupido Formation) and a low-salinity, lower temperature fluid in units above the La Peña Shale. There also seems to be a change in fluid characteristics in the Cupido

Formation. This trend is one where lower salinity and lower temperature fluids in bedding-parallel veins evolve to become higher temperature and higher salinity fluids in later strike-oblique veins.

The available samples and data are insufficient to determine whether and how the fluids might have changed according to vein type (i.e., over time) for other lithologies.

4. Carbon and Oxygen Isotopic Analyses: Methods and Results

I conducted carbon and oxygen stable isotopic analyses on the calcite veins from each of my samples collected in the Monterrey Salient. I analyzed 0.15 to 0.3 mg powder samples that were drilled with a Dremel tool from my vein and host rock samples. When drilling for the powders, one or two locations were chosen for each vein and host rock. Multiple spots were drilled in the vein if it exhibited color or crystallinity differences to determine if centimeter or smaller scale heterogeneities existed within the vein. Sampling locations were systematically selected to be several millimeters to centimeters from the vein-host rock boundary to enable me to assess whether fluid-rock interactions had occurred near the vein wall. A total of 117 powders were collected, of which 83 samples were from veins and the remaining 34 from host rock.

To determine the 13C and 18O isotopic ratios, a Thermo Finnigan MAT 253 Isotope Ratio

Mass Spectrometer (IRMS) was used to analyze the CO2 that was released from the powders after they were reacted with phosphoric acid. NBS-18 and NBS-19 were used as reference standards

58 that were analyzed multiple times during each sample run. The average corrected isotopic values for NBS-18 were -5.01‰ (2σ = 0.09) for 13C (PDB) and -23.0‰ (2σ = 0.1) for 18O (PDB). The corresponding corrected values for NBS-19 averaged 1.95‰ (2σ = 0.04) and -2.2‰ (2σ = 0.09) for 13C and 18O (PDB) respectively. These fall within accepted 13C and 18O values of NBS-

18 (-5.01‰, -23.00‰) and NBS-19 (+1.95‰, -2.20‰) according to studies by Coplen et al. (1983) and Ishimura et al. (2008). For the veins, the 13C values ranged from -8.85 to 4.21‰ and from

-14.94 to 3.38‰ in host rock samples. The 18O values ranged from -15.75 to -2.04‰ in vein samples and from -19.54 to -3.71‰ in host rock samples. Appendix A shows a table of all of the individual 13C and 18O isotopic values for both veins and host rocks.

To assess the degree of interaction between the vein-forming fluid and its associated host rock, I compared the 13C and 18O values of the veins and host rocks (Richards et al., 2002).

Figure 3.11 uses the difference in vein and host rock isotopic composition, represented by ∆, where

∆ = host - vein to assess the degree of fluid-rock interaction that occurred during vein formation

(e.g., Abart et al., 2002; Beaudoin et al., 2011). Isotopic values that fall within ∆ = ±1 show that the compositions of the veins are similar to their corresponding host rock, suggesting a high degree of fluid-rock interaction between these two components. If the amount of fluid-rock interaction is high enough to put the system in equilibrium, then this can be defined as a closed fluid system.

Values that fall outside of ∆ = ±1 represent a more open fluid system, where a lower degree of interaction has occurred between the vein-forming fluids and the corresponding host rock. This low degree of fluid-rock interaction can be due to fluids that migrate quickly through the system or reservoirs of fluid that precipitate minerals quickly without significantly interacting with the

59

Figure 3.11: Isotopic analysis of δ13C and δ18O comparing vein and host rock values of each vein type. Deviations from the Δ = 0 line indicate isotopic variations between host rocks and veins for A) δ13C and B) δ18O that could be attributed to the degree of fluid-rock interaction during vein formation.

60 surrounding rocks.

The data show that within each vein set there is evidence that veins formed in both open and closed system conditions. Approximately 60% of bedding-parallel, 50% strike-oblique, and

30% of cross-fold veins fall within isotopic ranges that could be interpreted to represent a closed fluid system for carbon (ΔC). Values of Δ for oxygen show that 60% of bedding-parallel, 50% strike-oblique, and 20% of cross-fold veins fell within isotopic ranges that represent a closed fluid system. Figure 3.12 compares vein and host rock isotopic values as a function of stratigraphic position and suggests that veins in units from the Tamaulipas Formation to Parras Shale show a higher degree of fluid rock interaction (percentage of samples with Δ ≤ ± 1 are 50% for the Parras

Shale, 75% Indidura Formation, and 100% Tamaulipas Formation for both 13C and 18O) compared with veins from the Zuloaga to the Cupido Formations (33% of the Cupido Formation samples, 11% of the La Casita Formation samples, and 50% of the Zuloaga Formation samples show Δ ≤ ± 1, whereas for 18O the percentage of samples that exhibit Δ ≤ ± 1 are 33% for the

Cupido Formation, 44% for the La Casita Formation, and 50% for the Zuloaga Formation). The differences between bedding-parallel to cross-fold veins suggest that the regional fluid system evolved from a closed system with a high degree of fluid rock interaction (shown by a high percentage of veins that reveal isotopic values within ∆ ≤ ±1) to an open system with less fluid- rock interaction (Δ ≥ ± 1). The percentage of cross-fold veins that exhibited isotopic ranges of a closed system was near zero in every unit, suggesting that these later veins formed almost entirely in an open system.

Figure 3.13 separates the isotopic values by vein type and emphasizes the isotopic composition change from bedding-parallel to cross-fold veins. The overall values for cross-fold

61

Figure 3.12: Isotopic analysis of δ13C and δ18O comparing vein and host rock values for each lithology. Deviations from the Δ = 0 line indicate isotopic variations between host rocks and veins for A) δ13C and B) δ18O that could be attributed to the degree of fluid-rock interaction during vein formation.

62

oblique oblique (B), and

-

parallel parallel (A), strike

-

Isotopic Isotopic analysis separating the three different vein types bedding

fold veins (C). Each graph has values for both the veins and their corresponding host rocks. both corresponding values their and for has (C). Each veins the veins fold graph

-

Figure Figure 3.13: cross

63 veins are lower for both 13C and 18O compared to bedding-parallel veins. It is possible that the reduced fluid-rock interaction in these veins caused the drastic difference in isotopic composition.

Figure 3.14 compares the 13C and 18O values of vein and host rock samples within each individual fold. These data appear to show a slight trend wherein 13C and 18O increase towards the foreland. Figure 3.14B represents a chaotic distribution of data and does not have any noticeable trend. Although there is no significant correlation between the isotopic values and the individual folds, the isotopic compositions between the hinterland and foreland portions of the salient are very distinct. This suggests that there might have been paleofluid system heterogeneity at the regional-scale and that this heterogeneity was created and controlled by processes or structures that were different in the orogenic foreland and hinterland.

I separated the isotopic data by stratigraphic position to test whether the hydrological boundary, identified by microthermometry, was also evident in the stable isotopes of veins throughout the region. I also divided the data by vein type and structural position (hinterland or foreland) to test whether there was any evidence for a spatial segregation or temporal evolution of the fluids. Figure 3.15 shows the 13C and 18O values for the upper paleohydrostratigraphic unit

(UHU) and the lower paleohydrostratigraphic unit (LHU) for each of the vein types (bedding- parallel, strike-oblique, and cross-fold veins), according to whether they are located either in the hinterland or foreland. For bedding-parallel veins, there is no significant difference between the

LHU and UHU. The values for the UHU are consistently higher compared to the LHU for the strike-oblique and cross-fold veins. There also seems to be a clear separation in the hinterland and foreland values for the strike-oblique veins, which can be partially seen for cross-fold veins.

Although Figure 3.15B confirms that some structural factor might be constraining the paleofluid

64

C)

C) Average C) Average isotopic for values each

ach ach fold.

numbered numbered consecutively from the hinterland to the foreland.

B) Foreland B)

Isotopic Isotopic values of vein and host rocks for all vein types and lithologies, which are separated into groups

A) Hinterland A)

correspond to correspond Asection in 2.11 figure and are used to show the location of e Figure Figure 3.14: according to location across the Salient.Monterrey Folds are A) Values for samples located in the hinterland and B) values for samples located in the foreland. The cross sections individual fold within both the hinterland and foreland. The error bars represent one standard deviation from the average. values.

65

parallel parallel

-

Cupido) for bedding

-

Parras) Parras) and LHU (Zuloaga

-

fold fold veins (C) in both the hinterland and foreland. Cross section A is given a line that

-

ua del ua Toro the San and the anticlines,Lucas which chose represent between arbitrarily to I the boundary

Isotopic Isotopic analysis separating the UHU (Tamaulipas

oblique (B), and cross

-

Figure Figure 3.15: (A), strike the separates Ag foreland. and hinterland

66 distribution, compartmentalization between the hinterland and foreland, it only plays a small role overall. The separation between the hinterland and foreland becoming less prominent in the cross- fold veins suggests the stratigraphical factors were the dominant control in paleofluid distribution.

Figures 3.16 shows isotopic values according to stratigraphic position and vein type. For strike-oblique and cross-fold veins, there seems to be a boundary between the Tamaulipas

Formation and the Cupido Formation, but for bedding-parallel veins this boundary seems to have been located lower, at the Taraises Formation. By confirming that the hydrostratigraphic boundary had changed over time, I can conclude that the Cupido Formation was initially a part of the UHU.

For the bedding-parallel veins a new graph was created (Figure 3.17), which shows a much clearer separation in isotopic values between the UHU and LHU compared to Figure 3.15A that used the

La Peña as the hydrostratigraphic barrier. Overall, the 13C and 18O values for the samples show an isotopic change from bedding-parallel to cross-fold veins, suggesting that the paleofluid system had evolved over time.

5. LA-ICP-MS Elemental Concentration Analyses: Methods and Results

Using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), I determined the elemental concentrations in selected samples of calcite veins collected across the

Monterrey Salient. Concentrations of calcium, magnesium, iron, and manganese (along with several other major, minor, and trace elements) were quantified using LA-ICP-MS – Eximer

193nm ArF laser at the Virginia Polytechnic Institute and State University in Blacksburg, Virginia.

With the assistance of the laboratory technician Luca Fedele, I analyzed 20-30, 90 m diameter spots on 19 polished thin sections (50-100 m thick) containing vein and some host rock material

67

Figure 3.16: δ13C and δ18O (‰ PDB) values of calcite veins and their associated host rock. Each vein data point is divided by vein type and lithology for A) δ13C and B) δ18O, whereas the gray areas represent the range of values for the host rocks (the edges of the gray boxes are one standard deviation from the average host rock value). Note that within a given stratigraphic unit, the vertical position of the data on each plot is for visual purposes only; it is not intended to reflect the position of samples or veins in that stratigraphic unit.

68

Figure 3.17: Isotopic analysis separating the UHU (Cupido-Parras) and LHU (Zuloaga-La Casita) for bedding-parallel veins in both the hinterland and foreland.

69

(Appendix B). An argon carrier gas was used to transport the ablated sample from the laser to an

Agilent 750oce quadrupole ICP-MS. The NIST 610 standard was ablated twice before and after ablation of each sample to calibrate the elemental concentration measurements. The NIST 610 glass is a homogeneous mixture of elements of known concentrations and has been extensively used in studies to determine concentrations of various elements in carbonate rocks (e.g., Vander

Putten et al., 1999; Raitzsch et al., 2010). Spots were ablated for 30-60 seconds, and using AMS software I was able to convert the raw voltage data from the ICP-MS into elemental concentrations in ppm and weight % for each ablated spot (the results are summarized in Appendix C).

There is little variation of major (Ca, Mg, Mn, Fe) elements between the calcite grains within each sample I examined. A few samples such as A004 and A018 had Mg-rich calcite

(dolomite) within the sample, but the remaining samples were dominantly and consistently calcite

(as seen from SEM analyses). Using ternary diagrams, I was able to compare relative abundances of Mg, Fe, and Mn within each sample (Figure 3.18). These plots show that veins from the La

Casita and Cupido Formations are enriched in Fe compared to the veins in the Parras and

Tamaulipas Formations, which are characterized by much higher concentrations of Mg. Between bedding-parallel and cross-fold veins there seems to be a decrease in Fe and an increase in Mn and

Mg. For the Cupido Formation the dominant concentration is Mg in cross fold veins, which are similar to the upper units. The enrichment of Fe in the veins of the lower units suggest formation waters were involved in the formation of these fracture sets, whereas the relatively high Mn and

Mg suggest more meteoric and marine waters (Brand and Veizer, 1980; Tucker and Wright, 1990;

Morad, 1998). The low Fe and Mn values in the cross-fold veins of the Zuloaga and Cupido

Formations could result from later stage dolomitization of the veins. According to Bethke and

70

Figure 3.18. Ternary diagrams of relative abundance of Mn, Mg, and Fe elemental concentrations. Data is separated according to vein types (Columns) and stratigraphic unit (Rows). Station locations can be seen in Figure 3.1.

71

Marshak (1990), dolomitization is characteristic of rocks that have been altered from interacting with sedimentary brines. It is possible that these brines migrated through this system during later stages of deformation and ultimately altered the elemental composition of the fluids that were precipitating these veins. Other late-stage veins in these lower carbonate units could also have higher Mg concentrations as a result of this Mg-rich fluid, though further analyses would need to be performed.

6. Integrated Model of the Paleofluid System

Despite the limitations of a small sample set, and the fact that the samples are widely distributed over a large geographic region, my systematic analysis and comparison of the data has revealed important trends and patterns that can be related to the regional-scale paleofluid system of the Monterrey Salient. Here I present a synthesis of my results and use them to develop a model for the progressive evolution of the paleofluid system in this specific salt-detached, narrowly tapering orogenic wedge.

6.1 Origin and Distribution of Fluids

By combining the 18O (‰ PDB) values measured from the calcite veins with the homogenization temperatures of the fluid inclusions for each sample, I can use the fractionation factor of Friedman and O’Neil (1977) to estimate the 18O (‰ SMOW) values of the vein-forming fluid. This fractionation factor is preferred compared to newer fractionation factors (e.g., Kim and

O'Neil, 1997) due to the high Th values of my fluid inclusions. Figure 3.19 shows the results of this calculation for each station and stratigraphic unit and suggests that there were three distinct

72

18 Figure 3.19: Graph combining inferred vein precipitation temperature (Th) and δ O (‰ PDB) to calculate the δ18O (‰ SMOW) of vein-forming fluids. Fluid δ18O curves calculated from the fractionation factor of Friedman and O’Neil (1977). The data points represent the average values for temperature and isotopic composition, whereas the error bars are one standard deviation from the average values. See Figure 3.1 for the location of each sampling station (labels on each data point).

73 paleofluid compositions in the Monterrey Salient. Regardless of the 18O (‰ PDB) values of the calcite veins, the Th of the inclusions, or the vein type for the LHU (i.e., Cupido, La Casita, and

Zuloaga), data from these units all plotted within 1-2‰ of the 8‰ 18O (SMOW) isoline for the vein-forming fluid. These values suggest that the vein-forming fluid was a mixture of basinal brines and meteoric water (Sheppard, 1986; Smith et al. 2013). The UHU, with the exception of samples from the Tamaulipas Formation, varied between 12-14‰ and could potentially be from a similar mixture of basinal brines and meteoric/marine water or that the fluid-rock interaction slightly altered the overall composition of the vein-forming fluids. For veins in the Tamaulipas

Formation, the 18O (‰ SMOW) is ~18‰, which suggests that a higher degree of interaction occurred between the vein-forming fluid and host rock. Worldwide, the 18O (‰ SMOW) values of Jurassic and Cretaceous carbonates are approximately 28‰ (Veizer et al., 1999) and a higher degree of fluid-rock interaction, facilitated by longer residence times and/or lower fluid-rock ratios, could have increased the 18O values of the vein-forming fluids in these units.

Overall the regional paleofluid system in the Monterrey Salient is spatially heterogeneous and primarily segregated according to stratigraphy, with a less significant, secondary segregation occurring between the hinterland and foreland. The data from stable isotopes, microthermometry, and LA-ICP-MS all show distinct, persistent paleofluid boundaries between the Tamaulipas and the Cupido Formations as well as the Cupido and La Casita Formations. This difference implies that the La Peña and Taraises units are acting as barriers that restrict fluid movement from the upper to lower stratigraphic units. LA-ICP-MS elemental concentration data illustrates that the

LHU have a higher concentration of Fe and Mn, whereas the UHU has a higher Mg concentration.

Salinity and homogenization data suggest this barrier is restricting high-temperature saline fluids

74 in the LHU and lower temperature fluids with little to no salinity in the UHU. For strike-oblique and cross-fold veins, which are interpreted to have formed later in the orogenic history of the salient (Fischer et al., 2009), there does seem to be a clear separation in isotope values between the hinterland and foreland, suggesting that there was some restriction to the fluid that created a regional-scale segregation of fluids across the orogenic wedge. Combining these analyses shows that the LHU may have been buffering high-temperature formation and saline brines derived from dehydration of the evaporites of the Minas Viejas Formation, whereas the UHU received fluids from deep percolation of meteoric and marine waters.

6.2 Open vs. Closed System Behavior

It is possible to use the Δ values of the stable isotopic data to constrain the degree of fluid- rock interaction across the regional paleofluid system. The fact that early forming, bedding-parallel veins consistently show high degrees of fluid-rock interaction throughout the entire salient suggests that the paleofluid system was initially closed and that vein-forming paleofluids everywhere were derived largely from the host rocks. This early, closed system evolved into a more open system with less interaction between the paleofluids and the host rocks. The extent of system opening appears to have varied between the upper and lower parts of the stratigraphic section, where the upper units had significantly more fluid-rock interaction compared to the lower units. This stratigraphic segregation of the paleofluid system is supported by the geochemical signatures of the vein and host rock samples, the majority of which define a distinct separation of fluids as a result of stratigraphic boundaries. The geochemical data of veins and host rocks, as well

75 as Th and Tm, all show distinct stratification within the Monterrey Salient during the majority of deformation, particularly in the later stages of orogenesis.

6.3 Evolution of the Paleofluid System

During the Laramide orogeny, the paleofluid system structure within the Monterrey Salient went through several stages of evolution. To portray the evolution of this system, I have developed a simplified model that combines my cross sections with the geochemical data and structural analysis (Figures 3.20 and 3.21). The overall evolution of the system is divided into three main stages that are identified by the structural and stratigraphic distribution of vein geochemistry, fluid temperatures and salinities.

Stage I (Figures 3.20A and 3.21A) occurred during the beginning stages of deformation and is recorded by bedding-parallel veins. The fluid flow system was restricted by the Minas Viejas evaporite, Taraises Formation, and some upper units (possibly the Parras Shale) that acted as aquitards. These low-permeability layers caused the fluid flow to be lithostratigraphically compartmentalized and created a vertically heterogeneous system that precipitated minerals from local fluids. Similarities in the 13C and 18O values of veins and their corresponding host rock suggest a closed system with a high degree of fluid-rock interaction.

Stage II (Figures 3.20B and 3.21B) indicates a change in barriers from the Taraises

Formation to the La Peña Formation, which causes higher temperature and salinity fluids to flow within the Cupido Formation. As deformation continued to affect the permeability of the Taraises

Formation, fluid was eventually able to migrate between these once-separated units. According to geochemical analyses, the La Peña Formation is now acting as the major barrier restricting fluid Migration of high temperature fluids into the Cupido Formation. The La Peña Formation is acting as the new hydrostratigraphic barrier. The increase in topographic relief, as a result of deformation, may have contributed to a slight hinterland to foreland migration of fluids. The fluids circulated within each fold and became compartmentalized between the hinterland and foreland.

Extensive fracturing leads to migration of high temperature fluids across the La Peña Formation.

Figure 3.20: Generalized model of the evolution of the regional-scale paleofluid system within the Monterrey Salient, 76 Mexico. The model identifies paleohydrostratigraphic units (HU) through fluid inclusion temperature, isotope composition, and elemental concentrations.

77

Figure 3.21: Generalized model of the evolution of the paleofluid system within the Monterrey Salient. This model is similar to Figure 3.20; however, it shows the smaller scale fluid distribution within a single fold.

78 flow between the UHU and LHU, though it may still have been acting as a weak barrier to fluid flow during stage 1. Isotopic data shows that there is a slight variation between the hinterland and foreland in the LHU (Figure 3.15B), leading to the hypothesis that orogen-scale hinterland to foreland fluid migration might have been taking place at this time and was being restricted by the newly formed structures (Figure 3.20). This thin tapering orogenic wedge did not have enough of a topographic relief to create the high hydraulic gradient that allowed for this regional-scale migration of fluids (as seen from the numerical models in Figures 1.4 and 1.5 by Pollyea et al.,

2015). The elevation gradient might not have been substantial; however, the fluid pressure gradient created by the compression and associated tectonic compaction of the region may have played a role in creating this hinterland to foreland flow. Though there might have been some regional- scale fluid distribution, the dominant factor in controlling paleofluid distribution was the stratigraphy.

Stage III (Figures 3.20C and 3.21C) occurs as cross-fold veins are forming, signifying abundant deformation, fold tightening, and extensive fracturing. Isotope values from these veins indicate that the vein-forming paleofluids were being distributed through a relatively open system with a low degree of fluid-rock interaction. The fracture network that formed during this time allowed for the interaction and vertical mixing of paleofluids between the UHU and LHU, where higher temperature fluids in the LHU migrated upwards to the UHU. There is some limited evidence for some segregation of paleofluids between the hinterland to foreland portions of the orogenic wedge at this time, but this is not as prominent as in stage II. This is possibly due to the abundant fractures being formed that allowed larger scale migration, causing mixing of fluids between the hinterland and foreland. It is also possible that the low taper angle of the orogenic

79 wedge was not significant enough to create a high topographic relief that would have initiated such a large-scale, hinterland-to-foreland migration (Pollyea et al., 2015). The reduction of the 13C values in the La Casita and Zuloaga Formations suggest an external source was providing lighter

C isotopes to be incorporated into the vein-forming fluids at this time. The carbon incorporated into the calcite may have been taken from thermal oxidation of hydrocarbon gases that migrated into the hinges of the anticlines, but the extreme erosion and rare preservation of these portions of folds throughout the region will make it difficult to acquire the additional data required to test this hypothesis.

The higher temperature and isotopic values for the Tamaulipas Formation make it anomalous among the data. During each stage of evolution, the Tamaulipas shows little to no variation in either temperature or isotopic data; the isotopic values of the fluid are significantly higher than the other units, and the Δ values for this unit suggest that its veins were formed in an almost entirely closed system. It is possible that the location of these samples, which are several kilometers east of any other station, has a different origin of fluids and paleofluid system structure.

7. Conclusion

By combining the geochemical analyses of the veins and host rock with the timing of the veins within the Monterrey Salient, this research defined and characterized an orogen-scale fold- related fluid-rock system. The paleofluid system in this region contains low-temperature and low- salinity fluids in the upper units (Tamaulipas Formation-Parras Shale) and high-temperature, high- salinity fluids in the lower units (Zuloaga Formation-Cupido Formation). The impermeable layers of both the Taraises Formation and the La Peña Formation acted as the hydrostratigraphic

80 boundary that separated these fluids. It is seen that the paleofluid system evolved over time as the

Laramide orogeny continued to deform the region.

The geochemical analyses give evidence that the paleofluid system was divided into three main stages. The first stage that occurred separated high-temperature and high-salinity fluids with low-temperature and low-salinity fluids between the Taraises Formation. The fluids had a high degree of interaction with the corresponding host rock as the system was mainly a closed fluid system. The second stage occurred as deformation created fracture networks that allowed migration of the high-temperature fluids into the Cupido Formation, where the La Peña Formation became the new hydrostratigraphic barrier. The paleofluid system also began to become more of an open system with less fluid-rock interaction. Isotopic analyses of veins show that fluid migration across the wedge created compartmentalization between the hinterland and foreland.

The last stage of the paleofluid system occurred as fluids migrated through fractures that had been formed at the hinges of the folds, creating an almost entirely open fluid system. There is also evidence of hydrocarbon migration in the lower units, accumulating in the hinges of the anticlines.

Overall, the paleofluid system is mainly affected by the stratigraphy, and the internal structures of the folds don’t seem to have had a huge effect on the distribution of fluids. It is possible that fluids were trapped within individual folds during deformation, causing the compartmentalization between the hinterland and foreland, though the fracture networks that were created might have prevented significant separation of fluids.

CHAPTER 4:

CONCLUSIONS

The goal of this study was to use veins and host rocks to characterize the paleofluid system structure of the thinly tapering orogenic wedge in the Monterrey Salient. By combing structural and geochemical analyses of veins with my new, balanced and restored cross sections, I was able to determine the distribution and infer the movement of vein-forming fluids and to make a conceptual model for the evolution of the Monterrey Salient’s fluid system. In this chapter, I summarize and critique my analyses on the paleofluid system of a thin tapering orogenic wedge. I first present my new and balanced cross sections that interpret the regional-scale subsurface geology of the Monterrey Salient. I then compare my structural analysis to characteristics of the paleofluid, recorded by my geochemical data. Finally, I critique my work, identifying where improvements can be made on my methods and determining how to progress or enhance my interpretations through future work.

1. Summary of the Structural Analyses

Construction and analysis of the new balanced cross sections reveals that the basement is segmented into several horst and graben features likely attributed to the opening of the Gulf of

Mexico. During detachment folding, evaporites at the base of the orogenic wedge migrated into anticline cores, sequentially lowering the regional level of adjacent synclines and causing them to become grounded at the basement. The stratigraphic layers had nearly constant thickness across

82 the Monterrey Salient before deformation; however, the layers in overturned fold at the El Chorro anticline underwent structural thickening, causing the thickness to almost double. Basement structure appears to have influenced the vergence of detachment folds, where the vergence of the fold is in the same direction as the dip of the fault surface.

2. Summary of the Geochemical Analyses

Veins throughout the region formed from 130˚C – 250˚C basinal brines, marine and meteoric waters in both open and closed fluid systems. The regional paleofluid system evolved through different stages of fluid distribution as deformation progressed. Initially, paleofluids were separated into upper and lower hydrostratigraphic units (UHU and LHU). At this time, high- temperature and high-salinity (15-30 wt% NaCl) fluids in the LHU were separated from lower temperature and lower salinity (0-15 wt% NaCl) fluids in the UHU by an impermeable shale layer.

The elemental concentration, salinity, and temperature data shows that LHU received formation waters and saline brines from the dehydration of evaporates of the Minas Viejas Formation, whereas the UHU derives fluids from percolating marine and meteoric waters. Isotopic analysis suggests that the additional fractures being created as deformation continued facilitated mixing between the UHU and LHU. Lower δ13C values in later stage veins in the LHU suggest that hydrocarbons migrated through the system. Overall, the regional stratigraphy, rather than individual structures, seems to have been the dominant factor controlling paleofluid distribution.

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3. Model of the Paleofluid System Compared to Real-World Orogenic Fluid Systems

This project determines that the paleofluid system had vertical migration of fluids, resulting in stratigraphy playing a larger role in the compartmentalization of fluids compared to individual folds. As seen from other research that looks at the distribution of fluid within orogenic wedges, a thin tapering orogenic wedge would not have enough topographic relief to create substantial, regional hinterland to foreland flow. Because of the low topographic relief, horizontal migration of fluids is very low, and because of that, the folds in this wedge do not play a large role in confining the fluid. As the orogenic wedge undergoes deformation, fracture networks are created within the hinges of the folds, which increases the permeability of the system. Even though these fractures can enhance lateral flow, the low topographic relief of the Monterrey Salient reduces the effectiveness for hinterland to foreland fluid migration.

4. Critique of Studies

The cross sections were constructed using only a handful of surface data and geologic maps. This completely limits the interpretations that can be made for the subsurface, seeing as no subsurface data were available. Though my sections follow basic principles of fold and thrust belts, there are a few areas that I couldn’t properly constrain. The faults in the southern region of my area created more complexity, and the lack of data and conflicting map interpretations for these faults prevented me from making a concise interpretation. Because of this, I had to make the geometry as simple as possible in order to have this area make geologic sense.

Additionally, the depth to basement couldn’t be calculated with Epard and Groshong’s

(1993) method, so a simpler method was used that constrained the basement to the trough of the

84 syncline. This method relies on the location of the syncline and can be better constrained if there was additional surface data. Though the basement faults were inferred to form as a result of rifting of the Gulf of Mexico, the location and displacement of these faults depended on the depth of the synclines along each section. The geometry of the stratigraphy greatly affects how the basement will be drawn, so the lack of data to constrain that geometry poses a huge problem.

The geochemical analyses had similar problems as the structural analysis, where the amount of data was limited by the amount of samples collected from the field. This project documents the distribution of fluid across a region that is several hundreds of km2, and the widely spaced sample locations leave very large gaps that cannot be filled. Due to the low sampling density, I could not properly constrain the characteristics of fluids within each fold and only identify differences in fluid between stratigraphic units and between the hinterland and foreland.

Increased sampling would allow me to better constrain the paleofluid system of such a large scale.

Stable isotope analyses were performed on every sample, though only one or two spots per sample, which reduces the reliability of that data. Because there are only one or two analyzed spots per sample, it is possible that there could be some error in the values, perhaps due to small-scale heterogeneity that was not captured. The fluid inclusion analyses had similar problems, where only a limited amount of samples could be analyzed due to the rarity of usable inclusions in some of my samples. To make a more reliable data set and reduce the amount of incorrect values, more analyses would need to be performed.

It is also important to note that vein isotopic data can be affected by a number of processes that are unconstrained in this study. Some possible factors are the variable amount of fluid-rock interaction, variable temperatures during vein formation, Rayleigh-type fractionation in the veins

85 as quartz and calcite precipitate, and the isotopic exchange between the fluid and additional gases.

Due to the high degree of fluid-rock interactions in my study area, veins that are located several kilometers from one another may have similar isotopic values due to being buffered by the same host rock, even if the fluids originated from different sources. It is also a possibility that, as the fluids precipitate calcite and quartz, the overall composition of the fluid can change. If the amount of minerals precipitating is significant, or if the overall volume of the fluid reservoir is small, then as the material is continuously removed from the fluid, it can be a major factor in the different isotopic compositions of the veins. The data collected in my study is not enough to address these issues; however, it is important to note these processes and their effect on the isotope data when doing analyses similar to this project.

5. Future Work

Though it is unlikely that subsurface data for this region could be attained, it is still possible to return to the field to collect more surface data and better constrain the geology at the surface.

Doing so would help to properly constrain the subsurface geology and ultimately lead to more viable cross sections.

One major shortcoming for the geochemical analyses was the lack of data for my region.

Not only was the amount of data not enough to tightly constrain the orogen-scale paleofluid system, it was also spread out across my region, making it harder to identify what is happening within each fold. If additional samples were to be collected, then it would be better to collect vein and host rock samples along a single transect. Vein and host rock samples would need to be collected for each stratigraphic unit and for each individual fold. Additionally, veins in every

86 fracture set would need to be collected within each of these stations to better constrain the evolution of the paleofluid system. This would allow analyses to understand if the fluid system differs within each individual fold and if the fluid within a specific unit is different from the hinterland to

13 foreland. The  C values of my cross-fold veins were affected by the methane (CH4) from the hydrocarbons, but the 18O values cannot be used to confirm this interpretation. It is possible to use 2H to confirm whether or not hydrocarbons truly migrated through this region.

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APPENDIX A STABLE ISOTOPE ANALYSES

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Station Sample Type Lithology δ13C (PDB) δ18O (PDB) 1 A001.4A CF La Casita -1.74 -13.26 2 A002.1A NS La Casita 0.17 -11.37 2 A002.1B NS La Casita 0.14 -11.77 2 A002.1B NS La Casita 0.20 -11.87 2 A002.2(A) NS La Casita -0.80 -12.39 2 A002.2(C) NS La Casita 1.31 -11.65 3 A003.1A BP Cupido 2.12 -9.90 3 A003.1B BP Cupido -0.08 -11.06 3 A003.2A BP Cupido 2.35 -6.66 3 A003.2B HR Cupido -5.89 -17.97 3 A003.2C BP Cupido 2.42 -6.64 3 A003.3A BP Cupido 2.30 -6.52 3 A003.3A BP Cupido 2.34 -6.47 3 A003.3B HR Cupido 1.33 -8.59 4 A004.1A CF Zuloaga -3.96 -10.84 4 A004.1B HR Zuloaga -0.71 -10.42 4 A004.2A CF Zuloaga -4.35 -11.17 4 A004.2B HR Zuloaga 2.29 -9.58 4 A004.2B HR Zuloaga -0.83 -12.96 4 A004.2C CF Zuloaga -3.17 -7.61 4 A004.3A CF Zuloaga -7.91 -7.51 4 A004.3B CF Zuloaga -8.85 -6.94 4 A004.3C CF Zuloaga -7.38 -7.86 4 A004.3D CF Zuloaga -8.23 -6.96 5 A005.2A CF La Casita -4.52 - 5 A005.2B HR La Casita -0.63 -12.85 5 A005.2B HR La Casita 0.71 -9.34 5 A005.2C CF La Casita -1.63 -12.96 8 A008.1A SO Zuloaga 0.70 -8.81 8 A008.1B HR Zuloaga 1.60 -8.95 8 A008.2A SO Zuloaga 1.60 -8.83 8 A008.2A SO Zuloaga 1.55 -8.86 8 A008.2B HR Zuloaga 1.75 -8.90 9 A009.1A CF Indidura 0.96 -8.83 9 A009.1B CF Indidura 0.97 -9.36 9 A009.1C HR Indidura 0.16 -10.13 10 A010.1A SO Cupido -3.13 -13.75 10 A010.2A SO Cupido -2.75 -13.31 10 A010.2B HR Cupido -7.46 -19.54 11 A011.1A BP La Casita -6.02 -8.83 11 A011.1B HR La Casita -14.56 -10.58 11 A011.1B HR La Casita -14.94 -10.54

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13 A013.1A CF Indidura -8.64 -11.93 13 A013.1B SO Indidura 0.24 -8.94 14 A014.1A BP Tamaulipas 2.19 -5.60 14 A014.1B HR Tamaulipas 2.33 -5.06 14 A014.2A HR Tamaulipas 2.22 -5.79 14 A014.2B CF Tamaulipas 2.38 -4.93 14 A014.2C CF Tamaulipas 2.47 -5.20 14 A014.2C CF Tamaulipas 2.46 -5.48 15 A015.1A SO Tamaulipas 1.22 -8.37 15 A015.1B SO Tamaulipas 1.61 -5.62 15 A015.1C SO Tamaulipas 2.22 -4.53 15 A015.2A BP Tamaulipas 2.18 -4.92 15 A015.2B HR Tamaulipas 1.99 -5.25 15 A015.3A CF Tamaulipas 2.04 -3.95 15 A015.3B HR Tamaulipas 1.65 -5.15 16 A016.1H HR La Casita -5.81 -13.50 16 A016.2A CF La Casita -1.70 -13.81 16 A016.2A CF La Casita 1.00 -10.64 17 A017.1A SO La Casita 0.99 -10.74 17 A017.1B SO La Casita -1.55 -9.92 17 A017.1C SO La Casita 0.98 -9.72 17 A017.2A CF La Casita -4.61 -8.85 17 A017.2B CF La Casita -0.61 -9.55 17 A017.2B CF La Casita -2.07 -9.84 17 A017.2C HR La Casita -0.73 -9.10 18 A018.1A CF Cupido -0.97 -9.69 18 A018.1B HR Cupido 3.38 -3.71 19 A019.1A CF Cupido 3.50 -2.04 19 A019.1B HR Cupido 2.20 -5.63 19 A019.1B HR Cupido 2.24 -5.52 20 A020.1A BP Cupido 2.12 -5.72 20 A020.1B BP Cupido 2.81 -5.48 20 A020.1C BP Cupido 2.75 -5.54 21 A021.1A BP La Casita 2.98 -5.46 21 A021.1B BP La Casita -1.09 -9.81 21 A021.2A BP La Casita -0.98 -9.58 21 A021.2B BP La Casita -1.23 -9.83 21 A021.3A BP La Casita -0.89 -9.59 21 A021.3B HR La Casita 3.34 -10.19 22 A022.1A CF Indidura -1.41 -10.59 22 A022.1A CF Indidura 1.89 -8.71 22 A022.1B HR Indidura 1.82 -8.82 22 A022.2 BP Indidura 1.67 -8.86

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23 A023.1A BP Indidura/Parras 2.26 -7.68 23 A023.1B BP Indidura/Parras 1.88 -8.00 23 A023.1C HR Indidura/Parras 1.00 -9.12 23 A023.2A BP Indidura/Parras 2.20 -8.05 23 A023.2B BP Indidura/Parras 1.64 -8.31 23 A023.2C HR Indidura/Parras 1.54 -7.93 24 A024.1 NS Parras -2.01 -10.08 24 A024.2A BP Parras -2.28 -9.98 24 A024.2B BP Parras -2.33 -9.96 24 A024.2B BP Parras -2.30 -9.97 25 A025.1A CF Parras 2.54 -4.50 25 A025.1B CF Parras 2.60 -4.56 25 A025.1C HR Parras 2.33 -4.49 26 A026.1A BP Parras 4.21 -8.94 26 A026.1B HR Parras 2.51 -11.60 26 A026.1C HR Parras 1.68 -10.19 26 A026.1D BP Parras 4.20 -9.93 26 A026.2A BP Parras 0.43 -8.39 26 A026.B HR Parras 0.66 -9.97 27 A027.1A BP Parras 1.92 -7.81 27 A027.1B BP Parras 3.16 -9.75 27 A027.1C HR Parras 0.58 -10.13 28 A028.1A BP Parras 0.04 -10.47 28 A028.1B HR Parras 0.05 -10.32 28 A028.1C BP Parras 0.08 -10.23 28 A028.2A SO Parras -0.24 -9.76 28 A028.2B SO Parras -0.10 -10.13

BP = Bedding-Parallel Vein SO = Strike-Oblique Vein CF = Cross-Fold Vein HR = Host Rock

APPENDIX B PHOTOMICROGRAPHS OF LA-ICP-MS SHOT LOCATIONS

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The photomicrographs are images of samples analyzed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Red squares represent host rock laser ablation sites and blue circles represent vein laser ablation sites. The diameter of the ablation spots is approximately 90 microns, so note that the shapes do not convey the exact size. The station location for each sample (station numbers are located on the upper left corner of each photograph) can be found using Figure 3.1.

1 cm

1 cm

99

A010.2A004.1

20 14 1 8 7 4 213 11 10 92 5 6 13 2 1 3 19 20 10 12 9 13 17 12 19 11 16 18 15 18 8 14 24 16 17 15 4 6 7 5 23 21 22

1 cm 1 cm

A011.1A006.A

20 21 10 22 6 12 4 5 12 7 19 11 3 9 16 10 9 8 5 4 17 18 13 11 6 15 8 2 14 3 14 2 1 15 7 13 1 16 17 1 cm 1 cm

A014.1A008.1

13 14 40 1011 12 939 8 15 7 5 8 1 2 4 16 6 9 10 3 27 28 11 12 6 7 31 27 26 23 17 18 30 19 36 29 33 34 5 4 35 32 25 38 37 22 28 24 25 26 22 21 20 21 13 14 20 17 16 19 24 23 3 2 1 18 15 1 cm 1 cm

100

A015.1

26 7 25 9 6 10 19 11 8 24 5 23 18 2 22 3 12 15 4 20 16 1 17 13 14 21

1 cm

A015.2 5

8 6

7 4 9 3 16 17 18 19

10 2

15 11 14 20 1

12 13

1 cm

A015.3

14 15 6 5

4 12 7 11 9 8 10 19 3 17 18 16 1 2

13 1 cm

101

A016.1

2 9 10 13 3 1

17 12 11 18 4 14

15 7 5 16

8 6 21 20 19 1 cm

A017.2 18 6 19 20 7 12 11 4 5 3

8 17 1 16 13 10 9 15

2 14

1 cm

A018.1 8 15 7 16 17 18 9 1 19 20 21 22 14 25 24 23 3 10 26 27 33 34 28 13 32 6 31 35 2 29 5 30 4 11 12

1 cm

102

A021.3

25

24 23 3 11 4 13 18 16 12 6 19 17 15 7 5 14 20 10 8 21 9 2 22 1

1 cm

A022.1 7 5 14 13 15 6 12 23 22 11 24 8 16 21 20

9 10

19 18 2 17 1 4 3

1 cm

A023.1 16 9 8 7 17

12 11 10

6

13 14 15 1 4 3 5 2

1 cm

103

A026.1

1 4

2 10

17 12 5

11 9 3

14 13 6 7 15 16 8

1 cm

A028.1

6 21 5 20 1 7 2 19 8 3 12 17 11 4 16 18 9

13 10 14 15

1 cm

APPENDIX C ELEMENTAL CONCENTRATIONS

105

Sample Spot # Mg (PPM) Ca (PPM) Mn (PPM) Fe (PPM) A002.2 1 464.4 396,252.5 412.5 2,445.8 2 232.4 397,232.9 2,030.8 467.6 3 223.2 397,404.8 1,883.6 442.8 4 277.1 397,525.1 1,485.1 471.3 5 475.2 396,526.6 2,228.8 634.0 6 234.4 397,148.8 2,098.0 478.7 7 244.7 397,181.2 1,992.4 483.6 8 85.6 390,899.4 8,619.2 804.0 9 2,906.6 393,233.0 3,471.7 2.9 10 266.7 390,844.5 7,745.3 1,431.2 11 174.7 390,471.9 8,535.4 1,151.8 12 2,676.6 394,351.7 2,367.0 3.0 13 548.0 396,614.6 340.1 2,707.6 14 148.4 397,843.3 1,016.8 254.6 15 285.8 396,917.1 2,248.5 548.6 16 569.1 393,687.6 3,289.3 1,960.6 17 437.6 398,923.5 378.9 389.9 18 348.4 396,887.4 2,192.1 657.1 19 285.7 396,861.9 2,357.6 575.0 20 280.1 396,914.5 2,261.7 559.4 A003.3 1 1,528.3 395,506.4 400.4 2,142.4 2 1,588.0 395,468.6 480.5 2,076.4 3 1,348.2 395,863.6 510.5 1,956.3 4 1,581.0 395,282.7 577.5 2,058.7 5 1,563.1 395,128.7 511.3 2,234.1 6 1,341.5 395,629.1 591.7 1,939.3 7 1,904.5 394,596.6 333.9 2,332.8 8 1,452.0 395,500.9 857.4 1,690.5 9 1,195.1 395,880.0 618.4 1,814.0 10 3,548.0 391,138.1 287.7 3,338.3 11 1,868.4 394,809.0 293.2 2,272.1 12 1,893.1 394,559.2 271.0 2,411.9 13 1,033.3 396,001.6 418.9 2,189.5 14 2,492.3 393,339.7 419.6 2,737.1 15 1,862.0 394,656.0 435.3 2,239.1 16 4,123.8 390,315.6 326.4 3,799.9 17 1,322.9 395,751.5 605.5 1,927.6

106

18 3,585.4 391,522.9 335.7 3,358.4 19 1,475.8 395,439.7 540.9 1,994.3 A004.1 1 2,568.4 396,026.1 544.8 2.5 2 2,741.8 394,760.4 1,193.5 4.4 3 127,739.4 217,269.1 1,511.6 2.2 4 78,336.8 217,269.1 1,051.5 2.1 5 2,680.8 395,955.3 577.2 1.5 6 2,835.2 395,779.6 593.5 1.6 7 3,119.3 394,464.0 1,370.7 1.3 8 2,908.6 395,065.9 1,090.4 1.9 9 132,081.5 217,269.1 1,709.8 0.8 10 2,252.3 396,391.2 558.3 0.8 11 1,985.4 396,726.4 618.7 0.8 12 126,743.2 217,269.1 2,002.1 1.4 13 2,420.1 396,004.7 492.3 0.6 14 2,159.9 396,013.1 553.3 0.8 15 2,248.2 396,309.8 528.9 0.7 16 124,771.8 217,269.1 2,689.4 1.2 17 2,242.9 396,297.7 610.6 1.2 18 2,301.4 396,099.0 783.2 3.8 19 129,326.3 217,269.1 1,730.8 18.1 20 131,809.4 217,269.1 1,624.8 17.1 21 2,139.5 396,082.9 655.1 2.3 22 125,243.7 217,269.1 1,670.6 2.7 23 128,349.4 217,269.1 1,755.3 1.0 24 128,807.3 217,269.1 1,779.7 0.8 A006A 1 1,124.2 394,992.3 1,151.3 1,542.0 2 1,441.1 393,928.7 1,269.0 1,791.2 3 1,074.2 395,234.2 1,110.8 1,400.3 4 1,284.4 394,395.3 1,255.5 1,641.1 5 1,094.9 394,984.6 1,225.0 1,532.4 6 970.6 395,306.2 1,008.9 1,279.5 7 1,296.3 394,320.1 1,222.3 1,633.3 8 979.0 395,619.3 1,035.1 1,255.2 9 988.9 395,657.3 1,070.6 1,267.7 10 1,171.1 394,951.3 1,135.8 1,458.3 11 1,120.4 395,151.4 1,057.6 1,380.0 12 1,095.8 395,138.4 1,100.4 1,422.7

107

13 1,189.7 394,859.2 1,177.8 1,574.2 14 1,096.7 394,994.1 1,184.6 1,519.7 15 1,246.6 394,666.7 1,221.3 1,589.4 16 4,771.0 70,245.6 234.5 7,173.4 17 4,794.5 91,405.0 303.5 5,492.2 A008.1 1 2,153.2 396,904.7 212.1 0.7 2 2,163.7 396,915.3 217.0 0.7 3 2,494.2 396,569.0 142.8 0.6 4 1,653.8 397,562.0 180.3 0.6 5 2,161.6 397,166.6 82.1 0.6 6 2,128.6 396,961.1 158.7 0.7 7 422.8 399,368.4 101.6 1.3 8 2,461.2 396,537.1 222.1 0.7 9 2,113.3 397,005.2 180.2 0.6 10 2,412.7 396,596.1 201.0 0.7 11 2,202.6 396,865.9 159.1 0.6 12 2,129.1 397,013.2 214.0 0.7 13 2,313.9 396,754.8 218.4 0.6 14 2,408.4 396,622.8 221.3 0.8 15 2,134.9 397,071.4 210.0 0.7 16 1,579.6 397,669.1 173.7 0.8 17 2,010.6 397,281.0 101.7 0.7 18 1,755.0 397,568.6 193.5 0.6 19 2,347.6 396,847.2 94.8 0.6 20 2,140.5 397,196.3 99.8 0.8 21 240.6 399,383.9 75.1 0.7 22 315.7 399,504.0 65.6 1.5 23 258.8 399,699.3 63.2 1.4 24 2,485.5 396,433.0 207.1 0.7 25 194.7 399,744.5 70.3 38.1 26 214.3 399,803.5 63.4 0.8 27 192.2 399,737.4 74.2 44.8 28 335.5 399,675.9 80.4 1.0 29 2,144.9 394,978.7 84.4 105.9 30 2,347.8 392,188.2 75.3 77.5 31 2,096.7 395,380.0 82.9 32.7 32 1,912.4 389,302.6 82.2 520.2 33 1,882.8 395,504.7 83.0 207.4

108

34 2,166.6 390,927.4 84.6 2,004.6 35 1,884.1 396,592.1 86.9 39.7 36 1,701.2 390,838.4 56.5 50.6 37 1,915.8 358,378.4 77.1 229.1 38 2,146.8 394,121.9 85.9 230.7 39 1,543.1 396,907.9 69.8 79.7 40 1,705.2 396,962.3 79.6 27.9 41 1,904.3 396,641.8 87.6 36.2 A010.2 1 310.5 390,320.4 8,728.4 1,251.6 2 432.0 393,739.5 4,776.5 1,439.3 3 901.6 392,774.1 4,985.1 1,519.5 4 435.7 392,399.4 6,303.5 1,332.6 5 297.8 392,550.6 6,244.5 1,414.1 6 1,772.3 394,071.2 1,944.5 2,065.0 7 818.6 393,909.5 3,940.1 1,542.8 8 1,003.6 393,723.6 3,622.6 1,733.6 9 819.5 395,020.0 2,398.5 1,893.3 10 894.0 395,482.3 1,444.9 2,005.4 11 1,546.5 394,704.4 1,495.0 2,145.9 12 867.5 395,111.0 2,136.0 1,928.2 13 967.8 395,275.3 1,646.3 1,959.8 14 780.5 395,078.6 1,828.1 2,434.0 15 1,488.1 394,323.8 1,880.5 2,175.4 16 1,300.3 393,358.2 3,254.7 2,070.9 17 1,087.5 393,123.1 4,167.2 1,766.8 18 248.0 393,490.7 5,687.0 1,086.8 19 1,219.9 394,610.5 2,295.7 1,501.5 20 1,449.4 394,490.6 1,633.4 2,317.7 A011.1 1 3,155.8 394,973.5 103.4 19.6 2 710.5 397,212.5 823.6 2.5 3 854.4 398,423.7 445.1 0.8 4 564.1 397,178.3 2,003.2 1.9 5 81.4 398,896.1 1,154.9 0.8 6 402.6 397,182.5 2,321.9 1.4 7 327.6 397,055.7 2,420.4 1.1 8 337.4 396,838.3 2,616.5 1.0 9 346.1 396,628.3 2,844.2 12.7 10 1,198.0 398,031.0 481.9 0.7

109

11 985.1 398,343.2 491.0 0.7 12 1,026.6 398,195.9 368.4 0.9 13 3,924.5 392,804.0 304.3 1.0 14 894.9 398,415.8 463.6 0.8 15 819.6 398,497.4 587.8 1.6 16 578.3 389,857.8 147.5 1,599.1 17 1,677.6 341,512.4 147.9 2,729.3 18 3,323.7 394,056.3 165.7 0.7 19 1,168.8 397,911.0 643.1 0.9 20 553.2 398,347.5 567.4 0.7 21 161.9 397,939.2 1,954.6 6.8 22 19,703.6 5,518.8 111.0 49,711.2 23 19,009.3 27,341.1 109.4 30,992.2 24 18,742.3 5,319.7 92.0 43,211.8 25 7,629.9 531,296.8 189.7 16,046.1 26 2,635.9 358,695.5 354.9 1,653.4 27 3,668.4 392,586.5 348.8 27.2 A014.1 1 2,250.5 396,814.4 80.3 104.3 2 1,428.6 397,447.0 76.3 162.2 3 1,678.0 397,507.1 76.7 101.8 4 1,808.8 385,372.0 77.3 119.7 5 1,529.6 397,658.3 74.9 85.7 6 1,991.4 397,049.5 80.5 131.1 7 1,553.4 397,653.4 73.2 90.9 8 810.5 398,831.2 68.2 40.4 9 997.9 398,505.6 68.3 43.3 10 1,022.9 398,552.5 71.7 12.7 11 1,107.7 398,237.5 71.7 28.3 12 903.5 398,687.1 73.2 32.6 13 1,839.6 397,404.6 79.7 68.9 14 1,229.3 398,232.8 72.0 46.7 15 1,049.3 398,467.2 72.9 34.6 16 1,068.0 398,319.4 66.4 51.6 17 1,651.7 397,513.4 74.5 101.8 18 1,621.4 397,646.7 73.5 94.1 19 1,340.6 397,952.1 70.9 76.3 20 1,696.3 397,407.7 73.2 82.8 21 1,391.0 397,811.0 79.9 84.1

110

22 1,729.5 397,028.2 70.1 100.7 23 1,398.2 397,828.2 76.4 44.1 A015.1 1 1,903.0 394,811.9 206.8 1.1 2 1,977.5 394,768.8 210.8 2.0 3 1,239.5 394,113.4 103.1 0.6 4 2,041.0 395,084.3 183.7 1.0 5 1,384.3 394,238.0 132.2 1.2 6 2,219.2 396,849.9 215.1 33.4 7 2,043.8 397,263.5 198.5 0.6 8 2,131.4 396,985.8 208.5 0.6 9 1,871.2 394,910.8 197.4 1.2 10 2,204.3 395,461.9 251.5 0.7 11 1,041.5 397,090.6 181.3 1.0 12 2,084.7 395,333.1 232.8 0.5 13 2,002.8 394,432.4 195.8 0.6 14 2,226.6 396,929.4 219.5 0.7 15 921.9 397,042.3 106.4 0.7 16 899.3 397,529.2 116.6 1.6 17 1,097.0 396,691.3 99.2 0.7 18 1,726.4 395,369.7 206.2 0.8 19 1,835.1 352,243.9 163.2 241.0 20 2,418.9 393,412.0 166.8 348.1 21 5,656.3 374,625.9 161.3 262.0 22 2,425.1 394,873.0 150.3 141.7 23 2,578.3 394,806.4 152.0 105.6 24 2,329.2 395,303.1 176.5 145.5 25 2,442.6 391,122.6 181.5 1,658.9 26 2,350.9 395,447.8 183.0 707.4 27 1,420.7 396,488.5 110.1 0.7 A015.2 1 1,732.0 395,753.7 90.8 32.0 2 2,558.1 395,795.9 73.3 0.8 3 2,268.6 396,314.2 73.4 1.2 4 2,134.8 396,619.7 74.9 0.7 5 2,418.2 395,947.9 70.5 0.7 6 2,590.9 395,721.6 73.4 0.8 7 2,602.8 395,814.6 75.4 0.7 8 2,277.4 396,404.6 76.2 1.2 9 2,269.4 396,200.8 81.4 0.8

111

10 2,716.6 395,833.2 77.9 0.8 11 2,588.2 395,843.0 76.3 0.7 12 2,523.7 395,911.8 68.6 0.7 13 2,541.3 395,751.6 71.4 0.8 14 2,664.3 395,753.9 75.7 0.8 15 2,499.9 396,059.1 76.8 0.7 16 2,187.4 396,546.1 74.0 0.7 17 2,607.7 395,714.4 73.4 0.7 18 2,308.8 396,248.9 73.8 0.7 19 2,573.8 396,077.4 80.5 0.8 20 2,474.0 396,128.9 77.4 0.7 21 2,651.2 395,948.5 81.4 0.7 A015.3 1 2,075.5 396,916.2 97.8 5.5 2 1,780.1 397,132.5 88.0 0.6 3 2,736.0 395,756.0 103.0 7.3 4 1,332.2 395,651.9 93.4 2.9 5 913.7 394,906.9 75.2 0.7 6 2,052.8 396,883.6 110.0 164.6 7 2,038.3 397,154.7 100.0 0.7 8 1,890.6 397,140.5 95.5 0.7 9 2,173.6 396,551.6 106.1 157.7 10 1,869.7 397,154.8 103.4 49.3 11 1,808.8 397,251.0 102.1 30.4 12 14,131.8 337,518.6 111.6 99.1 13 1,855.0 397,113.8 102.8 133.2 14 1,741.0 395,159.8 109.7 0.7 15 1,361.5 395,608.2 97.4 0.6 16 1,374.2 395,542.6 104.6 50.1 17 1,439.2 395,915.6 110.5 0.8 18 1,811.8 394,909.9 107.8 1.1 19 1,704.3 395,146.5 103.7 0.9 20 1,529.3 395,606.3 99.3 0.7 21 1,640.7 395,567.1 101.6 0.7 A016.1 1 1,504.5 393,759.1 1,114.3 1,580.7 2 2,109.8 391,145.2 1,041.3 1,974.5 3 1,303.7 394,229.5 849.4 1,412.8 4 1,833.1 392,589.7 1,035.8 1,768.8 5 1,795.7 392,841.3 969.1 1,667.0

112

6 1,958.4 390,663.1 1,097.5 1,744.7 7 1,895.1 392,912.0 970.9 1,718.3 8 2,017.2 392,314.1 1,159.0 1,803.9 9 1,040.3 395,505.3 766.9 1,412.4 10 2,413.6 390,287.8 1,088.0 2,048.1 11 1,568.3 393,707.8 1,019.6 1,525.6 12 2,161.0 390,716.7 1,137.3 1,694.4 13 1,125.1 394,900.5 827.6 1,341.1 14 1,451.2 393,807.1 1,005.4 1,369.4 15 2,127.3 391,755.4 1,096.7 1,876.2 16 2,158.1 390,819.8 1,141.3 1,722.4 17 1,846.3 392,658.3 1,137.5 1,665.5 18 1,849.6 392,641.1 1,138.4 1,669.8 19 1,902.2 391,329.7 1,071.9 1,722.7 20 2,281.5 389,373.6 1,197.9 1,942.3 21 2,404.8 388,327.0 1,231.8 1,959.8 A017.2 1 1,945.5 394,626.9 606.6 0.7 2 1,918.1 394,031.6 698.2 0.7 3 1,056.1 395,728.1 613.5 0.7 4 982.2 397,093.7 445.8 0.7 5 4,005.5 394,060.5 260.3 0.6 6 6,516.5 391,644.6 250.9 0.6 7 3,229.4 394,624.8 320.9 0.7 8 4,025.3 393,975.7 270.6 0.7 9 2,010.1 395,290.5 661.4 0.8 10 1,979.1 391,140.7 657.9 0.7 11 1,632.2 393,014.4 642.7 0.7 12 4,847.2 393,601.0 270.7 0.8 13 1,942.6 396,783.6 168.4 0.7 14 1,425.8 392,848.7 536.1 28.7 15 3,407.8 395,076.1 200.1 0.8 16 2,152.6 396,396.1 427.8 0.8 17 1,509.9 394,522.9 496.1 0.9 18 18,820.9 375,367.2 812.6 0.7 19 1,886.7 394,588.1 554.9 0.8 20 2,340.4 394,249.5 639.1 0.7 21 3,240.8 345,881.3 257.6 51.6 22 3,919.7 394,810.2 237.3 0.7

113

23 4,480.8 394,175.7 232.8 0.7 A018.1 1 119,611.5 217,269.1 37.3 0.5 2 118,845.9 217,269.1 36.2 0.5 3 123,423.3 217,269.1 44.4 658.3 4 118,059.4 217,269.1 38.2 4.3 5 122,645.1 217,269.1 44.9 1,122.7 6 125,917.0 217,269.1 40.7 3.3 7 121,938.5 217,269.1 42.1 49.3 8 1,297.2 398,347.3 100.8 24.5 9 122,765.9 217,269.1 43.9 0.5 10 125,518.0 217,269.1 48.7 8.1 11 87,889.1 217,269.1 36.5 31.9 12 120,702.1 217,269.1 44.2 7.7 13 129,093.7 217,269.1 47.6 0.4 14 122,887.1 217,269.1 45.9 2.2 15 984.2 398,429.0 173.0 37.0 16 772.2 399,011.7 56.6 1.0 17 1,010.2 398,658.0 57.2 0.7 18 779.8 398,939.8 46.3 1.1 19 122,564.1 217,269.1 41.0 0.4 20 121,170.4 217,269.1 40.3 0.5 21 130,381.2 217,269.1 368.8 2.4 22 129,835.4 217,269.1 45.8 0.5 23 133,143.7 217,269.1 51.6 1.4 24 1,567.3 397,592.5 59.3 84.1 25 119,480.4 217,269.1 40.8 22.1 26 116,109.6 217,269.1 40.6 284.2 27 123,026.3 217,269.1 44.6 399.7 28 124,738.0 217,269.1 48.8 0.4 29 120,620.4 217,269.1 45.2 5.8 30 119,475.1 217,269.1 60.4 2.1 31 1,636.8 398,029.0 59.1 0.7 32 1,274.9 398,305.6 137.7 0.8 33 3,647.7 395,705.2 78.3 0.7 34 2,816.5 396,629.7 120.2 0.7 35 1,759.9 397,939.5 94.5 0.8 A021.3 1 961.1 393,546.0 713.0 3,089.4 2 1,001.7 393,296.3 726.0 3,221.0

114

3 930.2 393,686.8 403.7 3,502.8 4 1,040.4 393,029.7 353.5 3,884.3 5 931.7 393,567.9 332.1 3,524.7 6 1,009.0 393,073.8 330.3 3,719.7 7 984.9 393,027.4 349.0 3,610.1 8 908.9 393,453.7 310.5 3,101.4 9 928.7 393,515.9 331.0 3,310.9 10 1,104.8 392,520.5 650.1 3,585.4 11 930.1 393,728.9 547.5 3,273.2 12 1,464.8 391,168.9 287.8 4,622.2 13 1,298.7 391,847.9 294.9 4,680.3 14 929.6 393,569.2 360.9 3,705.3 15 958.0 393,417.9 431.9 3,591.4 16 923.6 393,500.8 526.9 3,603.5 17 1,442.2 453,749.5 487.6 6,067.4 18 884.8 260,641.9 214.1 3,758.6 19 1,405.2 390,117.8 380.2 5,768.0 20 1,477.6 390,168.3 431.8 5,489.8 21 920.6 393,299.5 379.5 3,193.7 22 927.9 393,340.7 405.0 3,268.0 23 10,255.1 325,512.7 489.1 20,228.9 24 6,496.1 338,763.2 424.0 17,576.7 25 7,448.8 242,857.9 337.2 23,000.7 A022.1 1 722.6 396,507.2 109.9 766.5 2 710.5 396,313.1 103.8 741.5 3 96.9 49,076.3 12.4 98.1 4 870.8 396,061.8 95.1 665.5 5 709.1 396,342.5 111.8 719.2 6 748.1 396,088.4 97.9 745.5 7 669.2 397,417.2 94.4 596.3 8 853.0 396,340.4 94.8 658.4 9 679.7 396,659.4 107.1 750.3 10 744.6 396,464.8 115.6 792.9 11 621.0 396,851.7 110.7 711.4 12 719.4 396,685.1 98.0 650.0 13 715.6 396,492.0 100.4 720.0 14 690.8 396,674.5 107.7 741.7 15 735.6 396,197.6 94.4 680.8

115

16 719.8 396,626.7 104.4 688.1 17 682.4 396,367.4 112.0 772.7 18 649.5 396,598.3 104.7 642.0 19 640.4 358,496.2 99.4 630.7 20 736.1 395,667.3 109.1 790.0 21 615.8 396,711.1 111.6 717.8 22 719.3 395,686.3 114.7 754.4 23 704.1 396,170.7 110.8 742.7 24 685.1 396,123.4 111.5 760.3 A023.1 1 1,572.9 395,076.2 137.3 655.3 2 1,875.8 395,499.3 135.3 16.7 3 1,857.3 395,682.9 138.0 21.2 4 1,926.8 395,231.6 138.8 38.1 5 1,366.0 396,403.7 140.6 386.1 6 1,786.1 395,587.0 149.4 144.7 7 1,733.5 395,781.8 124.9 308.1 8 1,789.5 395,577.6 149.6 144.8 9 1,742.2 395,779.1 125.3 305.6 10 1,502.6 395,325.1 138.6 651.2 11 1,570.6 396,216.3 132.5 38.2 12 1,609.6 396,139.1 137.9 54.4 13 1,374.6 396,729.8 137.1 143.9 14 1,370.3 396,647.2 141.0 231.8 15 1,294.2 396,578.9 140.2 311.2 16 1,575.8 396,316.5 134.6 72.3 17 1,290.1 397,155.5 134.1 86.1 18 1,245.9 397,056.6 137.2 179.2 19 1,258.1 395,530.8 145.1 722.9 20 1,298.1 395,848.9 149.8 731.3 A026.1 1 1,330.2 396,490.9 217.4 15.0 2 1,119.7 396,926.1 217.6 13.2 3 1,567.6 395,740.5 206.3 17.5 4 733.2 398,130.9 211.6 4.2 5 928.3 397,399.9 196.6 4.7 6 1,265.4 396,568.1 201.7 12.5 7 1,533.7 396,079.2 201.3 15.7 8 1,158.5 396,647.6 180.7 3.8 9 1,689.3 395,622.5 202.0 20.1

116

10 1,077.4 396,933.8 202.4 5.1 11 1,995.2 394,352.4 184.3 23.3 12 991.4 397,221.0 203.8 4.4 13 1,541.5 395,848.2 188.9 20.4 14 1,540.6 395,904.2 190.7 20.8 15 1,484.4 396,154.1 196.3 17.5 16 1,478.6 395,809.3 191.6 19.5 17 1,345.7 396,383.0 218.0 12.9 A028.1 1 1,639.8 389,946.1 659.8 5,467.8 2 1,534.9 390,563.7 767.4 5,133.5 3 1,885.8 387,989.4 710.9 5,952.8 4 1,539.0 361,235.6 723.1 4,980.2 5 1,697.1 388,618.2 621.9 6,211.0 6 1,763.4 387,451.0 660.8 7,069.0 7 1,697.6 382,840.5 711.4 5,887.8 8 1,674.8 389,849.7 717.7 5,535.2 9 1,532.2 390,631.2 787.2 5,335.1 10 1,963.4 387,794.1 671.9 6,240.6 11 1,424.9 389,829.6 657.4 5,693.7 12 1,171.4 391,516.1 716.5 5,111.8 13 983.0 392,350.7 768.0 4,810.2 14 1,878.3 389,212.1 716.4 5,945.7 15 1,541.0 390,030.2 691.0 5,251.9 16 1,803.6 388,158.1 725.4 5,999.5 17 1,612.4 389,014.2 682.8 5,511.3 18 1,503.4 390,135.9 783.6 5,331.6 19 1,667.9 389,829.4 744.2 5,860.5 20 1,654.9 389,750.3 753.3 5,731.8 21 1,709.8 389,037.2 635.3 5,803.0