Executive Summary ............................................... 1
Introduction .................................................... 3
Objectives, Approach, and Hydrogeologic Significance ............ 3
Elements of the Basin Floor .................................. 5
Elements of Basin Fill ....................................... 9
Structure .................................................... 9
Geologic Setting ................................................ 9
Data Types and Descriptions .................................... 12
Physical Properties ......................................... 12
Aeromagnetic Data ........................................... 13
Gravity Data ................................................ 18
Other Data .................................................. 18
Methods of Data Analysis ....................................... 20
Edge Detection .............................................. 20
Magnetic Anomaly Separation ................................. 21
Magnetic Depth Estimation ................................... 21
Model Construction ............................................. 24
Gravity Inversion ........................................... 24
Profile Models .............................................. 27
Integrated Three-Dimensional Model .......................... 31
Interpreted Elements of the Basin Floor ........................ 35
Precambrian Basement ........................................ 35
Pre-Rift Sedimentary Section ................................ 41
Intrusions .................................................. 44
Older Volcanic Rocks ........................................ 50
Interpreted Elements of Basin Fill ............................. 52
Santa Fe Group Sediments .................................... 52
Younger Volcanic Rocks ...................................... 57
Interpreted Structure .......................................... 57
Summary ........................................................ 65
Description of Digital Products ................................ 66
Acknowledgments ................................................ 66
References Cited ............................................... 67
Appendix 1. Well Data Used to Constrain Three-Dimensional
Integrated Model and Gravity Inversion ............ 77
Appendix 2. Well Data Used to Guide Three-Dimensional
Integrated Model .................................. 82
Appendix 3. Magnetic Depth Estimation Methods Used in This
Study ............................................. 84
Appendix 4. Other Point-Located Data .......................... 86
Plates
1. Composite of Selected Geophysical Interpretations at
1:100,000 Scale (in pocket and on CD)
2. Geologic Units Inferred to Directly Underlie the Santa Fe
Group at 1:100,000 Scale (on CD)
Figures
1-3. Maps showing:
1. Española Basin and areas used for various analyses ........ 4
2. Key basin elements addressed by geophysical
interpretation ............................................ 6
3. Generalized geology and geography of the study area ...... 11
4. Diagrams showing magnetic property information for
geologic units in study area ............................. 14
5-9. Maps showing:
5. Coverage of high-resolution aeromagnetic surveys ......... 17
6. Isostatic residual gravity and station locations for
area of gravity analyses ................................. 19
7. First vertical derivative of reduced-to-pole
aeromagnetic data ........................................ 22
8. Broad magnetic anomalies enhanced by lowpass filters ..... 23
9. Data coverage and types of independent constraining
data used for gravity inversion .......................... 26
10. Diagram showing simplified density-depth functions
developed from borehole density logs in the Albuquerque
and Española Basins ...................................... 27
11-13 Maps showing:
11. Elevation of base of basin fill derived from gravity
inversion ................................................ 28
12. Bedrock gravity map derived from gravity inversion ....... 29
13. Section lines and data used to construct three-
dimensional integrated model ............................. 30
14. Two sections demonstrating three-dimensional model and
forms of input ........................................... 34
15. Aeromagnetic map showing labels on interpreted sources
of selected features ..................................... 36
16. Isostatic residual gravity map for study area ............ 37
17. Two-dimensional gravity and magnetic model for Tesuque
profile .................................................. 38
18. Geologic map and aeromagnetic image of southeastern
part of study area ....................................... 39
19. Geologic map and aeromagnetic image of northeastern
part of study area ....................................... 40
20. Two-dimensional gravity and magnetic model for Pojoaque
profile .................................................. 42
21. Sections through three-dimensional model showing
general relations between three modeled surfaces ......... 43
22. Two-dimensional gravity and magnetic model for Alamo
Creek profile ............................................ 45
23-29 Maps showing:
23. Aeromagnetic image, interpretations, and geology of
southern part of study area .............................. 46
24. First vertical derivative image, interpretations, and
thickness of Santa Fe Group in southern part of study
area ..................................................... 48
25. Elevation of base of Santa Fe Group, derived from
three-dimensional model .................................. 54
26. Isopach thickness of Santa Fe Group, derived from
three-dimensional model .................................. 55
27. Comparison of bases of Ancha and underlying Tesuque
Formations in southern part of study area ................ 56
28. Demonstration of horizontal-gradient magnitude method
used to interpret faults from magnetic data .............. 59
29. Geologically mapped and geophysically interpreted
faults in study area ..................................... 60
30. Two-dimensional gravity and magnetic model for Seton
Village profile .......................................... 61
31. Map showing geologically mapped and geophysically
interpreted faults on base of Santa Fe Group surface ..... 63
32. Perspective view of basin model in relation to
topography ............................................... 64
Tables
1. Interpretation approach and constraints for key basin
elements ................................................... 7
2. Densities of geologic units ............................... 15
3. Bodies used in two-dimensional geophysical profile
models ................................................... 32
4. Digital georegistered files ............................... 67
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