Delaware Basin Structural Relationships_Manos
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The document summarizes the structural geology and tectonic development of the Delaware Basin and Central Basin Platform in West Texas and Southeastern New Mexico. It finds that the basins have a complex structure influenced by inherited rifting from 1.3-1.1 billion years ago. Movements during the Ancestral Rocky Mountains uplifts were accommodated along these preexisting weaknesses, resulting in geometries that do not align with expected patterns. Flexural subsidence in the Delaware Basin represents a superposition of profiles from the Central Basin Platform and Ouachita Mountains thrust belt. Interpretations of the basin's structure account for observed features and compare consistency.
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- 1. BERG - HUGHES C E N T E R Structural Relationships of the Delaware Basin and Central Basin Platform Telemachos A. Manos
- 2. BERG - HUGHES C E N T E R Conclusions Basin Layout A complex interplay of structural elements giving it the geometries we observe. Related to Ancestral Rocky Mountain uplifts, but the geometries do not align with what we would expect for Marathon Orogeny Inherited structures Permian Basin has a history of rifting which influences later movements Arrangement and trend of features might not align with ‘ideal’ structural geometries for later events. Tectonic movements are reactivated on preexisting planes of weakness Flexural Profile Superposition of two foreland basin profiles. Possibility of heterogeneity in the flexural rigidity. Two Interpretations Development of structure accounting for observed features. Comparing consistency of interpretations
- 3. BERG - HUGHES C E N T E R Uplift Depression Fold-Thrust Belt Modified from Anthony (2015) • West Platform Fault - Contact between DB and CBP • Timing and orientation of CBP uplift similar to that of other Ancestral Rocky Mountain Uplifts. • Orientation of E/W compression does not agree with NW advancement of OMTB Tectonic Stresses
- 4. BERG - HUGHES C E N T E R A A’ Complex structures on the CBP margin. Thrust, normal, and strike slip faulting. Hills (1984)
- 5. BERG - HUGHES C E N T E R Many of the features in the Permian Basin are inherited from prior rifting, and persist throughout basin development. Whitmeyer & Karlstrom (2007)
- 6. BERG - HUGHES C E N T E R Shumaker (1992), Galley (1958) • After Grenville Mid-continent rifting in (A), several yoked ‘sag basins’ were superimposed after breakup of Rhodinia (B). Timing and orientation similar to that of the Southern Oklahoma Aulacogen. • Igneous basement in DB dated to 1.3-1.1 Ga, suggesting dominant structural rifting in Grenville, and minimum structural influence in Rhodinia breakup. • Unit thicknesses of Tobosa Basin indicate timing and amount of sag post-breakup.
- 7. BERG - HUGHES C E N T E R • Delaware Aulacogen is similar in trend and timing to other Rhodinia-breakup related Aulacogens. • Predetermined planes of weaknesses reactivated during Ancestral Rocky Mountain uplifts. Walper (1977)
- 8. BERG - HUGHES C E N T E R • Tobosa Basin features persist through the Pennsylvanian, as the location of carbonate reefs and platforms are predetermined by inherited structural features. • By early Permian, compression will trend uplifts along rift features. • Uplifts may be related to advancement of the OMTB, but because faulting accommodates along preexisting planes of weakness, the geometries are not aligned with what we would expect. Late Penn/ Early PermLate Miss/ Early Penn Modified from Wright (2011)
- 9. BERG - HUGHES C E N T E R ReferenceTectonic PhasePeriod Modified from Romans (2003) E/W Compression during OMTB advancement
- 10. BERG - HUGHES C E N T E R C C’ • The Val Verde Basin, southeast of the CBP and in the immediate foredeep of the OMTB can be accurately modeled with constant flexural parameters. • Applying similar constraints west of the CBP in the DB yields different results Yang & Dorobeck (1995)
- 11. BERG - HUGHES C E N T E R Yang & Dorobeck (1995) B B’ • Synorogenic strata do not thicken drastically towards the OMTB, suggesting minimal flexural influence immediately west of the CBP. • Subsidence in the DB a composite of flexure from OMTB and CBP. • Yang & Dorobeck suggest the forebulge produced from OMTB may have been removed by loading from CBP during E/W compression
- 12. BERG - HUGHES C E N T E R Yang & Dorobeck (1995) • Flexural profiles accounting only for CBP loads do not predict observed thickness. • Either too narrow or too shallow • Varying flexural rigidity (D) can produce better matching profiles, suggesting crustal homogeneity – especially in the SW corner of the DB.
- 13. BERG - HUGHES C E N T E R Gravity anomalies within the DB and CBP basement, accounting for removal of sediment overlying the basal Ellensburger formation Adams & Keller (1996) • Gravity Anomalies over the DB and CBP further suggest crustal heterogeneity, as modeled by igneous bodies underlying basin features. • Consistent with dates of rifting, and wells penetrating basement
- 14. BERG - HUGHES C E N T E R Uplift Depression Fold-Thrust Belt Modified from Anthony (2015) Contact between DB and CBP – West Platform Fault
- 15. BERG - HUGHES C E N T E R • Diversity of features: thrusting, folding, overturned beds, flower structures. Shumaker (1992)
- 16. BERG - HUGHES C E N T E R • Yang & Dorobeck (1995) interpret a clockwise rotation of CBP blocks with emphasis on right lateral west platform faulting • Shumaker (1992) interprets counter-clockwise rotation of CBP blocks with emphasis on left lateral cross-platform blocks • Hoak et al., (1998) synthesizes the two interpretations side-by-side
- 17. BERG - HUGHES C E N T E R Fault map of basal Ellensburger Fm. With emphasis on CBP-bounding faults •Emphasis on NNW trending right-lateral strike-slip faults, clockwise block rotation. • Requires large amounts of right- lateral displacement on West Platform Fault, up to 10km (Hills, 1970) •Transpression causes interior block rotation of CBP, producing uneven E/W shortening along West Platform Fault in en echelon thrust pattern. Yang & Dorobeck (1995), Tai & Dorobeck (2000)
- 18. BERG - HUGHES C E N T E R • Shumaker’s model involves similarly divided CBP blocks, which rotate along a vertical axis. • Does not observe large amounts of right- lateral faulting along West Platform Fault • Emphasizes E/W trending left-lateral wrench faulting, suggesting regional compression. • E/W translation accounts for differences in observed deformation. • Model is confusing, because westward translation of blocks would cause counter- clockwise rotation
- 19. BERG - HUGHES C E N T E R • Hoak et. Al., (1998) agrees with Yang & Dorobeck’s model, stating there are several right-lateral offset features within the DB. • Yang & Dorobeck model is more internally consistent, agrees with surrounding fault geometries, and incorporates a wider study area. Walper (1977) Yang & Dorobeck (1995)
- 20. BERG - HUGHES C E N T E R Conclusions Basin Layout A complex interplay of structural elements giving it the geometries we observe. Related to Ancestral Rocky Mountain uplifts, but the geometries do not align with what we would expect for Marathon Orogeny Inherited structures Permian Basin has a history of rifting which influences later movements Arrangement and trend of features might not align with ‘ideal’ structural geometries for later events. Tectonic movements are reactivated on preexisting planes of weakness Flexural Profile Superposition of two foreland basin profiles. Possibility of heterogeneity in the flexural rigidity. Two Interpretations Development of structure accounting for observed features. Comparing consistency of interpretations
- 21. BERG - HUGHES C E N T E R Adams, D. & Keller, G. (1996). Precambrian basement geology of the Permian Basin region of West Texas and eastern New Mexico; a geophysical perspective. AAPG Bulletin, 80(3), 410-431. Retrieved from http://aapgbull.geoscienceworld.org/content/80/3/410 Anthony, J. (2015). PROVENANCE OF THE MIDDLE PERMIAN, DELAWARE MOUNTAIN GROUP: DELAWARE BASIN, SOUTHEAST NEW MEXICO AND WEST TEXAS. Repository.tcu.edu. https://repository.tcu.edu/handle/116099117/8303 Galley, J. E., (1958), Oil and geology in the Permian Basin of Texas and New Mexico, in Weeks, L. G., ed., Habitat of oil: Tulsa, Oklahoma, American Association of Petroleum Geologists, p. 395–446 Hills, J. (1970). Late Paleozoic Structural Directions in Southern Permian Basin, West Texas and Southeastern New Mexico. AAPG Bulletin, 54(10), 1809- 1827. Retrieved from http://archives.datapages.com/data/bulletns/1968-70/data/pg/0054/0010/1800/1809.htm?doi=10.1306%2F5D25CC3B-16C1-11D7- 8645000102C1865D Hills, J. (1984). Sedimentation, Tectonism, and Hydrocarbon Generation in Delaware Basin, West Texas and Southeastern New Mexico. AAPG Bulletin, 68(3), 250-267. Retrieved from http://archives.datapages.com/data/bulletns/1984-85/data/pg/0068/0003/0250/0250.htm Hoak, T.; Sundberg, K. & Ortoleva, P. (1998) Overview of the structural geology and tectonics of the Central Basin Platform, Delaware Basin, and Midland Basin, West Texas and New Mexico. Germantown, Maryland. UNT Digital Library.http://digital.library.unt.edu/ark:/67531/metadc678963/. Romans, B.W., (2003) Sedimentation Patterns of a Permian Basinal Cycle, Upper Cutoff, Brushy Canyon, and Lower Cherry Canyon Formations, Western Delaware Basin, West Texas and Southeastern New Mexico, U.S.A. [Unpublished Master’s Thesis]: Colorado School of Mines, 175 p. http://dx.doi.org/10.6084/m9.figshare.766363 Shumaker, R. (1992). Paleozoic structure of the Central Basin uplift and the adjacent Delaware Basin, West Texas. AAPG Bulletin, 76(11), 1804-1824. Retrieved from http://aapgbull.geoscienceworld.org/content/76/11/1804 Walper, J. L., (1977), Paleozoic tectonics of the southern margin of North America: Gulf Coast Association of Geological Societies Transactions, v. 27, p. 230–239. Whitmeyer, S. J., & Karlstrom, K. E. (2007). Tectonic model for the Proterozoic growth of North America. Geosphere, 3(4), 220-259. doi:10.1130/ges00055.1 Wright, W. (2011). Pennsylvanian paleodepositional evolution of the greater Permian Basin, Texas and New Mexico: Depositional systems and hydrocarbon reservoir analysis. AAPG Bulletin, 95(9), 1525-1555. doi:10.1306/01031110127 Yang, K. & Dorobek, S. (1995) The Permian Basin of West Texas and New Mexico: tectonic history of a “composite” foreland basin and its effects on stratigraphic development, in Dorobek, S. L., and Ross, G. M., eds., Stratigraphic evolution of foreland basins: SEPM (Society for Sedimentary Geology), v. 52, p. 149–174. Yang, K. & Dorobek, S. (1995). The Permian Basin of West Texas and New Mexico: Flexural Modeling and Evidence for Lithospheric Heterogeneity Across the Marathon Foreland. Special Publications Of SEPM. Retrieved from http://archives.datapages.com/data/sepm_sp/SP52/The_Permian_Basin_of_West_Texas.htm
- 22. BERG - HUGHES C E N T E R Questions
Editor's Notes
- My name is Telly Manos and this is my Presentation on “Structural Relationships of the Delaware Basin and Central Basin Platform”
- To give an overview of what I’ll be covering: -First I’ll give a general overview of the Basin Layout to orient you to the structural geometries. -In doing so, it will become apparent that the structural geometries don’t necessarily align with dominant tectonic patterns of the time. -Next I want to talk about inherited structures, and how they’re relevant to the basin development. -I want to talk about the flexural profile for the Delaware Basin, and how we can think of it as two foreland basin profiles superimposed atop each other. -Finally, I want to talk about possible interpretations for tectonic development of the basin, -specifically relating to the margin between the Delaware basin and the CBP, and how different interpretations may not be entirely consistent.
- -So this is our map view layout of the Permian Basin in west Texas -The blue areas represent structurally high areas, the white represents depressions -The orange along the bottom represents the trace of the Ouichita Marathon thrust belt, which defines the southern extent of the Permian basin. -The Permian as a whole represents the foreland basin system ahead of the OMTB. -The Greater Permian encompasses the DB, CBP, MB, and Val Verde Basin. -They’re all structurally separated internally by fault Bounded uplifts, and along the margin shelves by stratigraphic onlap. -The West Platform Fault zone encompasses the margin between the Delaware basin and the CBP. -The CBP is a basement uplift formed from E/W compression, similar to other Ancestral Rocky Mountain uplifts occurring during the Pennsylvanian -A question I’m not going to address in this presentation is “how did the ARM form” (because that’s a can of worms I’m not going to open) -Instead we can play with the assumption that E/W compression responsible for ARM uplifts is a result of foreland deformation ahead of the OMTB – leave it at that -in doing so though, we see that the uplifts are almost normal to the advancing thrust sheet, which really raises more questions than it answers.
- -Here’s a cross section going west to east across the Delaware. -this is typically what get’s modeled in the cross sections, stratigraphic terminations on the west margin -deepening towards the east, reaching the deepest portions directly adjacent to the CBP uplifts -Then we have this steeply dipping fault surface bordering the CBP. -this is the West platform fault zone that I mentioned earlier. It’s modeled as everything from thrusting and overturned beds, extension, strike slip, you name it. -Not a lot of people agree with a consistent notion of what’s going on here -We have to come up with a creative model that can explain all the structures we see here. -on a final note, most of the carbonate reefs are located directly above the CBP, suggesting there was a significant topographic influence at the time of their formation.
- -Next I want to talk about the basin history, and how it relates to the later features. -It’s important to keep the history in mind, because most of the later Permian features are inherited from prior events. -Our earliest event is going to be midcontinent rifting taking place during the Grenville represented by the purple worm. -We can see that the trace of this rifting continues up from the great lakes, and is interpreted as continuing all the way down to west texas -This rifting event is what’s going to define those steeply dipping fault detachment surfaces and establish preexisting planes of weakness. -It’s also going to lay our basement igneous rocks including a layered mafic intrusion under the CBP, and several felsic granite bodies under the adjacent basins
- -Secondary, we’re going to have a late proterozoic ‘sag basin’ superimposed on top of earlier rifting, causing additional subsidence along what was at this time a passive continental margin. -we don’t interpret major structural subsidence occurring during this event, even though there might be movement on the Grenville faults, -all of our igneous basement is dates past 1 Ga, so no intrusions are relevant to rifting during this time -We can determine the location and magnitude of this subsidence though by looking at unit thicknesses of the Tobosa Basin which existed prior to the DB. -Which is a series of passive margin carbonates accumulating during this subsidence - The Tobosa basin set the basal units for the Later Paleozoic units to be laid overtop -Of particular importance though, is the depocenter of then Tobosa coincides with the Depocenter of the later Delaware. -This suggests that the topographic controls of both basins share a similar feature – structural inheritance.
- -We see a similarity with other extensional basins formed at the same time, specifically the southern Oklahoma Aulacogen (or the Wichita Aulacogen). -both involve ancestral rocky mountain uplifts with adjacent extensional basins that were later inverted. -All these extensions are associated with the breakup of rhodinia, starting in the East with Mt. Rodgers, and progressing westward to the Tobosa. Indicating a timeline of rifting. -The Wichita and reelfoot aulacogens are more failed rift systems (think triangle geometries), while the Delaware is a passive-margin sag basin. -To reiterate: When we talk about the ‘Delaware Aulacogen’ most of those structural features were already pre-established by the rifting occurring during the Grenville. -Subsidence took place overtop of these features.
- -These structural features are going to persist through to the Permian, as the locations of our carbonate margins are predetermined by the topographic highs in the Tobosa Basin -Later in the late Pennsylvanian once we get E/W compression those uplift trends are going to align themselves with the preexisting planes of weakness formed during Grenville Rifting. -Now I want to point out the direction of movement along the OMTB: moving north/northwest. -Because the fault surfaces bordering the CBP are oblique to the direction of movement, we’re going to get transpressional movement along these preexisting faults instead of fracturing new surfaces parallel to regional compression.
- -So just to recap the tectonic timeline of our structural features: -Grenville rifting in the Proterozoic -Passive Margin sagging during the Eocambrian -Tectonic nothingness through the Mississippian -Finally the Marathon Ouachita Orogeny during the Pennsylvanian
- -Now I want to talk about the flexural profile of the Delaware Basin. -When we look east of the central basin platform and draw a cross section, we see all the classical elements of a foreland basin system. -We have our foredeep in the Val Verde, we have a nice forebulge in the Ozona Arch, and we have our backarch in the midland basin. -This profile can be readily matched using a flexural rigidity of 4X10^22 N M -However, when we jump across the Central Basin platform into the Delaware things change.
- -Our Delaware basin doesn’t follow the same constraints on the west side of the CBP that the rest of the Permian did on the east side. -The vertical exaggeration can be a bit misleading, but we can see we’re missing a forbulge, and Pennsylvanian thickness doesn’t get much thicker towards the thrust front. -Once way we can account for this change, is that there is significantly more E/W directed thrusting in the DB than there was in the MB -This way, we can think of the DB being two foreland basin profiles superimposed on each other, one directed N/S from the OMTB and one directed E/W from the CBP. -This causes certain features such as the forebulge or deflection curve to be overwritten, basically producing one synchronous subsidence depression.
- -However, things only get more complicated from here. -Yang and Dorobeck produced a series of flexural profiles incorporating topographic loads just from the CBP. -They determined that by varying the flexural rigidity and load, they couldn’t produce a profile matching observed thicknesses, suggesting the CBP wasn’t acting alone as a subsidence mechanism. -Their profile was either too narrow or too shallow. -One thing they did note though is that by varying the flexural rigidity across the basin, they could produce more consistent matches with observed thicknesses. -This suggests there’s heterogeneity in crustal composition across the basin leading to varied flexural parameters.
- -Adams and Keller in a 1996 publication further reinforced the idea of crustal heterogeneity when they compiled gravity anomalies over the Permian Basin. -when removing the overlying sediment, we see the gravity anomalies follow the trace of the CBP and DB, suggesting there's significant variability in the crustal makeup. -Using datapoints obtained from wells that had penetrated basement, they implied a series of igneous intrusions that could produce the densities leading to the gravity profile they measured. -This reinforced the idea that the Grenville were the dominant structural contributors
- -Moving forward I’d like to talk about the contact between the DB and CBP. -This West Platform fault is anything but uniform, and produces several interesting structures that define a lot of the oil plays in the basin.
- -Within this fault zone, we see thrusting, overturned beds, folding, a few areas of extension, and both right and left-lateral faulting normal to each other. -most importantly: Flower structures. -Ideally, we have to come up with a model that can account for all these features: so basically every movement ever.
- -Two schools of thought exist, one championed by Yang and Dorobeck in their 1995 publication series, the other championed by Robert Shumaker in a 1992 publication. -conveniently for me, shortly after there was also a great summary by Hoak et al. comparing the two interpretations and highlighting their main differences. -The best way to compare the two is that both models break the CBP into smaller fault-bounded blocks that are rotating along a vertical axis -Yang and Dorobeck interpret clockwise rotation, with dominant N transverse movement -Shumaker interprets coutner-clockwise rotation with dominant W transverse movement
- -So both models define their blocks based on fault maps of the Ellensburger formation, which is the basal Cambrian-Ordovician carbonates formed in the Tobosa Basin. -Any fault surfaces affecting Pennsylvanian and Permian strata have to go through this formation -They divided the CBP into two simple blocks, which are fault bonded and internally consistent -This model focuses on N-directed right-lateral wrench faulting along the trace of the west platform fault, estimating up to 10km of displacement. - This rotation causes clockwise rotation of these blocks. -I apologize for the potato quality of the figure on the lower left, but through rotation we can account for: (1) thrusting in the SW corners (2) extension along the NW corners (3) right lateral faulting joining the two (4) left lateral faulting separating the two blocks (5) increased displacement of cutoff points in the SW corners of each block
- -Shumaker’s model differs in that he places greater emphasis on E/W directed wrench faults with left-lateral movement. -His observations don’t include large amounts of right lateral faulting on the west platform fault, -He emphasizes E/W compression translating to differential amounts of compression along the CBP margin producing the observed displacements in cutoff points. -His model is confusing because the geometries he describes should produce counter-clockwise rotation, which is not what we observe (or what he maps) -This raises a larger ‘chicken or the egg’ question: Does lateral faulting induce rotation of these blocks, or does the block rotation induce lateral movement along the block margins?
- -Hoak et al. in his synopsis is more inclined to agree with Yang and Dorobeck. (1) They’re Aggies, so automatically their interpretation is better. (2) There is significant evidence of right-lateral faulting on the west platform fault (3) Their argument is more internally consistent, and incorporates more observed elements than Shumaker’s model (4) several features are right-lateral displaced between the east and west side of the CBP, including the Grisham anticline and the Grisham fault. -Interestingly enough, Walper goes so far as to call the Grisham anticline the ‘forebulge’ of the OMTB, and attributes it’s displacement due to the orocline in the OMTB. -This curve here extending further into the foreland than the right limb.
- So in conclusion: -I covered the general layout of the Delaware basin -I talked about the inherited structures and how they relate to the later geometries -I discussed attempts at modeling the flexural profile, and the implications that had for crustal heterogeneity -Finally I talked about two schools of thought concerning the development of the CBP, and how one was obviously better than the other.
- Here’s some references I used. Specifically, the two Yang and Dorobeck papers which basically tell you everything you need to know
- Thanks you! We will now have a few minutes for questions.