Spring 2021 Volume 43, Number 1

New Mexico Bureau of Geology and Mineral Resources / A Research Division of New Mexico Tech Spring 2021 Volume 43, Number 1 A publication of the New Mexico Bureau of Geology and Mineral Resources A Research Division of the New Mexico Institute of Mining and Technology Science and Service ISSN 0196-948X

New Mexico Bureau of Geology and Mineral Resources Contents Director and State Geologist Dr. Nelia W. Dunbar

Late Pennsylvanian Calcareous Paleosols from Central New Mexico: Implications Geologic Editor: Bruce Allen for Paleoclimate Production Editor: Belinda Harrison Tanner, Lawrence H. and Lucas, Spencer G...... 3–9 EDITORIAL BOARD Dan Koning, NMBGMR New Mexico Graduate Student Abstracts ...... 10–16 Barry S. Kues, UNM Jennifer Lindine, NMHU Gary S. Morgan, NMMNHS

New Mexico Institute of Mining and Technology President Dr. Stephen G. Wells

BOARD OF REGENTS

Ex-Officio Michelle Lujan Grisham Governor of New Mexico

Stephanie Rogriguez Acting Cabinet Secretary of Higher Education

Appointed Deborah Peacock President, 2018–2022, Corrales

Jerry Armijo Secretary-Treasurer, 2015–2026, Socorro

Dr. David Lepre 2021–2026, Placitas

Dr. Yolanda Jones King 2018–2024, Moriarty

Veronica Espinoza, student member 2021–2022, Sunland Park

New Mexico Geology is an online publication available as a free PDF download from the New Mexico Bureau of Geology and Mineral Resources website. Subscribe to receive email notices when each issue is available at geoinfo.nmt.edu/publications/subscribe

Editorial Matter: Articles submitted for publication should follow the guidelines at geoinfo.nmt.edu/publications/periodicals/nmg/ NMGguidelines.html Cover Address inquiries to Bruce Allen, Geologic Editor, New Mexico Bureau of Geology and Mineral Resources, 801 Leroy Place, Socorro, NM 87801. For telephone Located about 5 miles northeast of Socorro, the Ojo de Amado is a spring that feeds a pool that is inquiries call 575-835-5177 or send an email to an important source of water for local wildlife. “Ojo” literally means “eye” in Spanish, but the word [email protected] is used dialectically in New Mexico to refer to a spring. The Ojo de Amado is also known to locals geoinfo.nmt.edu/publications/periodicals/nmg as Bursum Springs, one of several geographic features in the state named after Holm Bursum (1867– 1953), a longtime resident of Socorro and an important political figure of the New Mexico Territory who ultimately served in the U. S. Senate from 1921 to 1925. The steeply dipping strata around the Ojo de Amado are Upper Pennsylvanian clastic and carbonate rocks of the Atrasado Formation. They are faulted up just east of the local eastern edge of the Rio Grande rift and along the western flank of the Cerros de Amado, a set of rugged hills developed in Upper Paleozoic strata. —Photograph by Spencer G. Lucas. Late Pennsylvanian Calcareous Paleosols from Central New Mexico: Implications for Paleoclimate

Spencer G. Lucas, New Mexico Museum of Natural History and Science, Albuquerque, NM 87104, [email protected] Lawrence H. Tanner, Department of Biological Sciences, Le Moyne College, Syracuse, NY 13214, [email protected]

Abstract Introduction Lucas, 2013). Gypsum beds are rare, with one well documented example in We document calcareous paleosols from Upper What have been called “climate-sensi- early Late Pennsylvanian (Missourian) Pennsylvanian (lower Virgilian) strata of the tive lithologies” are rock types specific strata (Rejas, 1965; Lucas et al., 2009; Burrego Member of the Atrasado Formation to a particular climate, the best known Falcon-Lang et al., 2011). Paleosols in the Cerros de Amado of Socorro County, being coal (wet), gypsum (dry) and cal- of Pennyslvanian age, especially cli- New Mexico. The Burrego paleosols are an mate-sensitive calcareous paleosols, excellent example of a scarce, climate-sensitive careous paleosols (seasonally wet/dry). lithology in the Pennsylvanian strata of New Such rock types play a prominent role have only been documented from two Mexico. These paleosols contain mostly in the interpretation of past climates, late Paleozoic basins in northern New stage II to III carbonate horizons, and their constrain climate models and are crit- Mexico (Tabor et al., 2008; Tanner and overall morphology suggests deposition and ical to paleogeographic reconstructions Lucas, 2017, 2018). Here, we add to pedogenesis under subhumid, seasonally dry this sparse record of climate-sensitive conditions. This conclusion is consistent with (e.g., Boucot et al., 2013; Cao et al., paleobotanical and other data that indicate 2019). However, the distribution of rocks in the New Mexican Pennsylva- such climate conditions were widespread on climate-sensitive lithologies remains nian strata a succession of calcareous Late Pennsylvanian Pangea. The mean value unevenly and incompletely docu- paleosols in lower Virgilian strata of of the oxygen-isotope ratios from Burrego Socorro County (Fig. 1). paleosol carbonates compares well with the mented, particularly in older geological values from Virgilian paleosols of the San time periods. Juan, the eastern Midland and Chama basins Indeed, in the Pennsylvanian Stratigraphic context of New Mexico-Texas, suggesting similar con- sedimentary rocks of New Mexico, rel- ditions of temperature and paleoprecipitation. atively few such rocks have been doc- Application of the diffusion-reaction model to The calcareous paleosols documented the mean carbon-isotope composition of the umented. Thus, coal beds are few and here are in the Burrego Member of

carbonate suggests a paleo-pCO2 of approx- mostly thin, localized and confined to the Atrasado Formation, strata that imately 400 ppmV, which is also consistent early Middle Pennsylvanian (Atokan) encompass the Missourian-Virgilian with estimates from correlative carbon- strata (e.g., Armstrong et al., 1979; boundary, in the Cerros de Amado of ate deposits that formed farther east in Kues and Giles, 2004; Krainer and Late Pennsylvanian Pangea. Socorro County (Figs. 1-2). Thompson

Figure 1. Three late Paleozoic basins in New Mexico that have documented calcareous paleosols of Late Pennsylvanian-early Permian age. Relevant publica- tions are A = Tanner and Lucas (2018); B= Tabor et al. (2008); C = Tanner and Lucas (2017); D = Mack (2003) and references cited therein; E = Tabor et al. (2008); F = this paper.

Spring 2021, Volume 43, Number 1 3 New Mexico Geology (1942) presented the first detailed litho- into the Cerros de Amado region east section described here, though very stratigraphy and biostratigraphy of the of Socorro (also see Kottlowski, 1960). close to one of the sections Lucas et Middle-Upper Pennsylvanian strata that He used Burrego Member much as did al. (2009) published (their Minas de crop out in central and southern New Thompson (1942), as a slope form- Chupadera section) was not studied by Mexico. In this monograph, Thompson ing, mixed clastic-carbonate interval them. We discovered this section during (1942) named six formation-rank units between two prominent limestone units, fieldwork in 2018. in the northern Oscura Mountains of the Council Spring Member (below) In the Cerros de Amado, the Socorro County that Lucas and Krainer and Story Member (above). Burrego Member is 13–55 m thick (2009) reduced in rank to members of Lucas et al. (2009), Barrick et and consists mostly of slope-forming the Atrasado Formation, including the al. (2013) and Krainer et al. (2017) mudstone and shale interbedded with Burrego Member. published stratigraphic sections of the arkosic/micaceous sandstone and Rejas (1965), in an unpublished Burrego Member and adjacent strata limestone (Rejas, 1965; Lucas et al., master’s thesis, brought much of Thomp- at several locations in the Cerros de 2009; Barrick et al., 2013; Krainer son’s (1942) stratigraphic nomenclature Amado and vicinity. However, the et al., 2017). Most limestone beds in the Burrego Member are evidently of marine origin, as they contain marine macrofossils, including algae, crinoids, molluscs and brachiopods. Conodont and fusulinid biostratigraphy indicates the Borrego paleosols are close in age to the Missourian–Virgilian boundary, and we consider them here to be of early Virgilian age (Lucas et al., 2009; Barrick et al., 2013).

Material and methods

We used standard field methods with a 1.5-m staff, tape measure and Brunton pocket transit to measure the thickness of strata in the stratigraphic section discussed here, which is located in the SE ¼ sec. 26, T2S, R1E (UTM coordi- nates are in the caption to Figure 2), (Fig. 2). Samples were collected for petrographic and isotopic analysis. To confirm the pedogenic origin of the carbonate, standard 30 μm petro- graphic thin sections were examined for pedogenic fabrics and textures and for evidence of diagenetic effects. Carbonate aliquots for isotopic analysis were obtained by selectively drilling micritic calcite in lapped slabs corresponding to prepared thin sections with an ultrafine engraving tool while viewing under a binocular microscope. The samples were analyzed for δ18O and δ13C by the Duke Environmental Stable Isotope Laboratory (Nicholas School of the Environment, Duke Uni- versity, Durham, North Carolina) using standard operating procedures (see Tanner and Lucas, 2018, for details). Figure 2. Stratigraphic section of the Burrego Member of the Atrasado Formation near Minas de We calculated paleo-pCO2 using Chupadera in Socorro County (base of section at UTM 333433, 3775122 and top at 333299, 3775300, the mean 13C value from 8 samples zone 13, datum NAD 83; inset map of New Mexico shows location of section in Socorro County). On δ left, lithostratigraphy of the measured section with the calcareous paleosols in the section labeled A–E. and the diffusion-reaction model of On right, field photographs of the calcareous paleosols A–E. Cerling (1991, 1999). But, as we did

Spring 2021, Volume 43, Number 1 4 New Mexico Geology not obtain organic matter from the section. These are marked by repetition sparse fossils of marine gastropods, 13 of specific types of B horizons (Bt, Btk capped by a 0.2 to 0.3-m-thick dark samples for determination of δ Com, we applied values from the literature or Bk) without an intervening A hori- to light limestone bed that is nodular, for formations of similar age and zon, suggesting an erosional episode and the weathered surface has vertical geographic proximity (within 2 degrees (Kraus and Hasiotis, 2006). channels up to 2.5 cm wide and 10 cm latitude), primarily from the published The stratigraphic section we long that are filled with smaller calcare- data supplements to Montañez et al. measured encompasses ~ 40 m of most ous nodules. We infer that these record (2007, 2016). of the Burrego Member and its upper root channels formed during subaerial contact with the overlying Story Mem- exposure and pedogenesis of the marine ber (Fig. 2). Most of this stratigraphic carbonate. The top of the unit is a 0.1 Outcrop description section is mudrock, about 82% of the m mudstone/limestone breccia consist- thickness of the strata measured. Minor ing of limestone blocks up to 4 cm in a Where the paleosols in the section dis- lithologies are sandstone/conglomerate red mudstone matrix with root traces play sufficiently distinctive pedogenic (11% of the section) and limestone and small calcareous nodules. This unit features to allow classification, we apply (7% of the section). represents a calcic Argillisol formed on the terminology of Mack et al. (1993) The section (Fig. 2) begins with red- the reworked limestone surface. in assigning names of paleosol orders, bed mudstone overlain by a thin-bed- Unit 14 is 2.9 m of dark brown, modified by adjectives describing the ded, ripple-laminated, very-fine grained fine-grained mudstone with a crumb most prominent subordinate charac- sandstone that is 0.5 m thick (units fabric, but the outstanding feature of teristic. The most common paleosol 2–3). This sandstone has a platy fabric the unit is the presence of numerous types we found in the measured section and contains some discrete calcareous rhizoliths. These are calcareous masses are calcic Argillisols and Calcisols to nodules and scarce root traces that that weather out of the outcrop face, argillic Calcisols. The calcic Argillisol increase in abundance upward and mostly vertically oriented and irregular denotes a paleosol horizon in which has a bioturbated/pedoturbated top. (noncylindrical) in shape. The masses the defining characteristic is a clay-rich The top 0.1 m is a well-developed are up to 1.0 m long, 0.1 m in diameter B horizon that is visibly enriched in carbonate horizon (Stage II of Gile et and have no internal structure. Most

CaCO3 in the form of nodules, i.e., a al., 1966) with carbonate nodules 1 to of these features have a rough, knobby Btk horizon. In any paleosol profile 2 cm in diameter, drab root traces and appearance because they consist of with multiple defining characteristics, rhizoliths up to 5 cm long. We consider vertically stacked, calcareous oblate such as illuviated clays and pedogenic unit 2 a truncated Calcisol that is spheroids of varying diameters. Many carbonate, whether they occur in the relatively immature, given the lack of of them taper downward, and some same horizon or in separate horizons, coalescing nodules, consisting only of exhibit branching, supporting their a subjective judgement was made to C and Bk horizons. It is overlain by 0.3 interpretation as rhizoliths. The unit determine which feature is dominant m of red mudstone (unit 4) followed also contains subhorizontal arcuate and which is subordinate. Thus, there by a 0.3-m-thick bed of coarse- soil fractures and irregular (botryoidal) may be a fine distinction between a grained, arkosic sandstone capped calcareous masses up to 0.1 m wide. calcic Argillisol and an argillic Calcisol. by a 0.1-m-thick limestone-pebble Unit 14 lacks any horizonation, so it In profiles where development of the conglomerate (units 5–6). Some of the is interpreted to represent a single B calcareous B horizons (Bk, or Btk if limestone pebbles in this conglomerate horizon containing calcareous nodules argillic and calcic) is stronger than the contain marine macrofossils, including and vertic fractures. We classify this argillic (Bt) horizons, we assign the des- brachiopods and gastropods. The unit as a calcic Vertisol that formed ignation Calcisol or argillic Calcisol, as overlying unit 7 is 11.3 m thick and is a through an extended interval of con- appropriate. In addition to Argillisols red mudstone slope with its upper half tinuous sedimentation (aggradation) and Calcisols, and variations thereof, covered by mostly colluvium. The lower during pedogenesis, in other words, a we recognize calcic Vertisols, paleosols half of this unit has numerous carbonate cumulative paleosol. The outcrop does with prominent vertic fractures and nodules isolated in the mudstone, but not contain the top of the unit, and no calcareous features in the B horizon. lacks distinct horizonation. Therefore, A-horizon is preserved. Many mudstone beds of varying thick- we consider this unit a calcic Protosol. The overlying 5.4 m of red mud- ness display pedogenic features, such Above unit 7 is a nodular and stone (unit 15) has clay-lined root traces as calcareous nodules, drab colors and bioturbated limestone (unit 8) rich and numerous carbonate nodules that root traces, but lack distinct horizona- in marine macrofossils, including increase upward to form a coalesced tion. We term these units Protosols, and echinoids, gastropods and nautiloids. (Stage III to IV) layer 0.6 m thick that where they contain calcareous nodules A 1.2-m-thick, very coarse-grained, is exposed over a lateral extent of 5 m. we label them calcic Protosols. Most arkosic sandstone bed (unit 9) above We regard this unit as the Btk horizon paleosol profiles in the section are has limestone rip-ups at its base and of an argillic Calcisol. The unit is truncated in that they lack a discernible displays somewhat indistinct, tabular truncated above abruptly by a massive, eluviated upper (A) horizon and display bedding. The overlying interval of 0.5-m-thick sandstone ledge (unit evidence of sediment removal. We also limestone (units 10–13) begins with a 16). The sandstone is overlain by 1.7 recognize compound profiles in the 0.2-m-thick bed of lime mudstone with m of red mudstone with drab-brown

Spring 2021, Volume 43, Number 1 5 New Mexico Geology mottling at the top (unit 17). The mud- Outcrop interpretation argillic Calcisols and Calcisols with stone contains numerous rhizoliths well-developed (Stage III to Stage IV and calcareous nodules that increase in As noted above, the Burrego Member sensu Gile et al., 1966; Machette, 1985) abundance vertically to form two hori- is a lithosome that includes a mixture carbonate horizons hosted in argillic zons, each approximately 0.3 m thick, of sediments of marine and nonmarine red beds. Examination of petrographic of carbonate nodules up to 8 cm in origin, and the section we studied is thin sections indicates that pedogenic diameter, which coalesce to form Stage representative of that. Thus, limestone carbonate in the section consists of II to III pedogenic carbonate horizons. beds in the section with marine inver- micritic calcite with displacive textures Nodules decrease in abundance in the tebrate fossils (units 8, 12 and 18) are and fabrics, including circumgranular upper 0.4 m of the overlying mudstone obviously of marine origin, whereas the cracking, that demonstrate a lack interval of unit 17. The transitional other strata are of nonmarine origin. of diagenetic replacement (Fig. 3). nature of the underlying and overlying The relatively thick intervals of Samples generally were selected from mudstone intervals of unit 17 suggests red mudstone that host the calcare- below the coalesced carbonate horizon that this unit represents a calcareous ous paleosols we studied are readily to maximize depth below the original paleosol, specifically a compound interpreted as nonmarine deposits of soil surface. argillic Calcisol with Btk (Stage II) and alluvial floodplains that have under- Bk (Stage III) carbonate horizons. gone variable amounts of pedogenesis. The overlying bed of limestone Sandstones in the section are likely of Paleosol analysis (unit 18) is a 1.3 m thick, thickly bed- fluvial origin, and limestone clasts in ded, cherty bioclastic wackestone with the conglomerate low in the section Four paleosols were sampled for isoto- abundant crinoidal debris. Above that (unit 6) contain marine invertebrate pic analysis (labelled A, C, D and E in is a covered slope 2.1 m thick overlain fossils, which suggests proximity to Figure 2). In ascending order these are: by a very coarse grained, micaceous, marine carbonate beds. Thus, we (1) a thin Calcisol with Stage II calcar- trough crossbedded sandstone (unit interpret the section as mostly repre- eous paleosol developed in a blocky, 20) that is 1.7 m thick. The uppermost senting floodplain deposition close to very-fine grained sandstone containing part of the Burrego Member is a 6.1 m the shoreline and sea, interrupted by calcareous rhizoliths (station A); sta- thick slope, mostly covered, but where marine incursions. tion B is a nodular carbonate formed bedrock is exposed on this slope it is red The section we studied includes on a marine limestone and was not mudstone (unit 21). The base of the over- meter-scale profiles of simple and sampled due to the likelihood of lying Story Member is a medium-bedded, cumulative paleosols, including calcic incorporation of marine carbonate; (2) cherty wackestone with fossils of algae, Argillisols, argillic Calcisols, Calcisols station C is a calcic Vertisol exposure, crinoids and brachiopods. and calcic Vertisols. Most samples for 2.9-m thick, notable for the abundance isotopic analysis were selected from of calcite-cemented rhizoliths up to 1 meter in vertical length in a mudstone matrix with blocky ped fabric; (3) sta- tion D is a Calcisol with a prominent Stage III nodular horizon; and (4) sta- tion E is a calcic Argillisol containing two nodular horizons exhibiting Stage II and Stage III morphology, likely representing stages in formation of a cumulative soil. Petrography reveals the presence of typical alpha-type fabrics in the car- bonate nodules sampled in the section, such as grain coronas and corroded floating grains that indicate that these nodules represent the accumulation of carbonate in the B horizon of paleosols (Fig. 3; Alonso-Zarza and Wright, 2010). Thus, we are confident that these carbonates formed within soils developed on alluvial muds. Isotopic analysis of eight carbonate samples from the Burrego Member are 13 tightly clustered and yielded δ Ccarb Figure 3. Petrographic features of Burrego Member calcic paleosols. A) Spar-filled voids and shrinkage values ranging from -6.4 ‰ to -5.6 ‰ fractures (sf). B) Mudstone clast surrounded by circumgranular crack (cc). C) Mudstone matrix with with a mean of -6.0 + 0.1 ‰ (VPDB) displacive micrite (dm). D) Mudstone clast surrounded by sparry grain halo (gh). (Table 1). The isotopic composition of

Spring 2021, Volume 43, Number 1 6 New Mexico Geology two samples from rhizoliths at Station from the Virgilian paleosols of the 2005). Thus, paleosol morphology C (-6.0 ‰, -5.6 ‰ (VPDB)) is the same Chama Basin of northern New Mexico supports the isotopic analyses in as measured in samples of carbonate (Tanner and Lucas, 2018), suggesting suggesting sediment deposition and nodules, suggesting micritization of the similar conditions of temperature and soil formation under widely varying root casts in the deep (>50 cm depth) paleoprecipitation. moisture conditions. soil environment and therefore repre- Overall, the morphology of the sentative of the isotopic composition paleosols in the Burrego Member sug- Table 1. Isotopic analyses of Burrego 18 of soil respired CO2. Values of δ O gests deposition and pedogenesis under calcareous paleosol samples. Values have a wider spread, ranging from -5.7 subhumid, seasonally dry conditions. in units ‰ VPDB. to -1.8 ‰, with a mean value of -3.4 The calcareous paleosol horizons vary 18 13 + 0.5‰ (VPDB). The greater range in maturity from Stage II to IV, and Unit δ O δ C for δ18O likely records pedogenic both cumulate and composite paleosol carbonate precipitation under a range profiles are present, suggesting higher Station A -3.8 -5.8 of temperature and/or precipitation rates of sedimentation during some conditions. The composition of the car- intervals, alternating with slow sedi- Station C-1 -3.5 -5.6 bonate is determined by a combination mentation during others (e.g., Deutz of factors in the diffusion model: plant et al., 2002; Monger et al., 2009). In Station C-2 -4.0 -6.0 respiration rate, isotopic composition particular, the “mega-rhizolith” horizon of the plant organic matter (OM), at Station C appears to be a single, Station D-1 -2.6 -6.2 atmospheric isotope composition and undifferentiated B horizon with an pCO . The isotopic composition of the exposed thickness of 2.9 m. This attests 2 Station D-2A -4.0 -6.1 plant OM tells us about the vegetation, to continuous aggradation of the sur- but only in the most general sense (C3 face contemporaneous with pedogenic vs C4), and nothing is known about processes, particularly root turbation. Station D-2B -5.7 -6.4 any possibly unique isotopic aspects of The interplay of sedimentation and Pennsylvanian plant OM. biological activity with pedogenesis Station E-1 -1.8 5.9 13 The lack of δ Com measurements suggests meteoric precipitation at the in this study makes application of the higher end of the range for which calcar- Station E-2 -2.1 -5.6 diffusion-reaction model of Cerling eous paleosol formation is considered (1991; 1999) somewhat problematic. possible (Birkeland, 1999; Retallack, However, the datasets of Montañez et al. (2007, 2016) provide useful Ma 13 measurements of δ Com that allow 299 series N AM "global" us to at least make an approximation stage stage of paleo-pCO2. Temperature of soil carbonate formation, the isotopic composition of atmospheric CO2 and the contribution of soil-respired CO2 (the S(z) term) are also required for Burrego Gzhelian application of the model. We assumed Virgilian Member values based on (but not identical to) Burrego paleosols Member δ 13C values those of Montañez et al. (2007, 2016), paleosols

13 13 pCO2 using values δ Com = -21.0 ‰, δ Ca 304 = -2.5 ‰ (composition of atmospheric o CO2), T = 25 C and S(z) = 3000 ppmV.

The S(z) value reflects the fact that Late Pennsylvanian carbonate precipitation mainly occurs during the drier months when plant Missourian productivity is decreased (Breecker, Kasimovian 2013). The Borrego carbonates yielded 307 13 a mean δ Ccarb of -6.0 ‰. Using the values cited above we obtained a Penn. Mosc. Middle Desm. paleo-pCO2 for the early Virgilian of ~ δ13C 400 ppmV. This estimate accords well -12 -10 -8 -6 -4 -2 with values presented by Montañez et pCO2 al. (2016) for the late Missourian, and 300 600 900 1200 1500 the early Virgilian (Fig. 4). The mean Figure 4. Compilation of Late Pennsylvanian δ13C data from Montañez et al. (2016), the pCO curve 18 carb 2 O value of -3.4 + 0.5 ‰ (VPDB) 13 δ of Chen et al. (2018) calculated from the Montañez et al. data, δ Ccarb values obtained in this study, and obtained compares well with the values the calculated pCO2 value from the Burrego Member.

Spring 2021, Volume 43, Number 1 7 New Mexico Geology Discussion Climate models, paleosol data and References paleobotany converge to identify a In New Mexico, sedimentary rocks distinct monsoonal pattern of moisture Alonso-Zarza, A.M. and Wright, V.P., 2010b, of late Paleozoic age are synorogenic in western Pangea during the Late Calcretes; in Alonso-Zarza, A.M. and Tanner, deposits of the Ancestral Rocky Moun- Pennsylvanian–early Permian, with L.H., eds., Carbonates in Continental Envi- tain (ARM) orogeny. Driven by the moisture sourced from Panthalassa ronments: Processes, Facies and Applications: Developments in Sedimentology 61: Elsevier, Gondwana–Laurussia collision that (e.g., Parrish, 1993; Tabor and Mon- tañez, 2004; Tabor and Poulsen, 2008). Amsterdam, p. 226–267. amalgamated late Paleozoic–Mesozoic Armstrong, A.K., Kottlowski, F.E., Stewart, W.J., Pangea (e. g., Kluth and Coney, 1981; There was a global shift from wetter Middle Pennsylvanian climates to drier Mamet, B.L., Baltz, E.H., Jr., Siemers, W.T. and Dickinson and Lawton, 2003), the Thompson, S., III, 1979. The Mississippiian Late Pennsylvanian climates that began ARM in New Mexico produced a and Pennsylvanian (Carboniferous) systems series of basement-cored uplifts sur- in New Mexico during the Middle in the United States—New Mexico. U. S. Geo- rounded by sedimentary basins during Pennsylvanian (Desmoinesian) when logical Survey, Professional Paper 1110-W, p. Middle Pennsylvanian (Atokan)-early floras with seasonally dry elements W1–W27. Permian (Wolfcampian) time (e.g., begin to appear and then become more Barrick, J., Lucas, S .G., and Krainer, K., 2013, Kues and Giles, 2004; Brotherthon et common during the Late Pennsylva- Conodonts of the Atrasado Formation (upper- al., 2020). The result was an archipel- nian and early Permian (DiMichele et most Middle to Upper Pennsylvanian), Cerros de Amado region, central New Mexico, USA: ago of islands (the uplifts) surrounded al., 2011, 2017). In central New Mexico, the New Mexico Museum of Natural History and by shallow-marine sedimentary basins Science, Bulletin 59, p. 239–252. during the Middle–Late Pennsylva- Atrasado Formation, including the Burrego Member, contains a succession Birkeland, P.W., 1999, Soils and Geomorphology, nian, followed by mostly nonmarine 3rd ed., Oxford, New York, 536 pp. of paleofloras that are all of “mixed” deposition in these and reconfigured Boucot, A.J., Chen, X., Scotes, C.R. and Morley, sedimentary basins during the early composition. This means that plants R.J., 2013, Phanerozoic paleoclimate: an atlas Permian culmination of the ARM that favored wet substrates and those of lithologic indicators of climate: SEPM orogeny. Around the fringes and on the from habitats with seasonal moisture Concepts in Sedimentology and Paleontology, flanks of the uplifts, nonmarine fluvial limitations are mixed together in no. 11, Map Folio, 28 maps. deposition took place in some locations the fossil assemblages and evidently Breecker, D.O., 2013, Quantifying and under- during the Pennsylvanian, such as the grew in close proximity. These floras standing the uncertainty of atmospheric CO2 concentrations determined from calcic section described here, and by early indicate climates that varied from subhumid to semiarid and arid paleosols: Geochemistry, Geophysics, Geosys- Permian time fluvial deposits (largely tems, v. 14, p. 3210–3220. siliciclastic red beds) were filling the (DiMichele et al., 2017). The Burrego paleosols formed in a Brotherton, J.L., Chowdhury, N.U.M.K., and formerly marine basins. Sweet, D.E., 2020, Synthesis of late Paleozoic subhumid climate under seasonally dry Calcareous paleosols are compara- sedimentation in central and eastern New tively common in lower Permian strata conditions. The pCO2 value of ~ 400 Mexico: Implications for timing of ancestral in New Mexico (particularly in the ppm we calculate is within the range of Rocky Mountains deformation: SEPM Abo Formation: Mack, 2003 and refer- values given by Montañez et al. (2016, Special Publication 113. doi: 10.102110/ ences cited therein), but a few Virgilian fig. 2) across the Missourian–Virgilian sepmsp.113.03. calcareous paleosols are the only Penn- boundary. Thus, the Burrego paleosols Cao, W., Williams, S., Flament, M., Sahirovic, S, sylvanian examples that have been doc- indicate a climate within the range of Scotese, C. and Müller, R.D., 2019, Palaeolat- itudinal distribution of lithologic indicators umented prior to the Burrego Member what were thought to be the climates of equatorial Pangea during the Late of climate in a palaeogeographic framework: record documented here. Thus, Tabor Geological Magazine, v. 156, p. 331–354. et al. (2008) briefly discussed a few late Pennsylvanian—subhumid and season- ally dry. The Burrego paleosols thus Cerling, T.E., 1991, Carbon dioxide in the atmo- Virgilian calcareous paleosols in the sphere: evidence from Cenozoic and Mesozoic add an important data point of climate Rowe–Mora basin (Taos trough) and paleosols: American Journal of Science, v. 291, in the Bursum Formation of southern sensitive lithologies from what was far p. 377–400. New Mexico, and Tanner and Lucas western, tropical Pangea during the Cerling, T.E., 1999, Stable carbon isotopes in (2018) documented similar late Vir- Late Pennsylvanian. palaeosol carbonates; in Thiry, M. and Simon- gilian paleosols in part of the Paradox Coinçon, R., eds., Palaeoweathering, palae- basin (Fig. 1). These workers concluded Acknowledgments osurfaces and related continental deposits: that the Virgilian paleosols indicate International Association of Sedimentologists, Special Publication 27, p. 43–60. highly variable climate ranging from The comments of the reviewers, D. O. Chen, J., Montañez, I.P., Qi, Y., Shen, S., and subhumid to semiarid with extremes Breecker and H. C. Monger, and the Wang, X., 2018, Strontium and carbon in seasonal precipitation, which is editor, B. D. Allen, improved the con- isotopic evidence for decoupling of pCO2 consistent with our interpretation of tent and clarity of the manuscript. from continental weathering at the apex of the Burrego paleosols. the late Paleozoic glaciation: Geology, v. 46, New Mexico was located near the p. 395–398. western end of the Pangean tropical belt during the Late Pennsylvanian.

Spring 2021, Volume 43, Number 1 8 New Mexico Geology Deutz, P., Montanez, I.P. and Monger, H.C., Kues B.S., and Giles K.A., 2004, The late Paleo- Tabor, N.J. and Poulsen, C.J., 2008, Palaeocli- 2002, Morphology and stable and radiogenic zoic Ancestral Rocky Mountains system in mate across the Late Pennsylvanian–early isotope composition of pedogenic carbonates New Mexico; in Mack G.H., and Giles, K.A., Permian tropical palaeolatitudes: a review in late Quaternary relict soils, New Mexico, eds., The Geology of New Mexico, A Geologic of climate indicators, their distribution, and USA: an integrated record of pedogenic over- History: New Mexico Geological Society, relation to palaeophysiographic climate printing: Journal of Sedimentary Research, v. Special Publication 11, p. 95–136. factors: Palaeogeography, Palaeoclimatology, 72, p.809–822. Lucas, S.G. and Krainer, K., 2009, Pennsylvanian Palaeoecology, v. 268, p. 293–310. Dickinson, W.R., and Lawton, T.F., 2003, stratigraphy in the northern Oscura Moun- Tabor, N.J., Montañez, I.P., Scotese, C.R., Sequential intercontinental suturing as the tains, Socorro County, New Mexico: New Poulsen, C.J. and Mack, G.H., 2008, Paleosol ultimate control of Pennsylvanian Ancestral Mexico Geological Society, Guidebook 60, p. archives of environmental and climatic history Rocky Mountains deformation: Geology, v. 153–166. in paleotropical western Pangea during the 31, p. 609–612. Lucas, S.G., Krainer, K., and Barrick, J.E., 2009, latest Pennsylvanian through Early Permian: DiMichele, W.D., Cecil, C.B., Chaney, D.S., Elrick, Pennsylvanian stratigraphy and conodont bio- Geological Society of America, Special Paper S.D., Lucas, S.G., Lupia, R., Nelson, W.J. and stratigraphy in the Cerros de Amado, Socorro 441, p. 291–303. Tabor, N.J., 2011, Pennsylvanian-Permian County, New Mexico: New Mexico Geologi- Tanner, L.H., and Lucas, S.G., 2017, Paleosols vegetational changes in tropical Euramerica; cal Society, Guidebook 60, p. 183–212. of the Upper Paleozoic Sangre de Cristo For- in Harper, J.A., ed., Geology of the Pennsyl- Machette, M.N., 1985, Calcic soils of the south- mation, north-central New Mexico: Record vanian-Permian in the Dunkard basin: 76th western United States: Geological Society of of early Permian palaeoclimate in tropical Annual Field Conference of Pennsylvania America, Special Paper 203, p. 1–21. Pangea: Journal of Palaeogeography, v. 6, p. Geologists Guidebook, Washington, PA, p. Mack, G.H., 2003, Lower Permian terrestrial 144–162. 60–102. palaeoclimate indicators in New Mexico and Tanner, L.H., and Lucas, S.G., 2018, Pedogenic DiMichele, W.A., Chaney, D.S., Lucas, S.G., their comparison to palaeoclimate models: record of climate change across the Pennsyl- Nelson, W.J., Elrick, S.D., Falcon-Lang, H.J. New Mexico Geological Society, Guidebook vanian–Permian boundary in red-bed strata and Kerp, H., 2017, Middle and Late Penn- 54, p. 231–240. of the Cutler Group, northern New Mexico, sylvanian fossil floras from Socorro County, Mack, G.H., James, W.C., and Monger, H.C., USA: Sedimentary Geology, v. 373, p. 98–110. New Mexico, U.S.A: New Mexico Museum 1993, Classification of paleosols: Geological Thompson, M.L., 1942, Pennsylvanian System in of Natural History and Science, Bulletin 77, Society of America Bulletin, v. 105, p. 129–136. New Mexico: New Mexico School of Mines, p. 25–99. Monger, H.C., Cole, D.R., Buck, B.J. and State Bureau of Mines and Mineral Resources, Falcon-Lang, H.J., Jud, N.A., Nelson, W.J., Gallegos, R.A., 2009, Scale and the isotopic Bulletin 17, 92 p. DiMichele, W.A., Chaney, D.S. and Lucas, record of C4 plants in pedogenic carbonate: S.G., 2011, Pennsylvanian coniferopsid forests from the biome to the rhizosphere: Ecology, v. in sabkha facies reveal the nature of seasonal 90, p.1498–1511. tropical biome: Geology, v. 39, p. 371–374. Montañez, I.P., Tabor, N.J., Niemeier, D., DiMi- Gile, L.H., Peterson, F.F., and Grossman, R.B., chele, W.A., Frank, T.D., Fielding , C.R., and 1966, Morphological and genetic sequences Isbell, J.L., 2007, CO2-forced climate and of accumulation in desert soils: Soil Science, v. vegetation instability during late Paleozoic 100, p. 347–360. deglaciation: Science, v. 315, p. 87–91. Kluth, C.F. and Coney, P.J., 1981, Plate tectonics Montañez, I.P., McElwain, J.C., Poulsen, C.J., of the Ancestral Rocky Mountains: Geology, White, J.D., DiMichele, W.A., Wilson, J.P., v. 9, p. 10–15. Griggs, G., and Hren, M.T., 2016, Climate Kottlowski, F.E., 1960, Summary of Pennsylva- pCO2 and terrestrial carbon cycle linkages nian sections in southwestern New Mexico during Late Palaeozoic glacial-interglacial and southeastern Arizona: New Mexico cycles: Nature Geoscience, v. 9, p. 824–831. Bureau of Mines and Mineral Resources, Parrish, J.T., 1993, Climate of the superconti- Bulletin 66, 187 p. nent Pangaea: Journal of Geology, v. 101, p. Krainer, K., and Lucas, S.G., 2013,The Penn- 215–33. sylvanian Sandia Formation in northern and Rejas, A., 1965, Geology of the Cerros de Amado central New Mexico: New Mexico Museum area, Socorro County, New Mexico: [M.S. of Natural History and Science, Bulletin 59, thesis]: New Mexico Institute of Mining and p. 77–100. Technology, Socorro, 128 p. Krainer, K., Vachard, D., Lucas S.G., and Ernst, Retallack, G.J., 2005, Pedogenic carbonate prox- A., 2017, Microfacies and sedimentary ies for amount and seasonality of precipitation petrography of Pennsylvanian limestones and in paleosols: Geology, v. 33, p. 333–336. sandstones of the Cerros de Amado Area, east Tabor, N.J., and Montañez, I.P., 2004, of Socorro (New Mexico, USA): New Mexico Permo-Pennsylvanian alluvial paleosols Museum of Natural History and Science, (north-central Texas): High-resolution proxy Bulletin 77, p. 159–198. records of the evolution of early Pangean Kraus, M.J. and Hasiotis, S.T., 2006, Significance paleoclimate: Sedimentology, v. 51, p. of different modes of rhizolith preservation to 851–884. interpreting paleoenvironmental and paleo- hydrologic settings: examples from Paleogene paleosols, Bighorn Basin, Wyoming, U.S.A.: Journal of Sedimentary Research, v. 76, p. 633–646.

Spring 2021, Volume 43, Number 1 9 New Mexico Geology New Mexico Graduate Student Abstracts New Mexico Geology recognizes the important research of graduate students working in M.S. and Ph.D. programs. The following abstracts are from M.S. theses and Ph.D. dissertations completed in the last 12 months that pertain to the geology of New Mexico and neighboring states.

New Mexico Institute of shelf to basin sandy turbidites and carbonate as the Nitt Monzonite. The Nitt Monzonite is mass-transport deposits sourced from the north pervasively potassically and phyllically altered Mining and Technology and northeastern shelf margins during Leonard- with local late-stage vein-controlled propylitic ian time (275 Ma). Compositional heterogeneity alteration assemblages. Carbonate-phyllic alter- TWO-STAGE LANDSLIDE EMPLACEMENT within this unit is poorly understood but strongly ation observed in the Nitt Monzonite consists ON THE ALLUVIAL APRON OF AN impacts the spatial and temporal distribution of of sericite + carbonate + quartz + chlorite ± EOCENE STRATOVOLCANO reservoir forming elements. Substantial research pyrite. This alteration style is atypical of the Chirigos, Michael G., M.S. has focused on the Bone Spring Formation, but classic quartz-sericite-pyrite (QSP) type phyllic little work has been undertaken to understand alteration of porphyry copper deposits. The Sawtooth Mountains, western New Mex- the depositional controls on intramember min- The Nitt Monzonite exhibits an inherently ico, comprise erosionally isolated klippen of eralogy and compositional heterogeneity of the low permeability (<<1% volume), yet hydrother- an initially contiguous landslide complex that formation within a chemostratigraphic frame- mal fluid has pervasively permeated and altered developed on the alluvial apron of an Eocene work. The aim of our research is to characterize this intrusion. Petrographic observations imply stratovolcano during late Laramide volcanic-tec- the bulk geochemical and lithologic heterogene- that mineral replacement reactions from the tonic activity. Volcanogenic siltstone, alluvial ity within the Bone Spring Formation to better interaction of a hydrothermal fluid produced sandstone and conglomerate of the lower Spears understand the depositional controls effecting net-zero to negative volume changes in the Nitt Group were deposited on mainly fine-grained stratigraphic hierarchy. Monzonite. This creation of space during miner- Baca Formation (fluvial flood-plain facies). The Element data is presented from 837 feet al-fluid reactions facilitated the infiltration of the klippen are underlain by a locally exposed, (255 meters) of Bone Spring Formation core hydrothermal fluid through the Nitt Monzonite, low-angle fault within fine-grained, laminated from Eddy and Lea county of New Mexico and resulting in the precipitation of secondary quartz basal Spears strata (distal fan). The lower fault identify compositional changes at the foot scale. in voids as phyllic alteration was developed and is overlain by a sheet 7–100 m thick of sandy Bulk element data collected via handheld XRF evolved in this hydrothermal system. volcanogenic sandstone (Volcaniclastic Unit of analyses conducted at an unbiased 6 inch spacing Electron microprobe data shows secondary Largo Creek, mid-fan facies) that is strongly in the cores. XRF bulk composition was analyzed phengites are of an intermediate composition, deformed by large-scale soft-sediment structures. statistically using principal component analysis known as aluminoceladonite, with a range of Another low-angle fault caps this sheet, and car- (PCA) and hierarchical cluster (HCA) analysis 2+ (K0.69-0.96Na0-0.26Ca0-0.03)Al1.641.94Mg0-0.25Fe ries less-deformed conglomerates (Dog Springs to determine stratigraphic heterogeneity from a )(Si A )O (OH F ). chemofacies standpoint. Distinct changes in min- 0-0.18 3.08-3.41 l0.59-0.92 10 1.88-1.96, 0-0.12 Formation, proximal fan facies). Secondary chlorite is Mg dominant, representing The lower fault, where exposed, has a poorly eralogy describe chemostratigraphic units that a clinochore end-member species, with a range of developed fault core, locally comprised of floury relate to depositional trends and the evolution of (Mg Fe2+ Mn Ti Al ) or foliated gouge, and surrounded by a thin, Delaware Basin stratigraphy in the Leonardian. 4.936.26 3.19-3.92 0.12-0.37 0-0.02, 2.14-2.64 poorly developed fractured damage zone. The Understanding the compositional hetero- (Si5.51-6.06Al1.94-2.49)O20(O16H15.61-15.85F0.11-0.26). upper fault has a well-developed cataclasite core, geneity of the Bone Spring Formation has Calcite is the exclusive carbonate mineral in the 0.12– ~0.40 m thick, with 1–3 primary slip sur- implications for petroleum system analysis in phyllic alteration assemblage. faces, rare pseudotachylyte, and local cataclastic the Delaware Basin and overlying hydrocarbon Microthermometric analyses of primary fluid injections into the upper plate. Striations on both reservoirs such as the Brushy Canyon Formation. inclusions in secondary quartz associated with faults are widely dispersed but cluster in two Our results help to define mechanical properties the phyllic alteration styles indicate the trapping directions, NNE and ESE. The main structure in intrinsic to the compositional architecture of the of a high-density fluid during quartz deposition. the upper plate is an E-vergent monocline. Bone Spring Formation and will help to improve Homogenization temperatures range from 172– We conclude that the landslide complex was future well development in the Delaware Basin. 427°C; with an average of 296°C. Halite-bearing emplaced in two events, first N-directed sliding Furthermore, our work demonstrates the suit- fluid inclusions are common within this second- down the alluvial apron, while the sediments ability of handheld XRF as a tool to quickly ary quartz and the measured salinities range were poorly consolidated. Most soft-sediment generate and assess large geochemical datasets from 43–54 wt.% NaCl equivalent, implying deformation probably occurred in this event, to describe stratigraphic changes in deep-water that some of the trapped fluid was hypersaline. due to loading and shear transmitted down deposits and in their relation to sequence strati- Primary liquid-dominant and vapor-dominant from the upper plate, causing liquefaction. The graphic evolution. fluid inclusions are locally present within some second event was likely due to W-side-up uplift individual hydrothermal quartz crystals, suggest- on the Laramide Hickman Fault, located west of CARBONATE-WHITE PHYLLOSILICATE ing the trapping of a boiling fluid occurred in the field area, likely was triggered by an earth- ALTERATION OF INTRUSIVE ROCK IN THE quartz, at least locally, during the history of the quake, and occurred at seismogenic slip rates, NORTHERN KELLY MINING DISTRICT, phyllic alteration. forming pseudotachylyte on the upper detach- NEW MEXICO Short-wave infrared spectroscopic analyses ment and injections, after the sediments were Herman, Colton Tate, M.S. (SWIR) performed on phyllically altered partially lithified. samples show Al-OH absorption wavelengths The polymetallic Kelly mining district is located between 2198–2214 nm with an average of CHEMOSTRATIGRAPHY OF THE BONE in the northern Magdalena Mountains, Socorro 2209 nm, consistent with other studies reporting SPRING FORMATION, DELAWARE BASIN, County, New Mexico approximately 170 kilo- aluminoceladonite. Shorter average Al-OH SE NEW MEXICO. meters south-southwest of Albuquerque. Miner- wavelengths (2203–2205 nm) of samples in the Foli, Isaac David, M.S. alization mainly occurs as manto-like carbonate south-central area of Hardscrabble Valley are replacement deposits (CRD) and locally minor characteristic of a more muscovitic composition, The Bone Spring Formation is a middle Permian skarn, both of which primarily replacedMis- which may imply proximity to the hydrothermal mixed carbonate and clastic turbidite petro- sissippian-age limestone. Hardscrabble Valley, fluid source. leum reservoir in the Delaware Basin of west located in the northern extent of the district, con- The geologic features of Hardscrabble Valley Texas and southern New Mexico. It consists of tains the Tertiary-age (28 Ma) intrusion known are inferred to have formed as a result of

Spring 2021, Volume 43, Number 1 10 New Mexico Geology initial development of a graben associated with of 81.9 ka, the calculated intra-dome eruptive vanadium and arsenic are released under collapse of the Magdalena caldera during the frequency is 1 eruption event per 5.5 ka for when oxidizing, alkaline conditions. Groundwater mid-Tertiary. This study infers that, although Valles caldera enters periods of sustained dome leaching experiments showed appreciable release not exposed at present erosion levels, a magma emplacement. Volume estimations, along with of uranium and vanadium, but not arsenic. The intruded the fault zone associated with the published volumes of the youngest eruptions, third study investigates the leachability of redis- graben and generated a magmatic hydrothermal indicate that the post-caldera dome and vent tributed-type ores from the Westwater Canyon fluid which interacted with indigenous carbonate complexes range in volume from 0.8 km3 to Member, and primary-type ores of the Jackpile strata in the subsurface. The dissolution of car- 14.1 km3 and have both increased and decreased Sandstone and Brushy Basin members. Here, bonate resulted in modification of the magmatic throughout post-caldera evolution. In contrast, leaching tests using alkaline lixiviants and ambient fluid which rose to upper structural levels and eruptive flux following caldera collapse has sys- groundwater showed that gangue mineralogy and reacted with the Nitt Monzonite, producing the tematically increased between each post-caldera the non-mineral hosts of uranium produce leach- carbonate phyllic alteration. This process may volcanic complex from 0.09 to 2.56 km3/ka ing trends entirely discordant to those of stoichio- be related to underlying calcsilicate alteration in during post-caldera evolution. Using new ages of metric minerals previously identified as important the subsurface rock units, with the potential for the caldera-forming ignimbrite, a syn-resurgent components in these deposits (meta-tyuyamunite, accompanying base metal mineralization. lava, and the oldest post-resurgent ring-fracture meta-autunite, uraninite). eruption, the resurgence durations at Valles QUANTIFYING THE TIMESCALES OF caldera are constrained to be between 74.4 ± RAINFALL-RUNOFF RELATIONSHIPS IN ERUPTIONS AND RESURGENCE FOL- 3.3 ka and 41.8 ± 6.7 ka. The average magmatic THE ARROYO DE LOS PINOS, SOCORRO, LOWING CALDERA COLLAPSE: 40AR/39AR flux during resurgence is between 0.52 and 0.92 NEW MEXICO DATING AND VOLUME ESTIMATIONS OF km3/ka, which is similar to pluton-filling rates, Richards, Madeline A., Ph.D. POST-CALDERA VOLCANISM AT VALLES suggesting that resurgence is partially explained CALDERA, NORTHERN NEW MEXICO by a significant decrease in magmatic flux follow- The Arroyo de los Pinos is an ephemeral tribu- Nasholds, Morgan Wade Maynard, Ph.D. ing the large fluxes that sustain caldera-forming tary to the Rio Grande located in central New magma bodies. Establishing an accurate timing Mexico, draining an area of 32 km2. In 2018 the Despite recognition as one of the greatest of rapid events during post-caldera evolution is US Bureau of Reclamation funded a sediment volcanic hazards in the southwestern United possible due to the combination of dating only transport study at the confluence of the arroyo States, many aspects of the post-caldera history sanidine grains without melt inclusion-hosted and the Rio Grande, with the goal of monitoring of Valles caldera are poorly constrained. This excess 40Ar and the ability of ARGUS VI mass sediment influx to the mainstream channel study provides 49 new high-precision 40Ar/39Ar spectrometer to identify problematic grains that in order to better inform sediment transport sanidine ages and surface volume estimations to skew the weighted mean ages. The eruptive fre- models. To supplement this study and to enable reveal insights into lifespans of dome emplace- quency during dome activity and increasing flux generalization to other ephemeral tributaries, ment as well as resurgence. Caldera collapse has important implications should Valles caldera more information was needed on up-basin flow and deposition of the Tshirege Member of the enter a new phase of volcanic activity. Likewise, generating processes. This thesis focuses on these Bandelier Tuff at 1231.6 ± 1.0 ka was followed developing similar comprehensive age and efforts to characterize the runoff generating by emplacement of 34 volcanic units erupted volume datasets is necessary to assess hazards at mechanisms. from vents on the resurgent dome and along the other Quaternary volcanic systems. A network of eighteen pressure transducers caldera-ring fracture. New ages indicate vent and and five rain gauges were installed throughout dome complexes that followed collapse were IMPLICATIONS OF CRYPTIC, NONSTOI- the arroyo’s watershed in various subbasin trib- emplaced during polygenetic and monogenetic CHIOMETRIC URANIUM MINERAL- utaries. Pressure transducers monitored water eruptive events. The Deer Canyon rhyolite IZATION ON THE FORMATION AND stage data, and these were converted to discharge eruptions began immediately following caldera LEACHABILITY OF SANDSTONE-HOSTED hydrographs for each flow event. The runoff formation and lasted until 1220.5 ± 3.6 ka for a URANIUM ORES, GRANTS DISTRICT, events monitored this way were all small, close total lifespan of 11.4 ka. Similarly, the Redondo NEW MEXICO to the threshold of runoff generation, and did Creek Member erupted between 1199.0 ± 5.9 Pearce, Alexandra Rose, Ph.D. not fully activate the channel network. Tipping ka and 1186.3 ± 2.9 ka for a lifespan of 12.7 bucket rain gauges monitored rainfall. Data ka. Cerro del Medio, the oldest post-resurgent This dissertation consists of three studies exam- collected from this network show that rainfall dome, is also the longest-lived ring-fracture ining sandstone-hosted uranium ores from the intensity, subbasin lithology and antecedent soil complex, erupting seven units in 25.2 ka between Grants uranium district in northwestern New moisture conditions are the primary factors that 1157.2 ± 3.1 and 1132.0 ± 4.7 ka. Following Mexico. The first investigates the mineralogy control runoff initiation, while total rainfall Cerro del Medio, Cerros del Abrigo erupted at of primary-type uranium ores from the Jackpile depth and lithology are the main controls on run- least twice between 1009.8 ± 1.7 and 997.0 ± Sandstone and Brushy Basin members of the off ratio, and subbasin area is the main control 1.6 ka. These longer-lived dome complexes are Jurassic Morrison Formation. These ores are on lag time. located within structurally-complex zones of the characterized by cryptic mineral and mineraloid Prior to transducer installation, a particularly caldera suggesting the dense network of faults mixtures, and uranium hosted by “uraniferous large flood on 7/26/2018 left behind high-water promote magma transport to the surface, pro- organic matter.” The host organic matter and the marks at several locations throughout the water- ducing long-lived eruptions. Conversely, the six uranium mineralization is interpreted as having shed. These high-watermarks were surveyed and dome and vent complexes that erupted between been fixed within the sediments during multistage used as a proxy for maximum flood stage at 804.7 ± 1.9 ka and 68.7 ± 1.0 ka have shorter groundwater mixing episodes involving one each location. Peak stage comparisons show that eruptive lifespans than the early post-caldera or more brines and humic acid-bearing fluid(s) maximum infiltration occurs in the lower third of eruptions. Three of the complexes—San Antonio that resulted in humate flocculation. The second the watershed that is dominated by alluvial cover Mountain, South Mountain, and the East Fork study evaluates the environmental geochemistry and where the channel develops a multi-threaded Member—are polygenetic with lifespans between of ores of the Jackpile Sandstone sampled from planform. Results from a relative gravity survey 5.2 and 5.5 ka. The Cerro Santa Rosa 2, Cerro the St. Anthony Mine in Cibola County, NM. conducted in 2018 confirm that maximum San Luis, and Cerro Seco domes are either mono- The site, slated for remediation, was assessed infiltration occurs in the lower elevations of the genetic or polygenetic with lifespans less than by its responsible party using a geochemical watershed, where the channel is multi-threaded the associated age uncertainties.The mapped model which used the uranylsilicate mineral and flows over alluvium. post-caldera units are grouped into a total of 15 uranophane to determine alternate abatement eruptive events, bracketed by measurable intra- standards for uranium in groundwater. In our and inter-dome repose periods. Combined with examination, we did not find uranophane. Batch the total duration of dome and vent lifespans leaching tests showed that significant uranium,

Spring 2021, Volume 43, Number 1 11 New Mexico Geology PENNSYLVANIAN-PERMIAN EVOLUTION gene and Quaternary Puysegur Subduction Zone arc zircons (92–223 Ma). Isolated, secondary OF THE DARWIN BASIN OF EASTERN of New Zealand. The formation of a subduction Cambrian peak ages occur at the 2.0 Ma strati- CALIFORNIA: BASIN DEVELOPMENT zone on the southwestern margin of Laurentia graphic horizon in the Mesilla basin and 3.1 Ma IN THE BACK-ARC OF THE INCIPIENT would end the transmission of transpressional stratigraphic horizon in the Socorro basin and CORDILLERAN SUBDUCTION ZONE. stress from the California-Coahuila Transform overlap in age with Cambrian intrusions that Vaughn, Lochlan Wright, Ph.D. Fault that drove Ancestral Rocky Mountains have been reported from parts of New Mexico uplift. Our timeline for the onset of Cordilleran and southern Colorado (519–516 Ma). All strati- The Pennsylvanian-Permian Darwin Basin of Subduction is independently supported by detailed graphic horizons record contributions derived Eastern California records the abrupt onset of studies of ARM basins which indicate that the slip from Precambrian basement sources that were large-magnitude subsidence of the southwestern on high-angle faults that drove ARM uplift ended being exhumed during Oligocene–Miocene rifting. margin of Laurentia. The basin formed in the at the Pennsylvanian-Permian boundary. Mixing models were determined from the Rio late Pennsylvanian but continuously expanded Grande rift corridor in southern Colorado and during the early Permian as subsidence and throughout New Mexico and used with detrital extensional faulting allowed calciclastic base-of- New Mexico State zircon provenance trends to better understand slope apron depositional systems to retrograde University the timing and nature of drainage development. on to the subsided slope and shelf. Areal expan- Inputs for mixing models required grouping sion of the Darwin Basin propagated east and source areas into three primary provinces that PROVENANCE AND SEDIMENT MIXING southeast through time and is marked by the first included detritus from (1) late Cenozoic volcanic TRENDS OF THE PLIO–PLEISTOCENE deposition of deep-water facies in areas that had fields primarily associated with the San Juan ANCESTRAL RIO GRANDE FLUVIAL been carbonate shelves since the Ordovician. A and Mogollon Datil volcanic fields, (2) recycled SYSTEM, RIO GRANDE RIFT, NEW MEXICO nearly identical stratigraphic and structural evo- Mesozoic strata (reflecting previously determined Parker Ridl, Shay, M.S. lution is present in the Pennsylvanian-Permian Mesozoic eolianite provenance signatures); and of southern California, indicating that the driver (3) recycled Paleozoic and Precambrian basement of subsidence in the Darwin Basin was able to Pliocene–Pleistocene strata that record axial-flu- that crop out along the Rio Grande rift flanks. affect a large swath of the southwestern margin vial sedimentation of the ancestral Rio Grande The earliest phase of drainage development of Laurentia at once. Furthermore, subsidence in fluvial system crop out in New Mexico and (~5.0–4.5 Ma) in northern New Mexico was the Pennsylvanian-Permian of California coin- southern Colorado, and they preserve the history characterized by elevated detrital contributions cides with a significant change in deformation of drainage evolution and late-stage exhumation from recycled Mesozoic stratigraphy likely style of Ancestral Rocky Mountains basins and of the Rio Grande rift. Presented here are new derived from the Colorado Plateau, whereas uplifts, suggesting that the driver of subsidence U-Pb detrital zircon data (N=8 samples; n=2382 basins in central and southern New Mexico were in California may have affected tectonics across analyses) from the Camp Rice and Palomas receiving detritus largely from rift flanks (i.e., southwestern Laurentia. Speculative basin formations collected at two to three stratigraphic Paleozoic and Precambrian sources) and late evolution models invoke tectonism associated intervals in the Socorro, Hatch-Rincon, Jornada Cenozoic volcanic-field sources. The late Pliocene with the Late Paleozoic continent-truncating del Muerto, and Mesilla basins. U-Pb ages were (3.1–2.6 Ma) phase of drainage development in California-Coahuila transform fault as the then integrated with similar, previous studies northern New Mexico was marked by a relative principal driver of subsidence in the Darwin from age-equivalent strata that are exposed in decrease in detrital contributions from recycled Basin and southern California. However, the southern Colorado and northern New Mexico to Mesozoic strata. The model shows nearly equal onset of large-magnitude subsidence in southern develop sedimentary mixing models for the entire detrital contributions from recycled Mesozoic and eastern California is spatially and tempo- Rio Grande rift corridor in this region. strata, rift flank, and volcanic field sources at the rally associated with the first appearance of New U-Pb detrital zircon data from the central 3.1–2.6 Ma stratigraphic horizon in central and magmatism and volcaniclastic sedimentation in and southern portion of the Rio Grande fluvial southern New Mexico. The Pleistocene (2.0–1.6 the Late Paleozoic of the southwestern U.S. The system record peak ages at 34, 167, 519, 1442, Ma) phase of drainage development records a geochemistry of these early to middle Permian and 1686 Ma, suggesting that the ancestral Rio shift in provenance in the southern rift basins igneous rocks, which include plutons and lavas Grande was receiving detritus from late Ceno- and models suggest decreased contributions in southern California and newly identified tuffs zoic volcanic fields (e.g., San Juan and Mogollon from late Cenozoic volcanic field and rift flank in eastern California, demonstrates that these Datil volcanic fields), recycled Mesozoic stra- sources, and increased contributions from recy- rocks formed in a continental subduction zone. tigraphy (Mesozoic eolianites), and Proterozoic cled Mesozoic stratigraphy. The presence of continental arc-derived igneous basement provinces (e.g., A-Type granitoids and Provenance data and mixing trends that rocks in the early Permian of California is inter- the Mazatzal and Yavapai provinces). Although demonstrate increased detrital contributions preted to indicate that the onset of Cordilleran peak ages across the southern Rio Grande rift from recycled Mesozoic strata of the Colorado Subduction occurred earlier than has previously are similar across all basins and stratigraphic Plateau support a model of headward erosion been recognized. horizons in this study, there are distinct spatial of the Rio Puerco into the Jemez Lineament and We present 15 new measured sections, facies and temporal, up-section changes in provenance southwestern margin of the Colorado Plateau analysis, clast and point counts, and new cono- recorded across the southern Rio Grande fluvial during the Plio–Pleistocene. Headward erosion dont biostratigraphy that document the Pennsyl- system in central and southern New Mexico. and possibly minor exhumation along the west- vanian-Permian evolution of the Darwin Basin. Basal strata (~5.0–4.5 Ma) record the largest ern margin of the rift resulted in increased detrital We also report on whole-rock geochemistry and contributions of detritus derived from the San contributions from the oldest and deepest parts XRD analysis of five previously unknown tuffs Juan and Mogollon Datil volcanic fields (34–29 of caldera sources between the Pliocene and late identified in the Darwin Basin. We propose that Ma) and lesser occurrences of recycled Cordille- Pliocene. These same caldera source areas were subsidence in the Darwin Basin and southern ran arc zircons derived from recycled Mesozoic less of a source for the system by the Pleistocene. California was caused by extension and dynamic stratigraphy from the Colorado Plateau. The topography above the incipient Cordilleran Sub- late Pliocene phase (3.1–2.6 Ma) marks similar ERUPTIVE VOLUME AND EXPLOSION duction Zone. We further suggest that the first contributions of detritus derived from late Ceno- ENERGY ESTIMATES FROM KILBOURNE appearance of this subsidence dates the onset of zoic volcanic fields and marks the emergence of HOLE MAAR, SOUTH-CENTRAL subduction, which appears to have begun shortly peaks that overlap with recycled Cordilleran arc NEW MEXICO before the Pennsylvanian-Permian boundary. Arc sources (217–82 Ma). Pleistocene (2.0–1.6 Ma) Vitarelli, Daniela C., M.S magmatism may have begun as early as 290 Ma, stratigraphic horizons show a relative decrease but was likely low-volume and confined to small of zircons that overlap in age with the San Juan portions of the southwestern plate margin during and Mogollon Datil volcanic field sources and an Maar-diatremes are a common type of mono- the Permian, as is the case for the nascent Neo- increase in contributions of recycled Cordilleran genetic volcano defined by ascending magma

Spring 2021, Volume 43, Number 1 12 New Mexico Geology interacting explosively with an external water ern Grand Canyon. This study refines the timing FLUVIAL GEOMORPHIC AND HYDRO- source, or phreatomagmatic activity. In terms of of this drainage reversal in the Salt River area LOGIC EVOLUTION AND CLIMATE area, Kilbourne Hole is an unusually large and by constraining the ages of paleoriver sediments CHANGE RESILIENCE IN YOUNG VOLCA- irregularly shaped, young (~20 ka) maar with deposited during the time of northeast-flowing NIC LANDSCAPES: RHYOLITE PLATEAU well exposed and accessible deposits. Traditional rivers, internal drainage and southwest-flowing AND LAMAR VALLEY, YELLOWSTONE field methods and complementary remote sensing rivers. These results provide insights into the NATIONAL PARK methods were used to investigate the potential evolution of the southern Colorado Plateau. Burnett, Benjamin Newell, Ph.D. eruptive volume, explosion energy, and eruption U-Pb dating of detrital zircon is used for maxi- progression of Kilbourne Hole maar to shed mum depositional ages and provenance analyses. Quaternary volcanism associated with the last light on large maar-forming eruptions. With a 40Ar/39Ar dating of detrital sanidine is used for caldera cycle in Yellowstone National Park minimum total eruptive volume of 0.23 km3, higher precision maximum depositional ages. included emplacement of ash-flow tuffs, massive Kilbourne is the largest known single maar by The majority of paleoriver samples that were rhyolite flows ranging from 79 to 484 ka, and eruptive volume. The deposits around the maar analyzed with both detrital zircon and sanidine valley-filling basalts. This study examines (1) the crater rim range in thickness from ~1 to ≥60 m. show similar maximum depositional ages. Mini- evolution of spring hydrology with flow age on The thickness of individual beds also varies, with mum or direct depositional ages are determined the Rhyolite Plateau, (2) initial development and beds generally increasing in thickness towards by overlying or interbedded volcanic units. evolution of stream networks on the rhyolite the north-northeast particularly up-section, The Mogollon Rim Formation is composed flows, and (3) the impact of the 630 ka caldera suggesting vent migration potentially occurred of river gravel, sandstone and mudstone on the formation and volcanic flow emplacement on at Kilbourne or that the vent was located north- southern rim of the Colorado Plateau that were Lamar Valley incision rates. ward towards the later stages of the eruption. deposited by northeast-flowing rivers. Results Integrated stream networks formed within 79 The deposits themselves lack a later magmatic indicate deposition began after 59.38 Ma in the kyr on the Rhyolite Plateau. Incision is focused phase and are dominated by fine ash and sand- Flying V Canyon area and from 37–33.55 Ma on steep flow margins and knickpoints and is waves, indicating emplacement largely by dilute in the Trout Creek section. The Whitetail Con- dependent on local stream power. Plugging of density currents (surges), suggesting that the glomerate represents the transition from north- fractures causes hydraulic conductivity of the water-magma ratio remained constant through- east-flowing rivers to internal drainage in the Salt flows to decline over time. Snowmelt infiltrates out the eruption and that explosions occurred River paleocanyon. Whitetail Conglomerate is as rapidly into younger flows, leaving ephemeral dominantly at greater-than-optimal scaled depths old as the interbedded 37.6 Ma dacite in Canyon surface streams, but many flow-margin springs (OSD), which produce abundant surges. The Creek fault side drainages, but deposition in experience a delayed snowmelt response and total explosion energy predicted by crater dimen- the axis of the Salt River paleocanyon occurred enhanced discharge during late-summer periods sions ranges from 5.21 x 1016 to 1.45 x 1017 J, between 30 and 21.8 Ma. The transition from of water stress, providing important refugia for which when compared to the explosion energies northeast-flowing rivers to internal drainage aquatic organisms threatened by climate change. derived from individual events, suggests a range occurred between 33.55–30 Ma, marking the age Incision rates over the past 630 kyr in the of 54 to 209 explosions of 6.94 x 1014 J would be of initial development of the southern edge of the Lamar Valley are greatest (≤ 0.55 mm/yr) where required to form Kilbourne Hole maar. Although Colorado Plateau. Apache Leap tuff flowed NE the greatest thickness of Quaternary volcanic the individual explosion energies predicted at down the Salt River paleocanyon nearly to Can- material was emplaced, where they are higher Kilbourne are not necessarily more energetic than yon Creek fault at 18.6 Ma. Internal drainage is than most rivers in the region. Incision rates are those predicted by previous maar studies, the documented by the 14.67 Ma Black Mesa basalt lowest (≤ 0.15 mm/yr) above a knickpoint caused thick deposits and large eruptive volume suggest that flowed onto underlying lake beds. The first by erosion resistant crystalline bedrock, and a prolonged eruption is likely responsible for the southwest-flowing river system in the Salt River in the upper reaches of two tributaries, where large maar-forming eruption and that in some paleocanyon deposited the Dagger Canyon con- I infer that faulting associated with caldera special circumstances, maar eruptions dominated glomerate after incising at least 200 m deep into formation led to stream capture of portions of by greater-than-OSD explosions may produce the Whitetail Conglomerate. The lower Dagger the headwater areas. large volumes. While further work is needed to Canyon conglomerate is present in tilted fault investigate the lateral changes in the deposits at blocks on the eastern side of Tonto Basin and the BASAL TRAVERTINE OF THE BOUSE Kilbourne, particularly in the west, and further western portion of the Salt River paleocanyon. FORMATION: GEOCHEMISTRY, DIA- assess the potential for vent migration at this The dip of bedding increases down-section from GENESIS AND IMPLICATIONS FOR THE location, this study has demonstrated that pro- 0 to 27o providing evidence that deposition INTEGRATION OF THE COLORADO RIVER longed activity, consistent water-magma ratios, occurred while the faults were active. Lower Ferguson, Christina, M.S. and greater-than-OSD dominated explosions can Dagger Canyon conglomerate deposition began result in large maar-forming eruptions and result after 12.49 Ma, presumably due to base level fall The Pliocene Bouse Formation is discontinuously in immense eruptive volumes. associated with Basin and Range extension. The exposed in the lower Colorado River region and is upper Dagger Canyon conglomerate is composed a record of the first arrival of the Colorado River of flat-lying river gravels and sandstone located to the Gulf of California 5 million years ago. It University of New Mexico at higher elevations than the lower Dagger consists broadly of a lower carbonate member Canyon conglomerate in Tonto Basin and the (travertine, marl, and bioclastic units) and an NEOGENE DRAINAGE REVERSAL AND Salt River paleocanyon. Deposition of the upper upper siliciclastic member (claystone, mudstone, COLORADO PLATEAU UPLIFT IN THE SALT Dagger Canyon conglomerate began after 7.34 and Colorado River sands). This paper focuses RIVER AREA Ma and a possible lag in fluvial deposition on the basal travertine (synonymous with “tufa”) Anderson, Jordan Curtis, M.S. occurred between the two facies. If a lag in flu- unit of the lower carbonate member. Because of vial deposition occurred then the upper Dagger its basal position and its chemical encrustation The modern Salt River flows southwest from the Canyon conglomerate represents a rejuvenation of pre-Bouse topography, the travertine can offer Colorado Plateau, through the Arizona Transition of the southwest-flowing river system in the Salt insight into the earliest depositional settings and Zone and into to the Basin and Range. Rivers in River paleocanyon after Basin and Range fault- may be a proxy for the composition of the waters this area flowed northeast during the Paleogene ing waned. A likely driver for this rejuvenation that deposited the first Bouse carbonates. Hence from the Laramide Mogollon Highlands into would be southern Colorado Plateau uplift by the the travertine unit, if it can be shown to preserve structural basins of the topographically lower building of Mount Baldy volcanic field 12–8 Ma. a primary geochemical signal, offers the potential southern Colorado Plateau area. One of these to discriminate between alternative hypotheses rivers carved the Salt River paleocanyon through for marine versus non-marine deposition of the a portion of the Mogollon Highlands known as Bouse carbonates of the Blythe Basin. This paper the Apache Uplift to similar depths as the mod- examines the geochemistry of the travertine unit

Spring 2021, Volume 43, Number 1 13 New Mexico Geology using stable isotopes of carbon and oxygen, travertine suggest influences from deeply circu- in a (possibly active) zone of inboard transtension. 87Sr/86Sr, petrographic examinations of thin lated geothermal groundwaters. We do not rule The remaining chapters focus on Late sections, and microprobe traverses. Testing for out mixing of marine and non-marine waters in Cretaceous and younger tectonism within the diagenesis included subsampling techniques and an estuarine environment to explain marine fos- Laramide foreland region, a world class study textural studies using thin section examinations sils and reported sequence stratigraphic and tidal area that is still vigorously debated after over and SEM investigations. sedimentary evidence, but the geochemical data 100 years. Chapter 2 utilizes apatite thermochro- The travertine unit forms an encrustation are more consistent with the interpretation that nology to addresses the timing of Cretaceous that drapes and mantles pre-Bouse topography, the initial travertine deposition in multiple Bouse (Laramide) and Miocene–Recent tectonism including volcanic bedrock and fanglomerates. basins (and the travertine depositing waters) recorded in distinctly situated samples within the The travertine unit is generally thin, often less were dominantly non-marine. Zuni Mountains of west-central New Mexico. than several meters thick although it can reach Chapter 3, through integrated apatite thermo- thicknesses of tens of meters. It is intermittent INTERPRETING AMALGAMATION chronology and basin stratigraphy, interprets a but fairly widespread in the Blythe Basin, the PROCESSES OF A FLUVIAL SANDSTONE OF ca. 95–70 Ma eastward sweep of Laramide onset southernmost of the Bouse basins, and also THE NACIMIENTO FORMATION IN THE of deformation (when it began) across northern is present in scattered locations in the more SAN JUAN BASIN, NEW MEXICO Arizona–New Mexico. Chapter 4 scales up the northern basins. Its facies include: porous tufa, Miltenberger, Keely Elizabeth, M.S. methodology of Chapter 3 with a regional scale microbialite domes (bioherms), vegetation-casts compilation effort to interpret an east-northeast (charophytes of marsh and probable non-marine Outcrop studies of fluvial sand bodies are directed sweep of time transgressive onset of origin), and botryoidal travertine, all onlapped important for the study of fluid transport Laramide deformation from Montana–South by and interfingered with marl and high energy and storage capabilities because the deposits Dakota to Arizona–New Mexico during the Late bedforms of bioclastic sandstone that were are heterogeneous. 3-D photogrammetry was Cretaceous–Paleogene. deposited before the first arriving Colorado used to evaluate the amalgamation processes These studies contribute to our understanding River sands. This Walther’s Law relationship of a multi-storey sheet sandstone in the San of plate tectonics and the role that intracon- suggests that the travertines are broadly coeval Juan Basin, NM. The Angel Peak Member was tinental deformation plays. Inboard plate with the other facies in the basal carbonate unit deposited in the proximal-medial transition of a margin deformation and its role on river system of the Bouse Formation. Stable isotope data for distributive fluvial system by a meandering river integration and potential ongoing deformation travertine reveal a covariation of δ13C with δ18O during the Paleocene. Within the study area, are described. Likewise, the timing and spatio- and a spread of values between (+4, +2‰) and amalgamation occurred by avulsion and reoc- temporal patterns of deformation shed light on (-16, -9‰) for the southern Blythe Basin and a cupation of channel-belts to produce five storeys the tectonic processes that operated during the regression line with R2 = 0.63. Northern basin of the multi-storey sheet sandstone. Within each Laramide orogeny, as well as additional Ceno- travertines have a similar covariation trend (R2 = storey is evidence of processes that are internal zoic exhumation related to epeirogenic uplift of 0.73). Travertines show multiple carbonate gener- to a channel-belt, such as bar migrations, small the western and southwestern United States. ations in thin section, but stable isotope analyses scour surfaces, and chute deposits. Vertical trun- did not show continuous or regular differences in cation by subsequent channel-belts has occurred LANDSCAPE EVOLUTION OF THE composition of subsamples. Silica diagenesis was to each storey. Miocene to present erosion has SOUTHERN COLORADO PLATEAU USING observed in the Buzzard’s Peak area where the also removed portions of the uppermost storeys LOW-TEMPERATURE APATITE THERMO- 4.834 Ma Lawlor Peak tuff is interbedded with within the detailed study area. The multi-storey CHRONOLOGY AND DETRITAL ZIRCON carbonates, but this area showed overlapping sheet sandstone of the Angel Peak Member was AND SANIDINE PROVENANCE STUDIES carbonate chemistry to other areas, although deposited as the San Juan Basin was almost full, Winn, Carmen L., Ph.D. somewhat more positive along the regression thus has many characteristics of amalgamation line. Compiled and new 87Sr/86Sr analyses show during low accommodation space. Chapter 1: Westernmost Grand Canyon that the basal Bouse carbonates have non-marine Conflicting hypotheses about the timing of values of ~ 0.711 (as opposed to 0.709 for sea- INTEGRATED STUDIES OF INTRACON- carving of the Grand Canyon involve either a 70 water) in all carbonate facies (marls, bioclastic TINENTAL DEFORMATION IN THE Ma (“old”) or < 6 Ma (“young”) Grand Canyon. unit, travertine, and numerous fossil types). Dou- INTERIOR WESTERN USA, CRETACEOUS This paper evaluates the controversial western- ble dissolution tests for 87Sr/86Sr values were per- TO RECENT most segment of the Grand Canyon where the formed in travertine and marl to evaluate potential Thacker, Jacob Oliver, Ph.D. following lines of published evidence firmly favor diagenetic changes: these revealed little change in a “young” Canyon. 1) North-derived Paleocene values (from 0.71051 to 0.71081; from 0.71056 The advent of plate tectonic theory satisfactorily Hindu Fanglomerate was deposited across the to 0.71074; and from 0.71088 to 0.71088). Plots explained a number of deformation belts around present track of the westernmost Grand Canyon, of δ18O versus 87Sr/86Sr and versus latitude show the world. However intracontinental deforma- which therefore was not present at ~55 Ma. 2) no covariation in 87Sr/86Sr over a wide range of tion (deformation inboard of a plate margin) The 19 Ma Separation Point basalt is stranded δ18O and facies types. remains poorly understood in plate tectonic between high relief side canyons feeding the main The combined data are interpreted as showing models. In order to further our understanding of stem of the Colorado River and was emplaced only limited carbonate diagenesis within the intracontinental tectonics and its effects, this dis- before these tributaries and the main canyon were basal travertine of the Bouse Formation such that sertation examines paleotectonic and neotectonic incised. 3) Geomorphic constraints indicate that carbonate geochemistry can be used as a proxy settings within the interior western USA. relief generation in tributaries and on plateaus for the waters that deposited them. Two possi- Chapter 1 focuses on late Miocene–Recent adjacent to the westernmost Grand Canyon took bilities are examined to explain the covariation deformation inboard of the San Andreas plate place after 17 Ma. 4) The late Miocene-Pliocene of δ18O with δ13C: 1) mixing of sea water (0, 0) margin fault and its role on the integration Muddy Creek Formation constraint shows that and meteoric water (-16, -7); or 2) evaporation history of the lower Colorado River. The neotec- no river carrying far-traveled materials exited at of basin water. We favor evaporation as the tonic analysis included geometric and kinematic the mouth of the Grand Canyon until after 6 Ma. dominant explanation based on the similarity fault data collected in key geologic units to Interpretations of previously-published low-tem- of travertine variation in northern (lacustrine) characterize the timing and style of deformation perature thermochronologic data conflict with and southern (debated marine versus lacustrine) in an area that has commonly been considered these lines of evidence, but are reconciled in basins, the presence of non-marine charophytes in to lack young deformation. It is found that post- this paper via the integration of three methods travertines, and absence of covariation between 12 Ma deformation in the region is cumulatively of analyses on the same sample: apatite (U-Th)/ δ18O and 87Sr/86Sr, consistent with evaporation significant and persisted before, during, and after He ages (AHe), 4He/3He thermochronometry but not mixing. Radiogenic 87Sr/86Sr and the deposition of the Bouse Formation—a unit that (4He/3He), and apatite fission-track ages and presence of localized zones of large volumes of represents the first arrival of the Colorado River— lengths (AFT). “HeFTy” software was used

Spring 2021, Volume 43, Number 1 14 New Mexico Geology to generate time-temperature (t-T) paths that The 35-15 Ma ignimbrite flare-up, initiation and thus is preferred as a hypothesized sink for predict all new and published 4He/3He, AHe, and of Basin and Range extension, and incision of the Music Mountain fluvial system. The maxi- AFT data to within assumed uncertainties. These the East Kaibab paleocanyon is associated with mum depositional age via both detrital sanidine t-T paths show cooling from ~100°C to 40–60°C 37,000 cubic kilometers of volume loss above the and detrital zircon is ~73 Ma, several tens of in the Laramide (70–50 Ma), long-term residence Kaibab datum. Post-6-Ma river integration of the million years older than the best age estimates of at 40-60°C in the mid-Tertiary (50–10 Ma), and Colorado River system through Grand Canyon 50-60 Ma and provides little new information. cooling to near-surface temperatures after 10 and probable young uplift is driving ongoing Detrital zircon age populations for the Buck Ma, and thus support a “young” westernmost deep incision and is associated with a minimum and Doe Conglomerate are also dominated by Grand Canyon. of 15,500 cubic kilometers of volume loss above peaks at ~1680 Ma and 1390 Ma, although A subset of AHe data, when interpreted the Kaibab datum, with at least 4,166 additional the 1390 Ma peak is significantly stronger in alone (i.e., without 4He/3He or AFT data), are cubic kilometers of volume loss from the Grand comparison with the older Music Mountain better predicted by t-T paths that cool to surface Canyon alone. Cliff retreat rates are highly lithol- Formation. There are very minor peaks of temperatures during the Laramide, consistent ogy dependent and range between 1.8 km/Ma for Mesozoic-aged zircons and a sharp peak at ~20 with an “old” Canyon. This inconsistency, which the Chocolate Cliffs, 2.4 km/Ma for the Jurassic Ma sourced from local volcanism, although this mimics the overall controversy, is reconciled (Vermillion) Cliffs, and 1.8 km/Ma for the Grey is only present in two of the 6 samples. These age by optimizing cooling paths so they are most Cliffs. We conclude that three periods of acceler- populations suggest continued unroofing of the consistent with multiple thermochronometers ated denudation of the southwestern Colorado Kingman uplift with increased contribution from from the same rocks and adjusting parameters Plateau, most likely driven by epeirogenic uplift, the 1390 Ma Peacock Mountain Granite and to account for model uncertainties. We adjusted represent punctuated periods of broad-scale cliff reworking of the Music Mountain Formation. model parameters to account for uncertainty in retreat that are coeval with evidence for signifi- Contemporaneous deposits include the lower the rate of radiation damage annealing during cant fluvial systems. The Colorado Plateau region portion of the Brown’s Park Formation from sedimentary burial in these apatites and thus is thus a type example of epeirogenic controls on northern Utah and the Rainbow Gardens Forma- possible changes in He retentivity. In the west- geomorphic re-shaping of plateau landscapes. tion in the Lake Meade region of eastern Nevada, ernmost Grand Canyon, peak burial conditions and a sample from the Table Cliffs Basin that (temperature and duration) during the Laramide Chapter 3: Provenance and Pathways of the unexpectedly yielded a population of ~20 Ma were likely insufficient to fully anneal radiation Music Mountain and Buck and Doe Paleorivers zircon U-Pb ages. Comparison of age spectra for damage that accumulated during prolonged, Scattered remnants of “Rim Gravels” on the these units with the Buck and Doe ages indicate near-surface residence since the Proterozoic. southern margin of the Colorado Plateau preserve that a relationship with the Rainbow Gardens The combined AFT, AHe, and 4He/3He analysis a direct record of its fluvial and erosional history. or the Brown’s Park Formation are unlikely, but of a key sample from Separation Canyon can Two paleoriver deposits containing well-de- that there is a high likelihood of a connection only be reconciled by a ‘young’ Canyon, but scribed gravels occur on the far southwestern with the “White Claron” sample from the Table thermochronologic uncertainties remain large corner of the plateau, the Paleocene (55–50 Cliffs Basin. Maximum depositional ages from for this geologic scenario. Additional new AFT Ma) Music Mountain Formation and the Oligo- detrital sanidine for three samples from the Buck (5 samples) and AHe (3 samples) data in several cene-early Miocene (24–18 Ma) Buck and Doe and Doe Conglomerate are 18.065 ± 0.017 Ma, locations along the canyon corridor also support Conglomerates (Young, 1999). Detrital zircon 25.52 ± 0.10 Ma, and 30.2 ± 0.2; the youngest of a “young” Canyon and suggest the possibility of analysis can provide clues to potential sources these is slightly younger than the Peach Springs variable mid-Tertiary thermal histories beneath and sinks of these deposits and more recently, Tuff (18.78 ± 0.02 Ma), which caps the type north-retreating cliffs. We conclude that appli- high-precision detrital sanidine studies have been section of the Buck and Doe Formation. cation of multiple thermochronometers from developed to tightly constrain the maximum The erosional history of the southern Colo- common rocks reconciles conflicting thermo- depositional ages and provenance of Cenozoic rado Plateau has been a topic of scientific debate chronologic interpretations and is best explained deposits. In this study, we use a combination of for over 150 years. Key conclusions include 1) by a “young” westernmost Grand Canyon. new and published detrital zircon and detrital both of these fluvial systems were sourced from sanidine data to determine provenance and the Kingman uplift to the south as shown by the Chapter 2: Formation of the Grand Staircase potential sinks of the Music Mountain Forma- 1390 Ma age population, 2) a potential connec- Dutton’s (1882) “Great Denudation” involved tion (n = 1090 U-Pb zircon ages and n = 5 detrital tion is proposed between the Music Mountain. the lateral erosion of Mesozoic strata northwards sanidine ages used for maximum depositional Formation and the San Juan Basin, which is also from the rim of Grand Canyon via cliff retreat. ages) and the Buck and Doe Conglomerates (n = based on this 1390 Ma population, and 3) we He described a “great stairway” of alternating 1028 U-Pb zircon ages and n = 6 detrital sanidine also propose a ca. 18 Ma connection between benches of erodible strata and cliffs of resistant ages used for maximum depositional ages). In the westernmost Buck and Doe sample and the strata now known as the Grand Staircase. We addition, we collected 4 samples (n = 670 U-Pb Miocene “White Claron” of the Table Cliffs Basin, analyze 52 samples from across the southwestern zircon ages) from formations in the Table Cliffs indicating there was no paleo Grand Canyon at Colorado Plateau and use linear inverse modeling Basin (e.g. Markagunt and Paunsaugunt Plateau that time. The timing of these fluvial systems is of apatite thermochronometric data in HeFTy regions) to evaluate it as a potential sink for the consistent with the major periods of denudation to determine continuous thermal histories for Music Mountain Formation. found in Chapter 2 and these paleorivers provide each sample. Results from these histories were Detrital zircon age populations for the Music potential pathways for the removal of this material. then passed through a MATLAB code to extract Mountain Formation are dominated by a 1691 temperatures of the weighted mean paths every 5 Ma age peak with a smaller 1390 Ma peak and TRIPLE OXYGEN ISOTOPE COMPOSITION Ma, combined with geologic constraints on dated a small portion of Mesozoic ages. Grenville-aged OF CARBONATES paleosurfaces, and interpolated across the study grains (~1100 Ma) are conspicuously absent. Wostbrock, Jordan A.G., Ph.D. area. These interpolations show reconstructed This age distribution indicates that the Music cooling patterns of the top contact of the Kaibab Mountain fluvial system is sourced from the This dissertation presents a method of analyzing the Limestone through time since 70 Ma and can be nearby Kingman uplift, where basement rocks triple oxygen isotope compositions of carbonates, used to estimate the geometry and rates of lateral of these ages occur. Comparison of this age presents an empirical calibration of the carbonate-wa- cliff retreat and resulting erosional volumetric distribution with coeval Laramide deposits from ter equilibrium fractionation line, presents a triple loss through time. We find three main times of the Uinta Basin, San Juan Basin, and Table Cliffs oxygen isotope equipped fluid-rock mixing model denudational cooling, each associated with major Basin reveal that while none of these basins are for carbonates to see through diagenesis, and applies through-going river systems. The Laramide orog- ideal matches, connections with the Table Cliffs all these findings to ancient carbonate samples. Using eny (70–50 Ma) and incision of Paleocene fluvial or Uinta Basins are unlikely. The San Juan Basin modern carbonates and associate water, the following valleys is associated with 55,750 cubic kilome- provides a potential match for age populations, equations are calculated to describe equilibrium triple ters of volume loss above the Kaibab datum. particularly the significant ~1390 Ma age peak, oxygen isotope fractionation of carbonates:

Spring 2021, Volume 43, Number 1 15 New Mexico Geology ( ) 6 and 1.5–1.45 Ga Trampas groups of the Picuris Pecos volcanic complex. Juxtaposition of amphi- 18 _2.84______​± 0.02 ​ × ​10​ ​ ( ) ( ) ​1000lnα ​ ​ Ο​ ​ = ​ 2 ​ − 2.96​± 0.19 ​ ​1 ​,​ cc−wt ​T​ ​ Mountains and Rio Mora areas of northern New bolite-grade upper plate rocks against 1.48–1.45

− 1.39​(​ ± 0.01​)​ Mexico combined with new geochronologic Ga metasedimentary lower plate rocks are the ​ θ​ ​ = _​ ​ + 0.5305 ​(2)​.​ ​ c c−wt​ T and thermochronologic constraints. These data product of progressive thrusting from 1.50 to Using these fractionation equations provides suggest the following tectonic evolution. An 1.40 Ga, synchronous with development of an extremely useful tool to determine whether early bedding-parallel S1 fabric is present only syntectonic foreland basins. The 1.45 Ga granite a carbonate sample is altered or preserves its in pre-Trampas Group rocks and is interpreted and pegmatites show only minor penetrative original isotopic composition. In samples that to be related to early isoclinal folds and thrusts. strain but are considered broadly syntectonic are altered, a fluid-rock mixing model is used to All groups were folded by F2 and F3 fold genera- with waning deformation at 1.45–1.40 Ga. A see through the diagenesis. Applying these tools tions during the Picuris orogeny. New U-Pb dates modern analog is the Tien Shan–Tarim basin to ancient carbonate rocks shows that many from monazite cores of about 1.5 Ga in alumi- region of the interior Tibetan Plateau inferred samples thought to be pristine are altered and are nous gneisses from the Vadito–Hondo group for the Picuris tectonism. New 40Ar/39Ar dates confusing paleoenvironmental interpretations. aluminous contact zone within the Pecos thrust on hornblende and muscovite constrain cooling This work shows that seawater temperature sheet are interpreted as onset of Picuris orogeny through ~500°C and ~350–400°C respectively and isotopic composition is unchanged over the prograde tectonism. This onset of heating/ and provide insight into cooling rates following Phanerozoic, an important consideration when deformation is thus close in age, and apparently the Picuris orogeny, and hence the nature and reconstructing paleoenvironments. pre-dates deposition of the Trampas Group at timing of demise of Picuris orogenic uplifts. ~1488 ± 6 Ma in the footwall of the Pecos and Hondo and Trampas group rocks cooled through STRUCTURAL AND GEOCHRONOLOGIC Plomo thrusts. Growth of metamorphic garnets 500°C 1420–1381 Ma and through 350°C from CONSTRAINTS ON THE DURATION OF at 1.45- 1.40 Ga from previous studies and new 1378–1359 Ma. This is similar to new data with THE PICURIS OROGENY AND DEMISE OF monazite rim dates of ~1.45 Ga may record 40Ar/39Ar cooling data from muscovite from the AN OROGENIC PLATEAU, NORTHERN NM metamorphism close in age to deposition of the Petaca pegmatite district (mean cooling age of Young, Daniel J., M.S. thrust-bound 1.453 ± 10 Ga Marqueñas Forma- 1375 ± 10 Ma), and similar ages in basement tion. Regional cross sections show that the mod- exposures from neighboring mountain ranges. Metasedimentary and igneous basement rocks ern surface exposure represents an exhumed ~15 Slow cooling from >500 to <350°C from ~1420 in northern New Mexico record episodic pulses km middle crustal duplex system that juxtaposes, to ~1360 Ma suggests cooling rates of ~3°C/Ma of tectonism during cratonic growth from 1.8 to from north to south: 1) 1.45 Ga triple point over 60 Ma following peak triple point meta- 1.38 Ga. Continued challenges involve parsing (>550 C, 3.5 kbars) polyphase metamorphic morphism. To explain this protracted cooling the deformational features attributable to the tectonites in the Copper Hill anticline-Hondo we propose that an orogenic plateau was built Yavapai Orogeny (1.71–1.68 Ga), Mazatzal syncline thrust sheet made between the Pilar and by thrust duplexing and penetrative folding orogeny (1.66–1.60 Ga), and Picuris orogeny Plomo thrusts, 2) a similar grade thrust-bound in northern New Mexico during the Picuris (1.5–1.38 Ga) in this region and understanding Marqueñas tectonite that makes up the Plomo orogeny followed by relatively slow erosional how older structures may have been overprinted shear zone, 3) the 1.45 Ga Peñasco granite that removal. Erosion of much of the region initiated and reactivated to explain the observed strain. intrudes Vadito Group rocks between the Plomo by 1.1–1.3 Ga, resulting in deposition of the De This paper presents regional cross-sections of shear zone and the Pecos master thrust, and 4) Baca Group and correlative strata. the 1.7 Ga Vadito, 1.68 to 1.50 Ga Hondo, overriding volcanic rocks of the ~1.72–1.65 Ga

Spring 2021, Volume 43, Number 1 16 New Mexico Geology New Mexico Bureau of Geology and Mineral Resources Publications 2021

Upcoming Publication The Rio Chama: A River Guide to the Geology and Landscapes

The 135-mile Rio Chama of northern New Mexico is a major tributary of the Rio Grande. From its alpine head- waters at the Continental Divide of the glaciated San Juan Mountains in southern Colorado, this hidden gem flows across the Colorado Plateau in a spectacular canyon cut into Mesozoic sedimentary rocks, in places up to 1,500 feet deep. Towering, vibrant, sandstone cliffs, heavily wooded side can- yons, superb camping, and a diversity of historical sites offer an outstanding wild river backdrop for the boater, angler, hiker, or camper. This book contains detailed river maps of the seven sec- tions of the Rio Chama, plus its three resplendent reservoirs, from the Colorado headwaters to its confluence with the Rio Grande near Española. The Chama Canyon section, below El Vado Dam and through the Chama Canyon Wilderness, is one of the finest, multi-day, whitewater trips in the South- west. The Rio Chama will be printed in 2021.

Available at our bookstore! Order online or call 575-835-5490!

The Geology of Southern New Mexico’s Parks, Monuments, and Public Lands is the companion book to The Geology of Northern New The GeoloGy of SouThern new Mexico’S Mexico’s Parks, Monuments, and Public Lands. ParkS, MonuMenTS, and Public landS Available Now! outhern New Mexico has a Mount Taylor map and guide book! Swonderful combination of spectacular scenery and a sparse population. The state’s diverse and interesting geology is reflected

in its numerous state parks and P monuments (including Carlsbad ark S

Caverns and White Sands M , S

National Parks) as well as other ou T hern onu M en TS publicly accessible lands ranging T in size from the multi-million acre Gila wilderness to small he G roadside turnoffs and picnic areas. This book, crafted by n eolo G y , geoscientists but written for the interested public, ew and provides an understanding of the M P

exico exposed rock units that record more of ublic than 1.7 billion years of geologic and ’ biologic changes in this region. With S For more information about the bureau, our

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nearly 400 full-color photographs, and S geologic maps, and illustrations, this publications or to order online, book illuminates not just the rocks and fossils of southern New Mexico, but visit our website at geoinfo.nmt.edu. also archaeological/historical sites as well as the water, mineral, and energy resources of the region. Call (575) 835-5490 or email us at [email protected] New Mexico Tech 801 Leroy Place, Socorro, New Mexico 87801

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Publisher: New Mexico Bureau of Geology and Mineral Resources Publication Date: April 15, 2020 Category: New Mexico Travel and Geology ISBN: 978-1-883905-48-4 Format: Full color, 8” x 10” paperback, 404 pages, sewn binding Distributor: NMBGMR Publications, [email protected] Editor: Peter Scholle, [email protected]

New Mexico Bureau of Geology and Mineral Resources A Research Division of New Mexico Tech