<<

Effects of global climate changes on continental sedimentation: A case study from the southern Central

Andrea Stevens Goddard1 and Barbara Carrapa2 1Center for Integrative Geosciences, University of Connecticut, Storrs, Connecticut 06269, USA 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA

ABSTRACT tectonic forcing. Although several studies have Sedimentation rates are valuable proxies for changes in tectonics, climate, and sediment proposed using sedimentation rates on geologic routing systems. We use sedimentation rates from the Bermejo foreland basin of the southern time scales as a for changing climate, this Central Andes to evaluate the role of global Miocene– changes on continental application has primarily been applied to tec- erosion and sedimentation in non-glaciated landscapes. Our compilation identifies a tripling of tonically quiescent settings (e.g., Smith, 1994; sedimentation rates between ca. 10 and 8.5 Ma coinciding with a period of short-lived global Peizhen et al., 2001). warming and increased seasonality, and a decrease by half in sedimentation rates between This study demonstrates that changes in Mio- ca. 6 and 5 Ma coinciding with increased global cooling and aridity. Both the increase and cene–Pliocene global climate provide a clear decrease in sedimentation rates occured during periods of heightened tectonic activity. Our and measureable control on the sedimentation results suggest that periods of aridity can reduce erosion and mask contemporaneous tec- rates in non-glaciated, tectonically active land- tonic signals, and that more humid, variable climate conditions amplify the signal of tectonic scapes such as the Bermejo foreland basin in forcing in the sedimentary record. This work shows that changes in sedimentation rates can the southern Central Andes, 27°–31°S (Fig. 1). accurately filter climatic variabilities out of the overprinting tectonic signal. Here, paleoclimate proxies confirm that global Miocene–Pliocene climate changes are recorded INTRODUCTION (103–105 yr) time scales, independent measure- in the sedimentary record (Latorre et al., 1997; Sedimentary basins contain a record of (1) ments of erosion rates can isolate the effect of Ruskin and Jordan, 2007; Bywater-Reyes et al., tectonic forcing, (2) climate, and (3) the geom- climatic changes or catchment reorganization 2010; Amidon et al., 2017). Geochronologic etry of the sediment routing (catchment on the sedimentary system (e.g., Romans et controls make it possible to calculate Miocene– area) (Smith, 1994; Peizhen et al., 2001; Allen al., 2016), but on geological time scales (>106 Pliocene sedimentation rates at nine indepen- et al., 2013; Amidon et al., 2017). However, yr), erosion rates must be indirectly calculated dent depocenters throughout the basin (Beer, extracting the unique signal of each of these con- using techniques such as low-temperature ther- 1990; Jordan et al., 1990; Reynolds et al., 1990; trols remains a fundamental challenge in the geo- mochronology (e.g., Reiners and Brandon, 2006) Carrapa et al., 2006, 2008; Levina et al., 2014; sciences. On historical (102 yr) and intermediate and are more likely to reflect longer-timescale Amidon et al., 2016; Stevens Goddard and Car- rapa, 2017). Precise constraints on the timing of tectonic forcing, as well as drainage reorgani- Modern Mean Precipitation N 10 50 100 F B 7 A zation, provide the context to isolate the effects kilometers 5.0 m sec -1 of climatic changes on the sedimentation rate. LTC 5 28 °S CLIMATE, EROSION, AND TECTONICS OF THE SOUTHERN CENTRAL ANDES 0° VN Sedimentology, stable isotopic, and clay min- 3 eralogy studies have been used to reconstruct 29 °S LF paleo­climate in the southern Central Andes throughout the (Latorre et al., 1997; 10° S 1 Ruskin and Jordan, 2007; Strecker et al., 2007; S HN o HC T Amidon et al., 2017). However, the effects of Lo u RA w th HS 30 °S - A Miocene–Pliocene climatic variability on ero- la m t i sion and sedimentation rates remains unclear. 0.8 t e 20° S u r i d c ecipitation (mm/day)

e a

Pr n J

e Figure 1. A: South American mean annual 0.6 t TPA 31 °S precipitation from NASA Tropical Rainfall Measuring Mission (TRMM) data (1998–2013) Mean 30° S (Huffman et al., 2014) and ERA-Interim (https:// 70° W 69° W 68° W 67° W www.ecmwf.int/en​ /forecasts​ /datasets​ /archive​ ​ 0.4 F = Fiambalá, LTC = Rio La Troya Catamarca, -datasets/reanalysis​ -datasets​ /era-interim)​ and VN = Vinchina, LF = La Flecha, RA = Rio Azul, T = Talampaya, HN = Huaco North, HC = Huaco Central, annual mean 850 hPa winds (Dee et al., 2011). HS = Huaco South, TPA = Talacasto, Pachaco, Albarracin Black box indicates study area shown in B. B: 40° S Basement and Sedimentary/ Geologic map of study area, modified from Ste- 0.2 Volcanic Arc Rocks Metasedimentary Rocks Permo- vens Goddard and Carrapa (2017). White circles Westerlies - clastic clastic depict locations of stratigraphic sections with 65° W 55° W 45° W basement - Mesozoic Paloeozoic geochronologic constraints used to calculate marine 0 Cenozoic arc marine the sedimentation rates for this study.

GEOLOGY, July 2018; v. 46; no. 7; p. 647–650 | https://doi.org/10.1130/G40280.1 | Published online XX Month 2018 ©GEOLOGY 2018 Geological | Volume Society 46 | ofNumber America. 7 For| www.gsapubs.org permission to copy, contact [email protected]. 647 Increased precipitation associated with a transi- (Allmendinger and Judge, 2014; Fosdick et al., The increase in sedimentation rate between ca. tion to less-arid climates in the 2015) and has been predicted to produce cor- 10 Ma and 8.5 Ma occurs during a period of has been shown to facilitate erosion (Bookhagen responding increases in erosional flux into the increased shortening in the Precordilleran fold- and Strecker, 2012; Allen et al., 2013). However, Bermejo foreland basin (Jordan et al., 2001). and-thrust belt (Allmendinger and Judge, 2014; in some cases, more-humid climates enable the Changes to catchment geometry, which can also Fosdick et al., 2015), which, however, has been growth of vegetation that impedes erosion and change sediment flux (Allen et al., 2013), can associated with a decrease in catchment area reduces sedimentation rates (Bull, 1991; Molnar, be independently identified using provenance between ca. 12 Ma and 10 Ma and should thus 2001). Another scenario, that of high climatic records. In the southern Bermejo foreland basin, produce a decrease in sedimentation rate, oppo- variability, keeps sediment routing systems in provenance studies identify an eastward migra- site of what we observe. At the same time, a disequilibrium, a condition that increases sedi- tion and decrease in catchment area between ca. global increase in temperature (Holbourn et al., mentation rates regardless of relative humidity 12 Ma and 10 Ma (Levina et al., 2014; Fosdick et 2013) and increased humidity (Ruskin and Jor- or aridity (Peizhen et al., 2001). However, ero- al., 2015), likely a response to concurrent defor- dan, 2007) are consistent with the appearance of sion in arid to semi-arid climates like the south- mation in the Andean Precordillera (Fig. 1). fluvial megafans in the Bermejo foreland basin ern Central Andes (Fig. 1) is widely thought (Stevens, 2017), an indicator of monsoonal-type to increase in periods of higher precipitation SEDIMENTATION RATES OF THE climate conditions at this time (Leier et al., 2005; (Bookhagen and Strecker, 2012). SOUTHERN CENTRAL ANDES Uba et al., 2007). This suggests that accelerated The Middle to Late Miocene is generally We used published con- sedimentation rates at 10–8.5 Ma may be largely characterized by a warmer climate than the drier straints from magnetostratigraphy (Johnson et al., controlled by a more-vigorous climate charac- and cooler Pliocene, with an overall global cool- 1986; Reynolds et al., 1990; Malizia et al., 1995) terized by warmer and more humid conditions. ing trend recorded by geochemical proxies from and U-Pb geochronology (Amidon et al., 2016; Overall, these data suggest that a warmer, more- the world’s oceans (Zachos, 2001; Holbourn et Stevens Goddard and Carrapa, 2017) to calcu- humid, and variable climate (monsoonal-like) al., 2013). Within this record, a notable period late sedimentation rates from nine depositional increased sediment production and delivery in of brief global warming occurred at ca. 10.5 areas located between 27°S and 32°S. We used the Central Andes. This trend is consistent with Ma, which has been linked to transient melting locations within a single connected depocenter observations as far north as Bolivia (Uba et al., of polar ice, high-amplitude climate variabil- (Bermejo foreland basin) in order to avoid pos- 2007) implying that climate-induced increases ity, a global increase in clastic flux into oceans, sible local structural complexities. For consis- in erosion in the Late Miocene cannot solely and low carbonate productivity (Holbourn et al., tency, we used the compacted thicknesses of the be attributed to changes in regional topography 2013; Preiss-Daimler et al., 2013). Along the sedimentary sections reported by previous work- (e.g. Uba et al., 2007). . Central Andes, a more humid climate has been ers, and thus our rates only reflect a minimum Our study identifies a widespread and recognized by at least 9 Ma through 7.5 Ma (Fig. 2). Our compendium of sedimentation rates synchronous decrease in sedimentation rates based on stable proxies from paleosols in the southern Central Andes identifies two peri- between ca. 6 Ma and 5 Ma (Fig. 2). Interest- (Ruskin and Jordan, 2007). The presence of allu- ods of high-magnitude, synchronous changes in ingly, this period of time is also characterized by vial megafans throughout the Bermejo foreland sedimentation rates (Fig. 2): (1) an increase in heightened tectonic activity (Allmendinger and basin at ca. 10–8 Ma is consistent with enhanced sedimentation rates between ca. 10 Ma and 8.5 Judge, 2014; Fosdick et al., 2015). Heightened climate variability during this period (Leier et Ma, and (2) a decrease in sedimentation rates tectonic activity at this time predicts an increase al., 2005; Uba et al., 2007; Stevens, 2017). between ca. 6 Ma and 5 Ma. in the sedimentation rate; however, these pre- Antarctic glaciations in the Late Miocene Seven out of nine stratigraphic sections dictions do not match the observed decrease are thought to have affected surface climate document an increase in sedimentation rates in the regional sedimentation rate. Instead, we and atmospheric circulation patterns that deliver between ca. 10 Ma and 8.5 Ma, spanning over attribute the decrease in sedimentation rates to moisture to (Fig. 1), enhancing 350 km along strike in the foreland basin (Figs. the onset of global cooling and increased arid- aridity in the Central Andes (Amidon et al., 1 and 2). The average sedimentation rate at ca. ity in the Pliocene (Latorre et al., 1997; Zachos,

2017). The global transition from C3 to C4 plants 10 Ma, recorded at seven locations, is 0.36 mm/ 2001; Amidon et al., 2017). This interpretation at ca. 7 Ma in the Central Andes (Latorre et al., yr. By ca. 8.5 Ma, the average sedimentation rate is supported by a contemporaneous decrease in 1997) has been linked to an increase in summer- taken from those seven locations is nearly three erosion rates documented in the southern Ber- dominated rainfall, global cooling, and aridity times that value, at 1.05 mm/yr (Fig. 2). The mejo foreland basin (Amidon et al., 2017), but (Ruskin and Jordan, 2007; Bywater-Reyes et al., three stratigraphic sections with Miocene–Plio- is at odds with models of a global increase in 2010; Amidon et al., 2017). This shift toward cene strata span 250 km along strike, and docu- Pliocene erosion rates (e.g., Herman et al., 2013) a more-arid climate beginning at ca. 7 Ma has ment a synchronous decrease in sedimentation in non-glaciated areas. been associated with a decrease in erosion rates rates between ca. 6 Ma and 5 Ma (Fig. 2). At ca. between 6.1 and 5.3 Ma (Amidon et. al., 2017). 6 Ma, the average sedimentation rate from these CLIMATE AS A REGULATOR In tectonically active areas such as the south- depositional centers is 0.94 mm/yr (Fig. 2). By OF TECTONIC SIGNALS IN THE ern Central Andes, isolating the effects of climate ca. 5 Ma, sedimentation rates decrease by over SEDIMENTARY RECORD change on the sedimentary system is difficult half in all three of the depositional centers, to The decrease in sedimentation rates during a because tectonic deformation and catchment an average of 0.43 mm/yr (Fig. 2). period of heightened activity of the Precordille- reorganization may change the sediment flux ran fold-and-thrust belt between ca. 6 Ma and 5 in the sediment routing system (e.g., Jordan et INTERPRETATION OF REGIONAL Ma—in an increasingly arid climate—contrasts al., 2001; Allen et al., 2013). However, well- SEDIMENTATION RATES with the tripling of sedimentation rates associ- documented Precordillera thrust belt propaga- Our compilation of along-strike Miocene– ated with tectonic forcing between ca. 12 Ma tion west of the Bermejo Basin can temporally Pliocene sedimentation rates from the Bermejo and 9 Ma in a semi-arid, more-seasonal climate constrain tectonically induced fluxes into the foreland basin exhibits a striking synchronicity (Fig. 2). We use this observation to suggest that sedimentary system. Neogene deformation of in both the magnitude and timing of changes in climate may regulate the effects of tectonic forc- the Precordilleran thrust belt occurred in pulses sedimentation rates, suggesting that the underly- ing on erosion and sediment accumulation in between ca. 21–19 Ma, 12–9 Ma, and 5.5–2 Ma ing control is regional to global in scale (Fig. 2). the surrounding basins. A semi-arid but warmer

648 www.gsapubs.org | Volume 46 | Number 7 | GEOLOGY Increasing a Allmendinger and Southern Central Andes Paleoclimate Records p Increasing Judge, 2014; b Amidon et Fluvial Humidity b,p Megafanso Aridi cation al., 2016; cAmidon et et al., 2017; d Beer, 1990; e Carrapa et al., 2006; Global Climate Global Warming Global Cooling Event & Global Climatic f m, r r q n Carrapa et al., 2008; Climatic Optimum Event Expansion of C grasses Disequilibrium g long-term global coolingm,r 4 Johnson et al., 1986; h Jordan et al., 1990; i a Levina et al., 2014; Accelerated Shortening in Andean Precordillera j Malizia et al., 1995; ? ~20 mm/yr ~8 mm/yr k Reynolds et al., 1990 l Stevens Goddard and Sedimentation Rates N Carrapa, 2017; mZachos, Fiambalá e,f 2.00 .67 .71 .42 2001, nPeizhen et al., 2001; oStevens, 2017; Rio La Troya Catamarca l pRuskin and Jordan, 2007, 1.6.40 qLatorre et al., 1997, rHolbourn et al, 2013 Vinchinab,l .82 1.2 1.2 .30 .60 Sedimentation .27 .47 .72 .87 .55 La Flechak, l Rates (mm/yr) 0.0 - 0.20 h .40 .40 - .60 Rio Azul 0.20 - 0.30 .10 ~.20 ~.35 Campo del Talampaya j 0.30 - 0.40 0.40 - 0.50 d Huaco North, Central, & South (avg) .25 .65 .8 0.50 - 0.60 Huaco Central g .17 .92 .58 0.60 - 0.70 .35 .45 .03 .61 Talacasto, Pachaco, Albarracin i 0.70 - 0.80 S 0.80 - 0.90

15 10 } } 5 0.90 - 1.0 0 Time (Ma) increasing sedimentation decreasing sedimentation 1.0 + rates rates Figure 2. Compilation of regional sedimentation rates from nine locations throughout the Bermejo foreland basin, southern Central Andes. Red color bar signifies increasing sedimentation rates with progressively darker fill. Gray bars highlight periods of synchronous changes in the regional sedimentation rate, including an increase at ca. 10 Ma to 8.5 Ma, and a decrease at ca. 6 Ma to 5 Ma. Periods of increased shortening (and rates) in the fold-and-thrust belt of the Andean Precordillera, west of the Bermejo foreland basin, are plotted with black bars. Published global and regional climatic records are indicated by red and blue arrows. and more-humid climate beginning at ca. 10.5 characterized by a decrease in sedimentation strongly impacted continental sedimentation in Ma (Holbourn et al., 2013) may have enhanced rates which we attribute to a global increase in the Central Andes. The threefold increase in sed- erosional processes and amplified the signal of aridity at ca. 6 Ma. In contrast, the synchronous imentation rates between ca. 10 Ma and 8.5 Ma tectonic forcing, facilitating high-magnitude increase in erosion rates throughout the Ber- has likely contributed to an increase in global (doubling, tripling) changes in the sedimenta- mejo foreland basin between ca. 10 Ma and 8.5 clastic delivery into the ocean, with a potential tion rate during the transition between periods of Ma, which has previously been interpreted to impact on global ocean productivity. active deformation and quiescence. Conversely, result primarily from increasing tectonic activity, sustained aridity established between ca. 6 Ma may in fact have been significantly amplified by ACKNOWLEDGMENTS and 5 Ma may have served as a dampener of monsoonal-type conditions (Ruskin and Jordan, Stevens Goddard acknowledges funding from a National Science Foundation Graduate Research Fel- erosional processes, so that even in periods of 2007; Stevens, 2017). lowship, the National Geographic Young Explorer’s heightened tectonic forcing, the magnitude of grant 9744–15, and a Geological Society of America increase in sedimentation rate is low to unde- CONCLUSION Graduate Student Research grant. We thank Julie Fos- tectable. In this scenario, climate serves as a The synchronicity of changes to regional dick, Patricia Alvarado, Gustavo Ortíz, and R. Hernán Aciar for insightful conversations on Andean geology. regulator of tectonically driven changes to ero- sedimentation rates in the Late Miocene–Plio- Paul Goddard plotted the global climate data. We thank sion and sedimentation. If true, this requires cene Bermejo foreland basin demonstrates that Jim Schmitt for editorial handling and Andrew Leier that changes in sedimentation rates attributed sedimentation rates serve as a faithful recorder and an anonymous reviewer for thoughtful reviews. to evolving tectonic boundary conditions should of changes in climatic regimes. During periods always be interpreted in a well-constrained cli- of sustained aridity, erosion may be reduced to REFERENCES CITED matic context, and vice-versa. In cases where a degree that even major changes to the tectonic Allen, P.A., Armitage, J.J., Carter, A., Duller, R.A., Michael, N.A., Sinclair, H.D., Whitchurch, A.L., climate severely dampens erosion, the signal of regime do not produce a measureable change and Whittaker, A.C., 2013, The Q s problem: Sed- tectonic forcing may not be recorded by a cor- in sedimentation rates. This study shows that iment volumetric balance of proximal foreland responding increase in sedimentation rate. We climate exerts a significant control on erosion basin systems: Sedimentology, v. 60, p. 102–130, suggest that this is the case for the period of tec- and sedimentation in tectonically active regions, https://​doi​.org​/10​.1111​/sed​.12015. Allmendinger, R.W., and Judge, P.A., 2014, The Argen- tonic forcing beginning at ca. 5.5 Ma that is not in some cases completely eclipsing the effects tine Precordillera: A foreland thrust belt proximal accompanied by a contemporaneous increase of tectonics. Our study also demonstrates that to the subducted plate: Geosphere, v. 10, p. 1203– in regional sedimentation rates, but rather is global climate changes in the Late Miocene have 1218, https://doi​ .org​ /10​ .1130​ /GES01062​ .1.​

GEOLOGY | Volume 46 | Number 7 | www.gsapubs.org 649 Amidon, W.H., Ciccioli, P.L., Marenssi, S.A., Lima- a cooling climate: , v. 504, p. 423–426, Preiss-Daimler, I.V., Henrich, R., and Bickert, T., 2013, rino, C.O., , G.B., Burbank, D.W., and Ky- https://​doi​.org​/10​.1038​/nature12877. The final Miocene carbonate crash in the : lander-Clark, A., 2016, U-Pb ages of detrital and Holbourn, A., Kuhnt, W., Clemens, S., Prell, W., and Assessing carbonate accumulation, preservation volcanic zircons of the Toro Negro Formation, Anderson, N., 2013, Middle to late Miocene step- and production: Marine Geology, v. 343, p. 39– northwestern : , provenance and wise climate cooling: Evidence from a high-res- 46, https://doi​ .org​ /10​ .1016​ /j​ .margeo​ .2013​ .06​ .010.​ sedimentation rates: Journal of South American olution deep water isotope curve spanning 8 mil- Reynolds, J.H., Jordan, T.E., Johnson, N.M., Dam- Earth Sciences, v. 70, p. 237–250, https://​doi​.org​ : Paleoceanography, v. 28, p. 688–699, anti, J.F., and Tabbutt, K.D., 1990, Neogene de- /10​.1016​/j​.jsames​.2016​.05​.013. https://​doi​.org​/10​.1002​/2013PA002538. formation of the flat- segment of the Amidon, W.H., Fisher, G.B., Burbank, D.W., Ciccioli, Huffman, G., Bolvin, D., Braithwaite, D., Hsu, K., Argentine-Chilean Andes: Magnetostratigraphic P.L., Alonso, R.N., Gorin, A.L., Silverhart, P.H., Joyce, R., and Xie, P., 2014, Integrated Multi- constraints from Las Juntas, La Rioja province, Kylander-Clark, A.R.C., and Christoffersen, M.S., satellitE Retrievals for GPM (IMERG), ver- Argentina: Geological Society of America Bulle- 2017, Mio-Pliocene aridity in the south-central sion 4.4: NASA Precipitation Processing tin, v. 102, p. 1607–1622, https://doi​ .org​ /10​ .1130​ ​ Andes associated with Southern Hemisphere cold Center, https://​pmm​.nasa​.gov​/sites​/default​ /0016-7606​ (1990)102​ <1607:​ NDOTFS>2​ .3​ .CO;2.​ periods: Proceedings of the National Academy /files​/document​_files​/IMERG​_ATBD​_V4.5.pdf Reiners, P.W., and Brandon, M.T., 2006, Using ther- of Sciences of the United States of America, (accessed 1 March 2018) mochronology to understand orogenic erosion: v. 114, p. 6474–6479, https://​doi​.org​/10​.1073​ Johnson, N.M., Jordan, T.E., Johnsson, P.A., and Nae- Annual Review of Earth and Planetary Sciences, /pnas​.1700327114. ser, C.W., 1986, Magnetic polarity stratigraphy, v. 34, p. 419–466, https://doi​ .org​ /10​ .1146​ /annurev​ ​ Beer, J.A., 1990, Steady sedimentation and lithologic age and tectonic setting of fluvial sediments in an .earth​.34​.031405​.125202. completeness, Bermejo Basin, Argentina: The eastern Andean foreland basin, San Juan Province, Romans, B.W., Castelltort, S., Covault, J.A., Fildani, Journal of Geology, v. 98, p. 501–517, https://​ Argentina, in Allen, P.A., and Homewood, P., eds., A., and Walsh, J.P., 2016, Environmental signal doi​.org​/10​.1086​/629421. Foreland Basins: International Association of Sed- propagation in sedimentary systems across tim- Bookhagen, B., and Strecker, M.R., 2012, Spatiotem- imentologists Special Publications, v. 8, p. 63–75, escales: Earth-Science Reviews, v. 153, p. 7–29, poral trends in erosion rates across a pronounced https://doi​ .org​ /10​ .1002​ /9781444303810.ch3.​ https://​doi​.org​/10​.1016​/j​.earscirev​.2015​.07​.012. rainfall gradient: Examples from the southern Jordan, T.E., Rutty, P.M., McRae, L.E., Beer, J.A., Ruskin, B.G., and Jordan, T.E., 2007, Climate change Central Andes: Earth and Planetary Science Let- Tabbutt, K., and Damanti, J.F., 1990, Magnetic across continental sequence boundaries: Paleope- ters, v. 327–328, p. 97–110, https://​doi​.org​/10​ polarity stratigraphy of the Miocene Rio Azul dology and lithofacies of Iglesia Basin, north- .1016​/j​.epsl​.2012​.02​.005. Section, Precordillera Thrust Belt, San Juan Prov- western Argentina: Journal of Sedimentary Re- Bull, W.B., 1991, Geomorphic Responses to Climatic ince, Argentina: The Journal of Geology, v. 98, search, v. 77, p. 661–679, https://doi​ .org​ /10​ .2110​ ​ Change: Oxford, UK, Oxford University Press, p. 519–539, https://​doi​.org​/10​.1086​/629422. /jsr​.2007​.069. 326 p. Jordan, T.E., Schlunegger, F., and Cardozo, N., 2001, Smith, G.A., 1994, Climatic influences on continental Bywater-Reyes, S., Carrapa, B., Clementz, M., and Unsteady and spatially variable evolution of the deposition during late- filling of an exten- Schoenbohm, L., 2010, Effect of late Cenozoic Neogene Andean Bermejo foreland basin, Argen- sional basin, southeastern Arizona: Geological aridification on sedimentation in the Eastern tina: Journal of South American Earth Sciences, Society of America Bulletin, v. 106, p. 1212– Cordillera of northwest Argentina (Angastaco v. 14, p. 775–798, https://doi​ .org​ /10​ .1016​ /S0895​ ​ 1228, https://​doi​.org​/10​.1130​/0016​-7606​(1994)​ basin): Geology, v. 38, p. 235–238, https://​doi​ -9811​(01)00072​-4. 106​<1212:​CIOCDD>2​.3​.CO;2. .org​/10​.1130​/G30532​.1. Latorre, C., Quade, J., and McIntosh, W.C., 1997, The Stevens, A.L., 2017, Cenozoic evolution of the Sierras

Carrapa, B., Strecker, M., and Sobel, E., 2006, Ceno­ expansion of C4 grasses and global change in the Pampeanas tectonomorphic zone between 27.5°S zoic orogenic growth in the Central Andes: Evi- late Miocene: Stable isotope evidence from the and 30.5°S [Ph.D. Thesis]: Tucson, Arizona, Uni- dence from sedimentary rock provenance and Americas: Earth and Planetary Science Letters, versity of Arizona, 404 p. apatite fission track thermochronology in the v. 146, p. 83–96, https://​doi​.org​/10​.1016​/S0012​ Stevens Goddard, A.L., and Carrapa, B., 2017, Using Fiambalá Basin, southernmost Puna Plateau mar- -821X​(96)00231​-2. basin thermal to evaluate the role of Mio- gin (NW Argentina): Earth and Planetary Science Leier, A.L., DeCelles, P.G., and Pelletier, J.D., 2005, cene-Pliocene flat-slab subduction in the southern Letters, v. 247, p. 82–100, https://doi​ .org​ /10​ .1016​ ​ Mountains, , and megafans: Geol- Central Andes (27°S-30°S): Basin Research, v. 30, /j​.epsl​.2006​.04​.010. ogy, v. 33, p. 289–292, https://​doi​.org​/10​.1130​ p. 564–585, https://doi​ .org​ /10​ .1111​ /bre​ .12265.​ Carrapa, B., Hauer, J., Schoenbohm, L., Strecker, /G21228.1. Strecker, M.R., Alonso, R.N., Bookhagen, B., Carrapa, M.R., Schmitt, A.K., Villanueva, A., and Gomez, Levina, M., Horton, B.K., Fuentes, F., and Stockli, B., Hilley, G.E., Sobel, E.R., and Trauth, M.H., J.S., 2008, Dynamics of deformation and sedi- D.F., 2014, Cenozoic sedimentation and exhuma- 2007, Tectonics and climate of the southern Cen- mentation in the northern Sierras Pampeanas: An tion of the foreland basin system preserved in the tral Andes: Annual Review of Earth and Planetary integrated study of the Neogene Fiambala basin, Precordillera thrust belt (31–32°S), southern cen- Sciences, v. 35, p. 747–787, https://​doi​.org​/10​ NW Argentina: Geological Society of America tral Andes, Argentina: Tectonics, v. 33, p. 1659– .1146​/annurev​.earth​.35​.031306​.140158. Bulletin, v. 120, p. 1518–1543, https://doi​ ​.org​ 1680, https://​doi​.org​/10​.1002​/2013TC003424. Uba, C.E., Strecker, M.R., and Schmitt, A.K., 2007, /10​.1130​/B26111​.1 Malizia, D.C., Reynolds, J.H., and Tabbutt, K.D., Increased sediment accumulation rates and cli- Dee, D.P., et al., 2011, The ERA-Interim reanaly- 1995, Chronology of Neogene sedimentation, matic forcing in the central Andes during the late sis: Configuration and performance of the data stratigraphy, and tectonism in the Campo de Ta- Miocene: Geology, v. 35, p. 979–982, https://doi​ ​ assimilation system: Quarterly Journal of the lampaya region, La Rioja Province, Argentina: .org​/10​.1130​/G224025A​.1. Royal Meteorological Society, v. 137, p. 553–597, Sedimentary Geology, v. 96, p. 231–255, https://​ Zachos, J., 2001, Trends, rhythms, and aberrations in https://​doi​.org​/10​.1002​/qj​.828. doi​.org​/10​.1016​/0037​-0738​(94)00132​-E. global climate 65 Ma to present: Science, v. 292, Fosdick, J.C., Carrapa, B., and Ortíz, G., 2015, Fault- Molnar, P., 2001, Climate change, flooding in arid p. 686–693, https://​doi​.org​/10​.1126​/science​ ing and erosion in the Argentine Precordillera environments, and erosion rates: Geology, v. 29, .1059412. during changes in subduction regime: Reconcil- p. 1071–1074, https://doi​ .org​ /10​ .1130​ /0091​ -7613​ ​ ing bedrock cooling and detrital records: Earth (2001)029​<1071:​CCFIAE>2​.0​.CO;2. and Planetary Science Letters, v. 432, p. 73–83, Peizhen, Z., Molnar, P., and Downs, W.R., 2001, Manuscript received 16 March 2018 https://​doi​.org​/10​.1016​/j​.epsl​.2015​.09​.041. Increased sedimentation rates and grain sizes Revised manuscript received 30 May 2018 Herman, F., Seward, D., Valla, P.G., Carter, A., Kohn, 2±4Myr ago due to the influence of climate Manuscript accepted 4 June 2018 B., Willett, S.D., and Ehlers, T.A., 2013, World- change on erosion rates: Nature, v. 410, p. 891– wide acceleration of mountain erosion under 897, https://​doi​.org​/10​.1038​/35073504. Printed in USA

650 www.gsapubs.org | Volume 46 | Number 7 | GEOLOGY