Quaternary Science Reviews 197 (2018) 224e245

Contents lists available at ScienceDirect

Quaternary Science Reviews

journal homepage: www.elsevier.com/locate/quascirev

Chronology, stratigraphy and hydrological modelling of extensive wetlands and paleolakes in the hyperarid core of the Atacama Desert during the late quaternary

* Marco Pfeiffer a, b, , Claudio Latorre c, d, e, Calogero M. Santoro f, Eugenia M. Gayo g, h, Rodrigo Rojas i, María Laura Carrevedo e, Virginia B. McRostie d, j, Kari M. Finstad k, Arjun Heimsath l, Matthew C. Jungers m, Ricardo De Pol-Holz h, n, Ronald Amundson a a Department of Environmental Science, Policy and Management, University of California Berkeley, 130 Mulford Hall, Berkeley, CA, 94720, USA b Departamento de Ingeniería y Suelos, Facultad de Ciencias Agronomicas, Universidad de Chile, Santa Rosa, 11315, La Pintana, Chile c Departamento de Ecología, Pontificia Universidad Catolica de Chile, Santiago, Chile d Centro UC del Desierto de Atacama, Pontificia Universidad Catolica de Chile, Santiago, Chile e Institute of Ecology and Biodiversity (IEB), Santiago, Chile f Instituto de Alta Investigacion, Universidad de Tarapaca, Antofagasta, 1520, Casilla 6-D, Arica, Chile g Laboratory for Stable Isotope Biogeochemistry, Departamento de Oceanografía, Facultad de Ciencias Naturales y Oceanograficas, Universidad de Concepcion, Casilla 160-C, Concepcion, Chile h Center for Climate and Resilience Research (CR)2, Chile i CSIRO Land & Water, Po Box 2583, Brisbane, QLD, 4001, Australia j Departamento de Antropología, Pontificia Universidad Catolica de Chile, Santiago, Chile k Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA l School of Earth and Space Exploration, Arizona State University, ISTB4, Room 795, 781 E. Terrace Road, Tempe, AZ, 85287, USA m Department of Geosciences, 306 Olin Science Hall, Denison College, 100 West College Street, Granville, OH, 43023, USA n GAIA-Antartica, Universidad de Magallanes, Punta Arenas, Chile article info abstract

Article history: The halite-encrusted salt pans (salars) present at low elevations in the hyperarid core of the Atacama Received 19 December 2017 Desert in northern Chile are unique features of one of the driest and possibly oldest deserts on Earth. Received in revised form Here we show that these landscapes were shallow freshwater lakes and wetlands during the last glacial 26 July 2018 period and formed periodically between ~46.9 ka and 7.7 ka. The moisture appears to have been sourced Accepted 1 August 2018 from increased Andean runoff and most of our chronologies for these deposits were coeval with the Available online 24 August 2018 Central Andean Pluvial Event (17.5e14.2 ka and 13.8e9.7 ka), but we also find evidence for older as well as slightly younger wet phases. These environments supported a diverse hygrophytic-halophytic vege- Keywords: Atacama desert tation, as well as an array of diatoms and gastropods. Using a regional hydrological model, we estimate Hyperaridity that recharge rates from 1.5 to 4 times present were required to activate and maintain these wetlands in Wetlands the past. Activation in the late Pleistocene was part of a regional enhancement of water resources, Late quaternary extending from the Andes, downstream and through riparian corridors, to the lowest and most arid Paleogeography portions of the desert itself. This fundamentally unique environment was encountered by the earliest South America human explorers in the region, and most likely facilitated migration and encampments on a landscape Sedimentology that at present lacks macroscopic life on its surface. © 2018 Elsevier Ltd. All rights reserved.

1. Introduction

The Atacama Desert has experienced hyperarid, and nearly lifeless, conditions for much of the past several million years * Corresponding author. Department of Environmental Science, Policy and (Hartley et al., 2005; Jordan et al., 2014). The most severe aridity has Management, University of California Berkeley, 130 Mulford Hall, Berkeley, CA, 94720, USA. been maintained in an inland forearc basin known as the Central E-mail address: [email protected] (M. Pfeiffer). Depression (Fig. 1), where an absolute desert (e.g. without https://doi.org/10.1016/j.quascirev.2018.08.001 0277-3791/© 2018 Elsevier Ltd. All rights reserved. M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 225

Fig. 1. a) Map of South America showing the location of the Atacama Desert, red box corresponds to b) altitudinal map showing the location of the Atacama Desert in southern Peru and northern Chile with inset box of figure in c) overview map of the Atacama Desert and the Central Andes Region illustrating the location of salars (black polygons), perennial streams (blue lines), the Central Depression (dotted gray polygons), the absolute desert (dashed white line), the boundary (red dashed line) between summer (north-east) and winter (south-west) precipitation sources and the location of the Pampa del Tamarugal (PDT) and Aguas Blancas (AB) basins. Salars discussed in the text are labelled. The two insets correspond to details of the PDT and AB basins detailed in Fig. 2a and b respectively. d) Map of South America showing the moisture sources that impact the Atacama Desert and Central Andes Region. Tropical (summer) sources are indicated in green, and the extra tropical (winter) source is indicated in blue. The gray box corresponds to the inset of figure in 1c. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

macroscopic life across most of its surface) presently exists (18e26 the region surrounding Aguas Blancas (AB), in the southern part of S) (Gajardo, 1994; Marquet et al., 1998; Luebert and Pliscoff, 2006). the Desert (Fig. 1). Using field observations, GIS, paleoecological, In the Central Depression, the presence of Miocene and Pliocene geohydrological modelling, and radiocarbon dating, we report ev- alluvial deposits impregnated with highly soluble salts attests to idence of late Quaternary lakes and wetlands in the basins in both the limited dilution by rainwater during a protracted interval (Rech areas. Some of these fossil hydrological features are synchronous et al., 2003b; Ewing et al., 2006; Amundson et al., 2012; Jordan with the Central Andean Pluvial Event (CAPE e 17.5e14.2 ka and et al., 2014). 13.8e9.7 ka), a widespread wet period consisting of two phases One of the prominent geomorphic features of the Central separated by a centennial-scale arid period that has been docu- Depression are large salt-encrusted landscapes (salt flats-salt mented by numerous authors (Maldonado et al., 2005; Latorre encrusted playa) that cover basins, which are termed salar in et al., 2006; Nester et al., 2007; Quade et al., 2008; Placzek et al., Spanish. These rough, and sometimes nearly impassable, land- 2009, 2013; Gayo et al., 2012; Díaz et al., 2012; De Porras et al., scapes have rugged efflorescent crusts of nearly pure halite up to 2017). However, our observations also record earlier pluvials than 0.5 m in thickness. In general, it is well understood that salars form the CAPE pointing to a deeper and richer history of desert hydro- largely by the evaporation of shallow groundwater and the subse- logical response to Andean climate. In general, the picture that quent redeposition of salts (Stoertz and Ericksen, 1974; Finstad emerges is that the stark aridity of the present desert landscape is et al., 2014, 2016). Salt crusts, however, often extend beyond greatly dissimilar to the conditions during late Pleistocene wet these groundwater-driven environments due to wind transport and events, where active streams drained the western slope of the deposition of salt (Finstad et al., 2018). Although salars clearly form Andes, and numerous wetlands and lakes were present in areas from the evaporation of water, the timing of this events in the that today are absolute desert. Central Depression of the Atacama Desert has been largely specu- lative, and the hydrological conditions that would have favoured 2. Regional setting their formation are unknown. In recent years, a changing view of late Quaternary paleoclimate The Central Depression of the Atacama Desert is a broad longi- and hydrology of the Andes-Atacama Desert interface has emerged. tudinal forearc depression that lies between a Coastal Range and Wetlands along stream margins have been documented at higher the Andes between 18 and 27 S. Elevations range between 1000 elevations (Betancourt et al., 2000; Rech et al., 2002; Quade et al., and 1600 m above sea level (m a.s.l.). This paper is centered on two 2008), Pleistocene and Holocene terrace development along basins along this low elevation feature, the Pampa del Tamarugal streams has been observed and dated (Nester et al., 2007; Gayo (PDT) basin in the north, and the Aguas Blancas (AB) basin toward et al., 2012), and incredibly, the remains of late Pleistocene hu- the south (Fig. 1). man occupation has been discovered on ancient fluvial terraces Present rainfall in the region is a function of latitude and altitude that are now entirely devoid of water and life (Latorre et al., 2013). (Houston, 2006a), and its relationship to modern regional clima- These studies inspire questions about how regionally pervasive tology has been used as a clue to interpreting past conditions such changes in climate were, and how deeply into the Atacama (Quade et al., 2008, Placzek et al., 2009, De Porras et al., 2017). There Desert system did these events penetrate and persist. are two major climate patterns that bring precipitation to the re- In this study, we surveyed salars and surrounding landscapes in gion: in the north (and east), summer precipitation of tropical two differing parts of the Atacama Desert hyperarid core (Fig.1): (1) origin is derived from the Atlantic, whereas winter rain associated salars in the semi-closed Pampa del Tamarugal (PDT) basin of the with a northward migration of extratropical storm fronts can occur northern Atacama Desert, and (2) salars and drainage systems in during positive phases of ENSO (Garreaud and Aceituno, 2001), and 226 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 delivering increased precipitation in southern Atacama and along The PDT derives its name from the scattered (and reforested) the coast (Houston, 2006b)(Fig. 1ced). The summer (tropical) stands of native Prosopis tamarugo and saltgrass (Distichlis spicata) moisture system has two well-known operating modes: i) one of a that are able to obtain moisture from the shallow groundwater in a north-northeast origin tends to dominate rainfall in the Central few restricted areas (Calderon et al., 2015; Chavez et al., 2016; Andes, and ii) a southeast-derived moisture source tends to Garrido et al., 2016). With the exception of this phreatic vegetation, dominate summer rainfall toward the southern section of the the region is largely barren at altitudes <2300 m (Gayo et al., 2012). northern Atacama (Vuille and Keimig, 2004). Precipitation in- There is no permanent surface fresh water in the lower basin, creases with elevation, from less than 1 mm yr 1 below 2300 m except for the perennial Quebrada Tiliviche to the north and Loa a.s.l. to 300 mm yr 1 around 5000 m a.s.l. (Houston, 2006b). river to the south (Fig. 2a). Despite the lack of surface water, the basin has become an important groundwater resource that is recharged by sporadic streamflow discharges associated with 2.1. Pampa del Tamarugal basin extreme rainfall events (JICA, 1995; Houston, 2002; Houston, 2006a) and by basal groundwater fluxes from the eastern sub- The Pampa del Tamarugal (PDT) is a major geographical feature basins and through deep-seated fractures (Magaritz et al., 1990; 0 0 in the northern Atacama Desert (19 17 -21 50 S, 1000 m a.s.l.) Aravena, 1995; Jayne et al., 2016; Scheihing et al., 2018). Both (Fig. 2a). The PDT is a semi-enclosed basin, and is hydrologically recharge mechanisms act on different spatial and temporal scales recharged from precipitation from the Andes to the east. Salars in and originate in the Andes, where precipitation is largely derived the PDT are fed by groundwater, and several drain southward into from eastward advection of moist air masses during summer when the Loa river (Salar de Pintados, S. de Bellavista, S. Viejo and S. de favorable synoptic conditions (e.g. the Bolivian high) persist at high Llamara) (Fig. 2a). The PDT lies atop a thick sedimentary sequence altitude i.e. > 5km(Garreaud et al., 2009). deposited unconformably over eroded bedrock basement of The drainages that enter the PDT flow through a series of can- metamorphic (e.g. phyllite) and sedimentary (e.g. sandstone, yons connected to the Western Andean Cordillera to the north and limestone) origin (Saez et al., 1999). Sediment began accumulating to the Sierra de Moreno toward the south (Table 1; Fig. 2). The in the Oligocene, and has continued into the present, although drainages in the Sierra de Moreno are completely disconnected sedimentation rates decreased drastically c. 11 Myr ago and have from the Altiplano drainage basin and have almost no permanent remained low ever since, especially in the southern portion of the basin (Nester and Jordan, 2012). The long-term sedimentary sequence is derived from two distinct sources: (1) alluvium and Table 1 Estimated average discharge into the Pampa del Tamarugal basin, northern Aquifer volcanics descending west toward the basin axis from the Andean (from JICA, 1995). Runoff coefficient is a dimensionless value and correspond to the plateau, and (2) riverine, lacustrine, and evaporite deposits from fraction of rainfall that flows toward the drainage system. the Loa river and other major streams along the southern basin axis. Catchment Area (km2) Recharge (L s 1) Runoff coefficient Although there is ample evidence for saline lakes or wetlands in pre-Quaternary sediments, there have been no reports of wetland Aroma 1746 310 0.055 Tarapaca 1786 318 0.056 or lacustrine conditions in any of the basins of this region during Quipisca 846 72 0.041 the late Quaternary (Saez et al., 1999; Kirk-Lawlor et al., 2013). Sagasca 971 89 0.033 Instead, halite and sulfate capped landscapes are the most striking Quisma 298 21 0.032 features of the lowest elevations at present (Stoertz and Ericksen, Chacarilla 1440 159 0.046 Ramada 244 7 0.016 1974).

Fig. 2. a) Map of the PDT Basin and Loa river basin showing the extent of the absolute desert (dull orange), main streams (quebradas) draining toward the basin in blue (most of them are intermittent), extension of the northern Aquifer of the PDT in purple, salars are dotted white polygons and insets show location of Fig. 4a,b,c corresponding to salars of Pintados, Bellavista and Llamara respectively. b) Map of the Antofagasta region showing extent of the absolute desert (in dull orange) and drainage systems of the AB basin and Quebrada del Chaco. Black box inset corresponds to the Salar de Aguas Blancas shown in Fig. 8. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.) M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 227 surface water flow (Nester et al., 2007). Under modern recharge groundwater discharge springs along the western slopes of the conditions, the lowest elevations of the PDT maintain a water table Andes (>2700 m a.s.l.), which infiltrate into the ground soon after a few meters below the surface (Rojas and Dassargues, 2007; Rojas emerging (Saez et al., 2016). Near Salar de Aguas Blancas, a fresh- et al., 2010). The streams of Aroma and Tarapaca in the northern water aquifer of limited extent is present, and is reportedly one of portion of the PDT possess riparian ecosystems at much lower al- only two resources south of the Loa river in the Central Depression titudes than those in the southern portion as surficial waters are (Bonilla, 1973; Herrera and Custodio, 2014; Renner and Aguirre, transported longer distances into the distal portions of the basin 2015). The estimated recharge of this aquifer is less than 10 L s 1 before disappearing by evaporation and infiltration (Gayo et al., and it is derived from groundwater fluxes coming from the highest 2012). elevations of the Andes (almost 5000m a.s.l), east of Salar de Punta Negra (Herrera and Custodio, 2014; Renner and Aguirre, 2015). Because of its extremely low modern recharge rate, the aquifer is 2.2. Aguas Blancas basin considered to be either fossil or hydrologically inactive, and has been rejected as a freshwater source for urban centers in the region In the southern part of the Atacama Desert, the Central (Bonilla, 1973; Risacher et al., 1999). Except for localized patches of Depression becomes more irregular, with a number of small saltgrass and saltbush clustered near brackish groundwater-fed mountains and valley systems within the broader pre-Andean oases, the region around Aguas Blancas is devoid of plants fl plateau. Vast expanses of Mio-Pliocene gravel uvial deposits of (Marquet et al., 1998). dominate the Central Depression (Marinovic et al., 1995). In this subregion, salars are found along and at the ends of drainage sys- tems that arise in the Sierra de Varas, at the Cordillera de Domeyko 3. Material and methods Range (Fig. 2b) (Stoertz and Ericksen, 1974). This part of the Atacama Desert has long lacked any evidence of 3.1. Site characterization and field sampling permanent prehistoric occupation, and Spaniard colonizers labelled it the “despoblado de Atacama” (Depopulated Atacama) Observations and sampling occurred largely during field seasons (Núnez~ et al., 2001). However, at higher elevations adjoining the in 2009, 2010, 2013, 2015, and 2016. The regions were extensively low Desert, evidence of late Pleistocene wetlands and human examined via satellite imagery coupled with on-the-ground ob- occupation have been discovered at the Salar de Punta Negra and servations and analyses. Samples were collected over the various adjacent inland basins (Grosjean et al., 2005; Quade et al., 2008). field seasons, archived, and then analyzed as reported below. The surface freshwater resources today are restricted to a few We describe multiple stratigraphic profiles within and adjacent

Fig. 3. Example of features seen at the outcrop, hand sample and microscopic scales: (a) Section of profile RA773 at Salar de Aguas Blancas basin, lens cap is 52 mm wide (see Fig. 13 for location); (b) Fossil ripple cast in the upper section of profile BV-01 (Salar de Bellavista, see Fig. 5 for section), indicative of a beach paleoenvironment present during the later stages of sedimentary deposition. Ripples are capped by a halite crust that formed by the upward accumulation of salt as groundwater evaporated near the surface; (c) Standing stems of the halophyte Tessaria absinthioides on the surface at Pique Lacalle (above Profile RA 781; see Fig. 10 for section). These stems were dated to 11 ka, revealing the extreme regional aridity (and lack of biological decomposition) since wetland desiccation; (d) Fossil freshwater gastropod (Heleobia sp.) from Salar de Bellavista dated to 16.6 ka (section BV- 04 Fig. 5); (e) Cross-polarized thin section showing irregular lamination and dark micrite with fenestral (dissolution) porosity in the carbonate layer of profile RA796 at Salar de Aguas Blancas (see Fig. 10 for section). These features are similar to those often formed by algal mats (stromatolite); (f) SEM image of a dolomite rhombi crystal agglomeration interpreted as an authogenic primary crystal deposited in an evaporitic environment of high salinity (Profile RA773; see Fig. 10 for section); (g) Discostella stelligera diatom species at profile BV-01 (Fig. 5); (h) Cross section of cf. Tessaria absinthioides stained with safranin. This specimen is from a 12.7 ka old stem collected at Salar de Bellavista (Profile BV-03; see Fig. 5 for section); (i) Long cell fossil grass phytolith (white arrow) from Salar de Llamara (Section LL-01 Fig. 5). 228 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 to the salars of the PDT and AB. The outcrops examined in the PDT with HCl. Diatoms were identified and quantified under a trinocular were exposed by wind and water erosion in the AB region. Sedi- Carl Zeiss microscope, AxioLab A1, with an oil immersion objective mentary profiles were measured and described in the field and (1000 ). Diatoms analysis consisted in presence-absence of spe- sampled for subsequent geochemical analysis and fossil identifi- cies, and are graphically informed by a taxa presence-absence di- cation (Fig. 3). Petrographic thin sections and Scanning Electron agram. Standard floras were used for references, as well as data Microscope (SEM) analyses were performed on calcium carbonate- from specific publications (Krammer and Bertalot, 1986, Theriot bearing layers for microfacies analysis (Flügel, 2004). et al., 1987, Kobayasi and Mayama, 1989, Håkansson, 1996, Krammer et al., 1997, Rumrich et al., 2000, Hakansson,€ 2002, 3.2. Radiocarbon dating Antoniades et al., 2005, Díaz and Maidana, 2005, Underwood et al., 2005, Guerrero and Echenique, 2006, Prasad and Nienow, 2006, Both organic and inorganic samples were collected for radio- Wojtal, 2009, Cremer and Koolmees, 2010, Mather et al., 2010; Kiss carbon dating by accelerator mass spectrometry (AMS). Carbonate- et al., 2012, 2013, Shirokawa et al., 2012, Zhu et al., 2013, Vossel bearing shells were pretreated with 30% H2O2 for 24 h to remove et al., 2015, Acs et al., 2016, Hevia-orube et al., 2016). Optical mi- remnants of organic matter. Individual shells used for dating were croscopy images (1000 ) were taken using a digital SLR camera washed in ultrapure water and sonicated for 5 min to remove (Canon EOS Rebel) attached to the microscope. The nomenclature secondary carbonates. Bulk fine-grained carbonate samples used status of species or variety was verified using the Catalogue of for dating were leached with dilute HCl to remove secondary car- Diatom Names (Fourtanier and Kociolek, 2009). Diatoms were bonates. Following these pretreatments, samples were submitted grouped according to life forms and ecological characteristics to the AMS facility of University of California Irvine (UCIAMS). (Spaulding et al., 2010). There, all carbonate samples were dissolved in 85% phosphoric acid in disposable septum-sealed reactors. 3.5. Phytholith analysis Organic samples where pretreated by first removing excess salts by soaking and shaking in deionized water for 24 h, followed by One gram of sediment was oxidized for each phytolith sample. centrifugation. The process was repeated twice. Next, samples were Samples composed of both phytoliths and diatoms were mounted soaked in 0.5 M HCl solution to remove inorganic carbonates. on microscope slides (Stoermer et al., 1995). In order to view phy- Heavily humified peat samples were dissolved in base (1 N NaOH at toliths in 3D, a duplicate of each sample was prepared with 2 drops 75 C) and the soluble fraction was subsequently precipitated in of glycerol, and lower concentrations of the phytolith/diatom strong acid (HCl added dropwise), washed with Mili-Q water and samples (4 drops). This allowed for better visibility of the micro- then dried. Samples were then combusted at 900 C for CO2 pro- fossils. Phytoliths were identified using standard references and duction. Following cryogenic separation, CO2 was reduced to specific publications (Pearsall and Trimble, 1983; Piperno and graphite at 560 C with hydrogen and iron powder catalyst and the Pearsall, 1998; Albert et al., 1999, 2008; Korstanje and Babot, radiocarbon content measured at the UCIAMS. Radiocarbon ana- 2007; Babot, 2011). The entire slide mount (24 40 mm) was lyses were calibrated using CALIB 7.0 (SHCal13 calibration curve scanned at 40x in a polarized microscope. (Hogg et al., 2013), Intercept Method) and are reported as thou- sands of calendar years before present (ka). Due to the absence of 3.6. Hydrogeological modelling paired organic - carbonate samples within a given stratigraphic section, we could not establish a reservoir effect for our carbonate A hydrogeological model (Rojas and Dassargues, 2007; Rojas samples. Although little is known about the magnitude of this effect et al., 2010) was used to simulate the piezometric surface and po- in the Atacama (Geyh et al., 1999; Grosjean et al., 2001) our samples tential recharge rates to the Pampa del Tamarugal Aquifer (PTA) for were formed in shallow lakes with a continuous recharge of three pluvial periods, based on the estimated piezometric levels at running water, a rapid exchange with atmospheric CO2 is expected specific locations for the specific periods derived from our field- thus avoiding any significant reservoir effects. Also, due to the work and dating. The periods defined for this analysis correspond persistent arid conditions following wetland desiccation, we do not to: I) ~25.4 ka and 16.6e16.5 ka; II) 16.5e16.1 ka; III) 12.7e11.2 ka. expect diagenesis (e.g. CO2 exchange with groundwater) to have The model was previously calibrated by Rojas and Dassargues any significant effect on the measured ages. (2007) for steady state conditions in the PTA based on empirical data collected for the year 1960 conditions, when the basin was in 3.3. Identification of botanical remains natural equilibrium (JICA, 1995), and was further validated by Rojas et al. (2010). Model parametrization, limiting boundary conditions Plant macrofossil remnants were separated for taxonomic and aquifer geometry remained unchanged from the original identification. Leaf litter samples were separated and identified model. The hydrogeological model was implemented and numer- underneath a binocular scope (50x). Plant macrofossils were ically solved using MODFLOW-2005 (Harbaugh, 2005). This soft- identified with the reference collections of modern flora at the ware contains a suite of packages and is considered an international Laboratorio de Paleoecología & Paleoambientes (LP2, Pontificia standard for simulation of groundwater conditions. MODFLOW- Universidad Catolica de Chile) and the Laboratory for Stable Isotope 2005 numerically solves the equations describing the three- Biogeochemistry (Universidad de Concepcion). Histological thin dimensional movement of groundwater for steady and transient sections of fossil trunks were prepared and identified from wood flow conditions within unregularly shaped aquifers. It can consider anatomical features. complex aquifer geometries, heterogeneous aquifer properties, and multiples sinks (e.g. drains, wells) and sources (e.g. recharge rates) 3.4. Diatom analysis comprising the groundwater flow system. Past groundwater levels for each profile were estimated based Freshwater diatoms were identified from an exposure along the on modern analogues of the species described in this work and southern margin of the Salar de Bellavista (BV-01; Fig. 2a). currently present in the region (DICTUC, 2007; Gayo et al., 2012; Approximately 1 g of dry sediment per sample was processed Chavez et al., 2016; Collado et al., 2016). Based on the elevation of following (Stoermer et al., 1995) (although 30% H2O2 was used lacustrine/wetland features, the approximate extent of the paleo- instead of using 30% H2O2 and HNO3). Carbonates were removed wetlands is extrapolated and mapped using the ASTER GDEM V2 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 229

(NASA) as our digital elevation model (DEM) on ArcGIS 10.4 (ESRI) (30 m horizontal resolution, ~17 m vertical accuracy at 95% confi- dence level on bare ground). For the northern part of the PDT (present day salars of Zapiga, Pintados and Bellavista) the extent of past wetlands are estimated based on simulations made with a previously validated and calibrated regional hydrogeological MODFLOW model (Rojas and Dassargues, 2007; Rojas et al., 2010). For the MODFLOW outcome, we consider a piezometric level of <1 m to estimate wetland/marshland extension and of <5m to es- timate Tamarugo trees forest in the PDT (see section 4.3 for further detail).

4. Results

Close inspection of satellite imagery, DEM's, and ground-based observations revealed evidence for incipient shore/water lines or perennial standing water conditions around many salars. When the elevation of these features were projected to other locations in a given basin, small hand-based excavations commonly revealed fossil plants and/or other evidence of past wetter conditions. In addition, prominent salt covered mounds within the Salar de Bellavista and other low-elevation basins in the Atacama are actually fossilized coppice dunes, which occasionally retained the remnants of Tamarugo trees and other halophytes (see unit C below). We identify and name stratigraphic units associated with sedi- ment discharge and deposition in salars from both basins. Profiles are located at the intersection of salars and distal ends of alluvial fans. Units are associated with periods of discharge and highstands, and contain facies that are laterally discontinuous due to variations in clastic sedimentation which can change rapidly in such envi- ronments. While there may be some correlation between units described in this work and those defined previously in other lo- cations in the Atacama (Rech et al., 2002, 2003a; Quade et al., 2008), the units defined here are assumed to have only a local extent and significance. The units described have a range of characteristics: (1) inter- calated fine and coarse grain layers, with characteristics that are common between the two basins; (2) clay and silt intercalated with horizontal laminated sands and gravels, reflecting cyclic stratigraphy of high water stands with low energy flow (such cyclicity is common for playa lake deposits, where high standing water periods are interspersed with drier periods of evaporitic deposits and coarser clastic sedimentation depending on location of the stratigraphic sequence within the basin (Handford, 1982)), (3) fine mud sediments and black peat organic layers, reflecting low energy environment with development of hydrophyte vege- tation, and (4) coarse, well-sorted laminated sands are also a common feature in both basins. A few sections described here, (5) also contain undated gravel deposits reflecting high energy stream discharge. We obtained 50 new radiocarbon ages from sediments and sub- fossil organic remains from PDT and AB basins, 24 of these corre- Fig. 4. Google Earth images with detailed location of stratigraphic sections at the spond to lacustrine/wetland contexts and 26 to remnant riparian Pampa del Tamarugal, a) Salar de Pintados, b) Salar de Bellavista and c) Salar de Lla- ecosystems (Appendices A and B). We have integrated these ages mara. See Fig. 2a for locations. Salars are demarcated by a pink polygon. (For inter- with previous work to discuss changes in late Quaternary hydro- pretation of the references to colour in this figure legend, the reader is referred to the logical and paleoecological patterns in both basins (Maldonado Web version of this article.) et al., 2005; Nester et al., 2007; Díaz et al., 2012; Gayo et al., 2012; Saez et al., 2016). This combined database now contains 154 radiocarbon ages and compiles all of the available paleoenvir- 4.1. Stratigraphy and chronology of the Pampa del Tamarugal onmental information for the studied watersheds (Appendix A and sections B). Radiocarbon ages obtained from carbonate lacustrine deposits are considered to be maximum ages due to potential, but The PDT consists of a series of small inland basins and salars, unquantified, reservoir effects (Geyh et al., 1997, 1999; Grosjean that are connected by overflow drainages. The salars lie at the et al., 2001). terminal end of alluvial fans that are fed by major canyons that 230 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245

Fig. 5. Stratigraphic sections from the PDT basin. All ages are in calendar years BP (See Appendix A). drain the Andes or Sierra de Moreno to the east. The entire system energy (e.g. fluvial) discharge and sedimentary infill into the basin. eventually drains into a small tributary of the Loa river (Quebrada Amarga). Here we describe stratigraphic profiles from Salar de 4.1.2. Unit B1 Pintados, S. de Bellavista and S. de Llamara (Location of sections in This unit was observed only in section BV-01 (Fig. 5). The unit is Fig. 4 and stratigraphy of sections in Fig. 5). The heavily mined and 75 cm thick, with a sequence of fine horizontally laminated sands in excavated Salar de Bellavista offers the greatest number of expo- a silt matrix intercalated with diatomaceous silt. Colors vary from sures (Fig. 4b). light reddish brown (5 YR 6/4) to light gray (5 YR 7/1) for sand, to pinkish white (5 YR 8/2) for the diatomite layers. An ensemble of 4.1.1. Unit A freshwater and brackish water diatom species occur in this unit. Unit A is > 1 m thick and consists of angular to subangular gravel The heavily silicified Alacoseria taxa is typical of turbulent water deposits. These beds generally do not exhibit sedimentary struc- columns (Vilaclara et al., 2010), which together with Cyclotella is an tures except for one bed with imbricated gravels at BV-01. The base indicator of high water levels and thermal stratification (Saros and of the unit is not exposed. There are no fossils and the unit has not Anderson, 2015). Other species found in brackish waters, such as been dated, but based on ages of the overlying units, it must be at Fragillaria capucina and Staurosirella construens and in soils, such as least 25e30 ka. It is exposed in two sections from the Salar de Staurosisa construens were also observed (Costello et al., 2013) Bellavista (BV-01 and BV-05; Fig. 5)reflecting a period of high- (Fig. 6). The unit is capped by a ripple cast with symmetrical crests M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 231

Fig. 6. Presence/absence diatom record from Salar de Bellavista (section BV-01), taken 60e75 cm below the present salar.

at 3.5 cm distance. The unit represents a low energy flow (lami- nated sands) that is probably the cause of channel migration to- ward the south after the basin filled in with gravels. Very fine sands containing a significant variety of diatoms reflect the presence of surface fresh to brackish water. Above this, the ripple cast and the size of the ripples, reflects waves impacting a beach shoreline along a lake of sufficient size to generate waves (Fig. 3b). Chronology of this unit is constrained by a single age of 25.4 from matrix car- bonate in the ripple cast. The section today has significant moisture (present c. 1.5 m beneath the surface) due to groundwater wicking, as continuous water flow through evaporation could have poten- tially add additional reservoir effects to our age, we treat this age as a maximum age.

4.1.3. Unit B2 This unit corresponds to a single exposure (BV-04) of very fine materials at Salar de Bellavista (Fig. 5). It is 30 cm thick, composed of two layers of well sorted red clay (10R 6/4) and yellowish silt (10R 7/6). It represents fine grained lacustrine deposits. The unit is not chronologically constrained, but it is overlain by unit b3 and is expected to be older than 16.5 ka.

4.1.4. Unit B3 This is a conspicuous unit present at Salar de Bellavista and Salar de Llamara (Sections BV-02, BV-04, BV-05, LL-02 and LL-03) (Fig. 5). The unit thickness observed varies from 20 to 60 cm and corre- sponds to intercalated horizontal well sorted laminated sands with yellowish silt (10R 7/6) and subordinate reddish silt (5 YR 6/3). We interpret it as a typical playa lake sequence reflecting cycles of fluctuating groundwater levels, with laminated sands representing low energy sheet flow discharge episodes when the water table was below the surface, whereas the periods of fine sedimentation fl fi Fig. 7. Presence/absence of phytoliths record from Salar de Llamara (sections LL-01 re ect a sur cial water table. Phytoliths analyses of this section and LL-02). show fluctuation between marshy plant communities dominated 232 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 by Poaceae, Juncaceae and Cyperaceae at the bottom and top of the 4.1.7. Unit E section, with an hiatus dominated by polyhedral phytoliths prob- Unit E is composed of a thick halite crust of up to 50 cm that ably of Prosopis trees in the middle of the section (Fig. 7). The unit corresponds to the modern salar surfaces (Fig. 5). It is actively contains numerous datable materials, such as black peat organic forming by evaporation and capillary wicking in the areas were layers, plant stems and freshwater gastropods (Heleobia sp.). Its groundwater is close to the surface (e.g. LL-01 and Pintados). chronology is constrained by 10 radiocarbon ages clustered be- Although we have no direct age for unit E, it must have begun tween 19.4e18.6 ka and 16.6e16.1 ka. forming in the Holocene and its site-specific onset age would therefore depend on the recent history of each individual salar. 4.1.5. Unit C Unit C corresponds to a cross-bedded loosely cemented sand 4.1.8. Unit F forming mounds of up to 1.5 m high at Salar de Bellavista (BV-03; This unit corresponds to a thin layer of ~10 cm of loose sand with Fig. 5). The mounds are made by phreato-halophytes of P. tamarugo interbedded seams of calcium carbonate dated to 15.5 ka (Fig. 5). It and Tessaria absinthioides trees and represent coppice dunes represents a water table near or above the surface. reflecting periods of wind-blown sedimentation around vegetation, probably as the surrounding lake beds and marshlands became 4.2. Stratigraphy, chronology and paleo-environments of the Aguas desiccated and their sediments were exposed to deflation. These Blancas basin features are very common along the northern edge of Salar de Pintados, the northern edge of Bellavista, as well as along the The present day Salar de Aguas Blancas is an evaporitic envi- eastern edge of the Salar de Llamara. The age constraint for this unit ronment that has been, and continues to be, highly modified by corresponds to a section in Bellavista (BV-03) with an age of 12.7 ka mining (Fig. 8). The fans and hillslopes adjacent to the Salar have on Tessaria sp. wood. been extensively stripped for nitrate (salitre). The area is now under even more intensive mining for nitrate and iodine (Perez-Fodich 4.1.6. Unit D et al., 2014). The considerable salt deposits suggest long term Unit D is represented at Salar de Llamara (LL-01 and LL-02) and (millions of years) additions and concentrations of salts from up- fi Pintados and is a sequence of ne layers of reddish and yellowish stream Andean sources or long-term atmospheric deposition of (7.5 YR 7/6) silt with overlying beds of horizontal laminated sands nitrogen (Michalski et al., 2004). Here, we focus only on the most (Fig. 5). The unit contains massive calcite beds with calcrete rhi- recent stages of salt and sediment accumulation, in two phreatic zoliths along the bottom of the section and is capped by a gypsum basins. e rich layer. Phytolith analysis of this unit at LL-01 (48 78 cm) Differential wind deflation at several locations provided op- e revealed long cells at the bottom (73 78 cm), with the upper part portunities for understanding the late Quaternary landscape evo- e (48 61 cm) exhibiting rondels similar to those found in Distichlis lution. Exposures of carbon-rich lacustrine material are easily spicata and oxalates similar to those of Prosopis sp. and Schinus observable as remnant mesas surrounded by shallow deflationary molle druses, both indicative of mostly groundwater fed ecosystems basins (Fig. 9). Although some correlation can be made between (Fig. 7). The LL-01 sequence of unit D ends with an organic matter- stratigraphic units of PDT and AB, we describe them separately due rich deposit at 12.8 ka. This unit corresponds to the main section of to the distance between both basins and differences in the nature fi pro le Qh (here LL-01) described and originally interpreted as and timing of discharge events (Fig. 10). lacustrine sediments by Finstad et al. (2016). Here, we reinterpret this unit as an environment with fluctuating water table levels, with palustrine conditions and a water table near or above the 4.2.1. Unit L surface interspersed with periods of deeper water table and distal Unit L is represented in two sections at Salar de Aguas Blancas alluvial fan deposits such as sand sheets. The absence of clear (RA773) and Pique Lacalle (RA781) (Fig. 10). It corresponds to a fi shorelines around Salar de Llamara and the open drainage toward sequence of ne sediments (silt and clay) with no gravels or the Loa river through Quebrada Amarga signifies that large bodies sand, deposited in a low energy environment. At Aguas Blancas fi of standing water would not have been possible in this sub-basin. (RA 773) the column has ne laminated sediments at the base Age constraints for this unit are based on three ages of 12.3 ka with a black mat peat near the top, overlain in turn by a white (soil organic matter), 11.4 ka and 11.2 ka (rizolith carbonates).

Fig. 8. Google Earth image showing the location of stratigraphic sections near Salar de Fig. 9. Remnant mesas around Salar de Aguas Blancas with deflationary depressions Aguas Blancas. (Map data: GoogleEarth, Digital Globe). exposing lacustrine sediments. M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 233

Fig. 10. Stratigraphic sections from the Aguas Blancas basin in the Antofagasta region. marl ~25 cm thick. At RA773, basal silty mud deposits correspond on this unit, but it is younger than the underlying unit of <8.4 ka to lacustrine facies, with the black mat near the top of the sec- (Fig. 10). tions represents a shoreline-strand or wetland. At Pique Lacalle, the unit correspond to clay deposits, rich in tubular pores and a 4.3. Past recharge rates for the Pampa del Tamarugal basin blocky structure with large CaCO3 lens capping the sequence. The unit reflects a period of enhanced recharge, with standing water in the lower basin at Aguas Blancas and palustrine conditions at Estimates of the past piezometric heads are obtained from fi Pique Lacalle. XRD and SEM analysis of the carbonate deposit of information in the stratigraphic pro les for each of the three RA773 shows primary dolomite formation, indicative of low lake apparent dated pluvial periods: Period I (~25.4 ka and 16.6 ka), is fi e levels and high salinity. The chronology of this unit is constrained based on pro les BV-01 and BV-04; Period II (16.5 16.1 ka), on fi e fi by three ages on peat humics and carbonate nodules and spans pro les BV-02 and BV-05; Period III (12.7 11.2 ka), on pro les BV- fi from 46.9 to 23.6 ka. 03 and Pintados-01 (See Fig. 4 for pro le locations and Fig. 5 for stratigraphic profiles). In order to arrive at these estimates, a se- ries of assumptions are made: i) To facilitate groundwater flow in 4.2.2. Unit M the aquifer, the southern and northern constant-head boundary Unit M is represented in two sections located in the Salar de conditions are moved upward by 20 m. Sensitivity analyses per- Aguas Blancas lower salt flat (Fig. 10). It corresponds to a sequence formed on the original model showed a limited impact of these of fine sand, massive at the bottom and laminated on top, overlain boundary conditions on the model performance indicators by a laminated and indurated layer of calcium carbonate of ~30 cm (Normalized Root Mean Squared Error) and evaporation fluxes capped with anhydrite polygons on top. The carbonate deposit is from salars; ii) Analysis of the stratigraphic profiles suggest the very porous, with calcified organic filaments, needle fibre calcite occurrence of a standing lake at Salar de Bellavista during the and peloids. It suggests near surface water tables around a lake Period I. This lake is simulated in the model as a Type III boundary margin or wetland. Porosity can be formed by microbial mats on condition (head and flux-dependent) with height equal to the the lake floor. Thin section analysis show dolomite crystals with terrain elevation þ0.1 m. This is imposed to minimize flow back to halite and anhydrite cements, likely resulting from the concentra- the aquifer and to mantain the extension of the free surface (lake tion of pool brines in a saline lake, though the sample may have extension). Given the conceptual model accepted by different been intruded by salt from post-wetland soil formation. Chronol- authors (Scheihing et al., 2018; JICA, 1995; Rojas and Dassargues, ogy of unit M is constrained by two ages on calcite deposits dated to 2007; Rojas et al., 2010; Jayne et al., 2016; Magaritz et al., 1990), <13.2 ka and <8.4 ka. These are likely maximum ages due to the area of Salar de Bellavista is most likely a groundwater possible reservoir effects. discharge zone, which does not contradict the conceptual model; iii) Analysis of the stratigraphic profilessuggestthelakeatSalar 4.2.3. Unit N de Bellavista observed during Period I, was not present during Unit N corresponds to a thin sequence (<10 cm) of muddy silt Periods II and III and thus it is replaced by an evapotranspiration deposits at Pique Lacalle. It has a thin lens of carbonate overlaid by zone for those periods; iv) Data from the stratigraphic profiles is blocky cemented silt most likely reflecting desiccation. We inter- used to locate cells in the model where the water table was close pret this unit as a palustrine environment, with shallow fluctuating or on the surface. These are included in the model as constant vegetation fringes. The unit age corresponds to standing stems of head boundary condition (Type I). Groundwater head in the cell is the halophyte T. absinthioides that dated back to 11.1 and 11.8 ka defined as the terrain elevation minus 0.2 m on the basis of the (Fig. 10). profiles BV-02 and BV-05 and the presence of organic peat ma- terial, and at surface elevation on the basis of profiles BV-03 and 4.2.4. Unit O Pintados-1; v) different combinations of recharge rates (as mul- This unit is similar to unit E in the PDT and corresponds to a tipliers of present-day recharge rates) and evapotranspiration halite crust of up to 25 cm thick. There is no chronologic constrain rates (between 1500 and 2000 mm yr 1) are tested until 234 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 piezometric heads observed in the stratigraphic profiles are reasonably approximated; vi) based on the model grid resolution (numeric cells between 200 and 1500 m), we report two sets of maximum groundwater depths at 1 and 5 m to reproduce areas close to water saturation at terrain level and the presence of vegetated areas in the PTD, respectively. We consider ground- water levels <1 m to the surface obtained with the model as representing wetlands/marshlands as they can be periodically inundated, and soils will thus have a capillary rise that will keep moisture near the surface maintaining sedges and grasses. A water table depth of <5m to sustain P. tamarugo trees is considered to be especially for recruitment, since Tamarugo trees can survive with water at much deeper depths but will not be able to colonize new areas if water tables are >5mbelowthesurface(Calderon et al., 2015; Chavez et al., 2016). The magnitude of past recharge rate increases, relative to those of today, were estimated by increasing current recharge levels within the hydrological model in multiples of 1.5,2.5x, 3.0x and 4.0x times, and then comparing these to observations for the different time periods at the salars de Bellavista and Pintados. For Period I (~25.4 ka and 16.6 ka), the best match to observations was obtained with ~3.0 current recharge rates. However, a standing water table at Bellavista and a potential connection between Pintados and Bellavista, required a recharge of 4.0 in the southernmost sub-basins (Quebradas of Quisma, Chacarilla and Ramada; Fig. 2a), and a 2.5 recharge for the other subasins (Quebradas Aroma, Tarapaca, Sagasca and Quipisca; Fig. 2a). For Period II (16.5e16.1 ka) recharge rates of 2.5 match the paleoenvironmental record. For Period III (12.7e11.2 ka), a recharge rate between 1.5 and 2.0 reproduces past piezo- metric levels. For all three periods, the model reveals that areas around the Fig. 11. Maps of the northern aquifer of the Pampa del Tamarugal with hydrological present village of La Tirana would have had ground water levels modelling results at four time intervals, beginning with a steady state calibration model for the year 1960. Groundwater level at 1m is considered to be able to sustain very close to the surface (Fig. 11). This also apparently occurred in phreatophyte vegetation as well as sedges and grasses, while <5m correspond to the the northern area around Zapiga, which is currently a well-known depth to which P. tamarugo trees can have optimal growth conditions. discharge area, with groundwater flowing into the Tiliviche canyon (JICA, 1995). In a paleo hydrological study of the PDT, Gayo et al. (2012) Table 2 fl Recharge estimates and calculated upper catchment rainfall (Mean Annual Precip- suggested for increased stream ow at slightly higher elevations itation -MAP) for the PDT tributaries for the three different pluvial events described. above the basin floor from 15.9 to 14.2 ka and 12e11.8 ka, which 3 1 would have been caused by an elevated water table. They estimated Catchment Recharge (m s ) MAP that matches augmented recharge rates (mm) paleoprecipitation amounts using a multi-linear regression model based on their paleoecological and geomorphological observations. 1.5 2.0 2.5 3.0 4.0 Their model is based on the relation between mean annual pre- Aroma 0.31 200.18 222.02 243.85 265.68 309.34 cipitation (MAP) in the upper catchments, watershed area and the Tarapaca 0.318 201.76 224.15 246.55 268.94 313.73 proportion of precipitation transmitted to river flow. Based on data Sagasca 0.089 159.91 166.18 172.45 178.71 191.25 Quipisca 0.072 139.09 144.16 149.23 154.30 164.44 from modern perennial catchments, Atacama surface runoff (Q in Quisma 0.021 122.48 123.96 125.44 126.92 129.88 3 1 m s ) is a function of: Chacarilla 0.159 171.31 182.51 193.71 204.90 227.30 Ramada 0.007 142.85 143.35 143.84 144.33 145.32 Q ¼1.12 - [0.00026*A] þ [0.0071*MAP] þ [11.23*C], where A corresponds to catchment area (km2), MAP is mean 5. Discussion annual precipitation in millimeters, and C is the runoff coeffi- cient. Gayo et al. (2012) used this relationship to estimate past 5.1. Pampa del Tamarugal-depositional setting and MAP, which is thus estimated to have increased three-fold during paleoenvironmental history 17.6e14.2 ka and 12.1e11.4 ka in order to activate the channels. By using a modern-day MAP of ~62 mm yr 1 for the upper Evidence for elevated groundwater levels in the PDT are repre- catchments, our estimates with this model show that precipita- sented by units B1, B2, B3 and D. Deposits in these units reflect tion increased in the upper watersheds from two to four-fold at typical conditions of fluctuating water levels within alluvial playas, 25.4 ka and 16.2e16.6 ka, with two to three times the current wetlands and lake facies. These facies reflect the intersection of a rates between 12.7 ka and 11.2 ka (Table 2). This increase in playa lake with terminal ends of distal alluvial fans. The oldest precipitation was characterized by significant decadal and annual evidence of standing water conditions at Salar de Bellavista is for variations as shown by d13C values on annual tree rings of Schinus unit B1: A carbonate cemented ripple cast (BV-01, Fig. 3b), dated to molle dated to ca. 15 ka (Gayo et al., 2012). ~25.4 ka. A wood fragment dated to ~26.9 ka has been found in M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 235 gravel deposits in nearby Chipana canyon (Appendix A.). This is described here for the low-elevation basins of the PDT differ greatly important as this reflects a perennial watercourse in a canyon that from the present conditions (Fig. 12). At Pintados, unit D shows ultimately drains into the Bellavista basin. Below the ripple cast, mottled carbonates and cf. D. spicata root molds formed <11.5 ka diatoms assemblages are dominated by planktonic taxa (Cyclotella and <11.3 ka, reflecting a palustrine environment -a wetland with taxa, Discostella stelligera and D. stelligera var. stelligera), indicating ephemeral standing water conditions. A cluster of ages also shows high levels of freshwater, although some epiphytic and benthic CAPE II discharge in the Chipana tributary between 12.8 and 12.5 ka diatoms are also present. D. stelligera is linked to thermal stratifi- (Nester et al., 2007; Gayo et al., 2012). cation and warm conditions (Rühland et al., 2003; Rühland and Smol, 2005; Harris et al., 2006; Hyatt et al., 2011)(Fig. 6). Unit B2 precedes the CAPE I pluvial and reflects perennial water 5.2. Salar de Aguas Blancas conditions due to the very fine sediments that remain undated. Unit B3 includes CAPE I (17.5e14.5 ka) and has several shoreline Three stratigraphic units present in the Salar de Aguas Blancas outcrops in the Salar de Bellavista (SBV), with ages on organic basin show evidence of increased groundwater levels during the matter clustering from 16.6 to 16.1 ka (BV-02, BV-04, BV-05; Fig. 5). late Pleistocene (Fig. 8). The depositional setting corresponds to a These ‘high stands’, now salt- or dust covered, contain black peat low gradient lake margin with low energy clastic deposits of silt organic matter, fresh to brackish water Heleobia sp. gastropods and clay and evaporitic deposits of carbonate and gypsum. Unit L, (Collado et al., 2016) and well-preserved plant macrofossils of the oldest unit in the basin (studied here), is represented by two D. spicata and T. absinthioides. Upstream of the Salar de Bellavista, sections at different locations within the basin. The highest there are more than 15 calibrated ages of riparian deposits, indi- standing and oldest outcrop contains a sequence of basal fine cating coeval discharge into the Chipana tributary from 16.0 to 13.5 laminated red silts (lacustrine), overlain by a black mat formed in a ka (Nester et al., 2007; Gayo et al., 2012). marsh or wetland dated to 46.9 ka (section RA773; Figs. 3a and 10). South of Salar de Bellavista, in the Salar de Llamara, unit B3 A change in pluvial conditions then followed, and the organic mat is reveals evidence for a pre-CAPE phase of rapid aggradation as ages capped by a thick fine dolomicrite mud carbonate dated at <23.6 ka. for sediment at 60 cm and 120 cm depth are all dated from 19.3 to This is interpreted to have been a shallow playa lake margin with 19.1 ka (Fig. 5). Phytolith analyses from the base of this section intense evaporative processes from highly saline brines. We traced (~115 cm depth), suggests a wetland plant community dominated the drainage system that feeds the Aguas Blancas region for a dis- by Poaceae, Juncaceae and Cyperaceae families (Fig. 7). These plants tance of 50 km upslope, to a large fossilized riparian wetland at are currently present 12 km to the southwest in the Quebrada Pique La Calle. Beneath the surface, laminated carbonates at 45 cm Amarga wetlands that drain the Salar de Llamara (DICTUC, 2007) (35.9 ka old), are interpreted as having been deposited in a palus- (Fig. 12). Above the basal portion of the section at 110 cm, poly- trine environment, which once covered ~6 km2. These sediments, hedral phytoliths from Prosopis trees appear, which only require which supported a late Pleistocene wetland, are deeply dissected shallow groundwater conditions to establish (<5m) (Calderon et al., by the present flood channels. Reconnaissance field observations 2015; Chavez et al., 2016). Poaceae, Juncaceae and Cyperaceae over a larger region revealed that there are likely multiple stages of phytoliths near the top of the section imply a return to wetter palustrine muds and salts, though we as yet have no other infor- conditions. An organic layer was dated to 18.56 ka in section LL-03 mation on these older sediments. The Pique La Calle section is (Fig. 5) and provides further evidence for the presence of surface capped by fine-grained sediments strewn with standing stems of water in de Salar de Llamara before CAPE I. T. absinthioides that were dated to 11.1 and 11.8 ka (Fig. 3c). Unit D is coeval with the CAPE II (13.8e9.7 ka) and is repre- Unit M, which was coeval with the CAPE II, is represented by two sented in sections LL-01 and Pintados (Fig. 5). Phytolith analyses exposures with carbonates of probable biogenic origin formed at from an interval between 48 and 78 cm of section LL-01 revealed 13.2 ka (RA796), and a laminated irregular micrite deposit with long cells at the base (73e78 cm), indicating the presence of irregular gypsum and halite cements that formed along a lake monocotyledons (e.g. sedges, grasses), whereas the upper part of margin or wetland at 8.4 ka (RA798). Since they were deposited in a the section (48e61 cm) exhibited rondels similar to those found in wetland setting, these land surfaces have accreted dust and sulfate, D. spicata and oxalates similar to those of Prosopis sp. and S. molle forming an overlying soil with regionally distinctive polygonal druses (Mcrostie, 2013). These microfossils suggest mostly structural patterns. This soil has been partially interwoven into the groundwater fed ecosystems. The LL-01 sequence of unit D ends underlying wetland deposits. As mentioned, differential scouring with an organic matter-rich deposit at 12.3 ka, implying the pres- by wind is now partially removing this wetland/eolian complex of ence of near surface water. Such paleoenvironmental conditions sediments.

Fig. 12. Contrast between (a) modern phreatic wetlands along Quebrada Amarga before the confluence with the Río Loa and (b) Salar de Llamara landscape covered by a thick salt crust (~50 cm) near section LL-02. See Fig. 4c for locations. 236 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245

5.3. Paleohydrology within the Atacama Desert Central Depression during the late quaternary

There is now a considerable database constraining the ages of wetter climates in the Central Andes during the late Quaternary (De Porras et al., 2017). These events created wetlands (Rech et al., 2002; Quade et al., 2008), possibly formed high elevation lakes (Grosjean et al., 2001), and activated streams (Nester et al., 2007; Gayo et al., 2012). Here, we find that these pluvial periods extended their impact to the low elevations of the Central Depression in the Atacama Desert, creating a mosaic of landscapes that greatly differed from present day conditions, and which extend the pluvial record further into the past. Here, we have identified several extensive wetlands with ages that significantly precede the CAPE-I (>17.6 ka) in the PDT (Fig. 13; Appendix A). The oldest of these at the PDT corresponds to evidence for a freshwater paleolake and beach deposits at the Salar de Bel- lavista. Diatoms in this section provide evidence for deep, thermally stratified freshwater conditions prior to the formation of ripple casts dated to ~25.4 ka. Additional evidence for this pre-CAPE pluvial event is found in dated material in the Quebrada Chipana (36.0 ka and 26.8 ka; Appendix A), which together suggests increased recharge into the Bellavista sub-basin. Simulations of recharge required to achieve these changes (See section 4.2) shows that in order to produce standing water at Salar de Bellavista at 25.4 ka and 16.5 ka (Profiles BV-01 and BV-04), aquifer recharge must increase by 2.5 to four-fold the current rate (976 L s 1). An increase of this magnitude would have expanded the area capable of sustaining P. tamarugo trees from 155 km2 today up to a maximum of ~1219 km2 around 25.4 ka and 16.6 ka (Fig. 11 e Supp. Fig. 1), considering groundwater depths of <5 m for optimal conditions and recruitment (Leakey, 1980; Calderon et al., 2015). For subsequent pluvial periods, including the CAPE, hydro- geological modelling indicates recharge rates that must be 2.5 and 1.5 times that of today at 16.2 ka and 12.8 ka, respectively. Indeed, our model reveals substantially increased areas of shallow Fig. 13. Late Quaternary paleoclimate records for the Atacama Desert and nearby Andean region (from north to south) compared to the established timing of CAPE I and groundwater (<1 m below ground level) for the entire period from II (gray boxes; De Porras et al., 2017); (A) Shoreline elevations from altiplano paleo- 25.4 ka to 11.3 ka near La Tirana-Pintados, and in the vicinity of lakes at Salar de Uyuni; (B) Positive hydroclimate anomalies for the PDT: wetlands and Zapiga in the northern PDT (Fig. 11). Plant remains found near La paleolake data are from this study (green crosses), the archaeological record corre- Tirana and in the Quisma and Quipisca ravines support the pres- sponds to the Quebrada Mani 12 archaeological site (red crosses from Latorre et al., ence of running water from 8.8 ka to 7.7 ka (Appendix A), which 2013) and riparian records from this study, Gayo et al. (2012), Tomlinson et al. (2015), Blanco and Tomlinson (2013) and Nester et al. (2007) (blue crosses); (C) Hy- suggests that tributary drainages were active in the early Holocene drological discharge towards the PDT based on the Hydrogeological model used in this due to moderately increased recharge (e.g. ~1.5 times current study; (D) Groundwater discharge levels inferred from paleowetlands (Rech et al., recharge values). During the CAPE in the southern PDT, hydro- 2002); (E) Lake levels inferred from a sediment core from Laguna Miscanti (Grosjean geological modelling indicates perennial runoff at 12.0e11.3 ka and et al., 2001); (F) Changes in the local water table at Salar de Punta Negra (Quade et al., 2008); (G) Record of positive hydroclimate anomalies from the Antofagasta permanent superficial discharge of groundwater until 7.8 ka (Gayo Region at Salar de Aguas Blancas: wetlands (green crosses, this study), rodent midden et al., 2012, Appendix A). Three sedimentary sections containing occurrence in absolute desert (orange crosses from Maldonado et al., 2005; Díaz et al., wetlands deposits in the Salar de Llamara suggest increased water 2012) and groundwater discharge deposits at Sierra de Varas (blue crosses) from Saez availability, with fluctuations in the water table near or above the et al. (2016). (For interpretation of the references to colour in this figure legend, the surface between 19.3 ka and 12.8 ka. Concurrently, 40 riparian sub- reader is referred to the Web version of this article.) fossil deposits from present-day inactive tributaries of the Salar de Llamara point to (highly variable) perennial stream discharge into the distal basin between 17.6 ka and 11.3 ka during the CAPE. The Our data also provide new evidence for the presence of periodic clustering of ages at 17.6e17.2 ka, 16.0e14.1 ka, 13.3e12.8 ka and surficial freshwater from 46.9 ka to <8.4 ka in the hyperarid Aguas 12.0e11.3 ka, however, suggests at least four possible large pluvial Blancas basin in the Antofagasta region. These paleolakes and events (Supp. Fig. 2). In summary, our observations and ages in the wetlands were synchronous for the most part with evidence of PDT reveal standing water in the sub-basins from 25.4 ka (and increased groundwater discharge at 24-26S(Saez et al., 2016). perhaps earlier) to 7.8 ka. The evidence suggests standing or near Similarly, with altitudinal changes in vegetation distribution surface water associated with a substantial increase in stream detected at 27.9e28.1 ka, 21.3 ka and 17.3 ka in rodent middens discharge and surficial outcropping of groundwater around <25.4 from the absolute desert of the Central Depression (Díaz et al., ka and from ~16.5 to 16.1 ka at Salar Bellavista. After this period 2012), as well as with the ca. 1000 m downslope migration of initial period of standing water, lakes dried out into wetlands in steppe grasses documented at higher elevations (25.5S) between Bellavista (12.7 ka) and Pintados (11.1 ka). This corresponds with 25 and 18 ka and between 17 and 10 ka (Maldonado et al., 2005) previous evidence for decreased recharge into the PDT during the (Fig. 13; Appendix B). This indicates that regional drainage systems CAPE II, as indicated by Gayo et al. (2012). in the present absolute desert have been affected by multiple M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 237 surface water recharge events during the late Pleistocene, as moisture preceding the CAPE. One possibility is that increased recently suggested by Díaz et al. (2012). effective moisture in the high Andes could have been a combination Activation of major westward drainage systems during the CAPE of slightly increased tropical moisture combined with lower tem- are known to have occurred at higher elevations in the central peratures during MIS-3, but especially later during the Last Glacial Atacama (Rech et al., 2002, 2003a), at Salar de Punta Negra (25S, Maximum (5e8 C below present day (Thompson et al., 2000)). As Quade et al., 2008) and in the Sierra de Varas (25S) (Saez et al., discussed above, several records show increased pre-LGM and LGM 2016). This latter drainage system, with catchment areas along tropical rainfall in the Andes (Blard et al., 2009, 2011, 2013). Such the western flank of the Andes and Cordillera de Domeyko Range, cold/wet conditions would have increased infiltration and terminates in salars located within the absolute desert of the increased groundwater discharge downslope towards the west. Central Depression Basin, including the Salar de Aguas Blancas Increased infiltration due to lower temperatures (but not increased (Supp. Fig. 3). Increased stream discharge throughout these sys- precipitation) along the western Andean slope may also explain tems suggests that these environmental conditions might have why there are so few LGM (or older) midden records in the existed at other localities in the Central Depression with drainage northern and central Atacama Desert (Latorre et al., 2005). systems connected to the Andes from 47 ka to <8.4 ka. In contrast to The second mechanism may be increased southerly moisture Pleistocene pluvial episodes, there is only minor evidence of Ho- sources. Middens become more common in the absolute desert to locene wet phases. Although this could be due to a lack of sampling, the west of the Andes and in the southern Atacama, where pollen we point out that most of these low elevation basins are capped by assemblages in LGM age middens from Quebrada del Chaco have thick salt crusts, that seem to require roughly 7e10 thousand years been taken as evidence for increased northward migration of cold to form (Finstad et al., 2016). Hence, the large and positive hydro- fronts stemming off the Southern Westerlies. This corresponds with climate anomalies necessary to increase the water table above the paleorecords in winter-precipitation dominated areas from central surface of these playas, most likely largely disappeared in the early and central-southern Chile (Lamy et al., 1998, Heusser et al., 1999, Holocene (<8.4 ka) and have not returned. Valero-Garces et al., 2005). These complex spatial patterns for pre- CAPE moisture probably suggest that mixed sources of moisture 5.4. Late Quaternary regional paleoclimate (east and west of the Andes) were likely involved, as suggested by Maldonado et al. (2005) for the Quebrada del Chaco record. 5.4.1. Evidence and mechanisms for a pre-CAPE pluvial(s) (>17.5 ka) 5.4.2. The Central Andean Pluvial Event (CAPE e 17.5e14.2 ka and A full chronology for pluvial events preceding the CAPE (i.e., 13.8e9.7 ka) in the hyperarid core of the Atacama Desert >17.5 ka) remains elusive. Only a handful of records exist that can The Central Andean Pluvial Event (CAPE) as defined by Quade help constrain these events, especially along the Western Andean et al. (2008) and reviewed in Gayo et al. (2012), is based on an Cordillera (18e22 S). Enhanced moisture is indicated by rodent ever-growing set of data showing enhanced Andean precipitation middens from Quebrada La Higuera (18 S) ca. 37 ka (Mujica et al., of tropical origin during the latest Pleistocene (Betancourt et al., 2015). Within the PDT the record is even more sparse, reduced to 2000; Grosjean et al., 2001; Latorre et al., 2002, 2005, 2006; Rech scattered evidence of wetter conditions at 36.1 ka and at 26.9 ka in et al., 2002; Maldonado et al., 2005; Nester et al., 2007; Quade Quebrada Chipana (20.5 S), 25.4 ka at Salar de Bellavista and from et al., 2008; Placzek et al., 2009; Gayo et al., 2012). Two major 19.4 to 19.1 ka and 18.6 ka at Salar de Llamara. These ages are part of phases separated by an arid period have been defined: CAPE I a fragmentary record now emerging from the PDT that shows a (17.5e14.2 ka) and CAPE II (13.8e9.7 ka). Whether these occurred as degree of overlap with the minor Sajsi lake cycle in the Bolivian several centennial-scale events or more prolonged periods lasting Altiplano, specifically from ~25 to 19 ka (Blard et al., 2011; Placzek millennia is not yet clear. The intensity, tropical moisture sources et al., 2006). Increased pre-CAPE moisture in the Atacama's hy- (e.g. Amazon vs Gran Chaco) and regional extent of the different perarid core also coincides with a wetter period between 27.9 ka phases of CAPE also has yet to be fully understood (see De Porras and 17.8 ka recorded at Jaragua cave in Brazil (21S 56.5W) at the et al., 2017 for a recent review). center of the South American Monsoon System (Novello et al., The integrated data suggests that discharge decreased from 2017). Further south, our pre-CAPE evidence for increased ground ~16.5 to 12.0e11.3 ka, coinciding with the observed variations in water levels in the Aguas Blancas basin (24 060 S69 580 W) at 46.8 riparian system vegetation assemblages, which indicate that CAPE ka, 35.9 ka and 23.6 ka coincides with the (poorly constrained) wet II was probably drier than CAPE I in the PDT (Nester et al., 2007; phase in the Salar de Atacama from 53.5 to 15.3 ka (Bobst et al., Gayo et al., 2012). This agrees with shoreline records from the 2001), and rodent midden pollen records showing increased Uyuni basin in the Bolivian Altiplano region, where the Tauca lake moisture at 57e40 ka and from 24 ka to15 ka (Maldonado et al., phase (16.4e14.1 ka and synchronous with the CAPE I), was much 2005). Plant macrofossils from rodent middens collected in the more intense than the later Coipasa lake phase (13 to ca.11 ka), absolute desert between 24 and 26 S have been interpreted to which was part of the CAPE II (Placzek et al., 2006, 2009, 2013). infer increased discharge into the desert from higher elevations at South of the PDT, however, the differences between CAPE pha- 28.1e27.9 ka, at 21.3 ka and 17.3 ka (Díaz et al., 2012). ses become less apparent. A summary of the record in this region Pre-CAPE pluvial events have also been inferred in two records shows that: i) elevated groundwater levels at Salar de Punta Negra along the eastern flank of the Andes: i) at the Pozuelos Basin in (24.5S) occurred during both intervals of the CAPE, showing similar Argentina (22S, 66 W) a deep paleolake existed from ca. 43e37 ka, conditions between 15.9 and 13.8 ka and 12.7 to 9.7 ka (Quade et al., a shallow paleolake from 37 to 23 ka and a saline lake formed 2008); ii) rodent middens from higher elevation sites within Que- 26e19 ka that then dried out (Mcglue et al., 2013); ii) at Salar brada del Chaco (25.5 S) reveal much wetter than present condi- Hombre Muerto (25S67W), a sediment core reveals the presence of tions between 17 and 15 ka, and moderately wetter than present a saline lake c. 45 ka interpreted as a very wet phase, followed by a conditions between 14 and 11 ka (Maldonado et al., 2005); iii) a saline pan at 44e38 and 24e20 ka indicating moderate wet phases high Andean lake sediment record from Laguna Miscanti (23 S) during these periods (Godfrey et al., 2003). A drying trend from the shows a wetter CAPE II than CAPE I (Grosjean et al., 2001), in older sediments into the LGM is thus apparent in both of these agreement with local rodent middens records at lower elevations records. (Latorre et al., 2002) and increased groundwater discharge (Rech Two very different mechanisms can be postulated for increased et al., 2002); iv) the Aguas Blancas record presented here shows 238 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 evidence for increased discharge during the CAPE II and lacks any with jasper veins were sites of multiple, and apparently long-term, evidence for the CAPE I, although this could be due to the recon- lithic workshops. Our preliminary observations suggest these lithic naissance nature of our observations. Indeed, just upstream from artifacts could be late Pleistocene age and we speculate that these the Aguas Blancas basin, a late CAPE I age of 14.5 ka occurs in a sites could be contemporaneous with archaeological sites that have paleowetland from Sierra de Varas (Saez et al., 2016). Evidence for been documented along the coastal desert (Castelleti et al., 2010; increased groundwater levels during the CAPE II occur at 13.81 and Salazar et al., 2015, 2018). Nevertheless, we have yet to explore and 8.4 ka in the Aguas Blancas basin and at 11.8e11.1 ka at the Pique La survey these wetlands for evidence of early human occupation, Calle paleowetlands (Appendix A). Upstream from our sites, such as the late Pleistocene site described at Salar de Punta Negra groundwater discharge increased in the Sierra de Varas from 12.2 to (Grosjean et al., 2005; Quade et al., 2008). 9.8 ka (Saez et al., 2016); v) Pollen records from rodent middens at three sites along the western Andean slope show that wetter 6. Conclusions conditions occurred from 14.2 to 8.5 ka (De Porras et al., 2017). We point out that these younger ages for the end of CAPE II are in good During the late Quaternary, different periods of enhanced agreement with our Aguas Blancas basin record and with paleo- recharge supported wetlands and lakes in the currently extremely e wetland stratigraphies in the central Atacama (22 24S) (Rech et al., dry Central Depression of the Atacama Desert between 20 and 25S, 2002). creating an interconnected network of surficial water from the Andes to the Coast that is nearly absent today in those latitudes. 5.5. Paleobiogeography of the hyperarid core and cultural impacts Those periods of water table rise, comprise a period that spans ~46.9 ka to 7.7 ka, encompassing a widespread pluvial period The new emerging view of the hyperarid Atacama Desert during known as the Central Andean Pluvial Event (CAPE) that occurred fi the late Pleistocene is one of signi cant intervals of semi- between 17.5 and 9.7 ka. Our record also adds to the still frag- fl continuous stream ow and abundant riparian habitats, with mentary record for pluvial event(s) preceding the CAPE in the re- wetlands and/or shallow lakes occupying what are now halite gion, pointing to a richer history to the desert response to wet encrusted salars or playa basins. These were prevalent in both the periods in the Andes. Combining the new evidence with regional northern and southern regions of the desert, although the mech- evidence of pre-CAPE wet periods show that the spatial and tem- anisms that caused these pluvials remains somewhat unclear. The poral extension of these wet periods are complex and suggests that rising water table in the PDT would have favoured habitat suitable most likely mixed sources of moisture (east and west of the Andes) for the colonization and expansion of P. tamarugo populations. The exists for these periods. Coinciding with most records for the PDT likelihood of semi-continuous low-density patches of phreato- region, discharge decreased from CAPE I to CAPE II, while the dif- halophyte vegetation communities and wetlands in the PDT rep- ferences between both become less apparent at the southern Ata- resents a fundamentally novel environmental model for the con- cama record of Aguas Blancas. ditions that existed at the time of the earliest human presence in We recommend that future archaeological research and explo- the region, and such conditions would have impacted interconti- ration needs to be organized around a newly revised model of the nental dispersion, colonization and settlement. The early hunter- late Pleistocene conditions in the Atacama Desert. A revised model gatherer open camp at Quebrada Mani (QM12) dated from 12.8 of the paleoenvironment can be overlain on the present lifeless and ka to 11.7 ka (Appendix A) coincides with increased discharge into waterless region, pointing to a more informed strategy for the PDT basin (Fig. 13)(Latorre et al., 2013). Associated riparian archaeological prospecting. The presently known Paleoindian or ecosystems and wetlands would have hosted abundant paleofauna proto-Archaic sites of Tiliviche 1-B (9.76 ka) (Nunez,~ 1986; Santoro used as prey by these early inhabitants, as evidenced by camelid et al., 2017) and Quebrada Mani 12 (12.8 ka) (Latorre et al., 2013; bones in the QM12 site (Latorre et al., 2013). Extinct Pleistocene Gayo et al., 2015)(Fig. 6) may be simply part of a fascinating early fi large mammals likely also bene ted from these conditions, as a exploitation of the region by humans, one that was, as it still is diverse fauna composed of sloths (Scelidodon chilensis and Mega- today, dependent on the availability of water. therium medinae), camelids (Lama sp.) and equids have been found in the PDT basin (Moreno et al.,1994; Frassinetti and Alberdi, 2001). As the archaeological evidence for early human presence in the PDT Acknowledgments continues to grow, the emerging view of the paleohydrology sug- gests abundant local biotic resources would have been available to Funding was provided by through the CONICYT Becas Chile these early desert settlers (Latorre et al., 2013; Maldonado et al., Scholarship and the Fulbright Foreign Student Program Scholarship 2016; Santoro et al., 2017). (M.P.), through FONDAP 1511009 (E.G., R.D.H), through CONICYT/ Further south in the Aguas Blancas basin, wetter and more PCI Project REDES 140139 (C.L., R.A., C.M.S.), through FONDECYT biologically rich episodes also occurred intermittently over the last 1160744 (C.M.S., C.L., E.MG), 11150210 (E.G.), CONICYT PIA Anillo 46,000 years (Fig. 13). These wetter periods also likely facilitated Soc 1405 (C.L. C.M.S., E.MG, V.B.M), CONICYT AFB 170008 (to C.L.) conditions for ecological transformations and human migration and through the Agricultural Experiment Station and NSF geo- within the absolute desert during the late Pleistocene. To date, biology and Low Temperature Geochemistry grant (R.A.). We there are no known early prehistoric sites in the Salar de Aguas appreciate the help of Moises Valladares in identifying gastropods Blancas basin, though early sites have been documented regionally and to Steven Ruzin and Denise Schichnes for wood histological fi at higher elevations (>3000 m) in the Salar de Punta Negra and thin section preparation. The original manuscript bene ted greatly Imilac basins (12.37e10.32 ka) (Lynch, 1986; Grosjean et al., 2005; from the suggestions of two anonymous reviewers. Cartajena et al., 2014), and along the coast at the sites of San Ramon and Alero Cascabeles (12.15e10.5 ka) (Salazar et al., 2011, 2015). We Appendix A. Supplementary data discovered numerous lithic workshops in the eastern Aguas Blan- cas basin that contain seashells, bones, and rounded andesite Supplementary data related to this article can be found at pebbles from the coast used as percussion tools. Basalt outcrops https://doi.org/10.1016/j.quascirev.2018.08.001. M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 239

Appendix A. Radiocarbon dates for riparian, wetland and archaeological record for the Pampa del Tamarugal

Riparian

No ID Lab. Code Lat Lon Elevation Material 14C yr St. Cal. yr 2 s (cal. yr Reference (m) BP dev. BP BP)

Quebrada Quipisca 1 IB-228 N.A. 20.08 69.36 2072 Plant remains 10,320 50 10070 328/344 a 2 IB-229 N.A. 20.08 69.36 2072 Plant remains 9190 40 8360 46/70 a Quebrada Quisma 3 IB-137 N.A. 20.51 69.36 1234 Wood 7860 40 8830 81/88 b 4 IB-138 N.A. 20.49 69.41 1094 Wood 12,310 50 12,350 153/120 a Quebrada Chacarilla 5 IB-54a N.A. 20.58 69.36 1229 Plant remains 10,380 70 10,500 143/221 b La Tirana 6 Pampa del Tamarugal-2013-1 UCIAMS- N.A. N.A. N.A. Plant remains 6980 20 7760 70/70 This 133680 study Quebrada Chipana 7 N05-22 UCIAMS- N.A. N.A. 1282 Wood 12,160 130 13,990 400/505 c 29221 8 Q.Chi-33 UCIAMS- 20.9 69.35 1240 Wood 12,210 80 14,050 280/250 This 133675 study 9 N05-21 UCIAMS- 1282 Wood 13,060 25 15,580 230/180 c 29216 10 QChi4-Sup UCIAMS- 20.9 69.34 1277 Burned stems 13,120 50 15,670 290/230 This 165626 study 11 Qchi-1 UCIAMS- 20.9 69.35 1240 Grass stems 13,200 35 15,820 175/190 This 126287 study 12 Qchi-2 UCIAMS- 20.9 69.35 1240 Escallonia angustifolia leafes 13,250 40 15,870 180/180 This 126288 study 13 QChi4-4 UCIAMS- 20.9 69.34 1277 Stems 13,360 160 16,010 520/490 This 165625 study 14 WP740 UCIAMS- 20.9 69.34 1271 Sedges 12,720 90 15070 454/331 This 165246 study 15 WP740 UCIAMS- 20.9 69.34 1271 Sedges 12,300 160 14280 514/670 This 165247 study 16 WP740 UCIAMS- 20.9 69.34 1271 Sedges 13,250 80 15870 278/272 This 165248 study 17 IB-122 N.A. 20.94 69.15 1949 Wood 24,810 230 26860 260/246 b 18 IB-116 N.A. 21 69.3 1348 Wood & Plant remains 12,470 70 12590 259/579 b 19 IV-318 N.A. 20.87 69.46 986 Plant remains 33,600 40 36060 339/458 b 20 IB-101 N.A. 20.9 69.34 1283 Plant remains 13,600 260 14380 120/112 b 21 IB-105 N.A. 20.9 69.33 1306 Plant remains 12,570 60 12840 471/335 b 22 IB-102 N.A. 20.9 69.34 1294 Plant remains 12,400 70 12450 318/411 b 23 IB-134 N.A. 20.98 69.43 983 Wood 13,010 70 13550 146/126 b Quebrada Mani 24 QM-19 UGAMS-4564 21.09 69.3 1265 Grass stems 9960 40 11,320 95/380 d 25 QM-17 UGAMS-4562 21.09 69.3 1260 Grass stems 10,030 40 11,450 190/440 d 26 QM-15B UGAMS-4561 21.09 69.3 1260 Grass stems 10,110 30 11,620 220/405 d 27 QM-15A UGAMS-4066 21.09 69.3 1260 Grass stems 10,260 40 11,900 140/290 d 28 QM-84 UCIAMS- 21.26 69.49 Wood from T1 10,950 30 12,760 50/115 This 165618 study 29 QM-81 UCIAMS- 21.09 69.31 1260 Prosopis wood from T1 10,985 30 12,780 70/190 This 123144 study 30 QM-32 UCIAMS- 21.09 69.31 1203 Stems 11,530 35 13,330 90/200 e 84340 31 QM-52 UCIAMS- 21.1 69.31 1226 Escallonia angustifolia leaves 12,220 35 14,060 140/280 This 165616 study 32 QM-62a UCIAMS- 21.11 69.33 Escallonia angustifolia leaves 12,730 30 15,120 210/360 This 123141 study 33 QM-4 CAMS-131272 21.1 69.32 1220 Escallonia angustifolia leaves 13,190 35 15,800 180/370 c 34 QM-77 UCIAMS- 21.1 69.33 1194 Escallonia angustifolia leaves 13,200 35 15,810 170/365 This 123142 study 35 QM-78 UCIAMS- 21.1 69.33 1199 Wood 13,350 45 16,010 205/400 This 133671 study 36 QM-31 UCIAMS- 21.09 69.31 1226 Escallonia angustifolia leaves 14,160 35 17,170 190/410 e 84738 Quebrada Sipuca 37 QS-15A UCIAMS- 21.26 69.31 1161 Wood 12,530 35 14,690 385/325 This 165615 study (continued on next page) 240 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245

(continued )

Riparian

No ID Lab. Code Lat Lon Elevation Material 14C yr St. Cal. yr 2 s (cal. yr Reference (m) BP dev. BP BP)

38 QS-16b UCIAMS- 21.26 69.32 1144 Escallonia angustifolia leaves 12,590 45 14,850 390/270 This 123146 study 39 QS-22 UCIAMS- 21.23 69.33 1123 Leaves 12,630 35 14,940 250/200 This 123150 study 40 QS-18 UCIAMS- 21.26 69.32 1144 Wood 12,770 35 15,170 170/150 This 123145 study 41 QS-17 UCIAMS- 21.26 69.31 1143 Escallonia angustifolia leaves 12,780 35 15,170 160/150 This 123147 study 42 QS-13 UCIAMS- 21.26 69.31 1162 Wood 13,080 40 15,610 260/195 This 145136 study 43 QS-20 UCIAMS- 21.25 69.32 1140 Escallonia angustifolia leaves 13,100 30 15,650 260/180 This 123149 study 44 QS-11 UCIAMS- 21.23 69.23 1446 Escallonia angustifolia leaves 13,140 45 15,720 260/230 This 165617 study 45 QS-12 UCIAMS- 21.26 69.31 1173 Escallonia angustifolia leaves 13,205 40 15,820 190/200 This 165619 study 46 QS-1 GX-32394 21.23 69.19 1559 Escallonia angustifolia leaves 13,330 80 15,980 250/250 c 47 QS-3 GX-32395 21.23 69.2 1552 Escallonia angustifolia leaves 13,400 70 16,070 250/220 c 48 QS-19 UCIAMS- 21.26 69.32 1141 Escallonia angustifolia leaves 13,510 35 16,210 185/185 This 123148 study 49 N05-10 UCIAMS- 21.23 69.2 CaCO3 rhizoliths 14,470 70 17,590 - 240/260 c 29222 Quebrada Tambillo 50 QT-5 GX-32397 21.43 69.25 1304 Escallonia angustifolia leaves 12,940 150 15,420 490/500 c 51 N05-11 UCIAMS- N.A. N.A. N.A. Wood 13,080 30 15,620 250/180 c 292220 52 QT-2013-03-2 UCIAMS- N.A. N.A. N.A. Escallonia angustifolia leaves 13,130 80 15,690 340/280 This 133682 study 53 QT-9 CAMS-131273 21.44 69.31 1131 Cortaderia atacamensis blades 13,220 35 15,840 170/180 c 54 QT-8 CAMS-129367 21.44 69.26 1291 Baccharis scandensleaves 13,280 70 15,910 230/240 c 55 QT-1 GX-32396 21.43 69.25 1336 Escallonia angustifolialeaves 13,290 80 15,930 255/265 c 56 QT-6 GX-32398 21.43 69.25 1307 Escallonia angustifolia leaves 13,310 180 15,940 605/505 c 57 QT-2013-03-1 UCIAMS- N.A. N.A. N.A. Canes 13,350 30 16,000 190/170 This 133681 study Lomas de Sal 58 L.d.S-6A UGAMS-4062 21.4 69.44 873 Stems 10,120 40 11,640 275/295 d 59 N06-11A UCIAMS- 21.43 69.46 Wood 10,170 20 11,770 160/200 c 29217 60 L.d.Se6B UGAMS-4063 21.4 69.44 873 Stems 10,320 40 12,010 200/360 d 61 N04-14a AA-62290 21.4 69.42 Escallonia angustifolia leaves 12,240 96 14,100 330/455 c 62 L.d.S-1 UCIAMS- 21.39 69.42 918 Escallonia angustifolia leaves 12,400 192 14,480 660/650 d 29216 63 N05-18 UCIAMS- 21.4 69.43 Schinus mollewood 12,440 30 14,440 270/310 c 29219 64 L.d.S-8 UGAMS-4064 21.43 69.46 859 Prosopis tamarugo leaves 12,490 40 14,580 340/360 d 65 L.d.S-5 UGAMS-4559 21.4 69.44 872 Caesalpinia aphylla flowers 12,630 40 14,940 260/220 d 66 N05-12a UCIAMS- 21.4 69.42 Schinus mollewood 12,740 30 15,130 205/150 c 29218 67 L.d.S-7 UGAMS-4560 21.43 69.46 861 Prosopis tamarugobark 12,950 40 15,410 190/220 d

Lacustrine and Wetland Deposits

Quebrada Maní 68 QM-22D UCIAMS- 21.09 69.3 1247 Organic remains 7040 230 7840 400/860 d 84741 69 QM-22B UCIAMS- 21.09 69.3 1247 Organic remains 10,120 430 11,680 1240/2295 e 84740 Salar de Llamara 70 SLM-12-02 UCIAMS- N.A. N.A. N.A. Root in lake bed 5990 20 6770 100/80 This 123133 study 71 SLM-12-01 UCIAMS- N.A. N.A. N.A. Soil Organic Matter 8680 25 9580 45/90 This 123134 study 72 SLM-2012-01 UCIAMS- N.A. N.A. N.A. Soil Organic Matter 8890 25 9960 210/200 This 133672 study 73 LL-01 - Qh 4 LLNLAMS- 21.2 69.68 750 Soil Organic Matter 10,570 310 12280 440/446 f 107707 74 LL-01 - Qh 10 LLNLAMS- 21.2 69.68 750 Carbonate 12,990 80 15480 163/139 f 107711 75 LL-02 - Qs 5 LLNLAMS- 21.35 69.58 764 Soil Organic Matter 16,100 120 19370 159/166 f 107585 76 LL-02 - Qs 8 LLNLAMS- 21.35 69.58 764 Soil Organic Matter 15,880 120 19110 177/134 f 107708 77 LL-03 - WP733eH2 UCIAMS- 21.21 69.64 807 In situ wood 17,050 35 18560 76/84 This 174237 study M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 241

(continued )

Riparian

No ID Lab. Code Lat Lon Elevation Material 14C yr St. Cal. yr 2 s (cal. yr Reference (m) BP dev. BP BP)

Salar de Bellavista 78 WP446Salar Bellavista UCIAMS- 20.83 69.68 944 Root (Carbonate lenses above 13,640 45 16380 190/230 This 165226 root) study 79 BV-05 - WP442Salar Bellavista UCIAMS- 20.82 69.66 944 Standing roots 13,490 45 16170 202/186 This 165227 study 80 BV-02 - WP455-IV-1Salar Bellavista UCIAMS- 20.83 69.71 947 Stems 13,430 60 16110 231/200 This .23 mgC 165228 study 81 BV-02 - WP455eV-1Salar Bellavista UCIAMS- 20.83 69.71 947 Stems 13,420 60 16100 232/197 This .20 mgC 165229 study 82 BV-02 - WP455IV-2Salar Bellavista UCIAMS- 20.83 69.71 947 Soil Organic Matter 13,760 45 16560 235/258 This 165236 study 83 BV-02 - WP455V-2Salar Bellavista UCIAMS- 20.83 69.71 947 Soil Organic Matter 13,730 50 16500 224/271 This 165237 study 84 BV-04 - WP797-ULSalar Bellavista UCIAMS- 20.85 69.7 949 Shells upper layer 13,780 45 16590 243/260 This 165240 study 85 BV-04 - WP797-LLSalar Bellavista UCIAMS- 20.85 69.7 949 Shells bottom layer 13,740 45 16520 220/263 This 165241 study 86 BV-03 - WP443 UCIAMS- 20.81 69.69 944 Wood (cf. Prosopis) 12,520 30 12700 363/329 This 174198 study 87 BV-01 - WP451-Ripple Cast UCIAMS- 20.83 69.66 947 Carbonate 23,060 80 25400 213/189 This 174234 study Salar de Pintados 88 WP597-VIPintados .19 mgC UCIAMS- 20.62 69.66 970 Rizolith 10,000 40 11370 124/239 This 165239 study 89 WP597-VPintados UCIAMS- 20.62 69.66 970 Carbonate mass 9740 30 11150 273/66 This 165250 study

Archaeological record Quebrada Maní

90 QM12c UCIAMS- 21.06 69.34 1240 Marine gastropod 10,660 25 11,200 770/910 e 89458 91 QM12c UCIAMS- 21.06 69.34 1240 Fibrous plant material 10,080 25 11,530 180/220 e 89015 92 QM12c UCIAMS- 21.06 69.34 1240 Fibrous plant material 10,120 25 11,640 240/160 e 89020 93 QM12c-3-N2W2 UCIAMS- 21.06 69.34 1240 Wood 10,120 30 11,640 240/170 e 145153 94 QM12c UGAMS-8241 21.06 69.34 1240 Wood 10,130 30 11,660 260/260 e 95 QM12b UCIAMS- 21.06 69.34 1240 Charcoal 10,155 25 11,730 320/240 e 84345 96 QM12c UCIAMS- 21.06 69.34 1240 Fibrous plant material 10,160 25 11,740 330/240 e 89017 97 QM12c UCIAMS- 21.06 69.34 1240 Fibrous plant material 10,170 25 11,750 250/230 e 89021 98 QM12c (QM-85c) UCIAMS- 21.06 69.34 1240 Wood 10,170 30 11,760 260/230 e 165623 99 QM12c UGAMS-7050 21.06 69.34 1240 Charcoal 10,210 30 11,850 200/160 e 100 QM12c UGAMS-8242 21.06 69.34 1240 Wood 10,220 30 11,870 160/140 e 101 QM12c UGAMS-8243 21.06 69.34 1240 Wood 10,340 30 12,040 200/330 e 102 QM12c UCIAMS- 21.06 69.34 1240 Animal dung 10,360 30 12,100 150/290 e 89022 103 QM12c-NOEO UCIAMS- 21.06 69.34 1240 CharcoalMyrica pavonis 10,380 25 12,170 190/220 e 145255 104 QM12b UGAMS-7048 21.06 69.34 1240 Charcoal 10,390 30 12,210 210/190 e 105 QM12c UCIAMS- 21.06 69.34 1240 Fibrous plant material 10,505 25 12,420 300/130 e 89019 106 QM12c UGAMS-7049 21.06 69.34 1240 Charcoal 10,800 30 12,700 30/30 e 107 QM12c UCIAMS- 21.06 69.34 1240 Charcoal 10,930 30 12,750 50/60 e 89018 108 QM12c UCIAMS- 21.06 69.34 1240 Charcoal 12,420 35 14,410 260/310 e 84346 109 QM12c UCIAMS- 21.06 69.34 1240 Charcoal 13,920 40 16,810 240/210 e 89016

References. Dates previously reported in: a) (Tomlinson et al., 2015); b) (Blanco, 2013); c) (Nester et al., 2007); d) (Gayo et al., 2012); e) (Latorre et al., 2013); f) (Finstad et al., 2016). 242 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245

Appendix B. Radiocarbon dates for the drainage systems analyzed in the Aguas blancas basin

Lacustrine and Wetland Deposits

No ID Lab. Code Lat Lon Elevation (masl) Material 14C yr BP St. dev. Cal. yr BP 2 s (cal. yr BP) Reference

Aguas Blancas 110 773e2 UCIAMS 182956 24.09 69.86 972 CaCO3 nodule 19,600 50 23,560 250/240 This study 111 773e3 UCIAMS 183040 24.09 69.86 972 Peat humics 43,670 780 46,880 1525/785 This study 112 798e3 UCIAMS 182958 24.08 69.91 962 CaCO3 massive 7680 20 8420 40/95 This study 113 796e5 UCIAMS 182959 24.08 69.92 961 CaCO3 laminae 11,380 25 13,180 85/45 This study Pique Lacalle 114 781e0 UCIAMS 183034 24.49 69.64 1569 Wood 9685 20 11,050 2560/1230 This study 115 781e5 UCIAMS 182957 24.49 69.64 1569 CaCO3 laminae 32,080 190 35,940 450/405 This study 116 782e0 UCIAMS 183035 24.49 69.94 1599 Wood 10,190 20 11,810 180/130 This study

Rodent-middens

Quebrada del Chaco 117 526B GX26827 25.46 69.41 2860 Faecal Pellet 13,030 340 15,490 12780/970 g 118 509C GX26672 25.44 69.45 2670 Faecal Pellet 15,120 560 18,280 1415/1325 g 119 519 GX26820 25.44 69.45 2670 Faecal Pellet 17,070 290 20,550 725/790 g 120 509B GX26671 25.44 69.45 2670 Faecal Pellet 19,400 770 23,340 1765/1910 g 121 512 GX26832 25.44 69.45 2670 Faecal Pellet 20,110 340 24,150 810/380 g 122 518 GX26826 25.44 69.45 2670 Faecal Pellet 33,880 e 38,070 3900/2165 g 123 508 GX26670 25.44 69.45 2670 Faecal Pellet 36,350 e 40,470 4255/3445 g 124 509D GX26673 25.44 69.45 2670 Faecal Pellet 38,880 e 42,820 3790/3405 g 125 504 GX26831 25.41 69.21 3460 Faecal Pellet 10,010 70 11,440 210/305 g 126 496 GX26847 25.41 69.2 3500 Faecal Pellet 10,310 260 11,980 730/685 g 127 499B GX26815 25.41 69.22 3470 Faecal Pellet 10,660 140 12,520 470/220 g 128 498A GX27168 25.41 69.22 3470 Faecal Pellet 11,300 170 13,110 350/310 g 129 511A GX26817 25.41 69.21 3450 Faecal Pellet 12,640 640 14,890 1660/1820 g 130 500A GX26828 25.41 69.21 3450 Faecal Pellet 12,730 350 14,980 1130/1060 g 131 500C GX26843 25.41 69.21 3450 Faecal Pellet 12,810 390 15,110 1260/1130 g 132 515A GX27164 25.41 69.29 3470 Faecal Pellet 12,870 140 15,310 540/480 g 133 498B GX26814 25.41 69.22 3470 Faecal Pellet 13,910 140 16,790 470/440 g 134 511B GX26841 25.41 69.21 3450 Faecal Pellet 14,150 180 17,140 580/495 g 135 510A GX26825 25.41 69.22 3450 Faecal Pellet 16,480 250 19,830 625/630 g 136 499A GX26823 25.41 69.22 3470 Faecal Pellet 40,490 1630 44,130 2545/2910 g Sierra del Buitre 137 145-A GX32020 25.23 70.25 1650 Faecal Pellet 14,190 470 17,300 460/590 h 138 113-A CAMS-133246 25.23 70.24 1550 Faecal Pellet 23,000 130 27,900 220/160 h 139 113-B GX32019 25.23 70.24 1550 Faecal Pellet 23,280 1230 27,900 1550/1510 h Cerro Tres Tetas 140 CTT 71 CAMS-133248 24.34 70.13 1900 Faecal Pellet 17,800 70 21,300 120/150 h 141 CTT 72 CAMS-133249 24.34 70.13 1900 Faecal Pellet 23,290 130 28,100 160/230 h Barazarte 142 BZT157 AA69850 24.09 70.17 1177 Faecal Pellet 16,160 120 19,300 320/190 h Juncal 143 687 AA65820 25.74 69.4 2765 Faecal Pellet 15,740 130 18,900 200/330 h 144 689-A AA65821 25.74 69.4 2765 Faecal Pellet 29,900 440 34,500 460/480 h

Groundwater Discharge Deposits

Alto de Varas 145 AVB 13 Beta 401669 24.82 69.18 3446 Organic Sediment 8860 40 9860 180/100 i 146 AVB 9 Beta 384874 24.82 69.18 3446 Plant 9260 30 10,370 115/120 i 147 AVB 1a Beta 384873 24.82 69.18 3446 Plant 8220 40 9120 110/145 i 148 AVB 1 Beta 385822 24.82 69.18 3446 Organic Sediment 10,390 40 12,200 205/310 i 149 AVA 1 Beta 384872 24.82 69.18 3446 Plant 12,450 40 14,480 315/335 i 150 AVA 1 Beta 385821 24.82 69.18 3446 Organic Sediment 12,470 40 14,530 330/255 i Chepica 151 CH 10 Beta 384881 24.98 69.32 2915 Organic Sediment 9760 30 11,170 80/60 i 152 CH 5 Beta 384880 24.98 69.32 2915 Organic Sediment 10,330 30 12,020 110/90 i Cachinalito 153 CA-2 Beta 384877 25.14 69.55 2564 Charred Sediment 9770 30 11,180 85/55 i 154 CA-2 Beta 385824 25.14 69.55 2564 Organic Sediment 9770 30 11,180 85/55 i

References: Dates previously reported in: g) (Maldonado et al., 2005); h) (Díaz et al., 2012); i) (Saez et al., 2016).

References Albert, R.M., Lavi, O., Estroff, L., Weiner, S., Tsatskin, A., Ronen, A., Lev-Yadun, S., 1999. Mode of occupation of Tabun cave, Mt Carmel, Israel during the Mous- terian period: a study of the sediments and phytoliths. J. Archaeol. Sci. 26, Acs, E., Ari, E., Duleba, M., Dressle, M., Genkal, S.I., Kiss, K.T., 2016. Pantocsekiella a 1249e1260. new centric diatom genus based on morphological and genetic studies. Fottea Albert, R.M., Shahack-Gross, R., Cabanes, D., Gilboa, A., Lev-Yadun, S., Portillo, M., 16, 56e78. M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 243

Sharon, I., Boaretto, E., Weiner, S., 2008. Phytolith-rich layers from the late of Sciences. bronze and iron ages at Tel dor (Israel): mode of formation and archaeological Frassinetti, D., Alberdi, M.T., 2001. Los macromamíferos continentales del Pleisto- significance. J. Archaeol. Sci. 35, 57e75. ceno Superior de Chile: resena~ historica, localidades, restos fosiles, especies y Amundson, R., Dietrich, W., Bellugi, D., Ewing, S., Nishiizumi, K., Chong, G., Owen, J., dataciones conocidas. Estud. Geol. 57, 53e69. Finkel, R., Heimsath, A., Stewart, B., 2012. Geomorphologic evidence for the late Gajardo, R., 1994. La vegetacion natural de Chile: clasificacion y distribucion Pliocene onset of hyperaridity in the Atacama Desert. Geol. Soc. Am. Bull. 124, geografica. 1048e1070. Garreaud, R., Aceituno, P., 2001. Interannual rainfall variability over the south Antoniades, D., Douglas, M.S., Smol, J.P., 2005. Benthic diatom autecology and american altiplano. J. Clim. 14, 2779e2789. inference model development from the Canadian high arctic Archipelago 1. Garreaud, R.D., Vuille, M., Compagnucci, R., Marengo, J., 2009. Present-day south J. Phycol. 41, 30e45. american climate. Palaeogeogr. Palaeoclimatol. Palaeoecol. 281, 180e195. Aravena, R., 1995. Isotope hydrology and geochemistry of northern Chile ground- Garrido, M., Silva, P., Acevedo, E., 2016. Water relations and foliar isotopic waters. Bull. IFEA 24, 495e503. Composition of Prosopis tamarugo phil., an endemic tree of the Atacama Desert Babot, M.D.P., 2011. Cazadores-recolectores de los andes centro-sur y proc- growing at three levels of water table depth. Front. Plant Sci. 7. esamiento vegetal: una discusion desde la puna meridional Argentina (ca. Gayo, E.M., Latorre, C., Jordan, T.E., Nester, P.L., Estay, S.A., Ojeda, K.F., Santoro, C.M., 7.000-3.200 anos~ AP). Chungara 43, 413e432. 2012. Late Quaternary hydrological and ecological changes in the hyperarid Betancourt, J., Latorre, C., Rech, J., Quade, J., Rylander, K., 2000. A 22,000-year record core of the northern Atacama Desert (~ 21 S). Earth Sci. Rev. 113, 120e140. of monsoonal precipitation from northern Chile's Atacama Desert. Science 289, Gayo, E.M., Latorre, C., Santoro, C.M., 2015. Timing of occupation and regional set- 1542e1546. tlement patterns revealed by time-series analyses of an archaeological radio- Blanco, N., Tomlinson, A., 2013. Carta Guatacondo. Region de Tarapaca. carbon database for the South-Central Andes (16e25 S). Quat. Int. 356, 4e14. Blard, P.-H., Lave, J., Farley, K., Fornari, M., Jimenez, N., Ramirez, V., 2009. Late local Geyh, M.A., Grosjean, M., Núnez,~ L., Schotterer, U., 1999. Radiocarbon reservoir ef- glacial maximum in the Central Altiplano triggered by cold and locally-wet fect and the timing of the late-glacial/early Holocene humid phase in the conditions during the paleolake Tauca episode (17e15 ka, Heinrich 1). Quat. Atacama Desert (northern Chile). Quat. Res. 52, 143e153. Sci. Rev. 28, 3414e3427. Geyh, M.A., Schotterer, U., Grosjean, M., 1997. Temporal changes of the 14 C reser- Blard, P.-H., Lave, J., Sylvestre, F., Placzek, C., Claude, C., Galy, V., Condom, T., voir effect in lakes. Radiocarbon 40, 921e931. Tibari, B., 2013. Cosmogenic 3He production rate in the high tropical Andes Godfrey, L., Jordan, T., Lowenstein, T., Alonso, R., 2003. Stable isotope constraints on (3800 m, 20 S): implications for the local last glacial maximum. Earth Planet Sci. the transport of water to the Andes between 22 and 26 S during the last glacial Lett. 377, 260e275. cycle. Palaeogeogr. Palaeoclimatol. Palaeoecol. 194, 299e317. Blard, P.-H., Sylvestre, F., Tripati, A., Claude, C., Causse, C., Coudrain, A., Condom, T., Grosjean, M., Núnez,~ L., Cartajena, I., 2005. Palaeoindian occupation of the Atacama Seidel, J.-L., Vimeux, F., Moreau, C., 2011. Lake highstands on the altiplano Desert, northern Chile. J. Quat. Sci. 20, 643e653. (tropical andes) contemporaneous with heinrich 1 and the younger dryas: new Grosjean, M., Van Leeuwen, J., Van der knaap, W., Geyh, M., Ammann, B., Tanner, W., insights from 14 C, UeTh dating and d 18 O of carbonates. Quat. Sci. Rev. 30, Messerli, B., Núnez,~ L., Valero-Garces, B., Veit, H., 2001. A 22,000 14 C year BP 3973e3989. sediment and pollen record of climate change from Laguna Miscanti (23 S), Bobst, A.L., Lowenstein, T.K., Jordan, T.E., Godfrey, L.V., Ku, T.-L., Luo, S., 2001. northern Chile. Global Planet. Change 28, 35e51. A 106ka paleoclimate record from drill core of the Salar de Atacama, northern Guerrero, J.M., Echenique, R.O., 2006. Discostella taxa (bacillariophyta) from the Río Chile. Palaeogeogr. Palaeoclimatol. Palaeoecol. 173, 21e42. limay basin (northwestern patagonia, Argentina). Eur. J. Phycol. 41, 83e96. Bonilla, R., 1973. Estudio Hidrogeologico del Salar de Aguas Blancas. Geologo Håkansson, H., 1996. Cyclotella striata complex: typification and new combinations. Memoria de Título , Universidad de Chile. Diatom Res. 11, 241e260. Calderon, G., Garrido, M., Acevedo, E., 2015. Prosopis tamarugo Phil.: a native tree Hakansson,€ H., 2002. A compilation and evaluation of species in the general Ste- from the Atacama Desert groundwater table depth thresholds for conservation. phanodiscus, Cyclostephanos and Cyclotella with a new genus in the family Rev. Chil. Hist. Nat. 88, 18. Stephanodiscaceae. Diatom Res. 17, 1e139. Cartajena, I., Loyola, R., Nunez, L., Faúndez, W., 2014. Problemas y perspectivas en la Handford, C.R., 1982. Sedimentology and evaporite genesis in a Holocene conti- interpretacion del registro espacial de Punta Negra e Imilac. In: Falabella, F., nental-sabkha playa basindbristol Dry Lake, California. Sedimentology 29, Sanhueza, L., Cornejo, L.E., Correa, I. (Eds.), Distribucion espacial en sociedades 239e253. no aldeanas: del registro arqueologico a la interpretacion social. MODFLOW-2005 Harbaugh, A., 2005. The U.S. Geological Survey Modular Ground- Castelleti, J., Reyes, O., Maltrain, G., Martínez, I., Galarce, P., Velasquez, H., water Modeldthe Ground-water Flow Process [Online]. Available: https://pubs. Ogalde, J.P., 2010. Ocupaciones en abrigos rocosos en la costa de Taltal: patron usgs.gov/tm/2005/tm6A16/PDF/TM6A16.pdf. Accessed July 5th 2018. de uso del espacio desde momentos Holocenico Tempranos. Actas del XVII Harris, M.A., Cumming, B.F., Smol, J.P., 2006. Assessment of recent environmental Congreso Nacional de Arqueología Chilena 685e695. changes in New Brunswick (Canada) lakes based on paleolimnological shifts in Chavez, R., Clevers, J., Decuyper, M., de bruin, S., Herold, M., 2016. 50 years of water diatom species assemblages. Botany 84, 151e163. extraction in the Pampa del Tamarugal basin: can Prosopis tamarugo trees Hartley, A.J., Chong, G., Houston, J., Mather, A.E., 2005. 150 million years of climatic survive in the hyper-arid Atacama Desert (Northern Chile)? J. Arid Environ. 124, stability: evidence from the Atacama Desert, northern Chile. J. Geol. Soc. 162, 292e303. 421e424. Collado, G.A., Valladares, M.A., Mendez, M.A., 2016. Unravelling cryptic species of Herrera, C., Custodio, E., 2014. Origen de las aguas de pequenos~ manantiales de la freshwater snails (Caenogastropoda, Truncatelloidea) in the Loa river basin, costa del norte de Chile, en las cercanías de Antofagasta. Andean Geol. 41, Atacama Desert. Syst. Biodivers. 14, 417e429. 314e341. Costello, M.J., Bouchet, P., Boxshall, G., Fauchald, K., Gordon, D., Hoeksema, B.W., Heusser, C.J., Heusser, L.E., Lowell, T.V., 1999. Paleoecology of the southern chilean Poore, G.C., Van Soest, R.W., Stohr,€ S., Walter, T.C., 2013. Global coordination and lake district-isla grande de chiloe during middleelate llanquihue glaciation and standardisation in marine biodiversity through the World Register of Marine deglaciation. Geogr. Ann. Phys. Geogr. 81, 231e284. Species (WoRMS) and related databases. PLoS One 8 e51629. Hevia-orube, J., Orive, E., David, H., Díez, A., Laza-Martínez, A., Miguel, I., Seoane, S., Cremer, H., Koolmees, H., 2010. Common diatoms (Centrales and Fragilariaceae, 2016. Molecular and morphological analyses of solitary forms of brackish Bacillariophyta) of modern and fossil freshwater environments in The Thalassiosiroid diatoms (Coscinodiscophyceae), with emphasis on their Netherlands. Nova Hedwigia 90, 343e381. phenotypic plasticity. Eur. J. Phycol. 51, 11e30. De Porras, M., Maldonado, A., Pol-Holz, D., Latorre, C., Betancourt, J., 2017. Late Hogg, A.G., Hua, Q., Blackwell, P.G., Niu, M., Buck, C.E., Guilderson, T.P., Heaton, T.J., Quaternary environmental dynamics in the Atacama Desert reconstructed from Palmer, J.G., Reimer, P.J., Reimer, R.W., 2013. SHCal13 Southern Hemisphere rodent midden pollen records. J. Quat. Sci. 32, 665e684. calibration, 0e50,000 years cal BP. Radiocarbon 55, 1889e1903. Díaz, C., Maidana, N., 2005. Diatomeas de los Salares Atacama y Punta Negra, II Houston, J., 2002. Groundwater recharge through an alluvial fan in the Atacama Region, Chile. Centro de Ecología Aplicada Ltda, Santiago, Chile. Desert, northern Chile: mechanisms, magnitudes and causes. Hydrol. Process. Díaz, F.P., Latorre, C., Maldonado, A., Quade, J., Betancourt, J.L., 2012. Rodent mid- 16, 3019e3035. dens reveal episodic, long-distance plant colonizations across the hyperarid Houston, J., 2006a. The great Atacama flood of 2001 and its implications for Andean Atacama Desert over the last 34,000 years. J. Biogeogr. 39, 510e525. hydrology. Hydrol. Process. 20, 591e610. DICTUC, 2007. Estudio de Impacto Ambiental Proyecto Pampa Hermosa Pramar Houston, J., 2006b. Variability of precipitation in the Atacama Desert: its causes and AmbientalSociedad Química y Minera de Chile (SQM). hydrological impact. Int. J. Climatol. 26, 2181e2198. Ewing, S.A., Sutter, B., Owen, J., Nishiizumi, K., Sharp, W., Cliff, S.S., Perry, K., Hyatt, C.V., Paterson, A.M., Rühland, K.M., Smol, J.P., 2011. Examining 20th century Dietrich, W., Mckay, C.P., Amundson, R., 2006. A threshold in soil formation at water quality and ecological changes in the Lake of the Woods, Ontario, Canada: Earth's aridehyperarid transition. Geochem. Cosmochim. Acta 70, 5293e5322. a paleolimnological investigation. J. Great Lake. Res. 37, 456e469. Finstad, K., Pfeiffer, M., Amundson, R., 2014. Hyperarid soils and the soil taxonomy. Jayne, R.S., Pollyea, R.M., Dodd, J.P., Olson, E.J., Swanson, S.K., 2016. Spatial and Soil Sci. Soc. Am. J. 78, 1845e1851. temporal constraints on regional-scale groundwater flow in the Pampa del Finstad, K., Pfeiffer, M., Mcnicol, G., Barnes, J., Demergasso, C., Chong, G., Tamarugal Basin, Atacama Desert, Chile. Hydrogeol. J. 24, 1921e1937. Amundson, R., 2016. Rates and geochemical processes of soil and salt crust JICA, 1995. The study on the development of Water Resources in northern Chile. formation in Salars of the Atacama Desert, Chile. Geoderma 284, 57e72. Technical reports. Centro de Informacion de Recursos Hídricos, Direccion Finstad, K.M., Pfeiffer, M., Mcnicol, G., Tuite, M., Williford, K., Amundson, R., 2018. General de Aguas, Ministerio de Obras Públicas. Japanese International Coop- A late Quaternary paleoenvironmental record in sand dunes of the northern eration Agency, Direccion General de Aguas, Pacific Consultants International, Atacama Desert, Chile. Quat. Res. 90, 127e138. Santiago, Chile. Flügel, E., 2004. Microfacies Data: Fabrics. Microfacies of Carbonate Rocks. Springer. Jordan, T.E., Kirk-Lawlor, N.E., Blanco, N.P., Rech, J.A., Cosentino, N.J., 2014. Landscape Fourtanier, E., Kociolek, J.P., 2009. Catalogue of Diatom Names. California Academy modification in response to repeated onset of hyperarid paleoclimate states 244 M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245

since 14 Ma, Atacama Desert, Chile. Geol. Soc. Am. Bull. 126, 1016e1046. Novello, V.F., Cruz, F.W., Vuille, M., Stríkis, N.M., Edwards, R.L., Cheng, H., Emerick, S., Kirk-Lawlor, N.E., Jordan, T.E., Rech, J.A., Lehmann, S.B., 2013. Late Miocene to early De Paula, M.S., Li, X., Barreto, E.D.S., 2017. A high-resolution history of the south Pliocene paleohydrology and landscape evolution of northern Chile, 19 to 20 S. american Monsoon from last glacial maximum to the Holocene. Sci. Rep. 7. Palaeogeogr. Palaeoclimatol. Palaeoecol. 387, 76e90. Nunez,~ L., 1986. Evidencias arcaicas de maíces y cuyes en Tiliviche: hacia el semi- Kiss, K., Klee, R., Ector, L., Acs, E., 2012. Centric diatoms of large rivers and tributaries sedentarismo en el litoral fertil y quebradas del norte de Chile. Chungara25 e47. in Hungary: morphology and biogeographic distribution. Acta Bot. Croat. 71, Núnez,~ L., Grosjean, M., Cartajena, I., 2001. Human Dimensions of Late Pleistocene/ 311e363. Holocene Arid Events in Southern South America. Interhemispheric Climate Kiss, K.T., Genkal, S.I., Ector, L., Molnar, L., Duleba, M., Bíro, P., Acs, E., 2013. Linkages, 7. Morphology, taxonomy and distribution of Stephanodiscus triporus (Bacillar- Pearsall, D.M., Trimble, M.K., 1983. Archaeological Investigations of the Mudlane- iophyceae) and related taxa. Eur. J. Phycol. 48, 363e379. waimea-kawaihae Road Corridor, Island of Hawaii: an Interdisciplinary Study Kobayasi, H., Mayama, S., 1989. Evaluation of river water quality by diatoms. Korean of an Environmental Transect, Bernice P. Bishop Museum Departmental Report J. Phycol. 4, 121e133. Series, 83-1. Phytolith analysis of soil samples: report 18. Korstanje, M.A., Babot, M.D.P., 2007. Microfossils Characterization from South An- Perez-Fodich, A., Reich, M., Alvarez, F., Snyder, G.T., Schoenberg, R., Vargas, G., dean Economic Plants. Plants, People and Places: Recent Studies in Phytolith Muramatsu, Y., Fehn, U., 2014. Climate change and tectonic uplift triggered the Analysis. Oxbow Books, Oxford, UK, pp. 41e72. formation of the Atacama Desert's giant nitrate deposits. Geology 42, 251e254. Krammer, K., Bertalot, L.H., 1986. Bacillariophyceae. 1. Teil: Naviculaceae. Piperno, D.R., Pearsall, D.M., 1998. The Silica Bodies of Tropical American Grasses: Krammer, K., Lange-Bertalot, H., Ettl, H., 1997. Subwasserflora von mitteleuropa: Morphology, Taxonomy, and Implications for Grass Systematics and Fossil bacillariophyceae. Subwasserflora von mitteleuropa: bacillariophyceae. Gusty Phytolith Identification. Smithsonian institution press Washington, DC. Fischer. Placzek, C., Quade, J., Betancourt, J.L., Patchett, P.J., Rech, J.A., Latorre, C., Matmon, A., Lamy, F., Hebbeln, D., Wefer, G., 1998. Late Quaternary precessional cycles of Holmgren, C., English, N.B., 2009. Climate in the dry central andes over geologic, terrigenous sediment input off the Norte Chico, Chile (27.5 S) and palae- millennial, and interannual Timescales 1. Ann. Mo. Bot. Gard. 96, 386e397. oclimatic implications. Palaeogeogr. Palaeoclimatol. Palaeoecol. 141, 233e251. Placzek, C., Quade, J., Patchett, P., 2013. A 130ka reconstruction of rainfall on the Latorre, C., Betancourt, J.L., Arroyo, M.T., 2006. Late Quaternary vegetation and Bolivian Altiplano. Earth Planet Sci. Lett. 363, 97e108. climate history of a perennial river canyon in the Río Salado basin (22 S) of Placzek, C., Quade, J., Patchett, P.J., 2006. Geochronology and stratigraphy of late Northern Chile. Quat. Res. 65, 450e466. Pleistocene lake cycles on the southern Bolivian Altiplano: implications for Latorre, C., Betancourt, J.L., Rech, J.A., Quade, J., Holmgren, C., Placzek, C., causes of tropical climate change. Geol. Soc. Am. Bull. 118, 515e532. Maldonado, A.J., Vuille, M., Rylander, K., 2005. Late Quaternary History of the Prasad, A.K., Nienow, J.A., 2006. The centric diatom genus Cyclo- Atacama Desert. 23 S: the Archaeology and Environmental History of the tella,(Stephanodiscaceae: bacillariophyta) from Florida Bay, USA, with special Southern Deserts. National Museum of Australia Press. reference to Cyclotella choctawhatcheeana and Cyclotella desikacharyi, a new Latorre, C., Betancourt, J.L., Rylander, K.A., Quade, J., 2002. Vegetation invasions into marine species related to the Cyclotella striata complex. Phycologia 45, absolute desert: a 45; th000 yr rodent midden record from the CalamaeSalar 127e140. de Atacama basins, northern Chile (lat 22e24 S). Geol. Soc. Am. Bull. 114, Quade, J., Rech, J.A., Betancourt, J.L., Latorre, C., Quade, B., Rylander, K.A., Fisher, T., 349e366. 2008. Paleowetlands and regional climate change in the central Atacama Latorre, C., Santoro, C.M., Ugalde, P.C., Gayo, E.M., Osorio, D., Salas-Egana, C., De Pol- Desert, northern Chile. Quat. Res. 69, 343e360. Holz, R., Joly, D., Rech, J.A., 2013. Late Pleistocene human occupation of the Rech, J.A., Pigati, J.S., Quade, J., Betancourt, J.L., 2003a. Re-evaluation of mid- hyperarid core in the Atacama Desert, northern Chile. Quat. Sci. Rev. 77, 19e30. Holocene deposits at Quebrada Puripica, northern Chile. Palaeogeogr. Palae- Leakey, R., 1980. Biology and potential of Prosopis species in arid environments, oclimatol. Palaeoecol. 194, 207e222. with particular reference to P. cineraria. J. Arid Environ. 3, 9e24. Rech, J.A., Quade, J., Betancourt, J.L., 2002. Late quaternary paleohydrology of the Luebert, F., Pliscoff, P., 2006. Sinopsis bioclimatica y vegetacional de Chile. Editorial central Atacama Desert (lat 22e24 S), Chile. Geol. Soc. Am. Bull. 114, 334e348. Universitaria. Rech, J.A., Quade, J., Hart, W.S., 2003b. Isotopic evidence for the source of Ca and S in Lynch, T.F., 1986. Un reconocimiento arqueologico en el salar de Punta Negra, soil gypsum, anhydrite and calcite in the Atacama Desert, Chile. Geochem. Segunda Region. Chungara, pp. 75e88. Cosmochim. Acta 67, 575e586. Magaritz, M., Aravena, R., Pena,~ H., Suzuki, O., Grilli, A., 1990. Source of ground water Renner, S., Aguirre, I., 2015. Groundwater in the Chilean North: a Brief Synopsis. in the deserts of northern Chile: evidence of deep circulation of ground water Risacher, F., Alonso, H., Salazar, C., 1999. Geoquímica de aguas en cuencas cerradas: from the Andes. Ground Water 28, 513e517. I, II y III regiones-Chile. Maldonado, A., Betancourt, J.L., Latorre, C., Villagran, C., 2005. Pollen analyses from a Rojas, R., Batelaan, O., Feyen, L., Dassargues, A., 2010. Assessment of conceptual 50 000-yr rodent midden series in the southern Atacama Desert (25 300 S). model uncertainty for the regional aquifer Pampa del Tamarugal-North Chile. J. Quat. Sci. 20, 493e507. Hydrol. Earth Syst. Sci. 14, 171. Maldonado, A., Santoro, C.M., Uribe, M., De Porras, M., Capriles, J., Gayo, E., Rojas, R., Dassargues, A., 2007. Groundwater flow modelling of the regional aquifer Valenzuela, D., Angelo, D., Latorre, C., Marquet, P., Domic, A., Mcrostie, V.B., of the Pampa del Tamarugal, northern Chile. Hydrogeol. J. 15, 537e551. Castro, V., 2016. Climate change and social complexity in the Atacama Desert Rühland, K., Priesnitz, A., Smol, J.P., 2003. Paleolimnological evidence from diatoms during the late quaternary. PAGES Magazine 24, 56e57. for recent environmental changes in 50 lakes across Canadian Arctic treeline. Marinovic, S., Smoje, T., Maksaev, J., Herve, A., Mpodozis, M., 1995. Hoja Aguas Arctic Antarct. Alpine Res. 35, 110e123. Blancas. Region de Antofagasta. Rühland, K., Smol, J.P., 2005. Diatom shifts as evidence for recent Subarctic warming Marquet, P.A., Bozinovic, F., Bradshaw, G., Cornelius, C., Gonzalez, H., Gutierrez, J.R., in a remote tundra lake, NWT, Canada. Palaeogeogr. Palaeoclimatol. Palaeoecol. Hajek, E.R., Lagos, J.A., Lopez-Cortes, F., Nunez, L., 1998. Los ecosistemas del 226, 1e16. desierto de Atacama y area andina adyacente en el norte de Chile. Rev. Chil. Rumrich, U., Lange-Bertalot, H., Rumrich, M., Lange-Bertalot, H., 2000. Iconographia Hist. Nat. 71, 593e617. Diatolmologica 9. Diatomeen der Anden von Venezuela bis Patagonien/Tierra Mather, L., Macintosh, K., Kaczmarska, I., Klein, G., Martin, J., 2010. A Checklist of del Fuego. Gantner Verlag KG, Germany. Diatom Species Reported (And Presumed Native) from Canadian Coastal Wa- Saez, A., Cabrera, L., Jensen, A., Chong, G., 1999. Late Neogene lacustrine record and ters, Her Majesty the Queen in Right of Canada. palaeogeography in the QuillaguaeLlamara basin, Central Andean fore-arc Mcglue, M.M., Cohen, A.S., Ellis, G.S., Kowler, A.L., 2013. Late Quaternary stratig- (northern Chile). Palaeogeogr. Palaeoclimatol. Palaeoecol. 151, 5e37. raphy, sedimentology and geochemistry of an underfilled lake basin in the Puna Saez, A., Godfrey, L.V., Herrera, C., Chong, G., Pueyo, J.J., 2016. Timing of wet episodes plateau (northwest Argentina). Basin Res. 25, 638e658. in Atacama Desert over the last 15 ka. The groundwater discharge deposits Mcrostie, V.B., 2013. The Role of Plant Production in Subsistence and Cultural (GWD) from Domeyko range at 25 S. Quat. Sci. Rev. 145, 82e93. Changes during the Formative Period in the Atacama Puna, Southern Andes, Salazar, D., Arenas, C., Andrade, P., Olguín, L., Torres, J., Flores, C., Vargas, G., Chile (1400BC-500AD). A Re-evaluation based on the Analyses of Microfossils Rebolledo, S., Borie, C., Sandoval, C., Silva, C., 2018. From the use of space to Attached to Hoes and Grinding Tools, and Isotopic Analyses of Human Bones. territorialisation during the Early Holocene in Taltal, coastal Atacama Desert, PhD. University College London. Chile. Quat. Int. 473, 225e241. Michalski, G., Bohlke,€ J., Thiemens, M., 2004. Long term atmospheric deposition as Salazar, D., Figueroa, V., Andrade, P., Salinas, H., Olguín, L., Power, X., Rebolledo, S., the source of nitrate and other salts in the Atacama Desert, Chile: new evidence Parra, S., Orellana, H., Urrea, J., 2015. Cronología y organizacion economica de from mass-independent oxygen isotopic compositions. Geochem. Cosmochim. las poblaciones arcaicas de la costa de Taltal. Estudios atacamenos,~ pp. 07e46. Acta 68, 4023e4038. Salazar, D., Jackson, D., Guendon, J.L., Salinas, H., Morata, D., Figueroa, V., Moreno, P.I., Villagran, C., Marquet, P.A., Marshall, L.G., 1994. Quaternary paleo- Manríquez, G., Castro, V., 2011. Early evidence (ca. 12,000 BP) for iron oxide biogeography of northern and central Chile. Rev. Chil. Hist. Nat. 67, 487e502. mining on the Pacific coast of South America. Curr. Anthropol. 52, 463e475. Mujica, M.I., Latorre, C., Maldonado, A., Gonzalez-Silvestre, L., Pinto, R., Pol-Holz, R., Santoro, C.M., Capriles, J.M., Gayo, E.M., De Porras, M.E., Maldonado, A., Santoro, C.M., 2015. Late Quaternary climate change, relict populations and Standen, V.G., Latorre, C., Castro, V., Angelo, D., Mcrostie, V., 2017. Continuities present-day refugia in the northern Atacama Desert: a case study from Que- and discontinuities in the socio-environmental systems of the Atacama Desert brada La Higuera (18 S). J. Biogeogr. 42, 76e88. during the last 13,000 years. J. Anthropol. Archaeol. 46, 28e39. Nester, P., Jordan, T., 2012. The Pampa del Tamarugal forearc basin in northern Chile: Saros, J., Anderson, N., 2015. The ecology of the planktonic diatom Cyclotella and its the interaction of tectonics and climate. Tectonics of Sedimentary Basins: implications for global environmental change studies. Biol. Rev. 90, 522e541. Recent Advances 369e381. Scheihing, K., Moya, C., Struck, U., Lictevout, E., Troger,€ U., 2018. Reassessing Hy- Nester, P.L., Gayo, E., Latorre, C., Jordan, T.E., Blanco, N., 2007. Perennial stream drological Processes that Control Stable Isotope Tracers in Groundwater of the discharge in the hyperarid Atacama Desert of northern Chile during the latest Atacama Desert (Northern Chile). Water Resources Management in the Atacama Pleistocene. Proc. Natl. Acad. Sci. U. S. A. 104, 19724e19729. Desert: Pivotal Insights into Arid Andean Groundwater Systems of Northern M. Pfeiffer et al. / Quaternary Science Reviews 197 (2018) 224e245 245

Chile, vol. 5, p. 91. mixed-species biofilms. Limnol. Oceanogr. 50, 755e767. Shirokawa, Y., Karino, K., Mayama, S., 2012. Developmental plasticity and Valero-Garces, B.L., Jenny, B., Rondanelli, M., Delgado-Huertas, A., Burns, S.J., genotypeeenvironment interactions influence valve morphology in the Cyclo- Veit, H., Moreno, A., 2005. Palaeohydrology of Laguna de Tagua Tagua (34 300 S) tella meneghiniana species complex (Bacillariophyceae). Eur. J. Phycol. 47, and moisture fluctuations in Central Chile for the last 46 000 yr. J. Quat. Sci. 20, 245e253. 625e641. Spaulding, S., Lubinski, D., Potapova, M., 2010. Diatoms of the United States Vilaclara, G., Martinez-Mekler, G., Cuna, E., Ugalde, E., 2010. Diatom-inferred (Available at: Westerndiatoms. colorado. edu). palaeoenvironmental changes of a Pliocene lake disturbed by volcanic activity. Stoermer, E.F., Edlund, M.B., Pilskaln, C.H., Schelske, C.L., 1995. Siliceous microfossil J. Paleolimnol. 44, 203e215. distribution in the surficial sediments of Lake Baikal. J. Paleolimnol. 14, 69e82. Vossel, H., Reed, J.M., Houk, V., Cvetkoska, A., Van De Vijver, B., 2015. Cyclotella Stoertz, G., Ericksen, G., 1974. Geology of Salars in Northern Chile. In: Geological paleo-ocellata, a new centric diatom (Bacillariophyta) from Lake Kinneret Survey Professional Paper 811. US Geological Survey, Reston, Virginia. (Israel). Fottea 15, 63e75. Theriot, E., Håkansson, H., Kociolek, J.P., Round, F.E., Stoermer, E.F., 1987. Validation Vuille, M., Keimig, F., 2004. Interannual variability of summertime convective of the centric diatom genus name Cyclostephanos. Br. Phycol. J. 22, 345e347. cloudiness and precipitation in the central Andes derived from ISCCP-B3 data. Thompson, L.G., Mosley-Thompson, E., Henderson, K.A., 2000. Ice-core palae- J. Clim. 17, 3334e3348. oclimate records in tropical south America since the last glacial maximum. Wojtal, A.Z., 2009. The diatoms of kobylanka stream near krakow (wyzyna_ kra- J. Quat. Sci. 15, 377e394. kowsko-Cze˛stochowska upland, S Poland). Pol. Bot. J. 54, 129e330. Tomlinson, A., Blanco, N., Ladino, M., 2015. Carta Mamina.~ Region de Tarapaca. Zhu, K., Bi, Y., Hu, Z., 2013. Responses of phytoplankton functional groups to the Underwood, G., Perkins, R., Consalvey, M., Hanlon, A., Oxborough, K., Baker, N., hydrologic regime in the Daning River, a tributary of Three Gorges Reservoir, Paterson, D., 2005. Patterns in microphytobenthic primary productivity: China. Sci. Total Environ. 450, 169e177. species-specific variation in migratory rhythms and photosynthetic efficiency in