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The aim of this paper is to reconstruct an 11,000-year history of depositional environmental change in southeastern Brazil, based upon the integration of particulate organic matter and stable isotope (C and N) data from a 136-cm sediment core from Lake Canto Grande. These proxies are used to explore the evolution of terrestrial and marine influence on the lake. Isotopic (δ 13 C: −27.87‰ to −31.9‰; δ 15 N: −0.07‰–4.9‰) and elemental (total organic carbon - TOC: 0.58%–37.19%; total nitrogen - TN: 0.08%–1.73%; C/N: 0.3 to 54.7) values recorded in Lake Canto Grande suggest that the sedimentary organic matter was derived from mostly C 3 land plants and freshwater phytoplankton. Particulate organic matter and cluster analyses distinguished four associations characterized by the predominance of amorphous organic matter, followed by phytoclasts and palynomorphs. These results indicate two different phases of lake evolution. The first phase (136 - 65 cm; ∼10,943 cal yr. B.P. to ∼8529 cal yr. B.P.) is recorded by sand layers interbedded with mud, which contain amorphous organic matter (AOM, 45–59%) and phytoclasts (opaques - OP: 6–18%; non-opaques – NOP: 17–23%) which indicate a floodplain area. The second phase (65–0 cm; ∼8529 cal yr. B.P. to ∼662 cal yr. B.P.) comprises mud, AOM (68–86%) and palynomorphs (PAL, 8–16%) related to lake establishment comparable to modern conditions. Thus, characterizing particulate organic matter, in combination with stable isotopes, proved to be invaluable proxies for lacustrine paleoenvironmental change through the Holocene. [ABSTRACT FROM AUTHOR]

Future groundwater recharge estimations are helpful tools for water resources management. However, there is a need for more information about it in many parts of the world, including the Portoviejo River watershed (PRW) in the West of Ecuador, a semi-arid zone with a water deficit where climate change impacts could increase pressure on groundwater resources. Geographical Information Systems were used in this paper, owing to their simplicity of inputs and accuracy of outputs, to estimate current and future (2021–2070) groundwater recharge in the PRW. The study is divided into two stages: 1) a runoff map based on soil permeability, land use, and terrain slope, and 2) current and future recharge calculations using the Thornthwaite and Mather water balance method. Future precipitation and temperature data from an ensemble of four Global Circulation Models were used as inputs, along with a map of runoff spatial distribution. The representative concentration pathways (RCP) 4.5 and 8.5 were the climate change scenarios used in this study. The results showed that the location of the groundwater recharge zone would be impacted by future precipitation and temperature variability in both scenarios for the next fifty years. For the decade 2060–2070 and the scenario RCP 4.5, the highest recharge rate zones were located in the lowlands of the PRW surrounding Portoviejo city. In scenario RCP 8.5, the highest groundwater recharge areas increase considerably in the entire PRW. Currently, the highest groundwater recharge zones are in the highlands of the PRW. The future groundwater recharge scenarios provide information to decision-makers regarding land use, since the future groundwater recharge zones will be in the expansion areas of Portoviejo city. [Display omitted] • This study has established groundwater recharge for two climate change scenarios. • GIS and R were used for estimating future groundwater recharge zones (GRZ). • A runoff map was built using soil permeability, land cover, and slope terrain. • Future variability in precipitation and temperature would affect GRZ. • Future GRZ will be placed in urban growth zones near to the current Portoviejo city. [ABSTRACT FROM AUTHOR]

Patagonia features the most extensive glaciers of the Southern Hemisphere, excluding Antarctica, and a vast inventory of glacial landforms, so it is thought to have played a key role in (paleo)glacier studies since the late 19th century. However, no systematic attempts to characterize the specific research trends and the scientific community focused on Patagonian cryosphere have been conducted so far. To fill this gap, we analyzed the metadata associated to 305 articles compiled from the Web of Science database following a bibliometric approach covering the period between 1976 and 2020. Our results point to an irregular but net increase on the number of contributions on Patagonian (paleo)glaciers. Mass balance analyses based on satellite data of present-day glaciers and the reconstruction of past glacier activity by dating glacial landforms formed during the Last Glacial Termination, were the most addressed topics during the analyzed period. Patagonian (paleo)glacier studies are mostly published in generic Earth Sciences publications, followed by Quaternary and glaciological journals. Most of the studies were led by scientists from the United Kingdom, followed by Chile, Argentina and United States. In terms of collaborations, these studies can be divided into two main clusters, one composed by researchers from United States, Chile and Argentina institutions, and another mostly composed by British researchers. So far, the most prolific authors are nearly equally distributed in nationality, yet gender inclusion and international collaborations are still caveats that must be solved. Even though our query on the Web of Science missed highly influential (so-called) grey literature, such as local scientific journals and technical reports, the reviewed scientific literature unambiguously indicates that Patagonia is a privileged location for (paleo)glaciers studies worldwide and that it will continue offering vast opportunities to tackle critical questions related to global cryosphere and past-to-present climate changes. • Patagonia is a privilege site for studying present and past glacier dynamics and the evolution of climate changes at hemispheric and global scale. • Glacier dynamics during the 20th century and and the Last Glacial Termination are the most common topics addressed in past decades in the WOS. • Patagonian (paleo)glacier studies has contributed to the development or improvement of diverse analytical techniques. • United Kingdom, United States, Chile and Argentina produced the largest number of WOS-listed papers on (paleo)glaciers in past decades. • The related scientific community is fairly heterogeneous. Although, inclusion and international collaboration issues still need to improve. [ABSTRACT FROM AUTHOR]

This paper presents the first study of nonmarine ostracods recovered from the Danian of the upper Yacoraite Formation (Balbuena IV sequence) Salta Basin. Six species were identified: Ilyocypris triebeli , Ilyocypris argentiniensis , Neuquenocypris (Alleniella)? sp. 1; Neuquenocypris (Alleniella)? sp. 2; Penthesilenula sp. and four indeterminate species. The ostracod fauna shows fluctuations in abundance, diversity, and preservation associated with different phases of the paleolake evolution. This distribution, clearly delineated by the depositional facies, corroborates previous geochemical analyses and high-resolution sequence stratigraphy developed for the section. In general, the most abundant occurrences of ostracods coincide with high-frequency transgressive tracts of the lake system, which form long-term wettest interval of the upper Yacoraite Formation. • First study with ostracods for the Balbuena IV sequence of the Yacoraite Formation, Salta Basin, Argentina. • Six nonmarine ostracods species are identified. • Temporal distribution of ostracods is in agreement with U/Pb radiometric dating. • Ostracod abundance is correlated with the climatic fluctuations of the dry and wet periods of the paleolake. [ABSTRACT FROM AUTHOR]

The Araucaria Plateau is a geomorphological unit that occupies approximately three-quarters of the terrain in the southern region of Brazil. The plateau displays different altitudinal levels (600 to <1400 m a.s.l.) that are locally recognized as remnants of planed surfaces (S8-S1). These surfaces are maintained by basic (S3-S8) and acidic (S1 and S2) volcanic flows from the Neocretaceous period of the Paraná Basin. The largest extent of this plateau is located in a humid subtropical climate zone. Colluvial, colluvial-alluvial, alluvial sediments and paleosols (Ab diagnostic horizons) occur predominantly in S2. The paleosols are located in low-hierarchical-order fossil valleys (first- to fourth-order in Strahler's stream classification) and valley heads, which are referred to as paleovalleys in this paper. We employed these paleosols as stratigraphic level markers of the pedogenesis of the regional Upper Quaternary and propose their importance as records of the paleoenvironmental conditions of the Araucaria Plateau in areas above 1200 m a.s.l. These paleosols were dated by 14C and show ages between 23.8 ± 0.05 kyr BP (28.06-29.08 kyr cal. BP) and 41.16 ± 0.48 kyr BP (44.13-45.58 kyr cal. BP). The calibrated ages are related to Marine Isotope Stage 3 (MIS 3), in which the last period of global warming occurred (approximately 60-25 kyr cal. BP). We integrated the morphological, pedogeochemical, clay fraction mineralogy, micromorphological and δC-13 analyses of five paleosols from S2 to verify the paleoenvironmental conditions of the Araucaria Plateau and its correspondence with the paleoclimatic phenomena that were identified on a global scale during MIS 3 in the Southern Hemisphere. We obtained the following conclusions: a) the properties of paleosols reflect pedological processes that are adjusted to the paleoenvironmental conditions at the end of MIS 3 and the transition to MIS 2 (Last Glacial Maximum); b) aplasmogenic partial acidolysis was the predominant pedogeochemical process during MIS 3; c) during this period, the water regime was sufficiently humid to develop hydromorphic horizons in the valley bottoms of the entire drainage network to the valley heads; d) regional change toward a drier hydric regime occurred in MIS 2, when erosion of the paleosols predominated; and e) in MIS 1 (current Holocene interglacial), burial of the paleosols and relief inversion occurred, which resulted in fossilization of the valleys. [ABSTRACT FROM AUTHOR]

Glaciers in the southern province of the Southern Volcanic Zone (SVZ) of Chile (37–46°S) have experienced significant frontal retreats and area losses in recent decades which have been primarily triggered by tropospheric warming and precipitation decrease. The resulting altitudinal increase of the Equilibrium Line Altitude or ELA of glaciers has lead to varied responses to climate, although the predominant volcanic stratocone morphologies prevent drastic changes in their Accumulation Area Ratios or AAR. Superimposed on climate changes however, glacier variations have been influenced by frequent eruptive activity. Explosive eruptions of ice capped volcanoes have the strongest potential to destroy glaciers, with the most intense activity in historical times being recorded at Nevados de Chillán, Villarrica and Hudson. The total glacier area located on top of the 26 active volcanoes in the study area is ca. 500 km2. Glacier areal reductions ranged from a minimum of −0.07 km2 a −1 at Mentolat, a volcano with one of the smallest ice caps, up to a maximum of −1.16 km2 a −1 at Volcán Hudson. Extreme and contrasting glacier–volcano interactions are summarised with the cases ranging from the abnormal ice frontal advances at Michinmahuida, following the Chaitén eruption in 2008, to the rapid melting of the Hudson intracaldera ice following its plinian eruption of 1991. The net effect of climate changes and volcanic activity are negative mass balances, ice thinning and glacier area shrinkage. This paper summarizes the glacier changes on selected volcanoes within the region, and discusses climatic versus volcanic induced changes. This is crucial in a volcanic country like Chile due to the hazards imposed by lahars and other volcanic processes. [ABSTRACT FROM AUTHOR]

Abstract: During fieldwork carried out in January 2009 at Aurora do Tocantins (Tocantins State, northern Brazil), we recovered a fragmentary right maxilla (UNIRIO-PM 1006) of Catagonus stenocephalus from a sedimentary deposit of presumed late Pleistocene age in a karstic cave. This paper aims to: (1) provide the first record of C. stenocephalus in the northern region of Brazil (and consequently, also the northernmost one); (2) update the geographic distribution of C. stenocephalus; (3) present a date for the specimen; and (4) discuss the palaeoenvironmental and palaeobiogeographical implications of the finding. The species C. stenocephalus (Lund) is known from the Bonaerian (middle Pleistocene) and Lujanian (late Pleistocene to earliest Holocene) ages in Argentina, Uruguay, Brazil and Bolivia. The new record presented here extends the geographical distribution of C. stenocephalus more than 1000km north from the former northernmost record (caves of Lagoa Santa region). Peccaries of the genus Catagonus have several morphological features associated with cursorial habits in relatively open and dry environments. The new distributional range of C. stenocephalus is coincident with the Chacoan subregion, characterized by dry climates and open areas. As the studied material comes from the top of the carbonate layer, this may suggest that the deposition of the C. stenocephalus remains described here is synchronous with the onset of a wetter climate phase. This argument is also in accordance with the datation results, around 20ky BP, just after the last glacial maximum. This increasingly wet climate, which may also be related to the climatic changes that occurred during the late Pleistocene/early Holocene, could be a factor in the extinction of C. stenocephalus in South America. [Copyright &y& Elsevier]

Abstract: This paper deals with a loess profile located southeast of Córdoba (64° 05′ 30W to 31°30′ S) that was dated in Beijing University using the OSL method according to Simple Aliquot Regeneration Protocol. This study provides some inferences regarding climatic and environmental features, such as transport agents and probable sources of the materials. The profile, located inside Llanura Pampeana, is approximately 6.80m in depth and comprises ages between 22.4±3.2 and 9.9±0.3ka. Throughout the profile, and for all grain sizes, major minerals are quartz and feldspar, with micas, and opaques as subordinates. Illite and chlorite appear as traces, though the last one was not confirmed in the finest fraction analysis. Calcite is abundant in the uppermost sample and decreases downwards. In the base of the profile, and in the clay fraction, XRD showed illite, swellable clay minerals (smectite+mixed layers) and kaolinite traces. It was concluded that the profile would have been derived from the accumulation of sediments, along several events very similar in transport conditions, even though there are some indications that about 21ka BP, water availability was slightly smaller than for the rest of the profile. This change was also established in some other places, allowing some regional correlations. According to the analyzed data, about 19ka BP, water availability again increased. [Copyright &y& Elsevier]

Abstract: Lakes are key sites for studying paleoclimates. Llancanelo Lake (southern Mendoza Province, western Argentina) is an endoreic, highly saline water body located in the southern extreme of a tectonic basin, the Central or Huarpes Depression. The lake is located between the Andean Cordillera, San Rafael Block and Payenia Volcanic Field. The lake evolved as a major regional depocenter during the Pliocene-Quaternary, hence it contains important thicknesses of intra and extra basinal clastic and evaporitic sediments mainly dominated by volcaniclastic products. The main conditioning factors in the lake evolution were arc and back-arc volcanism as well as climatic changes. Geomorphological and sedimentary evidence supports the hypothesis that the lake was in past times larger than in present days. This paper estimates the lake’s former extension on the western lacustrine plain using electromagnetic induction (EMI) and geoelectricity (Multielectrode Resistivity Meter) surveys, as well as shallow wells, along an 8km long transect perpendicular to the lake’s western shoreline. The geophysical and sedimentological information, as well as microfaunal studies, lab analysis and petrographic/EDAX determinations, support the presence, in the subsoil, of a lacustrine sequence at least 30m thick composed mainly of volcaniclastic sediments. Volcanic eruptions and climatic changes influenced the evolution of the lake, producing intercalations in the lacustrine sedimentary sequences of ash layers, evaporites, soils, and eolian and swamp deposits. [Copyright &y& Elsevier]

This paper presents preliminary results of paleoclimatic signatures of conifer woods during the deposition of the basal Crato and topmost Romualdo members of the Santana Formation within the Tropical Equatorial Hot Arid Belt (late Aptian, Araripe Basin, Brazil). Analysis was carried out using standard thin sections, and the anatomical details were studied in transmitted light. The wood growth pattern from the lowermost laminated lacustrine carbonate level of the Crato Member was characterized by the absence of true growth rings and the common presence of wood growth interruptions, and could be linked to a tropical, equable but erratically humid environment. In an interlayered fine-to-coarse sandstone level attributed to a fluvio-deltaic interval, the wood growth pattern was homogeneous, lacking true growth rings, with weakly delineated growth interruptions over long radial distances. In this level the growth pattern could be related with a transition to a more equable tropical climate during a relatively humid period. In contrast, the wood pattern from the carbonate succession of the uppermost Romualdo Member, interpreted as a lagoon area with marine influence, showed true growth rings with abrupt ring boundaries and rings of variable width, also including frequent growth interruptions. This pattern could be linked to a monsoonal-like climate, subjected to distinct cyclical conditions and periodical droughts during the growing season. • Preliminary wood growth data showed changing climate along the Santana Formation. • A tropical, erratically humid climate was inferred for the lacustrine Crato Member. • Equable humid conditions occurred in the fluvio-deltaic Crato Member. • A tropical monsoon-like climate was inferred for Romualdo Member. [ABSTRACT FROM AUTHOR]

Abstract: Low resolution of the continental sedimentary record is a common source of skepticism about the application of geomorphology and sedimentology to Quaternary studies. In spite of this, when supported by independent proxy data, geomorphology and sedimentology may favor palaeo-hydrologic interpretation. This paper associates geomorphologic, stratigraphic, sedimentologic, isotopic, palynologic and geochronologic data. The research was conducted in valley head sites in southern Brazilian highlands, under mild subtropical climate. The results point to environmental changes, the ages of which coincide to Marine Isotopic Stages (MIS) 5b, 3, 2 and 1. Although late-Pleistocene temperatures and precipitation were lower than those of today, the study valley heads seem to have sustained locally wetter environments, which fed shallow soil–water saturated zones. These saturated zones are believed to have expanded during transitions between stadial and interstadial states, contributing to hillslope erosion and sedimentation regardless of the sign of the climatic change. The interior organization of holocenic slope-wash deposits suggests that the mid-Holocene climate was drier than today’s and was under the influence of seasonally contrasting precipitation regimes. The predominance of overland flow-related sedimentary records suggests that an excess of precipitation over evaporation influenced local palaeo-hydrology. This palaeo-hydrologic condition seems to have been recurrent and also explains the alternating periods of pedogenesis and sedimentation. [Copyright &y& Elsevier]

The initial infill of the Patagonian Broken Foreland is related to Miocene, syn-orogenic, volcaniclastic successions accommodated in intermontane basins. In the last years several works have paid attention to these successions due to their role in the comprehension of the timing of deformation, the relationship between arc-volcanism and the environmental signals, and the climate changes related to the growth of the orogen. In this paper we perform the U-Pb geochronology and the sedimentologic and paleosols analyses of a Miocene, syn-orogenic, volcaniclastic succession (La Pava Formation) located at the northern part of Patagonian Broken Foreland. The results indicate that the syn-kinematic sedimentation (evidenced by growth strata and progressive unconformities) proceeded between ~19 Ma to ~14 Ma, associated with arc-derived volcaniclastic deposits, under alluvial conditions with profuse paleosols development. The facies analysis combined with the paleosols and provenance studies indicate episodic and cyclic supply of pyroclastic materials, which were mainly delivered from the catchment area of the system, affected by explosive volcanism. A succession of stacked paleosols was recorded into 3 sections, bounded by unconformities, which record from Alfisols-like, Vertisol-like to Andisols-like paleosols. Paleosols variations were related to the effects of tectonic events, climate changes or to the increase of volcanic supply in comparison to soil-forming processes. The results obtained in this work are considered substantial to unravel the tectonic, volcanic and paleoclimatic framework of the North Patagonian Andes. • Northern Patagonian Broken Foreland (PBF) was mainly configured between 19–14 Ma. • La Pava Formation constitutes the initial infill of the northern PBF. • Alluvial systems set with profuse paleosols occurrence in syn-kinematic conditions. • Syn-kinematic sedimentation proceeded associated with arc-derived volcaniclasts. • Paleosols variations relate to changes in tectonics, climate or volcanic conditions. [ABSTRACT FROM AUTHOR]

Shallow lakes are distinctive aquatic ecosystems of the Pampean region. In this paper, climatic, morphometric and chemical-environmental aspects of six lacustrine bodies of the Salado River basin, Buenos Aires, are analyzed. The climatic variability of the region was estimated and linked to the behavior of each water body during the studied period (2017–2018); precipitations displayed deviations from the mean values, with periods of deficit in spring and summer, and excess in autumn. The analysis of satellite images showed a group of lakes with very low variation of the morphometric parameters because they have gates that keep the water level constant. On the contrary, those without anthropic intervention displayed a greater morphometric variability, since the water levels have been directly linked to local weather fluctuations. From a chemical-environmental perspective, changes were observed both at the regional (p = 0.015) and local (p = 0.0014) levels. Differences among sites cannot be characterized by a single variable but by a set of them. The dominant cation in the Pampean shallow lakes is the Na+ coming from the contact of groundwater with loessic sediments. Lakes showed a particular anionic dominance that not following a seasonal but a particular pattern. These are mainly linked to the characteristics of the substrate (presence of marine sediments or gypsum deposits). The great vulnerability of these environments to global and regional climatic changes, anthropic modifications and a large number of shallow lakes in the area, allow finding different scenarios (geomorphological, ecological, hydrogeological, etc.) to assess their vulnerability and predict their behavior against future climate scenarios in an economically important area for Argentine. Image 1 • Shallow lakes morphometric characteristics are related to their geomorphologic context. • Sodium is the main cation, mainly as a result of Pampean loess degradation. • Presence of different anions and water types are conditioned by lake sediments. • Local rainfall determinate water levels in unmodified systems. • In anthropised sites, hydrological and morphological parameters are less variable. [ABSTRACT FROM AUTHOR]