The prehispanic site of Tiwanaku, located in northeastern Bolivia, was the focus of many studies during the past few decades. However, much of the site remains unexplored, leaving many questions unanswered about the location of dense archaeological deposits, the nature of urban organization, and water management strategies—specifically those located in the eastern sector of the Akapana Pyramid. Orthophoto mosaics and Digital Elevation Models derived from drone imagery helped identify archaeological features and anthropogenic mounds. New magnetic survey produced with a cesium gradiometer was merged with previous surveys (fluxgate and cesium gradiometer). The integration of maps and plans from six areas of a previous archaeological investigation within a common Geographical Information System helped relate geophysical anomalies to archaeological features. Our results demonstrate a high level of urban organization associating monumental buildings to open ritual spaces and to densely populated areas during Tiwanaku IV (500–800 CE) and V (800–1100 CE). The complexity of the urban organization is also demonstrated by landscape modifications such as a complex water management system and at least three terraces that augmented the monumentality of the Akapana Pyramid This interdisciplinary approach, innovative in Bolivia, provides new insight into one of the most significant archaeological sites in the Andes.

Instances of fault-controlled monogenetic volcanism across the subduction arc of the Central Andes at ~ 23°S illuminate the nature of different parental melts being delivered to the crust. Evidence of magmatic history is preserved in bulk rock geochemistry, the content of melt inclusions, and mineral compositions. Volcanism in this region is dominated by felsic and intermediates lavas as the thickened crust (55 – 65 km) and vast volumes (> 500,000 km3) of mid-crustal magma beneath the Altiplano-Puna high plateau region prevent mafic magmas from reaching the surface (Davidson & De Silva, 1991; Beck et al., 1996; Perkins et al., 2016). However, small volumes of relatively undifferentiated lava have been delivered from the lower crust to the surface along zones of crustal weakness without extensive processing by crustal assimilation and/or extended storage in sub-volcanic magma chambers. Monogenetic eruptions of less-differentiated lava provide important constraints on compositions normally obscured by crustal processing in the Central Andes. Basaltic andesite sampled within the frontal arc (Cerro Overo maar) is a regional mafic end-member and approximates the composition of parental arc magmas derived from partially-molten lower crustal regions where mantle-derived magmas interact with the surrounding lithosphere and undergo density differentiation (MASH zones). Basaltic olivine-hosted melt inclusions from Cerro Overo provide a glimpse of less-evolved melt composition from this region and suggest mobilization of MASH magma by injection of basaltic melt. Basaltic andesite sampled from the eastern (back) margin of the frontal arc (Puntas Negras – El Laco) is another regional mafic endmember, representing a mantle-derived magma composition that is transitional between subduction arc magmatism and intraplate magmatism of the back-arc. The internal crystal architecture revealed by major and trace element zoning of olivine phenocrysts indicates Cerro Overo magma experienced continuous ascent, while Puntas Negras magma experienced a brief period of stalling or storage near the brittle-ductile transition zone (~ 25 km). Aphyric intermediate monogenetic lavas sampled west of (before) the frontal arc display Adakite-like signatures (e.g. high Sr/Y and Sm/Yb) represent small amounts of melt generated with a significant contribution from direct melting of the metabasaltic slab or delaminated lithospheric root at high pressure. These three magmatic regimes sampled at monogenetic centers approximate different end-member compositions being delivered to the lower crust of the Central Andes from which the range of intermediate main arc volcanism in the Altiplano-Puna region is ultimately derived.

Indiana University-Purdue University Indianapolis (IUPUI) / Hydroclimatic variability in the eastern Colombian Andes is examined using a decadally-resolved, multiproxy lake sediment record from Laguna de Ubaque, Colombia. Hydroclimate trends are examined and compared to existing local, regional, and trans-Andean records to enhance existing knowledge of Late Holocene Colombian precipitation and assess potential hydroclimatic forcing mechanisms in tropical South America. Sedimentological analyses, including percent lithics, grain size, C:N and magnetic susceptibility are sensitive to hydroclimate and lake level while charcoal size and concentrations reflect fire variability. Results show that deep lacustrine conditions characterized by laminated deposits were not established until approximately 3500 cal yr B.P., prior to which, terrestrial C:N values and unstructured sediments indicate that drier, marsh-like conditions prevailed. Between 3500 and 2000 cal yr B.P., interrupted only by a 300-year arid interval from 2800 to 2500 cal yr B.P., greatly increased overall clastic deposition indicates a broad precipitation maximum while decreased sand deposition and the preservation of finely laminated sediment indicate deep lake conditions. After 2000 cal yr B.P., decreased clastic deposition suggests reduced precipitation, but the continued accumulation of laminated sediments indicates that conditions were wet enough to fill the basin continuously until the present day. These observations address two of the driving questions of Andean paleoclimate: were the northern and southern Andes in vi phase during the Holocene, or out of phase, and what are the main drivers of Holocene Andean climate? We find that the early part of Ubaque’s record more closely resembles southern Andean precipitation records until 2000 cal yr B.P., at which point it abruptly switches to resemble northern precipitation records. We attribute this to a combination of the southward migration of the intertropical convergence zone (ITCZ), and an increase in eastern Pacific sea surface temperatures (SST). In addition, we find that Colombian hydroclimate records exhibit a bimodal precipitation pattern, which we attribute to their location either on the Andean slopes or in the high interior Andes.

No description available.

Peatlands store nearly one third of the soil global carbon, and approximately 10% of the world's drinkable water on only 3% of the land surface. Peatlands store large amounts of carbon from the organic matter due to the reduced decomposition rates in the soil allowing the accumulation of new plant growth each year. Rising temperatures and increasing nutrient inputs from human activities can accelerate decomposition rates in the soil transforming peatlands from sinks to sources of carbon, and reducing their ability to regulate the local hydrological cycles. To identify how rising temperatures and increasing human originated disturbances have peatlands, I studied the current vegetation patterns and related them to elevation, temperature and disturbance environmental gradients, explored the recent history (last 200 years) of the peatland vegetation, and built models that described the past rates of gains by primary production and losses due to decomposition; finally I constructed a forecasting model to describe the dynamics of northern Andean peatlands. Past vegetation and historic production and decomposition rates were estimated from 210Pb chronologies. Results indicate a strong effect of the interaction between elevation and the intensity of human disturbance; superficial carbon stocks were negatively affected by human disturbances that at the same time favored the encroachment of upland vascular species. Elevation was an important gradient with lower peat accumulation rates at higher elevations, except when water from glacial meltdown was supplied in which case production reached extremely high values. Modeling of peatland dynamics indicated increasing decomposition rates in sites with high human disturbance, an effect that propagated towards the future in the form of net losses of carbon in the upper part of the peat column. Conversely, sites with low human disturbance or at high elevations but receiving water from glacial meltdown become larger carbon sinks. In conclusion, climate change is having a direct and measurable effect on the dynamics of northern Andean peat dynamics; however, the effects become less predictable when interactions with the climatic or human systems are included. The rate of peat degradation due to modifications in the environment indicates the urgency to better understand the northern Andean peatland ecosystems. In conclusion: high elevation peatlands in the Northern Andes are ecosystems that offer extremely important ecological services but that may have started an irreversible decline.

Violence has been found ubiquitously across human societies and throughout time. An act of violence can be defined as purposeful harm brought upon one individual as a direct or indirect result of the actions of another. The purpose of this research is to develop a quantitative approach to examining lethality using frequency distributions for location of trauma on the cranium in order to model patterns of interpersonal violence. This is accomplished through the study of a skeletal sample, from the prehispanic Chachapoya (existing around A.D. 800 – 1535), discovered at the site of Kuelap in the northern Peruvian Andes. Metric data were gathered from 81 individuals including males, females, and subadults. The data consisted of precise location of traumatic injury measured from anatomical landmarks in each of five two-dimensional views of the cranium as well as estimated diameter of impact for all lesions. The lesions were separated between perimortem (lethal) and antemortem (non-lethal) in order to explore patterns of lethality that correlate with location of injury. A statistical difference (p > 0.05) in location could not be determined when the distributions were compared in five standard two-dimensional views or between the sexes. Statistical significance (p > 0.05), however, was encountered when the entire cranium was used for the distribution. This distribution showed that perimortem injuries tend to occur more frequently on the posterior aspect of the cranium while antemortem injuries tend to occur more frequently on the anterior for this sample. These results show that a quantitative approach to location of injuries to the cranial vault can reveal new patterns of violent interactions and aid in the study of violent behavior.

No description available.

El gato andino (Leopardus jacobita) y el gato del pajonal (L. colocolo) son dos especies de félidos de pequeño tamaño con una estrecha relación filogenética, por lo que comparten muchas características morfológicas y ecológicas. El gato andino se encuentra, a lo largo de toda su distribución en simpatría con el gato del pajonal, por lo que están sujetos a las mismas amenazas a su conservación, siendo categorizado a nivel internacional el primero como En Peligro y el segundo como Casi Amenazado. Ambas especies son muy poco conocidas, aunque en los últimos años la cantidad de estudios sobre ellas ha tenido un considerable incremento. El presente trabajo tiene como objetivo contribuir al conocimiento de las especies en estudio, aportando información ecológica básica, como abundancias poblacionales, dieta y patrones de uso del espacio y tiempo. El área de estudio se localizó en la región Altoandina de la Provincia de Jujuy, siendo la principal metodología utilizada el trampeo fotográfico. Se realizaron once campañas en seis diferentes áreas, con un esfuerzo de muestreo total de 9665 noches trampa. Se estimó que la densidad poblacional del gato del pajonal fue entre 11,15 y 6,42 (para estimaciones para el año 2006 y 2007 respectivamente) veces mayor que la del gato andino en el único área donde pudieron estimarse las abundancias de ambos, y podría suponerse que en las demás áreas la abundancia del gato andino fue aún menor. Estos valores resultaron en comparación con otras especies de tamaños similares, más bajos para el gato andino y más altos para el gato del pajonal. La dieta estuvo, en ambas especies, compuesta mayormente por mamíferos roedores. La mayor frecuencia fue para Phyllotis xanthopygus y se destacó como importante para ambas especies el chinchillón (Lagidium viscacha) por su gran biomasa. Los roedores Abracoma cinerea y Octodontomys gliroides para el gato andino y para el gato del pajonal Galea musteloides tuvieron relevancia por su biomasa y por ser los ítems que permitieron una cierta segregación del nicho trófico. La amplitud de nicho encontrada para el gato andino fue muy baja comparada con la del gato del pajonal y la superposición de nicho entre ambos félidos resultó muy alta. Se estudiaron los patrones de actividad de ambos félidos, el zorro colorado y el chinchillón. Los tres carnívoros tuvieron mayor actividad en la primera mitad de la noche mientras que los chinchillones fueron mayormente activos en la segunda mitad de la noche y la mañana. El gato andino mostró unos patrones de actividad más erráticos, con picos adicionales al mediodía y amanecer. Los patrones de actividad fueron más parecidos entre los carnívoros que entre los mismos y sus potenciales presas, los chinchillones. No se encontró un efecto de la iluminación por parte de la luna en ninguna de las especies estudiadas. En el análisis espacial de los patrones de actividad se encontró una fuerte asociación entre los félidos, no así entre los mismos y el zorro colorado. Al incluir el factor tiempo, en forma de días transcurrido entre capturas sucesivas en la misma trampa cámara, al análisis se encontró que los carnívoros no parecen evitarse en las áreas muestreadas por cada trampa cámara. Ha sido propuesto que la convivencia entre especies similares es posible gracias a la segregación de las diferentes dimensiones de su nicho ecológico. Sin embargo, no se encontró una clara segregación en ninguno de los aspectos analizados en esta tesis. Esto, sumado a las similitudes morfo-ecológicas previamente conocidas, indica que los félidos en estudio tienen un gran potencial de competición. Más aún, se sugiere que la baja abundancia encontrada para el gato andino en comparación con la del gato del pajonal, y quizás su fuerte especialización, podrían en parte ser explicadas por interacciones interespecíficas como la competencia. La mayoría de la información recolectada en esta tesis apoya el delicado estado de conservación del gato andino, y a su vez representan un avance en la comprensión de la ecología de los félidos altoandinos y hacia su conservación efectiva. Estos resultados sugieren la necesidad tanto de realizar más estudios, teniendo en cuenta factores que afectan la dinámica poblacional así como metapoblacional, como de considerar las interacciones interespecíficas en el diseño de planes de conservación y manejo. / Andean and Pampas cat (Leopardus jacobita and L. colocolo) are two closely related small felids; because of that, they share a number of ecological and morphological characteristics. The Andean cat shares all its distribution with the Pampas cat and the same conservation threats in that area. The conservation status at international level is Endangered for the Andean cat and Near Threatened for Pampas cat. Both species are poorly known although in the last years the amount of studies focused on them increased considerably. The present thesis aims to contribute to the knowledge of both species, providing basic ecological information, such as population abundance, feeding habits and patters of use of space and time. The study area was located in the High Andes, Jujuy Province. The main methodology was camera trapping. Eleven field campaigns were made in six different areas, and sampling effort totaled 9665 trap/nights. The estimated population abundance was between 11.15 y 6.42 times greater for Pampas cats than Andean cats, based on estimations in the same area for two consecutive years. The estimated abundances were lower for the Andean cat and higher for the Pampas cat when compared with other, similar-sized felid species,. Diet was represented in both species mostly by rodents. Phyllotis xanthopygus was the species with the highest frequency of occurrence. Mountain vizcachas (Lagidium viscacia) were also essential because of their great biomass. Additionally, Abracoma cinerea and Octodontomys gliroides for Andean cat and Galea mustelodes for Pampas cat, were important items because of their biomasses and relatively high frequencies and also because these rodents enabled a certain degree of niche segregation between these two cats. The niche breadth for the Andean cat was very low compared with that of Pampas cat and a great dietary overlap was found. The activity patterns were studied for both felid species, culpeo fox (Lycalopex culpaeus), and mountain viscachas. The carnivores had higher activity levels in the first half of the night whereas mountain vizcachas were more active during the second half of the night and in the morning hours. Andean cats showed more erratic activity patterns with peaks at midday and sunrise. Carnivore activity patterns were more similar to each other than to mountain viscachas. No effect of moonlight was found for any studied species. A strong association between felids was recorded in the spatial analysis of activity patterns, while the opposite occurred between each cat species and culpeo fox. Including time in this analysis, checking the time between consecutive captures in each location, we found that carnivore species did not avoid each other at the sampled sites. It is been proposed that species coexistence can be made possible through segregation in at least, some dimensions of their ecological niches. However, no clear segregation was found in any of the niche dimensions analyzed in this thesis. Because of that and the previously known morpho-ecological similitudes between these felid species, we conclude that these species have a great potential for competition and that the high specialization and low population abundance found for the Andean cat can be partially explained by interspecific interactions such as competition.

Los Andes Fueguinos ubicados entre el canal Beagle y el lago Fagnano, en el sector argentino de la Isla Grande Tierra del Fuego, exponen rocas metamórficas de muy bajo a bajo grado cuyos protolitos corresponden a sedimentitas, volcaniclastitas y volcanitas del Jurásico y el Cretácico Inferior de la cuenca de retroarco Rocas Verdes. La apertura de la Cuenca Rocas Verdes se remonta a tiempos jurásicos, asociada a un evento extensional (rift) ligado a la fragmentación de Gondwana. Durante el Cretácico Temprano, la Cuenca Rocas Verdes estaba limitada hacia el Sur-Sudoeste por un arco volcánico desarrollado sobre corteza continental, y hacia el Norte-Noreste por el margen sudoccidental de Gondwana (coordenadas actuales). Hacia el Cretácico “medio”, inició el cierre e inversión de la cuenca, producto de la colisión del arco magmático y la obducción de la corteza oceánica sobre el margen cratónico de Gondwana (Sudamérica). La estructura del núcleo orogénico o cinturón central de deformación de los Andes Fueguinos (zona de tesis) se caracteriza por una primera fase de deformación en condiciones dúctiles y metamorfismo regional (ca. 100 Ma), seguida por una fase (ca. 80-40 Ma) de naturaleza frágil/dúctil vinculada a fallamiento, levantamiento y la exhumación del orógeno. Este estudio se enfocó, por un lado, en mejorar el estado de conocimiento de la estratigrafía de la Cuenca Rocas Verdes de este sector del orógeno, reconociendo grados y tipos de metamorfismo, y la naturaleza de los protolitos de las rocas afectadas durante la deformación; y por otro, en la caracterización de las estructuras correspondientes a las dos fases principales, a fin de reconstruir la historia orogénica. Sobre la base de una hipótesis de trabajo previa, se corroboró la existencia de zonas de cizalla frágiles/dúctiles, posteriores a las estructuras de primera fase, que corresponden a superficies de despegue y corrimientos que funcionaron como un sistema de dúplex con apilamiento antiforme durante la segunda fase de deformación, transmitiendo acortamiento hacia el antepaís. / The Fuegian Andes located between the Beagle channel and lake Fagnano, on the Argentine side of the Main Island of Tierra del Fuego, expose very-low to low grade metamorphic rocks, whose protoliths correspond to Jurassic and Lower Cretaceous sedimentary, volcaniclastic and volcanic rocks of the Rocas Verdes back-arc basin. The opening of the Rocas Verdes basin initiated during jurassic times, as part of a rifting stage related to widespread regional extension due to the break-up of Gondwanaland. During the Early Cretaceous, the Rocas Verdes Basin was rimmed at its south-suthwestern end by a volcanic arc funded on continental crust, and to the North-Northeast by the southwestern margin of Gondwana (present coordenates). By the “middle” Cretaceous, the closure and inversión of the basin started, as a result of the collision of the magmatic arc and the obduction of the oceanic crust toward the cratonic margin of Gondwana (South America). The structure of the Fuegian Andes orogenic core, or central bel of deformation (study area) is characterized by a first phase of ductile deformation and regional metamorphism (ca. 100 Ma), followed by a brittle-ductile thrusting phase, related to the uplift and exhumation of the orogen. This study focused, on one hand, on improving the present stratigraphic knowledge of the Rocas Verdes basin in this sector of the mountain range, by recognizing metamorphic types and grades and the nature of the protoliths involved. On the other hand, the orogenic history through the closure of the Rocas Verdes basin is treated, by characterizing the geological structures related to the two main phases of deformation. Based on a previuos hypothesis, this study verifies the existence of fragile/ductile shear zones, posterior to first phase structures, and related to detachment surfaces and thrusts which acted as part of a duplex system with antiformal stacking during the second deformation phase, transferring shortening to the foreland.

La presente investigación está orientada a presentar algunas hipótesis que nos lleven a demostrar el fenómeno de aculturación religiosa en el área andina.