Drastic Vegetation Change in the Guajira Peninsula (Colombia) during the Neogene

Dry biomes occupy ~35% of the landscape in the Neotropics, but these are heavily human-disturbed. In spite of their importance, we still do not fully understand their origins and how they are sustained. The Guajira Peninsula in northern Colombia is dominated by dry biomes and has a rich Neogene fossil record. Here, we have analyzed its changes in vegetation and precipitation during the Neogene using a fossil pollen and spore dataset of 20 samples taken from a well and we also dated the stratigraphic sequence using microfossils. In addition, we analyzed the pollen and spore contents of 10 Holocene samples to establish a modern baseline for comparison with the Neogene as well as a study of the modern vegetation to assess both its spatial distribution and anthropic disturbances during the initial stages of European colonization. The section was dated to span from the latest Oligocene to the early Miocene (~24.2 to 17.3 Ma), with the Oligocene/Miocene boundary being in the lower Uitpa Formation. The early Miocene vegetation is dominated by a rainforest biome with a mean annual precipitation of ~2,000 mm/yr, which strongly contrasts with Guajira\u27s modern xerophytic vegetation and a precipitation of ~300 mm/yr. The shift to the dry modern vegetation probably occurred over the past three millions years, but the mechanism that led to this change is still uncertain. Global circulation models that include the vegetation could explain the ancient climate of Guajira, but further work is required to assess the feedbacks of vegetation, precipitation, and CO2

An image dataset of cleared, x-rayed, and fossil leaves vetted to plant family for human and machine learning

Leaves are the most abundant and visible plant organ, both in the modern world and the fossil record. Identifying foliage to the correct plant family based on leaf architecture is a fundamental botanical skill that is also critical for isolated fossil leaves, which often, especially in the Cenozoic, represent extinct genera and species from extant families. Resources focused on leaf identification are remarkably scarce; however, the situation has improved due to the recent proliferation of digitized herbarium material, live-plant identification applications, and online collections of cleared and fossil leaf images. Nevertheless, the need remains for a specialized image dataset for comparative leaf architecture. We address this gap by assembling an open-access database of 30,252 images of vouchered leaf specimens vetted to family level, primarily of angiosperms, including 26,176 images of cleared and x-rayed leaves representing 354 families and 4,076 of fossil leaves from 48 families. The images maintain original resolution, have user-friendly filenames, and are vetted using APG and modern paleobotanical standards. The cleared and x-rayed leaves include the Jack A. Wolfe and Leo J. Hickey contributions to the National Cleared Leaf Collection and a collection of high-resolution scanned x-ray negatives, housed in the Division of Paleobotany, Department of Paleobiology, Smithsonian National Museum of Natural History, Washington D.C.; and the Daniel I. Axelrod Cleared Leaf Collection, housed at the University of California Museum of Paleontology, Berkeley. The fossil images include a sampling of Late Cretaceous to Eocene paleobotanical sites from the Western Hemisphere held at numerous institutions, especially from Florissant Fossil Beds National Monument (late Eocene, Colorado), as well as several other localities from the Late Cretaceous to Eocene of the Western USA and the early Paleogene of Colombia and southern Argentina. The dataset facilitates new research and education opportunities in paleobotany, comparative leaf architecture, systematics, and machine learning.Fil: Wilf, Peter. State University of Pennsylvania; Estados UnidosFil: Wing, Scott L.. National Museum of Natural History; Estados UnidosFil: Meyer, Herbert W.. State University of Pennsylvania; Estados UnidosFil: Rose, Jacob A.. State University of Pennsylvania; Estados UnidosFil: Saha, Rohit. State University of Pennsylvania; Estados UnidosFil: Serre, Thomas. State University of Pennsylvania; Estados UnidosFil: Cúneo, Néstor Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; ArgentinaFil: Donovan, Michael P.. State University of Pennsylvania; Estados UnidosFil: Erwin, Diane M.. State University of Pennsylvania; Estados UnidosFil: Gandolfo, María A.. Cornell University; Estados UnidosFil: González Akre, Erika. State University of Pennsylvania; Estados UnidosFil: Herrera, Fabiany. National Museum of Natural History; Estados UnidosFil: Hu, Shusheng. State University of Pennsylvania; Estados UnidosFil: Iglesias, Ari. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Johnson, Kirk R.. Smithsonian Tropical Research Institute; PanamáFil: Karim, Talia S.. University of Colorado; Estados UnidosFil: Zou, Xiaoyu. State University of Pennsylvania; Estados Unido

A new species of \u3cem\u3eTarsoporosus\u3c/em\u3e Francke, 1978 (Scorpiones: Scorpionidae: Diplocentrinae) from northeastern Colombia

A new species of Tarsoporosus Francke, 1978 is described herein from two localities in La Guajira Peninsula, northeastern Colombia. This new taxon inhabits arid environments, and is morphologically close to Tarsoporosus flavus González-Sponga, 1984, from northwestern Venezuela. With this addition, the total number of described species in Tarsoporosus is raised to five, with at least two occurring in Colombia

Geochemistry and Geochronology of the Guajira Eclogites, northern Colombia : evidence of a metamorphosed primitive Cretaceous Caribbean Island-arc

The chemical composition of eclogites, found as boulders in a Tertiary conglomerate from the Guajira Peninsula, Colombia suggests that these rocks are mainly metamorphosed basaltic andesites. They are depleted in LILE elements compared to MORB, have a negative Nb-anomaly and flat to enriched REE patterns, suggesting that their protoliths evolved in a subduction related tectonic setting. They show island-arc affinities and are similar to primitive islandarc rocks described in the Caribbean. The geochemical characteristics are comparable to low-grade greenschists from the nearby Etpana Terrane, which are interpreted as part of a Cretaceous intra-oceanic arc. These data support evidence that the eclogites and the Etpana terrane rocks formed from the same volcano-sedimentary sequence. Part of this sequence was accreted onto the margin and another was incorporated into the subduction channel and metamorphosed at eclogite facies conditions. 40Ar-39Ar ages of 79.2±1.1Ma and 82.2±2.5Ma determined on white micas, separated from two eclogite samples, are interpreted to be related to the cooling of the main metamorphic event. The formation of a common volcano-sedimentary protolith and subsequent metamorphism of these units record the ongoing Late Cretaceous continental subduction of the South American margin within the Caribbean intra-oceanic arc subduction zone. This gave way to an arc-continent collision between the Caribbean and the South American plates, where this sequence was exhumed after the Campanian

Two Upper Cretaceous Flysch Sequences in the Caribbean Mountains of Venezuela and Their Relationship to Caribbean Tectonics

The Caribbean Mountains of Venezuela reach from the Venezuelan Andes to the Northern Ranges of Trinidad. Upper Cretaceous and Paleocene flysch units deposited in a marine euxinic basin are crucial in unraveling the evolution of the mountains. Two formations in the Acarigua region (near the termination in the Venezuelan Andes), the Rio Guache and Nuezalito formations, are the most complete sections of these flysch sequences. A sedimentary petrologic study was undertaken to determine the source areas for these formations, to put age brackets on the timing of uplift and rotation of portions of the Caribbean Mountains. The mountains are divided into five tectonic divisions: The Cordillera de la Costa Belt, the Tinaco Belt, the Paracotos Belt, the Villa de Cura Belt and the Flysch Basins. The remnants of an island arc system connected with the evolution of the mountains lies off the coastline. Plutonic clasts from the Nuezalito formation indicate that deposition occurred in a basin bounded on the north by the Tinaco and Villa de Cura belts, a Tinaco Belt correlative which now forms the Guajira Peninsula and possibly the island arc system. The southern margin of the basin was formed by the continental platform. Uplift, plutonism and metamorphism of several belts had already occurred by the time of deposition of the Nuezalito formation. The Rio Guache formation was deposited under similar conditions. More abundant metamorphic clasts suggest that uplift of the Cordillera de la Costa Belt occurred after the Nuezalito and before the Rio Guache formations were deposited. Analysis of graywackes from the two formations shows differences in composition attributable to depositional factors, but no clear variation in maturity which might indicate whether the Rio Guache formation was derived in part from recycled older sediments such as the Nuezalito formation. Comparison of monocrystalline to polycrystalline quartz ratios in the two formations shows the Rio Guache formation to be more mature, but this may have little statistical validity. Recent theories for evolution of the Caribbean Mountains speculate that the island arc, rotating to the south as a result of eastward movement of the Caribbean plate, collided with the continental craton, causing orogenesis to occur. Paleomagnetic data suggests that the Tinaco and Villa de Cura as well as the Guajira Peninsula also rotated. The Nuezalito basin rotated with these belts; consequently the timing of rotation cannot be fixed by the provenance of clasts in the Nuezalito formation. Changes in the style of orogenesis in the Caribbean Mountains are reflected in the clast types present in the Rio Guache and Nuezalito formations. A theory proposed by Crook (1974) states that graywackes reflect three different types of geotectonic terrains. The data collected from graywacke and pebble clast analysis indicates that this model is overly simplistic, and that perhaps the model should be replaced by more exact theories

Evidence for an eastward flow along the Central and South American Caribbean Coast

11 pages, 8 figures, 2 tables.-- Full-text version available Open Access at: http://www.iim.csic.es/~barton/html/pdfs.htmlHydrographic transects suggest an eastward flow with a subsurface core along the entire southern boundary of the Caribbean Sea. The transport of the coastal limb of the Panama-Colombia Gyre (PCG), known as the Panama-Colombia Countercurrent, decreases toward the east (from ∼6 Sv off Panama), as water is lost into the recirculation of the PCG. Off Panama, the flow is strongest at the surface, but, off Colombia, it is strongest at around 100 m. A portion of the counterflow (∼1 Sv) continues eastward along the Colombian coast as far as the Guajira region (12°N, 72°W), where it submerges to become an undercurrent beneath the coastal upwelling center there. The eastward flow also occurs in the Venezuela Basin, beneath the coastal upwelling region off Cariaco Basin and exits the Caribbean through the Grenada Channel at around 200 m depth. Numerical simulations suggest that this flow, counter to the Caribbean Current, is a semi-continuous feature along the entire southern boundary of the Caribbean, and that it is associated with offshore cyclonic eddies. It probably constitutes part of the Sverdrup circulation of the Tropical North Atlantic cyclonic cell.This work had financial support of the Colombian Institute for the Development of Science and Technology COLCIENCIAS, project 96-044 and the Colombian Navy. Also, the Office of Naval Research provided funding for C. N. K. Mooers and E. D. Barton during manuscript preparation.Peer reviewe

Tectonostratigraphic evolution of the Gulf of Venezuela.

Master's thesis in Petroleum Geosciences EngineeringThe Gulf of Venezuela is located at the boundary between the Cretaceous-Cenozoic deformation zone of the South American and Caribbean plates. It is an underexplored area lying between the hydrocarbon-rich Maracaibo Basin and the emergent plays such as the Perla field (Late Oligocene to Early Miocene carbonates) located on the allochthonous terrane. Gravity data, stratigraphy, structural styles, and subsidence plots reveal three main basement provinces in the Gulf of Venezuela: (1) A western Paleozoic basement (Maracaibo province) with continental-affinity similar to those in the Guajira Peninsula and the Maracaibo Basin; (2) a central province covering the area of the Urumaco trough offshore with Meso-Neoproterozoic rocks (Urumaco province); and (3) an easternmost province, with Cretaceous Caribbean arc rocks, related to the Leeward Antilles island arc system (Caribbean province). Two major interpreted strike-slip faults define the boundary between the main provinces. The Cuiza-Río Seco fault is the western flank of the Urumaco trough offshore and represents a structural and stratigraphic abrupt change that is proposed as the boundary between the Maracaibo autochthonous province and the allochthonous provinces. The Pueblo Nuevo fault is proposed to be the continuation onland of a major interpreted strike-slip fault, defining the boundary between the central and easternmost province. In addition, the Cuiza-Río Seco and Pueblo Nuevo faults accommodate strain partitioning as well as the Oca- Ancón fault but at different timing, due to oblique compression of the Caribbean plate against the South American plate. Furthermore, a pop-up structure associated with the Sierra de Perijá is recognized in the southernmost Maracaibo province, allowing to define about ̴ 70-80 km of right-lateral strike-slip displacement along the Oca fault. This fault has a relevant role to the present-day basement configuration, since it has displaced eastwards and segmented the northern part of the basement provinces, resulting in a more complex distribution that needs to be considered to reconstruct the geologic history. Considering the continuation of the Maracaibo block northwards, this region might hold promising opportunities for hydrocarbons exploration, where the Maracaibo Basin petroleum system might extends offshore into the Gulf of Venezuela.The Conjugate Basins, Tectonics and Hydrocarbons Project (CBTH)submittedVersio

Indigenous Water Governance in the Anthropocene: Non-Conventional Hydrosocial Relations Among the Wayuu of the Guajira Peninsula in Northern Colombia

The dissertation problematizes the supremacy of a global water management regime while discerning and defending local Wayuu hydrosocial relations. The Wayuu relationship with water—considered non-conventional, unsanitary or insecure according to hegemonic Western standards—can also be characterized positively as alternative, resilient, sustainable, adaptive and exceptional. Contemporary water governance presents challenges yet also opportunities for the Wayuu and other Indigenous peoples to (re)assert and (re)establish contextualized and culturally specific practices, traditions and ways of knowing that have been historically silenced by conventional water management. The Wayuu territory, located on the semi-arid Guajira Peninsula in northern Colombia, is widely considered a region suffering from chronic food and water insecurity, aggravated by climate change and exacerbated by widespread corruption and political instability. In response, a conventional approach presumes that the Wayuu are in urgent need of assistance and the solution to the water problem lies in installing waterworks; instructing the Wayuu in acceptable water, sanitation and hygiene behaviors; and instilling good water governance practices. I argue that this common discourse is a representation of reality that uses epistemological assumptions, vested authority, rhetoric and specialized terminology to present a dominant —yet deceptive and partial—depiction of Wayuu–water relations. While some resource management experts are confident that integration is possible between Indigenous and Western knowledge systems, critical social scientists from political ecology and ontological anthropology find bridging initiatives problematic. While political ecology emphasizes the politics and contested nature of water accessibility between different social actors, ontological anthropology underscores the deep ontological divide that impedes mutual understanding and integration of water knowledge systems. Informed by the debates in these fields, I use ethnographic evidence from over 80 Wayuu communities, including survey data, mapping, semi-structured interviews, participant observation and discourse analysis, to explore the (in)commensurability between “non-conventional” Wayuu hydrosocial relations and the dominant conventional water management regime. The dissertation research found that a generalized pattern of failed or faulty water development projects throughout Wayuu territory meant to increase water security often produce water insecurity and increased vulnerability, further exacerbating the precarity caused by anthropogenic climatic change

Socio-economic drivers affecting marine turtle conservation status: causes and consequences

Wildlife conservation is challenging. In part because we lack essential knowledge on species life-history, distribution or abundance, but also because threats are generally anthropogenic and we lack detailed understanding of the human dimensions of conservation. Numerous scholars have studied the relationship between poverty and its impact on the ecosystem condition, and the importance of environmental education and legal frameworks in successful conservation initiatives to improve enforcement and maintain relationships among traditional people and their environments. In relation to marine turtle conservation, there are significant knowledge gaps in relation to people and their role in conservation. Hence, in this thesis I evaluate human dimension aspects that affect the conservation status of marine turtles, and to improve our understanding of the relationships among human societies and wildlife conservation. To achieve my aim, I assessed four research objectives: 1) Evaluate how socio-economic drivers and legal frameworks affect the level of protection of marine turtles worldwide; 2) Identify and understand the conservation conflicts that impact marine turtle protection initiatives in the Caribbean basin; 3) Assess the historical and current demographic status of marine turtle stocks in the Gulf of Venezuela; and 4) Study the scale of use, cultural component and value of marine turtles to Wayuú Indigenous people, especially as a medicinal resource. Human societies are closely linked to their ecological environments and the conservation capacity of a country's government plays a key role in the protection of marine turtles. In chapter 2, I aimed to (1) evaluate the conservation capacity and enforcement within the 58 regional management units (RMUs) of the seven species of marine turtles throughout the world, using the Human Development Index (HDI) and economic levels as proxies; and (2) to predict the conservation status of 43 marine turtle RMU by merging several indices. To do this I developed a Conservation and Enforcement Capacity index (CECi) by integrating (1) the economic level of each country (defined by the United Nations); (2) the HDI (World Economic Situation and Prospects database); and (3) the risks and threats identified in the RMU framework. I then used the most recent conservation status of 15 recently IUCN assessed RMUs to predict the conservation status of the 43 RMUs without updated IUCN categorisation. I evaluated the conservation status of marine turtle RMUs in relation to the socio-economic situation of the region for each RMU. I found that using only the HDI as a proxy to assess the conservation capacity of the governments was weak. However, by using a multi-index model, I was able to predict the status of 33 of 58 RMUs, of them 57% may be of threatened conservation status due to their high CECi values. Consumptive use of threatened species, such as marine turtles, is one of the main challenges for environmental and conservation entities. In the case of marine turtles, this use is controversial. For this reason, in Chapter 3, I evaluated how consumptive use (legal and illegal) of marine turtles occurs (regulated or not) and is distributed worldwide. After an extensive literature review, I identified and categorised the regulations associated with the consumptive use of marine turtles. Of 137 countries with a marine-facing coastline and a presence of turtles. Of them I found that legislation prevents use in 98 of them (72%), and legal use occurs in 39. Among these 39 countries, use is regulated in 33 (85%) with parameters, such as ethnicity, region, size, quotas, and special permits. Conflicts among local, national, regional and international stakeholders (involved in marine turtle conservation) often they arise because people or groups involved come from different socio-economic backgrounds. In chapter 4, I narrow the scale of my thesis to the Caribbean region. I aim to identify and assess the conservation-based conflicts occurring in the Caribbean countries, identifying their frequency, level of severity, number of stakeholders' groups involved, the degree to which they hinder conservation goals, and potential solutions. I evaluated the presence and details of conservation conflicts provided by 72 respondents including conservation-based project leaders, researchers, and people involved in policy-based decision-making, conservation volunteers, and species experts with experience working on marine turtle conservation programs in the Caribbean. The respondents identified 136 conflicts, and I grouped them into 16 different categories. The most commonly mentioned causes of conflicts were: 1) the 'lack of enforcement by local authorities to support conservation based legislation or programs' (18%); 2) 'legal consumption of turtles by one sector of community clashing the conservation aspirations of other sectors of community (14%); and 3) 'variable enforcement of legislation to limit/prohibit use across range states of the species (10%). From the respondents, it is also apparent that illicit activities in the region are also impacting in the success of conservation based projects and programs. In chapters 5, 6, and 7, I narrow the focus of my thesis down to a country scale and examine the current state of knowledge species distribution and threats (Chapter 5), consumptive use and trade (Chapter 6) as well as indigenous (Wayuú) perspectives (Chapter 7) in the Venezuelan territory, and its effect on the current use of marine turtles (consumptive and non-consumptive). In chapter 5, I combined data from field-based studies with survey data from community based monitoring and historical records to investigate the distribution and threats to Venezuela's marine turtles. Overall, my findings confirm that five species of marine turtle use the Gulf of Venezuela, and I provide baseline stranding trends for four of them. I evaluated 1,571 records of stranded marine turtles comprising of 82% green turtles, 8% hawksbill turtles, 5% leatherback turtles, 4% loggerhead turtles, and 1% olive ridley turtles. I found that 82% of the all turtles recorded as stranded were immature. The co-occurrence of multiple species and both immature and adult-size turtles indicates that the Gulf of Venezuela provides important habitat for year-round feeding and development. As part of this baseline evaluation in the Gulf of Venezuela, in Chapters 6 and 7, I assessed the scale and cultural component of consumptive use of marine turtles in the region. To assess the scale and cultural component of this use, I interviewed residents and indigenous elders from the southwestern coast of the Gulf of Venezuela (Venezuelan part of the Guajira Peninsula), using a combination of in-depth and semi-structured interviews. I carried out a field and detailed market-based observations on the Guajira Peninsula to detect the sale and use of marine turtle products. I focused on three main categories of use; the type of use (e.g. traditional medicine, non-commercial cultural or commercial), the type of product, routes of trade, and the price of products. I identified types of products, routes of trade, and the prices of different products. All of the marine turtle species reported from the Gulf of Venezuela were used by people, sometimes commercially, and the prices of products varied among their type, species of origin, and the distance from the capture area to a marketplace. I obtained evidence connecting Wayuú Indigenous people's traditions and beliefs with marine turtle use, and also how up to 11 different marine turtle body parts are used for traditional medicine, and as an economic resource to sustain their communities. It is probable that illegal trade of marine turtle products is placing pressure on populations in the Gulf of Venezuela. I recommend the implementation of an inter-institutional conservation-portfolio be developed for the Peninsula to evaluate actions related to this concern

Neogene dinoflagellate cysts from the tropical americas

Marine palynomorphs, mainly dinoflagellate cysts and acritarchs, constitute excellent proxies for biostratigraphic and paleoceanographic studies in neritic sequences. Neogene marine palynological studies have mostly focused on the Northern Hemisphere, resulting in the scarcity of dinoflagellate cysts and acritarchs from tropical latitudes. Forty samples encompassing the late Chattian-late Burgidalian time interval (~24.1- 17.3 Ma) in the Southern Caribbean were analyzed for their marine palynological contents. A biostratigraphic scheme for the region is proposed and includes the upper Chattian-lower Aquitanian Minisphaeridium latirictum Interval Zone (~23.9-22.0 Ma), the upper Aquitanian Achomosphaera alcicornu Interval Zone (~22.0-20.3 Ma), and the Burdigalian Cribroperidinium tenuitabulatum Interval Zone (~20.3-17.5 Ma). Two peridinioid dinoflagellate cyst species, Cristadinium lucyae sp. nov., and Trinovantedinium uitpensis sp. nov., and the acritarch Quadrina? triangulata sp. nov. are formally described. A conspicuous shift from a peridinioid-dominated dinoflagellate cyst assemblage to a gonyaulacoid-dominated assemblage occurs near the Aquitanian- Burdigalian boundary (~20.7 Ma), indicating a reduction in marine primary productivity. This paleoproductivity shift is linked to the initial constriction of the Central American Seaway -- the oceanic pathway along the tectonic boundary between the South American plate and the Panama microplate --Abstract, page iv