Violence and conservation: Beyond unintended consequences and unfortunate coincidences     

《Geoforum》2016

While the relationship between violence and conservation has gained increasing attention in both academic and activist circles, official and public discourses often portray their entanglements as (unlucky) overlapping phenomena. In this article, we show how, under specific practices of state territorialization, conservation becomes both the means and reasons for violence. Based on ethnographic research in Colombia’s emblematic Tayrona National Natural Park, we detail how both the war on drugs and tourism promotion shape these state practices, and how they have translated into everyday, yet powerful, means of dispossession in the name of conservation. By analyzing the effects of the production of peasants as environmental predators, illegal occupants and collateral damage, we show how official conservation strategies have justified local communities’ political and material erasure, and how they have resulted in the destruction of their lived ecologies and the erosion of their livelihood strategies.  相似文献   

Age modelling for Pleistocene lake sediments: A comparison of methods from the Andean Fúquene Basin (Colombia) case study     

《Quaternary Geochronology》2014

Challenges and pitfalls for developing age models for long lacustrine sedimentary records are discussed and a comparison is made between radiocarbon dating, visual curve matching, and frequency analysis in the depth domain in combination with cyclostratigraphy. A core section of the high resolution 284-ka long temperature record developed from Lake Fúquene in the Northern Andes is used to explore four different age models (a–d). (a) A model based on 46 AMS ¹⁴C dates of bulk sediment is hampered by low concentrations of organic carbon. (b) A model based on the comparison of the radiocarbon dated pollen record to the well-established record from Cariaco Basin using curve matching and visual tie points. For the upper 26 m of the core this approach yields an age interval of 28–59.5 ka. (c) Another age model is based on curve matching and the Intcal09 radiocarbon calibration curve, yielding an age range of 22.5–80.4 ka for the same core interval. (d) Finally, a model is developed based on spectral analysis in the depth domain of the temperature-related altitudinal migrations of the upper forest line. This method identifies periodicities without a pre-conceived idea of age. The main frequency of 9.07 m appears to reflect the 41-kyr orbital signal of obliquity, which is tuned to the filtered 41-kyr temperature signal from the well-constrained LR04 marine benthic ∂¹⁸O stack record (Lisiecki and Raymo, 2005). Using this last age-modelling approach, the upper 26 m of core Fq-9C yields a temporal interval of 27–133 ka. Problems arising from radiocarbon dating carbon poor sediments from a large lake are addressed and the visual curve matching approach is compared to the analysis of cyclic changes in sediment records in developing an age model. We conclude that the frequency analysis and cyclostratigraphy model is the most reliable one of the four approaches. These results show that cyclostratigraphy may provide a useful method for developing an age model for long terrestrial records including multiple orbital cycles.  相似文献   

Producing nature and making the state: Ordenamiento territorial in the Pacific lowlands of Colombia     

Kiran Asher 《Geoforum》2009,40(3):292-302

In this paper, we explore how ordenamiento territorial, a territorial zoning policy in the 1991 Colombian Constitution remakes nature and helps constitute the state in the “economically backward” but “biodiversity rich” Pacific lowlands region. We draw on Gramscian insights on hegemony and the importance of conjunctures to trace how changes in the new Constitution and global biogeopolitics reconfigure nature and state power through the mandates of sustainable development, economic growth, and the conservation of biological and cultural diversity. Finally, we contribute to the literature on political ecology by showing how the political power of the state, nature, and capital are interwoven materially and symbolically in complex and contradictory ways.  相似文献   

Crustal structure and local seismicity in Colombia     

Anibal Ojeda  Jens Havskov 《Journal of Seismology》2001,5(4):575-593

Using P-wave travel time data from local seismicity, the crustal structure ofthe central and southern part of Colombia was determined. A very stableand narrow range of possible velocity models for the region was obtainedusing travel time inversion. This range of models was tested with earthquakelocations to select the best velocity model. The 1D velocity modelproposed has five layers over a halfspace, with interfaces at depths of 4,25, 32, 40 and 100 km and P-wave velocities of 4.8, 6.6, 7.0, 8.0, 8.1and 8.2 km/sec, respectively. According to this model the Moho lies at32 km depth on average. For P-waves, the station corrections range from–0.62 to 0.44 sec and for S-wave they range from –1.17 to 0.62 sec.These low variations in station residuals indicate small lateral velocitychanges and therefore the velocity model found should be well suited forearthquake locations and future starting model for 3D tomography studies.Using this new velocity model, the local earthquakes were relocated. Theshallow seismicity, < 30 km, clearly shows the borders betweentectonic plates and also the main fault systems in the region. The deepseismicity, > 80 km, shows two subduction zones in the country: theCauca subduction zone with a strike of N120^°E, dip of 35^°and thickness of 35 km, and the Bucaramanga subduction zone which has,for the northern part, a strike of N103^°E, dip of 27^° andthickness undetermined and, for the southern part, a strike ofN115^°E, dip of 40^° and thickness of 20 km. Based ondifferences of thickness of brittle crust in the subducted slab and spatialdistribution of the seismicity, the Cauca and Bucaramanga subduction zonesseem to represent independent processes. The Cauca subduction seems tobe connected to the process of the Nazca plate being subducted under theNorth Andes Block. In the Bucaramanga subduction zone, the transitionbetween southern and northern parts and changes in geometry of the slabseem to be gradual and there is no evidence of a tear in the slab, howeverthe local seismicity does not allow us to determine which plate or plates arebeing subducted. The Bucaramanga nest appears to be included into thesubducted slab.  相似文献   

Morphodynamics of a high discharge tropical delta, San Juan River, Pacific coast of Colombia     

Juan D Restrepo  Björn Kjerfve  Iván D CorreaJuan González 《Marine Geology》2002,192(4):355-381

The San Juan River has one of the most extensive and best developed deltas on the Pacific coast of South America, measuring 800 km². The river drainage basin measures 16?465 km² and is located in one of the areas with the highest precipitation in the western hemisphere. The annual rainfall varies from 7000 to 11?000 mm, and as a result the San Juan River has the highest water discharge (2550 m³ s⁻¹), sediment load (16×10⁶ t yr⁻¹), and basin-wide sediment yield (1150 t km⁻² yr⁻¹) on the west coast of South America. The San Juan delta growth began approximately 5000 years BP. The structure of the delta is determined by the interactions between fluvial deposition and the effect of 1.7-m significant swells, mostly from the SW, and strong tidal currents. Analysis of delta progradation indicates that during 1848-1992 the morphology of the delta was characterized by beach ridge accretion, spit growth, narrowing of inlets, and a general advance of the delta shoreline. During the past decade processes such as rapid erosion of the delta shore, narrowing of barrier islands, and breaching of a new inlet, are the result of a long-term relative sea-level rise of 2.6 mm yr⁻¹ due to tectonically induced subsidence coupled with a eustatic rise of sea-level. The delta also experiences strong oceanographic manifestations associated with the El Niño-La Niña cycle, causing regional sea-level elevation of 20-30 cm during El Niño years. Recent coastal subsidence in the delta is evidenced by: (1) increased occurrence of non-storm washover events; (2) increased erosion of barrier islands with average loss of 11 m yr⁻¹ during 1993-1997; and (3) a relative sea-level rise of 3.4 mm yr⁻¹ during 1991-1999. The morphology and recent evolution of the San Juan delta are unique when compared to other deltas of South America because of the singular combination of extreme climatic, geologic, and oceanographic conditions under which the delta has formed and the absence of human-induced impact in the drainage basin.  相似文献   

Hydrocarbon contamination in Cartagena Bay, Colombia     

Parga-Lozano CH  Marrugo-González AJ  Fernández-Maestre R 《Marine pollution bulletin》2002,44(1):71-74

This study deals with the levels of aromatic and aliphatic hydrocarbon quantification in sediments and organisms in Cartagena Bay (Colombia), 1996-1997. Sediments (14 stations) and bivalves (2 stations) were monitored at different times of the year. Areas with high values were in the north with concentrations above 100 microg/g with a maximum of 1415 microg/g. Areas with low values were located toward the south, near the outlet of the Canal del Dique and Barú Island, with values below 10 microg/g. In other areas concentrations were between 50 and 100 microg/g. A decrease in sediment concentrations of hydrocarbons has occurred since 1983, but levels in some sectors are still similar to those in polluted areas. Organisms have relatively low values (8-30 microg/g for bivalves, and 10-40 microg/g for fish).  相似文献   

Unusual cases of mining subsidence from Great Britain, Germany and Colombia   总被引：1，自引：0，他引：1  

F. G. Bell  L. J. Donnelly  D. D. Genske  J. Ojeda 《Environmental Geology》2005,47(5):620-631

Subsidence involves sinking of the ground surface. The movement generally is localised and may or may not involve some amount of horizontal movement. It may be rapid or take place gradually over a period of time. Subsidence may be brought about by natural causes as, for example, when the roof of a cavern in limestone is weakened to the extent that it is no longer self-supporting and so collapses. Other more exotic examples are associated with volcanism and earthquakes. Perhaps, however, subsidence is more frequently associated with movements caused by mining activities, that is, the removal of mineral deposits, be they in solid, liquid or gaseous form, from within the ground. Mining is one of the earliest activities of man and has taken place in every continent. Subsidence also can result from subsurface excavations such as tunnels, caverns, cellars and sewers. One of the added problems of some forms of subsidence is that it is impossible to predict. This, coupled with the fact that the presence of potentially collapsible voids may be unknown, unrecorded or simply forgotten about further complicates the problem. The objectives of this paper are to document and draw attention to a number of unusual examples of subsidence. These have been generated due to the mining of chalk in southern England, the collapse of slate mines and caverns in Germany, the underground extraction of evaporites in Northern Ireland, fault reactivation in Wales and northern England and the extensive extraction of pumice on the flanks of Galeras volcano in Colombia.  相似文献   

Structure and tectonics of the central segment of the Eastern Cordillera of Colombia     

Martín Corts  Bernard Colletta  Jacques Angelier 《Journal of South American Earth Sciences》2006,21(4):437

In the Eastern Cordillera of Colombia, a new structural model constrained by field data, paleontologic determinations, and interpretations of seismic reflection profiles is proposed. The model implies 70 km of shortening, including reactivation of basement structures as inverse faults in both flanks of the chain. These faults propagated within the lower Cretaceous strata, inducing passively rooted and transported thrust sheets as the successive basement faults were reactivated. Two structural styles are identified in the western flank: (1) positive flower structures in a transpressive regime, which affected rocks older than upper Paleocene and were unconformably covered by post–late Paleocene sediments, and (2) compressive structures during the late Miocene–Recent Andean phase. Presently, WNW-ESE compression reactivates Late Paleocene structures, which locally affect Andean trends. In the western margin of the Eastern Cordillera, the Cambao thrust takes up most displacement, whereas the Bituima fault takes only a minor part. To the south, this relationship reverses, suggesting complementary behavior by the Bituima and Cambao faults, as well as a transfer zone. This suggestion explains the southward termination of the Guaduas syncline as a structure related to the Cambao fault, whereas the Bituima fault increases its displacement southward, generating the Girardot foldbelt that takes over the structural position of the Guaduas syncline.  相似文献   

Urban Forest Values of the Citizenry in Three Colombian Cities     

C. Ordóñez  P. N. Duinker 《社会与自然资源》2014,27(8):834-849

Urban forests are an integral part of urban ecosystems and quality of life. With an overwhelmingly urban population, Latin American countries benefit considerably from their urban forests. However, little is known about the values that make such forests important. The goal of this study was to provide an overview of urban forest values in Colombia. Exploratory research was undertaken in the cities of Bogotá, Cali, and Pereira, with the use of field tours based on visits to five urban forest types, personal diaries, and focus groups. Recruitment was based on voluntary self-selection. Data were captured from 72 participants and analyzed via coding and theme extraction. The data demonstrate that Colombian urban dwellers value the urban forest in terms of a rich array of psychological, aesthetic, sociocultural, ecological, environmental, and economic themes. This study is a primer for eliciting urban forest values and developing typologies in a novel and effective way.  相似文献   

Petrology of the Betulia Igneous Complex,Cauca, Colombia     

《Journal of South American Earth Sciences》2014

The Betulia Igneous Complex (BIC) is a group of Late-Miocene (11.8 ± 0.2 Ma) hypabyssal intrusions of intermediate to felsic composition located in the SW of the Colombian Andes. These bodies have a calc-alkaline tendency and are related to the subduction of the Nazca plate under the South American plate. Diorites, quartz diorites and tonalities have porphyritic and phaneritic textures and are composed of plagioclase, amphibole, quartz, biotite, and orthoclase. Plagioclase is mainly of andesine-type and the amphiboles were classified mainly as magnesiohornblendes, actinolites, and tschermakites.BIC rocks have a narrow range of SiO₂ content (59–67wt%) and exhibit an enrichment of LILE and LREE relative to HFSE and HREE, respectively. These features are attributed to enrichment of LILE from the source and retention of HFSE (mainly Nb, Ta, and Ti) by refractory phases within the same source. The depletion of HREE is explained by fractionation of mineral phases that have a high partition coefficients for these elements, especially amphiboles, the major mafic phase in the rocks. Nevertheless, the fractionation of garnet in early stages of crystallization is not unlikely. Probably all BIC units were generated by the same magma chamber or at least by the same petrologic mechanism as shown by the similar patterns in spider and REE diagrams; fractional crystallization and differentiation processes controlled the final composition of the rocks, and crystallization stages determined the texture.Isotopic compositions of BIC rocks (⁸⁷Sr/⁸⁶Sr: 0.70435–0.70511; ¹⁴³Nd/¹⁴⁴Nd: 0.51258–0.51280; ²⁰⁶Pb/²⁰⁴Pb: 19.13–19.31; ²⁰⁷Pb/²⁰⁴Pb: 15.67–15.76; ²⁰⁸Pb/²⁰⁴Pb: 38.93–39.20) indicate a source derived from the mantle with crustal contamination. The model proposed for the BIC consists of fluids from the dehydration of the subducted slab (Nazca plate) and subducted sediments that generated partial melting of the mantle wedge. These basaltic melts ascended to the mantle–crust boundary where they were retained due to density differences and began to produce processes of melting, assimilation, storage, and homogenization (MASH zone). At this depth (∼40–45 km), fractional crystallization and differentiation processes began to produce more felsic magmas that were able to ascend through the crust and be emplaced at shallow depths.  相似文献