Browsing by Subject "San Juan"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Cenozoic sedimentation and exhumation of the foreland basin system in the Precordillera fold-thrust belt (31-32°S), southern central Andes, Argentina(2013-05) Levina, Mariya; Horton, Brian K., 1970-; Stockli, Daniel F; Ketcham, Richard AAndean retroarc shortening associated with flattening of the Pampean segment of the subducting Nazca plate has resulted in a thin-skinned, east-directed thrust system that partitioned and uplifted Cenozoic foreland basin fill in the Precordillera of west-central Argentina. The temporal and kinematic evolution of the Precordillera fold-thrust belt can be approached through detailed analyses of the clastic sedimentary deposits now preserved in intermontane regions between major thrust faults. In this project, we focus on the uppermost Oligocene–Miocene basin fill exposed in the axial and eastern Precordillera along the San Juan River (Quebrada Albarracín and Pachaco regions) and western flank of the frontal structure (Sierra Talacasto). The nonmarine successions exposed in these regions record hinterland construction of the Frontal Cordillera, regional arc volcanism, and initial exhumation of the Precordillera thrust sheets. Measured stratigraphic sections and lithofacies analyses of the preserved stratigraphic successions reveal initial development at ~24 Ma of an eolian depositional system influenced by regional volcanism and fluvial interactions, becoming a fully eolian system by 21-19 Ma. This system transitioned to a distributary fluvial system in which regions closer to the deformation front recorded sandy-gravelly braided stream sedimentation and regions farther east recorded more-distal floodplain-dominated deposition of thin-bedded mudstone and sandstone. The youngest sedimentary record is preserved in the Albarracin basin, a zone strongly influenced by explosive volcanism of nearby eruptive centers around 14 Ma, followed by a progradational alluvial-fan succession of pebbly, cross-stratified sandstone and thick, pebble to cobble conglomerate. Provenance changes recorded by detrital zircon U-Pb age populations suggest that initial deformation in the Frontal Cordillera coincided with the early Miocene transition from eolian to fluvial deposition in the adjacent foreland basin. The overall upward coarsening nature of the fluvial succession and increased presence of Paleozoic clasts reflect the eastward progression of thin-skinned deformation in the Precordillera and resultant structural partitioning of the synorogenic foreland successions. Using apatite (U-Th)/He thermochronometry we are able to further constrain the age of uplift-induced exhumation and cooling of several Precordillera thrust sheets to 12-9 Ma. This apparent pulse of exhumation is evident in all three sections, suggesting rapid, large-scale exhumation by synchronous thrusting above a single décollement linking major structures of the eastern Precordillera.Item Distances and proximities : Havana and San Juan from the point of view of literature and oral histories(2015-05) Mercado Diaz, Mario Edgardo; Salgado, César Augusto; Merabet, Sofian, 1972-Cuba y Puerto Rico have for long been considered sister islands, fighting together against the influences of the Spanish Empire and the United States. The decade of the 1950s, however, proved to be the splitting point for both islands, sending them into very different trajectories of development. In their shared experience of Spanish colonization and USA interventions, how do San Juan and Havana residents perceive and use space today in their particular socio-political contexts and how does this affect the resident's sense of citizenship? I closely engage with the different urban spaces using ethnographic data and photographs taken during my recent fieldwork, creative texts describing said spaces and case studies examining the formation of racial, gender and class identities. Focusing on a specific place on the Malecón, Havana's iconic esplanade, I examine how practices of leisure, intimacy (e.g. erotic homosexual and heterosexual encounters), and self-expression challenge the revolutionary rhetoric of "sameness" (i.e. absence of race, class, crime or gender violence). As for San Juan, I dissect the layers of significance in public visual representation, as exemplified in the artwork painted over an abandoned house in Santurce, the site for queer, artistic and marginal expression. The scene, two black women drinking on the porch, rescues a sense of citizenship lost to the class and racial polarization, fragmentation, and the "ruination" of San Juan. Finally, I argue that an archipelagic city, composed of the descriptions of specific places in different cities, has been created in the sea, a space of crossing, endurance and death, within these inter-capillary exchanges of people, cultures and habits. This archipelagic city, not spoken about directly but referenced semantically, aids in the construction of trans-national identities and perspectives, specific perceptions on time and space, and the production of media and cultural forms of expression. My goal is to tie together these narrative strands linking trans-oceanic places into an urban map surpassing its own geographical context.