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Index Page numbers in italic denote Figures. Page numbers in bold denote Tables. Abanico extensional basin 2, 4, 68, 70, 71, 72, 420 Andacollo Group 132, 133, 134 basin width analogue modelling 4, 84, 95, 99 Andean margin Abanico Formation 39, 40, 71, 163 kinematic model 67–68 accommodation systems tracts 226, 227, 228, 234, thermomechanical model 65, 67 235, 237 Andean Orogen accretionary prism, Choapa Metamorphic Complex development 1, 3 20–21, 25 deformation 1, 3, 4 Aconcagua fold and thrust belt 18, 41, 69, 70, 72, 96, tectonic and surface processes 1, 3 97–98 elevation 3 deformation 74, 76 geodynamics and evolution 3–5 out-of-sequence structures 99–100 tectonic cycles 13–43 Aconcagua mountain 3, 40, 348, 349 uplift and erosion 7–8 landslides 7, 331, 332, 333, 346–365 Andean tectonic cycle 14,29–43 as source of hummocky deposits 360–362 Cretaceous 32–36 TCN 36Cl dating 363 early period 30–35 aeolian deposits, Frontal Cordillera piedmont 299, Jurassic 29–32 302–303 late period 35–43 Aetostreon 206, 207, 209, 212 andesite aggradation 226, 227, 234, 236 Agrio Formation 205, 206, 207, 209, 210 cycles, Frontal Cordillera piedmont 296–300 Chachahue´n Group 214 Agrio fold and thrust belt 215, 216 Neuque´n Basin 161, 162 Agrio Formation 133, 134, 147–148, 203, Angualasto Group 20, 22, 23 205–213, 206 apatite ammonoids 205, 206–211 fission track dating 40, 71, 396, 438 stratigraphy 33, 205–211 (U–Th)/He thermochronology 40, 75, 387–397 Agua de la Mula Member 133, 134, 205, 211, 213 Ar/Ar age Agua de los Burros Fault 424, 435 Abanico Formation 71 Agua Dulce Metaturbidites 21, 23–24 Barreal-Las Pen˜as Deformation Zone 277, 279, 286 Agua Las Mun˜eras Creek 248, 254, 255, 261 Don˜a Ana Group 110 Agua Salada Volcanic Complex 32 Neogene pediplains 431, 432, 434, 437 Airy- Keiskanen compensation model 170, 171, 176, Rı´o La Sal Formation 111 177, 193 Valle del Cura Formation 111, 113, 115–117 Ajial Formation 31 Arboles megalandslide 334 Alfalfal debris flow 338 arc magmatism Algarrobal Formation 27, 34 Andean tectonic cycle 30, 31, 40–43, 42 Algarrobillo Pediplain 426, 428, 429, 430, 431–433 Gondwanian tectonic cycles 21–22 geochronology 434, 435, 436–437 retroarc 22 incision 440 basin deposits 22–23 uplift 438–439 western Sierras Pampeanas 19, 20 alluvial fans 5, 38, 249, 274, 278, 279 Argentina, central western Frontal Cordillera piedmont 296–300, 302–304 geographical features 369–370 see also Regional Aggradational Plain (RAP) seismicity 369, 371–380, 372 Almacenes lateral moraine 354, 355 ground effects 377, 379 Alojamiento Fault 273, 274, 275, 277 historical records 373, 374–375, 376, 377 Alto del Tigre High 28,32 seismic hazard 370, 379 Alto Tunuya´n basin 72–73, 74, 75 tectonic setting 370–371 Altos de Hualmapu Formation 31, 33 Arqueros Formation 32, 33, 34 Altos de Talinay Plutonic Complex 29 Arraya´n Formation 21, 23, 24 Alvarado depocentre 32 Arroyo Anchayuyo, alluvial fans 296, 297 Amarillo rockslide 334, 335, 336 Arroyo del Zancarro´n 115, 116 ammonoids, Agrio Formation 205, 206–211 Arroyo Guanaco Zonzo 117, 120 Amphidonte 206, 207, 208, 209 Arroyo Malo Formation 32 analogue modelling Arroyo Yaucha, fill terraces 299, 303, 304 basin width and tectonic inversion 84–87 Asociacio´n Pirocla´stica Pumı´cea (APP) 285, 296, 297, comparison with natural basins 95–102 298, 300, 304, 305, 315 results 87–95 Atacama Gravels 423 Anchayuyo fault 69, 75, 319, 321–322 Auquilco Formation 31, 32, 33 seismic potential 321–322 Austral Basin, U–Pb zircon dating 149 448 INDEX avalanches see rock avalanche deposits Cambrian Avile´ Member lowstand wedge 205 Famatinian tectonic cycle 17 U–Pb zircon dating 147–148 Pampean tectonic cycle 14,15 Azufrera-Torta surface 437 Campanario Formation 40 Can˜on del Atuel landslide 339 backarc basins Cantarito Gravels 437 Andean tectonic cycle 4, 30, 31, 34–35 Capdeville Anticline 273 inversion 69, 71 Caracol basin 228, 230, 237 Bajada del Agrio Group 37, 133, 134 Caracol Range, uplift 239, 241 Ban˜os Colorados creek thrust section 248, 252, 259, 273, carbonates, Cuyo Precordillera 17, 19 274, 278 Carboniferous, Gondwanian tectonic cycles 22–23, Ban˜os del Flaco Formation 31, 35 24, 25 Barrancas Anticline 320 Carri Lauquen Lake failure 340 1985 earthquake 375, 376, 377 Carrizalito Tonalite 17 Barrancas-Lunlunta fault, seismic potential 322 Casleo Formation 279–282 Barreal Block 280, 281 Caucete 1941 earthquake 373, 375 Barreal Fault 274, 279, 280 Caucete 1977 earthquake 373, 375, 377, 379 Barreal-Las Pen˜as Deformation Zone 5, 269, 271, 273, Caucete Group 19 274–284 Cavilole´n unit 31 earthquakes 282 Cenozoic fault scarps 279 Andean tectonic cycle 36–43 Late Cenozoic kinematics 275–276 Barreal-Las Pen˜as Deformation Zone Late Cenozoic tectonics ages 276–282 kinematics 275–276 palaeoseismological records 278–282 tectonic ages 276–282 Quaternary deformation and relief construction Central Depression 15, 16, 38, 70, 73,76 282–284 geological setting 65 Quaternary faults 272, 274–275 Cerrilladas Pedemontanas thrust belt 269, 270, 272, structural highs 283–284 311, 314 uplift 283 geological setting 65, 296 Barreal-Uspallata Basin 268, 270, 272 Cerro Calera Formation 31 basins Cerro Corrales 205, 208, 209 pre-Andean tectonic cycle 3, 26–29 comparison with Agrio Formation 211, 213 see also backarc basins; forearc basin deposits; Cerro de la Totora Formation 17 piggyback basins; retroarc basin deposits Cerro de las Cabras Formation 28–29 10Be age determination 40, 278, 279, 286, 315 Cerro El Salto megalandslide 334, 335 pediplains 433, 434, 437 Cerro Manantial Fault 273, 274, 275, 278, 279, 284 10Be concentration, catchment erosion rates 403, 405, Cerro Meso´n Alto pluton 73,75 407, 412 Cerro Salinas Anticline 277 Beazley Basin, vertical gravity gradient 191 Cerro Salinas-Montecito thrust system 246, 247 Bermejo Basin 26, 28, 178, 239 Cerros Colorados frontal range 255, 259, 260 rigidity 196 Cesco Formation 279, 283 vertical gravity gradient 191 Chacay Melehue Formation 133, 134 Boca Lebu Formation 37 Chacayal thrust system 66, 69, 70 Bolivian Orocline 16 Chachahue´n Groups 214 Bouguer anomaly 169, 194, 195, 196 Chachahue´n volcanic complex 206, 213–214 effect of Andean root 190–191, 196 deformation and uplift 215–217 flat slab transition zone 170, 171–172, 173 Early Cretaceous deposits 203, 205–213 inverse flexure modelling 186, 187, 188, 189 structural setting 214–215 Brownish-red Clastic Unit 37 magma components 214 tectonic setting 204–205 14C dating Chalet fault 299, 300, 320 Barreal-Las Pen˜as Deformation Zone 281, 282, 286 Chanic Orogeny 4, 14, 17, 25 Horcones valley deposits 363 deformation 20, 23 Cabeceras Creek 273, 279, 280, 281 Chanic unconformity 17 Cabeza de Toro megalandslide 334, 335 Chihuidos High 215, 216 Cacheuta Basin 72–73,74 Chilenia terrane 14,20 Cacheuta Formation 28–29 Choapa Metamorphic Complex, accretionary prism Cachiyuyo Pediplain 426, 428, 430, 431, 433 20–21, 25 geochronology 434, 436 Choiyoi Group 22, 24, 25, 132, 133, 134, 146, 331 uplift 439–440 thermochronometry 389–397 Cajo´n de Troncoso beds 31 uplift 385–387 Cajo´n Las Len˜as alluvial cone deposits 161 Choiyoi Magmatic Province 29 Caleta Horco´n Formation 38 Chos-Malal fold and thrust belt 18 Caleu pluton 36 Chupasangral fault 317 INDEX 449 36Cl, TCN dating 336–337, 347, 349, 351–354, 357, Cuesta del Viento Formation 228, 231 359, 360, 363–364 piggyback basin climate evolution 239–241 control on erosion and uplift 401–415 sedimentation 237–239, 238, 242 and landscape evolution 420–421 Cumbre surface 437 and landslides 337–338, 345 Cura-Mallı´n Formation 39–40 Coastal Batholith 23, 24, 25 Curanilahue Formation 37 Coastal Cordillera 1, 2, 15, 16, 70 Curepto-Bio Bı´o-Temuco basin 26, 27 crustal thickening 423 Cuyania terrane 14, 20, 167–168, 175, 176 geological setting 64–65, 329, 330, 331, 424, 425 Cuyo Basin 26, 27, 28, 69, 268, 271, 273, 295 gravity anomaly 191 Cuyo Group 32, 133, 134 influence of precipitation 440–441 Cuyo Precordillera 17, 19 pediplains 426, 427, 428, 429–442 structure 68, 70 dams, sedimentary 230–232, 233, 234, 236, 237, 279 topography and geomorphology 421, 422, 425, 427 debuttressing, and landslides 338, 339 mapping 427 deformation uplift 8, 74, 76–77, 439–440 deep crustal 64 Cobquecura pluton 29 conceptual models 64 Cogotı´ superunit 36 Maipo-Tunuya´n transect 69, 71–77 Colangu¨il batholith 22 kinematic model 67–68 Colimapu Formation 35, 161, 163, 164 thermomechanical modelling 65, 67 Colohuincul Complex 133, 141 Famatinian tectonic cycle 19–20 Conceptio´n Group 37 Quaternary retro-wedges 267–287 Confluencia Formation 38, 421, 425, 433, 439, 440 Quaternary thrust fronts 245–263 conoids 223, 232, 233 Del Cerro Negro de Capiz fault, seismic potential 322 continental breakup 14 Del Peral Anticline 317–319 Contreras Formation 71, 74 Del Peral fault, seismic potential 321 Coquimbo Formation 38, 421, 425, 430, 438, 439 Del Totoral fault, seismic potential 321 coquina 206–209, 210, 211, 213 density models 168–179 Cordillera de la Brea 111, 113, 118 2D models 174–176 Cordillera de la Ortiga 110, 111, 113, 117, 121, 122 depocentres Cordillera del Viento 132, 133, 141, 142 Andean tectonic cycle 29, 32, 168 depocentre 32 pre-Andean tectonic cycle 27, 28,29 Cordillera del Viento Formation 133, 134 Devonian, Famatinian tectonic cycle 17, 20 Co´rdoba terrane 15, 17 Diaguita Phase deformation 277–278, 284 Cordo´n de Barda Negra 259 Diamante deformation zone see Los Cordo´n del Plata piedmont 315, 316, 317 Alamitos-Papagayos-Diamante Cordo´n del Plata rock avalanches 337, 338 Deformation Zone Corredores Pediplain 426, 428, 429,
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  • 4 Three-Dimensional Density Model of the Nazca Plate and the Andean Continental Margin

    4 Three-Dimensional Density Model of the Nazca Plate and the Andean Continental Margin

    76 4 Three-dimensional density model of the Nazca plate and the Andean continental margin Authors: Andrés Tassara, Hans-Jürgen Götze, Sabine Schmidt and Ron Hackney Paper under review (September 27th, 2005) by the Journal of Geophysical Research Abstract We forward modelled the Bouguer anomaly in a region encompassing the Pacific ocean (east of 85°W) and the Andean margin (west of 60°W) between northern Peru (5°S) and Patagonia (45°S). The three-dimensional density structure used to accurately reproduce the gravity field is simple. The oceanic Nazca plate is formed by one crustal body and one mantle lithosphere body overlying a sub-lithospheric mantle, but fracture zones divide the plate into seven along-strike segments. The subducted slab was modelled to a depth of 410 km, has the same structure as the oceanic plate, but it is subdivided into four segments with depth. The continental margin consists of one upper-crustal and one lower-crustal body without lateral subdivision, whereas the mantle has two bodies for the lithosphere and two bodies for the asthenosphere that are separated across-strike by the downward prolongation of the eastern limit of active volcanism. We predefined the density for each body after studying its dependency on composition of crustal and mantle materials and pressure-temperature conditions appropriate for the Andean setting. A database containing independent geophysical information constrains the geometry of the subducted slab, locally the Moho of the oceanic and continental crusts, and indirectly the lithosphere-asthenosphere boundary (LAB) underneath the continental plate. Other geometries, especially that of the intracrustal density discontinuity (ICD) in the continental margin, were not constrained and are the result of fitting the observed and calculated Bouguer anomaly during the forward modelling.
  • The Ichnology of the Winterhouse Formation

    The Ichnology of the Winterhouse Formation

    The ichnology of the Winterhouse Formation By ©Robyn Rebecca Reynolds, B.Sc. (Hons) A thesis submitted to the School of Graduate Studies in partial fulfilment of the requirements for the degree of Master of Science Department of Earth Sciences Memorial University of Newfoundland October, 2015 St. John’s Newfoundland Abstract The Upper Ordovician Winterhouse Formation of Western Newfoundland contains a, hitherto undescribed, well-preserved and diverse assemblage of trace fossils. This study provides the first systematic ichnological review of the area. 20 ichnotaxa are documented herein from the mudstone and sandstone storm deposits of the formation. A detailed morphologic three-dimensional reconstruction and analysis of a complex Parahaentzschelinia-like burrow system that is prolific throughout the formation is also undertaken. This analysis allows for a reconsideration of the trace-maker’s ethology and paleobiology, and highlights a need for a systematic ichnotaxonomic review of Parahaentzschelinia. Additional reconstructions of natural mineral-filled fractures associated with Parahaentzschelinia-like burrows in the cemented silt-rich fine-grained sandstones illustrate that the burrows create planes of weakness within the cemented sandstone, along which natural fractures preferentially propagate. This suggests that these trace fossils create mechanical heterogeneities that can steer fracture development, and can potentially have a dramatic effect on reservoir charactertstics in bioturbated reservoirs where induced fracturing techniques may be employed. ii Acknowledgements Firstly I would like to thank my supervisor, Dr. Duncan McIlroy, for providing me with this opportunity, and for your support and mentorship throughout the past three years. In addition to everything I have learned from you about ichnology and sedimentology, your approach to research and your method of supervising/teaching has made me a stronger, more independent, and confident scientist.