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Intraplate tectonics: insights from mountain building in the Moroccan Atlas and related subsidence in the Ouarzazate foreland basin

Intraplate tectonics: insights from mountain building in the Moroccan Atlas and related subsidence in the Ouarzazate foreland basin

A first stage of mantle-related uplift (associated with alkaline magmatism at 40-45 Ma) was probably par- tially responsible for the transition from marine to continental environments coinciding with the early foreland basin stages, and ultimately culminated in the development of a broad uplifted area in the whole Atlas domain, which was submitted to erosion or sed- iment bypass in the following 23 Ma (as recorded by a generalized sedimentary hiatus from 37 to 14 Ma). The second stage of mantle-related uplift, placed by Babault et al. (2008) in post-Miocene times, was

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Reliability of magnetic fabric as paleostress indicator: a case study in Miocene lacustrine sediments from the Ebro foreland basin, N Spain

Reliability of magnetic fabric as paleostress indicator: a case study in Miocene lacustrine sediments from the Ebro foreland basin, N Spain

Abstract: This work deals with the comparison between ASM results from weakly deformed mudrocks that crop out at the internal part of the Ebro foreland basin and paleostress analyses obtained from fault populations and joint sets developed on limestone beds interbedded with the mudrocks. The coaxiali- ty found between the magnetic and paleostress ellipsoids shows the validity of AMS studies as pale- ostress indicators in foreland basins when sampling is restricted to weakly deformed mudrocks. Keywords: anisotropy of magnetic susceptibility, paleostress analysis, Ebro basin, weak deformation, mudrocks.

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Marine and transitional Middle/Upper Eocenen units of the Southeastern Pyrenean Foreland Basin (NE Spain)

Marine and transitional Middle/Upper Eocenen units of the Southeastern Pyrenean Foreland Basin (NE Spain)

The stratigraphic basis of this work has allowed the use of larger foraminifers in the biostratigraphic characteri- sation of the new Shallow Benthic Zones (SBZ). This part of the volume presents a description of the sedimen- tary cycles formed by the transgressive-regressive systems of the Lutetian and Bartonian in the southeastern sec- tor of the Ebro Foreland Basin. Concerning the Lutetian deposits studied in the Amer-Vic and Empordà areas, four sedimentary cycles have been characterised. The first and second are found within the Tavertet/Girona Limestone Formation (Reguant, 1967; Pallí, 1972), while the third and fourth cycles cover the Coll de Malla Marl Formation (Clavell et al., 1970), the Bracons Formation (Gich, 1969, 1972), the Banyoles Marl Formation (Almela and Ríos, 1943), and the Bellmunt Formation (Gich, 1969, 1972). In the Bartonian deposits studied in the Igualada area, two transgressive-regressive sedimentary cycles have been characterised in the Collbàs For- mation (Ferrer, 1971), the Igualada Formation (Ferrer, 1971), and the Tossa Formation (Ferrer, 1971). The Shal- low Benthic Zones (SBZs) recognised within the Lutetian are the following: SBZ 13, from the Early Lutetian, in the transgressive system of the first cycle; SBZ 14, from the Middle Lutetian, in the second cycle and the lower part of the transgressive system of the third cycle; SBZ 15, from the Middle Lutetian, in the remaining parts of the third system; SBZ 16, from the Late Lutetian, throughout the fourth cycle. The association of larger foraminifers in the first and second cycles of the Bartonian in the Igualada area has been used as the basis for the definition of SBZs 17 and 18 recognised in the Bartonian of the western Tethys.

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Ichnology and sedimentology reveal depositional characteristics of bay-margin parasequences in the Miocene Amazonian foreland basin

Ichnology and sedimentology reveal depositional characteristics of bay-margin parasequences in the Miocene Amazonian foreland basin

It is demonstrated below that these deposits result from unique sedi- mentary responses to several parameters, including, limited accommodation space, high-order cyclicity, and restricted embayment waters. The sedi- mentary successions thereby provide an important addition to bay-margin facies models. The ichnological and sedimentological database lead to the final interpretations, which could not be arrived at without the integration of the two datasets. The ichnological/sedimentological interpretations show the difficulty of assessing benthic paleoecology in a multi-stress environ- ment. Finally, an understanding of the paleogeography of the Amazon Ba- sin is essential to understand its natural history. Several studies have noted the high biodiversity present in the Amazon Basin during the Miocene. These observations have been explained by climatic change (Van Der Ham- men and Hooghiemstra 2000), island biogeography (Nores 1999), and var- iable habitat (Hooghiemstra and Van Der Hammen 1998).

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Facies analysis of the Asmari Formation in central and north-central Zagros basin, southwest Iran: Biostratigraphy, paleoecology and diagenesis

Facies analysis of the Asmari Formation in central and north-central Zagros basin, southwest Iran: Biostratigraphy, paleoecology and diagenesis

Three sections of the Oligocene-Miocene Asmari Formation, crossing central and north-central Zagros foreland basin in SW Iran, were measured and studied in order to interpret the biostratigraphy, paleoecology (based on distribution of benthic foraminifera) and diagenesis. Forty-three foraminifer genera and species were encountered in the studied areas and the following assemblage zones have been defined: 1) Nummulites vascus-Nummulites fichteli, 2) Lepidocyclina-Operculina-Ditrupa, 3) Archaias asmaricus-Archaias hensoni-Miogypsinoides complanatus, 4) Miogypsina-Elphidium sp. 14 - Peneroplis farsenensis, and 5) Borelis melo curdica-Borelis melo melo. According to this study, deposition of the Asmari Formation with association of hyaline, lamellar, perforate large and flat foraminifera first started in the basin and slope environments during the Rupelian in Dehdez and Tufe-Sefid areas. Lagoon depositional environment colonized by sea-grass epiphytic foraminifera was encountered during Chattian and Aquitanian in Bagh-e Malek and Dehdez areas and mostly lagoon and slope environments prevailed during Burdigalian in Bagh-e Malek and Dehdez areas, respectively. The main diagenetic processes that affected the Asmari Formation were dolomitization (replacement and cementation), compaction (stylolitization) and dissolution. The extent of these diagenetic overprinting seems to be mainly facies controlled.

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Revista Ingeniería Investigación y Tecnología | Facultad de Ingeniería UNAM

Revista Ingeniería Investigación y Tecnología | Facultad de Ingeniería UNAM

The Sierra Madre Oriental emerged from Late Creta- ceous up to Eocene, when the Mesozoic stratigraphic sequence, thrust-folded and faulted, by the northeast- ward compressive tectonic stresses from the Laramide Orogeny, against the Tuxpan-Island eastern. The Chi- contepec Foreland Basin formed within that tectonic framework, by the loading pressure of the uplifted Sie- rra Madre Oriental Orogene, on the passive unfolded and thermally in subsidence Cretaceous basement; which was bended and tilted southwestward forming a prism, synchronously to the loading of the detached from the thrust-front syn-orogenic slumps northeas- tern, and with turbidity currents flowing southeast- ward, along the axial depocenter of the elongate basin and parallel to the toe-thrust front of the Sierra Madre Oriental Orogene, during Early Paleocene.

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3D progressive evolution of a syncline depocentre from growth turbidite strata: the Annot syncline, SE France

3D progressive evolution of a syncline depocentre from growth turbidite strata: the Annot syncline, SE France

propagation folds (Apps, 1987). Nevertheless, precise kinematics and relative dating of the folds remain open questions. Studies of sandstone thickness varia- tions and their controlling structures will constrain the structural framework of the Alpine foreland basin. Furthermore, the turbidites can be used as horizontal paleomarkers and, where they are synchronous with growth folding, their geometries can record fold kine- matics. The main objectives of our study are to define the kinematics and relative dating of folds occurring in the Annot depocentre based on deformation recorded by the Annot Sandstone. The approach developed includes detailed structural field analyses and 3D geometrical modelling and trishear kinemat- ic modelling. The studied Annot depocentre covers an area of 70 km² (about 11 km NS by 6 km E-W), at 70 km N-W of Nice (Figs. 1a and 1b). It lies just at the intersection of the Digne thrust sheet (NNW- SSE) and the Castellane arc (E-W) (Fig. 1a). Two fold

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Impact of surface processes on the dynamics of orogenic wedges: analogue models and case studies

Impact of surface processes on the dynamics of orogenic wedges: analogue models and case studies

ured lower-plate, 2) tectonics of the foreland, and 3) drainage efficiency that controls the longitudinal transport of sediments far from the mountain relief. Experimental results suggest that the amount of sedi- ment stored in the foreland basins has a direct influ- ence on the structural style and kinematics of the oro- genic wedge. It may be responsible for important structural changes observed along strike in the oro- gens. Thus, mechanical forcing seems at least as sig- nificant as climatic changes that are often invoked to explain variability in the morphostructural evolution of mountain belts. In the experiments, as important volume of analogue materials is eroded from the geo- logical record, the combined effect of punctuated frontal thrusts, internal thickening and syndeforma- tional erosion-sedimentation leading to a cyclic van- ishing of tectonic units. Thus, some of the tectonic structures accommodating the convergence are defin- itively removed by erosion and no trace remains. In addition, units of the foreland basin involved in the accretionary process are continuously recycled by ero- sion-sedimentation processes, making it difficult to analyze the sedimentary record. This confirms that shortening estimates from restored cross sections in mountain belts are most likely underestimated. To summarize, analog models enable us to: 1) char- acterize the tectonic processes responsible for wedge growth, 2) better analyze, measure and model the kinematics and strain partitioning (i.e. amount of horizontal shortening vs. vertical movement on dif- ferent time scales), and 3) study the impact of cli- mate controlled surface processes on long-term deformation (steady-state growth or not, cyclicity of deformation processes) and determine the role of non-stationary processes in mountain building. Different evolutionary stages characterize the oro- genic wedges from the submarine deformation events that follow oceanic subduction and accretionary wedge formation, to the mountain building stage involving steep aerial reliefs subjected to surface processes that completely change the tectonic behav- ior of the growing wedge.

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A bonding evolution analysis for the thermal Claisen rearrangement: an experimental and theoretical exercise for testing the electron density flow

A bonding evolution analysis for the thermal Claisen rearrangement: an experimental and theoretical exercise for testing the electron density flow

single one V(C1,C2). Note that the TS is localized in the course of SSD-IV. Interestingly, neither topological signature nor breaking/forming processes confirm that the formation of the C1-C5 bond does not occur at the TS. In addition, significant changes in the basin populations of some basins are observed, in particular, an important increase in the basin population of the disynaptic basins V(O,C4) and V(C2,C3), whereas the disynaptic basins V(C1,C2) and V(C4,C5) reduce their respective populations considerably. The electronic flow in the course of SSD-IV prepares the system for the imminent formation of the C1-C5. Thus, the subsequent ELF-topological changes result in the creation of the non-bonding monosynaptic basin V(C5), and afterwards V(C1). It is worth noting that the appearance of these two monosynaptic basins in the course of the reaction does not really necessarily represent a diradical character. Bear in mind that the whole process has been considered on a uniform closed shell singlet spin state, and therefore, it lacks multireference character. Following the creation of these two non-bonding basins, a new topological change is observed connecting SSD-VI and SSD-VII; the monosynaptic basins V(C5) and V(C1) merge into the single disynaptic basin V(C1,C5), accounting for the formation of the C1-C5 bond for the very first time. As mentioned above, the bond breaking/forming processes for the C3-O/C1-C5 bonds, respectively, do not take place simultaneously, thus demonstrating the asynchronicity of the process despite the fact that the reaction proceeds via a concerted mechanism. Finally, due to a regular increment in the population of the disynaptic basin V(C2,C3), the last topological change connecting SSD-VII and SSD-VIII is observed, accounting for the transformation of the single C2-C3 bond into double C2=C3. In terms of ELF analysis, the disynaptic basin V(C4,C5) splits into two disynaptic basins V i=1,2 (C4,C5).

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Regional overview of the implementation of the Convention and its Strategic Plan 1997-2002: Africa

Regional overview of the implementation of the Convention and its Strategic Plan 1997-2002: Africa

South Africa has adopted 7 wetland-related policy instruments covering more or less wetland issues through Water Policy, Water Resource Protection Policy, Environmental Management Policy, Integrated Pollution and Waste Management Policy, Marine Fisheries Policy, Coastal Management Policy and River Basin Management Plans. The national Water Policy and in particular the Water Resource Protection Policy strongly incorporate the relevant obligations to the Ramsar Convention. However, River Basin and related plans developed prior to the above policies lack explicit consideration of water allocation to maintain basic ecological functioning of wetlands. As new plans are developed and existing plans are revised they will be required to comply with relevant policy and legislation.

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The fish fauna in tropical rivers: The case of the Sorocaba river basin, Sao Paulo, Brazil

The fish fauna in tropical rivers: The case of the Sorocaba river basin, Sao Paulo, Brazil

The fish fauna of the Sorocaba River basin showed similarities with reported data of the other studies. Its ichthyofauna was dominated by Characiformes and Siluriformes with 28 and 20 species, respectively. The Characidae fami- ly was the most representative. Matthews (1998) observed that there are many species per family in temperate river assemblages. On the other hand, in tropical river assemblages there are few species per family, but many families. In the Sorocaba River basin it was not different, 14 families were found, some of them repre- sented by only one species, as observed with Prochilodontidae, Serrasalmidae, and Erythri- nidae, among others.

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Andean Lower Tithonian (Picunleufuense Zone) ammonites and aptychus from Estancia Maria Juana, Southern Neuquén Basin, Argentina

Andean Lower Tithonian (Picunleufuense Zone) ammonites and aptychus from Estancia Maria Juana, Southern Neuquén Basin, Argentina

The Andean Neuquén Basin is emplaced through W-Central Argentina and a small part of Central Chile. Its southern end is delimited by a distinctive basement structure called the Huincul Arch (Dorsal de Huincul, see Fig. 1; De Ferraris 1947). This sector of the basin is usually denominated Picún Leufú Sub-Basin and has a Tithonian marine record of variable thickness, mainly represented by the Vaca Muerta, Carrín Curá, and Picún Leufú formations. The latter two units pass gradationally from the bituminous sandy shales and calcareous ne-grained sandstones of the Vaca Muerta Fm into near-shore green sandstones and platform limestones respectively (Leanza & Hugo 1997, Leanza et al. 2003).

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- New records of Piscicola geometra (Linnaneus 1758) (Hirudinea, Piscicolidae) in Ebro River Basin (N Spain)

- New records of Piscicola geometra (Linnaneus 1758) (Hirudinea, Piscicolidae) in Ebro River Basin (N Spain)

This note represents a contribution to the knowledge of the presence of the fish leech Piscicola geometra (Linnaeus 1758) (Hirudinea, Piscicolidae) in the Ebro River Basin. This species was collected in two rivers in the Ebro River Basin. Although this species has been reported from the Iberian Peninsula, these records are scarce and, to the author’s best knowledge, this study pre- sents the first record of Piscicola geometra in the Ebro River Basin.

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Landfalling tropical cyclones on the Pacific coast of Mexico: 1850-2010

Landfalling tropical cyclones on the Pacific coast of Mexico: 1850-2010

The Spearman rank correlation coefficients between the reconstructed time series for landfall and several annually averaged climate indices are presented in Table III. Note that both ENSO, as characterized by the Niño3 index, and the NAO show the same correlation (0.22), significant at the 99% level evaluated using a t-test with n-2 degrees of freedom. This low correlation is evident in somewhat elevated power in the wavelet analysis (see Fig. 6b). We have separated the time series into two subsets: (i) cases of landfall events when the Niño3 index is larger than 0.5 (73 cases) and (ii) cases of landfall events when the index is less than –0.5 (49 cases). There is no significant difference in the average of landfalls between these two subsets. Moreover, 57% of the landfalls occur during neutral years when the Niño3 index has values between –0.5 and 0.5, but the average landfalls per year are not significantly different than during either El Niño or La Niña conditions. Therefore, it appears that the ENSO phenomenon does not significantly influence the average cases of landfall of TCs that originate in the eastern North Pacific basin.

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Subsurface fire and subsidence at Valle del
				Potosí (Nuevo León, Mexico): Preliminary observations

Subsurface fire and subsidence at Valle del Potosí (Nuevo León, Mexico): Preliminary observations

Valle del Potosí basin is located in the arid western foothills of Sierra Madre Oriental Mountains in the state of Nuevo León. It is present at ~100 km south of Monterrey city and ~30 km west of Galeana town (Figure 1). During the last three decades, the basin has been experiencing subsurface fire and subsidence. Subsidence of the basin has affected the agricultural activity and local economy as the basin surface was used for cultivation. Futhermore, the

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Eocene strata from the Sabinas Basin and their
				bearing in sedimentary basin correlation in NE Mexico

Eocene strata from the Sabinas Basin and their bearing in sedimentary basin correlation in NE Mexico

On the basis of previous stratigraphic interpretations and recent fi ndings at El Arco, we suggest a new scheme of correlation between the Paleogene sections of three impor- tant sedimentary basins in northeastern Mexico (Figure 6). The Paleogene units at the Sabinas Basin are represented by the upper Potrerillos Formation, the Adjuntas Formation and the El Arco Lentil of the Hermanas formation. These units are equivalent to the Paleocene Upper Mudstone and Upper Sandstone Members of the Potrerillos Formation, and to the Lower Eocene Adjuntas Formation, and the basal middle Eocene Viento and Carroza formations of the La Popa Basin, respectively (Figure 6). Occurrence of the nautiloid Hercoglossa sp. cf. H. peruviana on the upper part of the Rancho Nuevo Formation in the Parras Basin suggests a direct correlation with strata of the Sabinas Basin, and indirectly with the upper part of the section in La Popa Basin. Sediment was being supplied to the three basins during middle Eocene time, possibly the beginning of the Lutetian, while seas were retreating from W-SW to E-NE in Northeastern Mexico (Figure 7).

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NATIONAL REPORT ON THE IMPLEMENTATION OF THE RAMSAR CONVENTION ON WETLANDS

NATIONAL REPORT ON THE IMPLEMENTATION OF THE RAMSAR CONVENTION ON WETLANDS

H. How can Ramsar Convention implementation be better linked with the implementation of water policy/strategy and other strategies in the country (e.g., sustainable development, energy, extractive industry, poverty reduction, sanitation, food security, biodiversity)? A wide process on finclusión of the Convention guidelines’ and resolutions into these sectors policies’ has to be initieted and/or strenghtened. On a local basis, wetland issues can be part of river basin/water respources plans. For instance,Brazil is working on integrating coastal and river basin management by designating a focal point of a coastal protected area to the local water council and the other way round, that is, that a water sector representant will participate on the PA management council. Another valuable mechanisms would be working with the linkage between environment and economy such as wetlands valuation

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Editorial: Economics at a River Basin Scale

Editorial: Economics at a River Basin Scale

Summing up, the papers in this Special Issue are all examples on how economic analysis can be adapted to better inform policy making. All of the papers can be seen as problem-driven approaches to convey the potential of economic analysis in a way that can be taken by stakeholders and policy makers to integrate knowledge and deal with the complex tradeoffs that are connatural to managing water at a river basin scale. They cover a review of the critical role of economic instruments in managing water worldwide (Gómez et al.), the management of water quality in France (Bourgeois), responses to water scarcity and droughts in Australia (Qureshi et al.), policy coordination in Colombia (Rausher et al.), and evaluation of economic impacts of water restrictions at different market scales in Italy (Pérez et al.). They provide a good sample of the virtually infinite opportunities of applied economic analysis at a river basin scale.

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Combined geophysical, geomorphological and geological studies at the active Lassee Segment of the Vienna Basin Fault System

Combined geophysical, geomorphological and geological studies at the active Lassee Segment of the Vienna Basin Fault System

Seismic crosslines (Fig. 2), which are covering the whole width of the Lassee Basin, consistently depict approxi- mately 3000 m thick Neogene sediments overlying pre- Neogene basement. In all sections fault mapping depicts a negative flower structure with major branch lines situ- ated at depths between 3500 and 5500 m, i.e. close to the interface between pre-Neogene basement and Neogene basin fill. We propose that the rheological difference between basement and basin fill pinpoints branch lines at this interface. The master fault is regarded to be thin- skinned rooting in the Alpine Carpathian floor thrust, which forms a major detachment at about 8 km depth (Royden et al., 1983; Royden, 1988). Neogene growth strata inside the flower structure prove Miocene (Badenian to Pannonian) faulting with large variations of growth strata thicknesses along the fault zone. Maximum vertical displacement occurs on the SE border faults of the flower with a minimum of 500 to 850 m of Badenian to Lower Sarmatian (15.5-12 Ma) displacement. Post- Lower Sarmatian displacement cannot be quantified due to the erosion of Pannonian strata in the footwall block. Displacement during this time interval, however, must

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Structural analysis and recent tectonics in the central Alboran Sea

Structural analysis and recent tectonics in the central Alboran Sea

Abstract: We analyze the distribution and character of recent deformations in the Alboran Ridge and neighbouring areas of the Alboran Sea (within the Gibraltar Arc System, in the Western Mediterranean). Shallow structure has been analyzed by integrating different geophysical datasets, such as multibeam swath-bathymetry and sub-bottom profiling and comparing with deeper sections shown in multichannel seismic profiles. We explore relationships between upper-crustal structures and shal- low seismicity, to decipher the position and nature of active fault segments. Pliocene to recent uplift of the Alboran Ridge has been produced by reverse to strike-slip faulting along NE-SW trending fault- systems that show a transpressive character. Major faults bounding the ridge gradually change their direction from NE-SW to NW-SE and connect with the transtensional Yusuf fault system, which includes the Yusuf Ridge and Basin. Towards the west, the ridge is affected by NNE-SSW trending folds, associated with high-angle faults at depth. These structures define a seismogenic, left-lateral fault zone connected to the south with the Al Hoceima seismic swarm.

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