Papers by Miquel Poyatos Moré
<p>The topographic history of an orogen results from the interactions of cl... more <p>The topographic history of an orogen results from the interactions of climate and tectonics, and it can be reconstructed from the sedimentary record of its peripheral basins. Previous tectonostratigraphic studies, including flexural models, and sparse stable oxygen and carbon isotope data from the South-Pyrenean foreland basin suggest that a major period of topographic growth occurred in the late Paleocene-early Eocene. To further test this hypothesis, we present a stack of 658 stable isotope measurements on whole-rock marine carbonate mudstone from a 4800-m-thick composite sedimentary succession which provides a 12 Ma continuous record of environmental conditions during the early to middle Eocene (54 to 42 Ma). From the base of this record (at 54 Ma), oxygen isotopes  (<em>δ</em><sup>18</sup>O values) show a faster decrease rate than the coeval global negative excursion associated with the Early Eocene Climatic Optimum (EECO). This local alteration of the global <em>δ</em><sup>18</sup>O signal indicates that topographic growth during this period, associated with significant tectonic activity, perturbed the oxygen isotopic composition of foreland waters. Thus, our data suggest that significant topographic uplift of the Pyrenean orogen started from at least 54 Ma and continued until ca. 49 Ma, reaching the maximum elevations of 2000±500m in this phase from previous isotope and flexural studies. In addition, our record shows that the long-term carbon stable isotope composition during this period remained relatively stable with no similarity to the global bell-shaped long-term trend of the EECO. This is consistent with the restricted physiography of the South-Pyrenean foreland basin, mainly influenced by local sedimentary and water inputs. Overall, the Pyrenean topographic growth from the Late Cretaceous to the Miocene displays several growth stages that seem to be primarily determined by episodes of an increased rate of tectonic plate convergence. The duration of these growth stages (several millions of years) is possible documentation of the response time of mountain ranges to tectonic perturbations. The results of this work, therefore, demonstrate that stable isotope measurements<em> </em>on whole-rock sediments in foreland basins can provide key information for tectono-climatic and topographic reconstructions of mountain ranges.</p>
A complete vertical section through a prograding basin margin clinothem succession will intersect... more A complete vertical section through a prograding basin margin clinothem succession will intersect the base-ofslope (BOSZ), shelf-edge (SERZ) and fluvial-marine (FMTZ) transition zones. A common assumption is that an observed SERZ at one stratigraphic level is similar in character to the one that supplied underlying slope and basin floor systems. However, this does not account for temporal and spatial changes in basin margin physiography, and sedimentary systems are likely to be different when delivering sand to the basin floor than when aggrading deposits in the shelf. Accurate reconstructions require sub-seismic scale analysis of transition zones from coeval clinothem topset, foreset and bottomset segments in successive basin margin clinothems, in order to adequately constrain the timing and nature of sediment dispersal across basin margins in the absence of a complete dataset.
BSRG Annual Meeting, Hull, United Kingdom, 18-21 December, 2013In the Ainsa basin, the Castissent... more BSRG Annual Meeting, Hull, United Kingdom, 18-21 December, 2013In the Ainsa basin, the Castissent sequence has been subdivided in two different composite depositional sequences: Castissent-1 (Cs-1) and Castissent-2 (Cs-2). This study focuses on the lower part of Cs-1, where the Fosado Channel Complex lies. Cs-1 was deposited synchronously with a high-deformation phase in the Pyrenean orogeny (Upper Ypresian to Lower Lutetian), with strong tectonic reactivation of the South-Central Pyrenean Unit; sediments were affected by the Atiart thrust (east) and later on by Los Molinos thrust (west). So far, the knowledge about Cs-1 was mainly its stratigraphic position within the Torla turbidite system, its physical correlation with the fluvio-deltaic feeding system of Castissent Fm. s.s., as well as its facies detail of the uppermost individual channel (the Fosado channel, s.s.), which has been used as a facies model for channel margin settings. Nevertheless, its high resolution stratigraphic study, its facies associations and architecture, still remains unknown in detail. Therefore, it has been possible to map and redefine the extension of the Atiart unconformity in the hanging wall of Los Molinos thrust. This 3rd order sequence boundary at the base of Cs-1 separates: (1) a lower mud-dominated unit, with a high content in debris flow deposits and fine-grained turbidites; and (2) the upper unit, mainly composed by a channel-overbank complex (channel-levee), forming sandy packages belonging to highly-heterogeneous channels. In the stacking pattern of the Fosado complex two main growing stages have been identified: Cs-1a and Cs-1b. Cs-1a displays a relatively high percentage of sand content in individual channels; on the contrary, Cs-1b is a mud-dominated unit, mainly composed by fine-grained channels and their related overbank deposits. This last unit would be the lowermost part of the slope fan related with the Castissent deltas. Consequently, the study has focused on the channel complex of Cs-1a unit, where a stacking pattern with unconformities is described and has led to organize it hierarchically in five 4th-order sequences (high resolution seismic scale). Each channel group shows a nested stacking pattern, with hyperconcentrated flow deposits at the base, and lateral and vertical accretion (up to 200x20 m), which is probably indicative of large-scale high-sinuosity channels.UAB - Stratigraphy Grou
International Conference and Exhibition, Melbourne, Australia 13-16 September 2015, 2015
Una tesis es eso, nada más que una tesis. La redacción de la memoria que plasma el trabajo realiz... more Una tesis es eso, nada más que una tesis. La redacción de la memoria que plasma el trabajo realizado durante 4 años es difícil, todo doctor que haya pasado por ello lo sabe, y más difícil aún es conseguir que esta memoria refleje las ideas del que la escribe, todo lo que se supone que se debe haber aprendido, y todas aquellas cosas que el científico en potencia que es el redactor lega a la ciencia presentando los datos que ha obtenido. No es fácil. Nadie ha dicho que lo sea. La sedimentología es una rama de la geología compleja. Con esto no quiero decir que las otras ramas no lo sean, simplemente que no las he tratado con suficiente profundidad como para ejercer un juicio de valor. No es necesario. Tengo la sensación de que estoy al comienzo, y así debe ser, de una carrera que me llevará a descubrir día a día la complejidad de nuestra disciplina y lo insignificantes que somos en el registro geológico del que también formamos parte, en cierto modo, si es que aún no soy consciente ahora. Estos años de plena dedicación a la investigación en el campo en el que se enmarca esta tesis me han enseñado a respetar el trabajo de otros, respetar el entorno donde trabajamos, a las personas que forman parte de él aún sin saberlo, y que en muchas ocasiones han sido partícipes de mi euforia y de mi desesperación, que no ha sido poca. A todos ellos, gracias. He conocido personas fantásticas, me he desengañado, he descubierto los pros y los contras del trabajo que hacemos, y a pesar de todo ello, quiero seguir adelante. Vienen tiempos difíciles, pero cuento con la ayuda de todos aquellos que ya han estado a mi lado y los que están aún por venir. Me adentro en la carrera del conocimiento, en busca de mi vida, haciendo lo que más me gusta hacer: geología de campo. El campo te mantiene en contacto con el medio natural, tanto el actual como el fósil, y en el trabajo que nosotros desarrollamos el campo es tan vital como lo somos nosotros mismos. El campo te castiga, te maltrata, pero te premia el esfuerzo, y siempre te espera, paciente, a que vuelvas, a que vuelvas a pasar por aquel margen del camino, por aquel barranco olvidado, por aquellas piedras que tan extrañas te resultaron el primer día, y que no obstante, ahora ya son rocas de lo más familiares. El campo es nuestro hogar, en él volvemos día tras día, porque la ciencia avanza, y nosotros somos científicos." "A thesis is nothing but simply a thesis. The writing up of a dissertation that must show the work performed along 4 years is difficult, all doctors who passed through this period know it, and even harder is to make this thesis reflect the ideas of the writer, all which is supposed to be learned, and of course all data and theories that the potential scientist aims to legate to science by presenting the results obtained from his research. This is not easy. Nobody said so. Sedimentology is a complex branch of Earth Sciences. I don't pretend to say the rest of geologic disciplines are easier, I've not been enough in contact with them to allow a value judgment. It doesn't make any sense. I have the feeling that I'm just beginning a scientific career that will lead me to discover day by day the complexity of our work and how insignificant we are within the geological record, where we somehow belong, if I'm not aware of it yet. These years of total dedication to research concerning the field of knowledge where this thesis is contained have allowed me to learn how to respect the work done by others, respect our working environment, as well as all people forming part without knowing it, people who have been in many occasions partakers of both my euphoria and despair, which has not been easy. To everyone, thanks. I met great people, I was also disappointed, I discovered the pros and cons of the work we do, and despite all, I want to carry on. Hard times are coming, but I hope the support of all those who have been by my side and those still to come. I plunge into the race for knowledge, looking for my life, doing what I like to do: field geology. The field keeps you in touch with the environment, both the modern and ancient, and in the task we develop fieldwork is so vital as ourselves. Fieldwork punishes you, abuses you, but it rewards your effort, always waiting patiently for you to get back and pass again through that side of the road, in that forgotten ravine, looking at those strange stones in the first days, which have been however converted in familiar rocks somehow. The field is our home, we go back there day after day, because science advances, and we're scientists."
Palaeogeography, Palaeoclimatology, Palaeoecology, 2021
Thick (>100 m-thick), highly bioturbated storm-influenced shallow-marine deposits are not freq... more Thick (>100 m-thick), highly bioturbated storm-influenced shallow-marine deposits are not frequent in the stratigraphic record, but they tend to be common in aggradational to retrogradational successions. Individual storm-event beds have typically low preservation potential in these successions, yet depositional settings are characterized on the basis of storms processes. Here we present a sedimentological study of a thick, bioturbated exhumed succession deposited during the early post-rift stage of the Neuquen Basin (Argentina) and compare its stratigraphic record with examples worldwide, in order to discuss the potential factors controlling the total overprint of storm-event beds during several million years. The Bardas Blancas Formation being 170–220 m thick in the study area is dominated by muddy sandstones and sandy mudstones, and it also includes subordinate proportions of clean sandstones and pure mudstones, collectively representing different environments of a storm-influ...
Sedimentology
Monitoring of modern deep-water channels has revealed how migrating channel-floor features genera... more Monitoring of modern deep-water channels has revealed how migrating channel-floor features generate and remove stratigraphy, improving understanding of how channel morphologies relate to their deposits. Here, seafloor and subsurface data are reconciled through an integrated study of high-resolution bathymetry and three-dimensional seismic data imaging a ca 150 km stretch of the trench-axial Hikurangi Channel, offshore New Zealand. On the seafloor, terraced channel-walls bound a flat, wide, channel-floor, ornamented with three scales of features that increase then decrease in longitudinal gradient downstream, and widen downstream: cyclic-steps, knickpoints and knickpoint-zones (in increasing size). Mass-transport deposits derived from channel-wall collapse, are bordered by wide and flat reaches of channel-floor upstream and by knickpoint-zones (reaches containing multiple knickpoints) downstream. In the subsurface, recognition of ten seismofacies and five types of surface enables identification of four depositional elements: channel-fill, sheet or terrace, levee, and mass-transport deposits. Integration of subsurface and seafloor interpretations reveals knickpoint-zones initiate on the downstream margins of channel-damming mass-transport deposits; they migrate and incise through the mass-transport deposits and weakly-confined deposits formed upstream, as the channel tends toward equilibrium. Downstream of a knickpoint-zone, a flat channel-floor is bounded by newly-formed terraces. Knickpoints migrate by eroding upstream and depositing downstream, generating filled concave-up (cross-sectional) surfaces in their wake. Within knickpoint-zones, knickpoint-generated surfaces are re-incised by subsequently-passing knickpoints to produce a composite bounding surface; this surface does not delineate the morphology of any palaeo-conduit. The Hikurangi Channel’s subsurface architecture records the localized erosional response to mass-transport deposit emplacement via knickpoint-zone migration, showcasing how transient seafloor features can build channelized stratigraphy. This model provides an additional mechanism to conventional models of channel deposit formation through ‘cut-and-fill’ over long stretches of channel. These findings may aid subsurface interpretation in systems lacking a contemporary self-analogue or with poor data coverage.
Journal of Sedimentary Research
The inception and evolution of channels in deep-water systems is controlled by the axial gradient... more The inception and evolution of channels in deep-water systems is controlled by the axial gradient and lateral confinement experienced by their formative flows. These parameters are often shaped by the action of tectonic structures and/or the emplacement of mass-transport deposits (MTDs). The Arro turbidite system (Aínsa depocenter, Spanish Pyrenees) is an ancient example of a deep-water channelized system from a bathymetrically complex basin, deposited in an active tectonic setting. Sedimentologic fieldwork and geologic mapping of the Arro system has been undertaken to provide context for a detailed study of three of the best-exposed outcrops: Sierra de Soto Gully, Barranco de la Caxigosa, and Muro de Bellos. These locations exemplify the role of confinement in controlling the facies and architecture in the system. Sedimentologic characterization of the deposits has allowed the identification of fifteen facies and eight facies associations; these form a continuum and are non-unique ...
Geosphere
Drilling of intrashelf Miocene clinothems onshore and offshore New Jersey has provided better und... more Drilling of intrashelf Miocene clinothems onshore and offshore New Jersey has provided better understanding of their topset and foreset deposits, but the sedimentology and stratigraphy of their bottomset deposits have not been documented in detail. Three coreholes (Sites M27-M29), collected during Integrated Ocean Drilling Program (IODP) Expedition 313, intersect multiple bottomset deposits, and their analysis helps to refine sequence stratigraphic interpretations and process response models for intrashelf clinothems. At Site M29, the most downdip location, chronostratigraphically well-constrained bottomset deposits follow a repeated stratigraphic motif. Coarse-grained glauconitic quartz sand packages abruptly overlie deeply burrowed surfaces. Typically, these packages coarsen then fine upwards and pass upward into bioturbated siltstones. These coarse sand beds are amalgamated and poorly sorted and contain thin-walled shells, benthic foraminifera, and extrabasinal clasts, consistent with an interpretation of debrites. The sedimentology and mounded seismic character of these packages support interpretation as debrite-dominated lobe complexes. Farther updip, at Site M28, the same chrono strati graphic units are amalgamated, with the absence of bioturbated silts pointing to more erosion in proximal locations. Graded sandstones and dune-scale cross-bedding in the younger sequences in Site M28 indicate deposition from turbidity currents and channelization. The sharp base of each package is interpreted as a sequence boundary, with a period of erosion and sediment bypass evidenced by the burrowed surface, and the coarse-grained debritic and turbiditic deposits representing the lowstand systems tract. The overlying fine-grained deposits are interpreted as the combined transgressive and highstand systems tract deposits and contain the deepwater equivalent of the maximum flooding surface. The variety in thickness and grain-size trends in the coarse-grained bottomset packages point to an autogenic control, through compensational stacking of lobes and lobe complexes. However, the large-scale stratigraphic organization of the bottomset deposits and the coarse-grained immature extrabasinal and reworked glauconitic detritus point to external controls, likely a combination of relative sea-level fall and waxing-and-waning cycles of sediment supply. This study demonstrates that large amounts of sediment gravity-flow deposits can be generated in relatively shallow (~100-200 m deep) and low-gradient (~1°-4°) clinothems that prograded across a deep continental shelf. This physiography likely led to the dominance of debris flow deposits due to the short transport distance limiting transformation to low-concentration turbidity currents.
Geophysical Research Letters, 2015
The calculation of formation timescales of alluvial fans and deltas on Mars is important as it ha... more The calculation of formation timescales of alluvial fans and deltas on Mars is important as it has direct implications for understanding the planet's hydrologic history. The robustness of sediment transport models is not in doubt but validation of the broad approach using a terrestrial example of similar scale and likely origin, where hydraulic parameters and timescales are known, is useful. Using a catastrophically formed terrestrial fan, where abundant sedimentological information is available, we find that the modeled hydraulic parameters and formation timescales are in very close agreement with the known values of the event. This supports the general modeling approach as applied to Mars fans but also highlights the added value of detailed sedimentary information when reconstructing hydraulics and timescales on Earth and Mars, which cannot be confidently gleaned from the final snapshot of surface geomorphology alone.
The analysis of shelf-edge clinoform trajectory in reflection seismic datasets or outcrop-based s... more The analysis of shelf-edge clinoform trajectory in reflection seismic datasets or outcrop-based studies has been widely employed as a tool to infer relative sea-level changes, to interpret long-term factors controlling the basin margin evolution, and to predict the timing of coarse-grained sediment delivery from continents to oceans. Accommodation-or sediment supply-driven models have been emphasised, with less focus on the role of the shelf-edge process regime in operation at individual clinothems, and how the process regime change in time and space (across strike). High resolution seismic profiles tied to cored and dated borehole data provide a means to link the depositional architecture (clinoform trajectory) to sediment dispersal processes and patterns. IODP Expedition 313 collected three research boreholes that intersected a set of Miocene clinothems offshore New Jersey to capture a complete record of relative sea-level change through integration of seismic stratigraphy, core a...
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Papers by Miquel Poyatos Moré