Los sedimentos marinos terciarios y recientes de la península de la guajira y su posible significado económico

Previous exploration for phosphate on the Guajira Peninsula carried out by INGEOMINAS and the U. S. Geological Survey found little evidence to support the possibility of discovering phosphate deposits there. While they primarily studied the stratigraphic equivalents of the phosphate-rich Upper Cretaceous sediments of the Cordillera Oriental, little attention was given to the Tertiary and Recent sediments of this region.  Recent geological mapping of the Alta Guajira indicates that this region was a stable flat marine platform interrupted only by a few islands (the present Serranías) during the Middle and Late Tertiary.  In fact, the present topography of the platform in the region of the Islas de los Monjes and probably the sedimentation there may closely resemble that of the Guajira Peninsula during the Tertiary. Based upon the improved understanding of the geochemical precipitation of marine phosphates and the geological environment of phosphate formation, we should expect to find phosphate forming on the present marine platform. For similar reasons, phospate precipitation may have occurred on the Tertiary platform as well. Armored with this understanding, a new appraisal of the phosphate potential of the Tertiary sediments seems warranted. The use of paleogeographic maps will be helpful in delimiting the facies changes and sedimentation of the Tertiary sequence. Such an approach may also be useful in the localization of small evaporite basins on the Tertiary platform as well and thus possible Tertiary deposits of halite, gypsum and other salts.La exploración previa para fosfatos en la Península de la Guajira, efectuada por INGEOMINAS y el Servicio Geológico de los Estados Unidos halló poca evidencia para apoyar la posibilidad de encontrar yacimientos fosfáticos allí. Aunque se estudiaron principalmente capas estratigráficamente equivalentes a los sedimentos fosfáticos del Cretáceo Superior de la Cordillera Oriental, se prestó poca atención a los sedimentos marinos de edad terciaria y reciente de esta región. La nueva cartografía geológica de la Alta Guajira indica que esta área era una plataforma marina estable y llana, Interrumpida solamente por unas Islas (las Serranías de hoy) durante el Terciario Medio y Tardío. En verdad, la topografía actual de la plataforma marina en la región de las Islas de los Monjes y probablemente la sedimentación allí, tienen semejanzas estrechas con las de la Península de la Guajira durante el Terciario. Con base en el mejor conocimiento de la precipitación geoquímica de fosfatos marinos y ambiente geológico de su formación, se espera encontrar fosfatos formados en la plataforma marina actual. Por las mismas razones, la precipitación de fosfatos habría ocurrido en la plataforma terciaria también.  Empleando este razonamiento, parece justificada una reevaluación de la potencialidad de fosfatos en las rocas terciarias de la Guajira.  El uso de mapas paleogeográficos serán esenciales para delimitar la sedimentación y los cambios de facies de la secuencia terciaria. También, tales métodos serán útiles para localizar pequeñas cuencas antiguas de evaporitas, que seguramente existieron, y así, depósitos posibles de yeso, halita y otras sales

The “Mera” lahar deposit in the upper Amazon basin: Transformation of a late Pleistocene collapse at Huisla volcano, central Ecuador

Over the last years, project work in teams has become commonplace in organizations. Studies have indicated that the motivational climate in which teams operate is highly relevant in determining employee behavior. This study investigates the effect of motivational climates, as defined by goal setting theory, on collaboration in project teams. In a survey among 173 senior project members from different organizations, we found that congruence between performance and mastery climates is positively and significantly related to collaboration behavior in teams. Furthermore, we highlight the moderating role of prosocial motivation in the relationship between (in)congruence in motivational climates and collaboration. Specifically, we find that under conditions of low prosocial motivation, a focus on either a mastery or a performance climate is preferable to adopting a congruence between these two climates, at least in terms of collaboration in teams

Cambios en los dinamismos eruptivos durante las erupciones de larga duración: el caso de las erupciones del 2006 del volcán Tungurahua (Ecuador)

El seguimiento de los potenciales cambios en los dinamismos eruptivos que ocurren durante las erupciones de larga duración representa un gran reto para la vulcanología actual y constituye una etapa crucial del monitoreo volcánico y de la evaluación de la amenaza. En muchos volcanes, los períodos eruptivos son largos (del orden de varios años), tiempo durante el cual los volcanes presentan una actividad intermitente, sin llegar a experimentar erupciones explosivas importantes, como por ejemplo en el volcán Ubinas (Perú) que se reactivó en el 2006 y cuya actividad se extendió hasta el 2008 (Rivera et al., 2010). En otros casos, el tiempo entre el inicio de la erupción y el paroxismo eruptivo puede ser relativamente largo, del orden de meses o años. Este fue el caso del volcán Tungurahua (Ecuador) que se reactivó en 1999, y cuyo paroxismo se produjo 7 años después de iniciada la actividad eruptiva. La población que vive bajo la amenaza volcánica en el caso de erupciones de larga duración tiende a acostumbrarse a las nuevas condiciones impuestas por el volcán, lo cual puede comprometer seriamente su capacidad de reacción ante los cambios en el tipo de actividad eruptiva. Por tal motivo, es primordial tener un mejor entendimiento de las causas por las cuales ciertos volcanes se mantienen con niveles de actividad bajo a moderadamente explosivos, mientras que otros sufren una evolución hacia una actividad altamente explosiva. Los estudios integrales (geofísica, petrología, cronología eruptiva) realizados en el volcán Tungurahua, permiten aportar ciertos elementos de respuesta a ésta interrogante

Measurement of the mass and lifetime of the Ωb−\Omega_b^- baryon

A proton-proton collision data sample, corresponding to an integrated luminosity of 3 fb$^{-1}$ collected by LHCb at $\sqrt{s}=7$ and 8 TeV, is used to reconstruct $63\pm9$ $\Omega_b^-\to\Omega_c^0\pi^-$, $\Omega_c^0\to pK^-K^-\pi^+$ decays. Using the $\Xi_b^-\to\Xi_c^0\pi^-$, $\Xi_c^0\to pK^-K^-\pi^+$ decay mode for calibration, the lifetime ratio and absolute lifetime of the $\Omega_b^-$ baryon are measured to be \begin{align*} \frac{\tau_{\Omega_b^-}}{\tau_{\Xi_b^-}} &= 1.11\pm0.16\pm0.03, \\ \tau_{\Omega_b^-} &= 1.78\pm0.26\pm0.05\pm0.06~{\rm ps}, \end{align*} where the uncertainties are statistical, systematic and from the calibration mode (for $\tau_{\Omega_b^-}$ only). A measurement is also made of the mass difference, $m_{\Omega_b^-}-m_{\Xi_b^-}$, and the corresponding $\Omega_b^-$ mass, which yields \begin{align*} m_{\Omega_b^-}-m_{\Xi_b^-} &= 247.4\pm3.2\pm0.5~{\rm MeV}/c^2, \\ m_{\Omega_b^-} &= 6045.1\pm3.2\pm 0.5\pm0.6~{\rm MeV}/c^2. \end{align*} These results are consistent with previous measurements.Comment: 11 pages, 5 figures, All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-008.htm

Observation of two new Ξb−\Xi_b^- baryon resonances

Two structures are observed close to the kinematic threshold in the $\Xi_b^0 \pi^-$ mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb$^{-1}$ recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content $bds$ are expected in this mass region: the spin-parity $J^P = \frac{1}{2}^+$ and $J^P=\frac{3}{2}^+$ states, denoted $\Xi_b^{\prime -}$ and $\Xi_b^{*-}$. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be $m(\Xi_b^{\prime -}) - m(\Xi_b^0) - m(\pi^{-}) = 3.653 \pm 0.018 \pm 0.006$ MeV$/c^2$, $m(\Xi_b^{*-}) - m(\Xi_b^0) - m(\pi^{-}) = 23.96 \pm 0.12 \pm 0.06$ MeV$/c^2$, $\Gamma(\Xi_b^{*-}) = 1.65 \pm 0.31 \pm 0.10$ MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of $\Gamma(\Xi_b^{\prime -}) < 0.08$ MeV at 95% confidence level. Relative production rates of these states are also reported.Comment: 17 pages, 2 figure

Constraints on the unitarity triangle angle γ\gamma from Dalitz plot analysis of B0→DK+π−B^0 \to D K^+ \pi^- decays

The first study is presented of CP violation with an amplitude analysis of the Dalitz plot of $B^0 \to D K^+ \pi^-$ decays, with $D \to K^+ \pi^-$, $K^+ K^-$ and $\pi^+ \pi^-$. The analysis is based on a data sample corresponding to $3.0\,{\rm fb}^{-1}$ of $pp$ collisions collected with the LHCb detector. No significant CP violation effect is seen, and constraints are placed on the angle $\gamma$ of the unitarity triangle formed from elements of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Hadronic parameters associated with the $B^0 \to D K^*(892)^0$ decay are determined for the first time. These measurements can be used to improve the sensitivity to $\gamma$ of existing and future studies of the $B^0 \to D K^*(892)^0$ decay.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-059.html; updated to correct figure 9 (numerical results unchanged

Observation of the Bs0→J/ψϕϕB_s^0 \rightarrow J/\psi \phi \phi decay

The $B_s^0 \rightarrow J/\psi \phi \phi$ decay is observed in $pp$ collision data corresponding to an integrated luminosity of 3 fb$^{-1}$ recorded by the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV. This is the first observation of this decay channel, with a statistical significance of 15 standard deviations. The mass of the $B_s^0$ meson is measured to be $5367.08\,\pm \,0.38\,\pm\, 0.15$ MeV/c$^2$. The branching fraction ratio $\mathcal{B}(B_s^0 \rightarrow J/\psi \phi \phi)/\mathcal{B}(B_s^0 \rightarrow J/\psi \phi)$ is measured to be 0.0115\,\pm\, 0.0012\, ^{+0.0005}_{-0.0009}. In both cases, the first uncertainty is statistical and the second is systematic. No evidence for non-resonant $B_s^0 \rightarrow J/\psi \phi K^+ K^-$ or $B_s^0 \rightarrow J/\psi K^+ K^- K^+ K^-$ decays is found.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-033.htm

Search for hidden-sector bosons in B0 ⁣→K∗0μ+μ−B^0 \!\to K^{*0}\mu^+\mu^- decays

A search is presented for hidden-sector bosons, $\chi$, produced in the decay ${B^0\!\to K^*(892)^0\chi}$, with $K^*(892)^0\!\to K^{+}\pi^{-}$ and $\chi\!\to\mu^+\mu^-$. The search is performed using $pp$-collision data corresponding to 3.0 fb$^{-1}$ collected with the LHCb detector. No significant signal is observed in the accessible mass range $214 \leq m({\chi}) \leq 4350$ MeV, and upper limits are placed on the branching fraction product $\mathcal{B}(B^0\!\to K^*(892)^0\chi)\times\mathcal{B}(\chi\!\to\mu^+\mu^-)$ as a function of the mass and lifetime of the $\chi$ boson. These limits are of the order of $10^{-9}$ for $\chi$ lifetimes less than 100 ps over most of the $m(\chi)$ range, and place the most stringent constraints to date on many theories that predict the existence of additional low-mass bosons.Comment: All figures and tables, along with supplementary material, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-036.htm