Holocene sands of the Spanish Central System were exclusively derived from plutonic, middle-upper grade and low-grade metamorphic rocks. Modal composition of studied sands is mostly controlled by grain size and source area lithology. Thus, sands derived from slates and schists plot near the QR edge on the QFR diagram for all grain size fractions. Sands derived from granitic or gneissic rocks have a wide dispersion on the QFR diagram, from the R pole to the QF edge, depending on sand grain size. Percentages of quartz types in granitic-derived sands are Qnu 42 , Qu 40 , Qp2–3 14 and Qp > 3 4 . Sands of gneissic origin have Qnu 51 , Qu 15 , Qp2–3 23 and Qp > 3 11 . Sands derived from slates and schists have Qnu 20 , Qu 12 , Qp2–3 5 and Qp > 3 63 . Quartz types easily discriminate sands of low-grade origin, but distinction of sands derived from plutonic rocks from those derived from middle-upper grade metamorphic rocks is difficult because of the highly variable Qu content of plutonic rocks related to strain history and crystallization conditions. Thus, quartz types must be used with caution in source discrimination if plutonic rocks are present in the source area.

Compositions of modern first-cycle sands derived from granitic and metamorphic terrains in the Spanish Central System have been analyzed in order to evaluate the contributions of different bedrock types. The results of this work indicate that sand composition normally does not permit quantitative statements concerning sourceland composition. This is due to the fact that each rock type has a different potential to generate sand, dependent on such properties as its mineralogy, average crystal size, and microfabric. We introduce the concept of sand generation index (SGI), which is a relative measure of the capacity of one bedrock type to generate sand with respect to another in a compound source area. SGI of granitoid is 14 to 20 times greater than SGI of slate-schist when these rock types appear in a dual crystalline source. In the case of a gneiss + slate-schist source rock association, the SGI of gneiss is about five times greater than the SGI of slate-schist, whereas the SGI of gneiss is similar to that of granitoid in case of a dual granitoid + gneiss source. Finally, our results show that quantitative estimates of source land composition based on QFR diagrams are hazardous if the concept of the SGI is disregarded. Palomares, M, and Arribas, J, 1993, Modern stream sands from compound crystalline sources: Composition and sand generation index, in Johnsson, M. J., and Basu, A., eds., Processes Controlling the Composition of Clastic Sediments: Boulder, Colorado, Geological Society of America Special Paper 284. 313 on June 13, 2015 specialpapers.gsapubs.org Downloaded from

Purpose The purpose of this paper is to explore the factors that influence the success of internal communication in Spanish companies, specifically the importance of the channels used, activities conducted through ISM and the role played by the communication professional. Design/methodology/approach The model employed argues that to obtain success in internal communication, three factors are considered necessary: first, communication professionals must participate in strategic decisions; second, they have to use together social media channel and classical channel to communicate with employees; and finally they must choose which activities they carry out during the use of social media. These elements are developed in the literature review. To research practices of internal digital communications and level of success of internal communication across types of organizations, a quantitative survey between professionals from Spanish companies was conducted. Findings The results revealed that the hierarchical level, participation in the strategic decision process and dedication of the communication practitioner, alongside with the use of face-to-face and online communication channels, and the perceived importance of communication activities conducted through social media platforms are the key factors that influence the quality of internal communication. However, no significant relationship between the level of success and the use of social media channels was found. Research limitations/implications The current study has several limitations that should be noted and addressed in future research. The main limitation lies in the fact that the dependent variable – success in communication – is entirely based on communication professionals’ perceptions. Replication studies can be conducted to cross-validate the results obtained from this study using business outcome metrics to measure the communication effectiveness. A further limitation is related to the sampling procedure. Obtaining a representative sample of communications professionals in Spanish companies poses a number of limitations due to the impossibility of having accurate data on the total population. Practical implications The findings of the current study provide important implications for public relations professionals on what (i.e. the content) and how to (i.e. the channels) communicate within an organization. In general, internal communicators should move from historical roles as information producers and distributors to advisory roles in strategic decision making. Additionally, the implementation and use of ISM should be carefully revaluated. Communication practitioners should examine and address the difficulties involved in choosing the correct channels, devoting the necessary time to their adequate management, analyzing employees’ feedback and improving the engagement. Originality/value The study shows that internal communication practices in Spanish companies are changing. The model used in this research can be applied in an individual organizat...

RESUMENLa sedimentación de la cuenca neógena del Guadalquivir entre las provincias de Cór-doba y Sevilla está formada por una potente sucesión margosa en la que se intercalan varias unidades arenosas que, de base a techo, se denominan: Arenas Basales, Arenas de Ubeda, Arenas del Guadalquivir, Arenas de Ecija, Arenas de Cuesta el Espino (todas ellas de edad Tortoniense superior), Arenas de Guadarcázar, Calcarenitas de Carmona (de edad Messiniense) y arenas pliocenas.Arenas Basales tienen una composición lítica, con alto porcentaje en fragmentos de roca metamórficos, y proceden de los complejos metamórficos del Macizo Hespérico paleozoico situado al N de la cuenca. Arenas del Guadalquivir y Arenas de Ecija están formadas por litoarenitas y sublitoarenitas cuyos fragmentos de roca son fundamentalmente carbonáti-coso En ambos casos, son arenas procedentes de orógenos reciclados; las primeras proceden de formaciones arenosas neógenas que afloran al N de la cuenca a causa de la retirada progresiva del mar neógeno de la cuenca del Guadalquivir. La unidad Arenas de Ecija procede de los mantos béticos emplazados al S de la cuenca en ese momento.Tanto la unidad Arenas Basales como Arenas del Guadalquivir son sedimentos originados en medios de plataforma continental y Arenas de Ecija está constituida por sedimentos originados en medio de abanicos submarinos.Por último, las Arenas de Guadarcázar y las arenas pliocenas son cuarzoarenitas y sublitoarenitas y proceden de la erosión de las formaciones infrayacentes. La alta madurez composicional y textural de Arenas de Guadarcázar se debe a que estas arenas han sido retrabajadas en un medio playero.La sucesión reflej~una etapa inicial con aportes de primer ciclo a partir de rocas metamórficas de cratón estable y una etapa posterior donde el área fuente es sedimento de orógeno reciclado.Al E de la cuenca, Arenas del Guadalquivir y Arenas de Ecija son litoarenitas y Arenas de Cuesta el Espino son sublitoarenitas. Las primeras proceden de orógenos reciclados mientras que las segundas proceden de bloque continental estable. La evolución composicional de las arenas en esta parte de la cuenca puede indicar una zona de borde de la misma.

RESUMENLa evolución de la red de drenaje y sus capturas en la depresión de Valverde del Majano, queda confirmada por las características texturales y composicionales de los depósitos fluviales y los perfiles de ríos y terrazas. El río Moros y Eresma presentan en la actualidad una disminución de madurez, debido a su encajamiento progresivo, mientras que los ríos residuales Balisa y Zorita sufren un estancamiento en su dinámica. Las oscilaciones en la madurez de los sedimentos están controladas en esta zona por cambios en las áreas fuente y en las pendientes de los canales, existiendo una asincronía en la evolución, en función del grado de rejuvenecimiento del canal y los cambios en la litología derivados de las capturas. Palabras clave: Capturas fluviales, sedimentos fluviales, madurez petrográfica, textura, composición. ABSTRACTDrainage pattern evolution and river captures in the Depression of Valverde del Majano (Segovia) has been confirmed by textural and compositional analysis of their fluvial deposits and longitudinal profiles. Moros and Eresma rivers show at present a diminish of their maturity due to renewed entrenchment, while Zorita and Balisa ones present little developement. Petrographical maturity changes are controlled in this case mainly by river slope and source areas changes. An asynchronical evolution, depending on channel stage of rejuvenation and lithological changes caused by headwaters piracy, has been established.