Zoogeographical affinities and the use of vertebrates in Xochicalco (Morelos, Mexico)

Xochicalco is a Mesoamerican locality that developed after the fall of Teotihuacan, and became one of the most important urban, ceremonial and military communities of its time. Chronologically, it is situated in the Epiclassic period (700–900 A.D.) and its buildings show a marked hierarchical distribution. The site is located in the current State of Morelos (Mexico), embedded in the Mexican Transition Zone between the two major American zoogeographic regions: Nearctic and Neotropic. The animal remains identified show a mixed assemblage from both regions. With the aim of exploring the relationship between the zoogeographical affinities of identified fauna and differential uses due to the hierarchical distribution of the site, the data were processed using two multivariate analyses in order to find the animals that characterize each social level. This comparison shows that some animals are common to all the social levels, suggesting easy availability, while a few others, mainly from the Neotropic area, were associated only with the elite places suggesting their quality as social markers. This approach offers an initial hypothesis about the different cultural attitudes toward the animals in a Mesoamerican locality, little studied, showing a positive relationship between the zoogeographic affinity and the social hierarchy.     

Estimates of heat flow and heat production and a thermal model of the São Francisco craton

An updated analysis of geothermal data from the highland area of eastern Brazil has been carried out and the characteristics of regional variations in geothermal gradients and heat flow examined. The database employed includes results of geothermal measurements at 45 localities. The results indicate that the Salvador craton and the adjacent metamorphic fold belts northeastern parts of the study area are characterized by geothermal gradients in the range of 6–17°C/km. The estimated heat flow values fall in the range of 28–53 mW/m², with low values in the cratonic area relative to the fold belts. On the other hand, the São Francisco craton and the intracratonic São Francisco sedimentary basin in the southwestern parts are characterized by relatively higher gradient values, in the range of 14–42°C/km, with the corresponding heat flow values falling in the range of 36–89 mW/m². Maps of regional variations indicate that high heat flow anomaly in the São Francisco craton is limited to areas of sedimentary cover, to the west of the Espinhaço mountain belt. Crustal thermal models have been developed to examine the implications of the observed intracratonic variations in heat flow. The thermal models take into consideration variation of thermal conductivity with temperature as well as change of radiogenic heat generation with depth. Vertical distributions of seismic velocities were used in obtaining estimates of radiogenic heat production in crustal layers. Crustal temperatures are calculated based on a procedure that makes simultaneous use of the Kirchoff and Generalized Integral Transforms, providing thereby analytical solutions in 2D and 3D geometry. The results point to temperature variations of up to 300°C at the Moho depth, between the northern Salvador and southern São Francisco cratons. There are indications that differences in rheological properties, related to thermal field, are responsible for the contrasting styles of deformation patterns in the adjacent metamorphic fold belts.     

Periodic orbits of an electric charge in a magnetic dipole field

Periodic orbits in the Stormer problem are studied using the symmetry lines of the Poincaré map introduced by De Vogelaere. Many known facts are explained by mean of these lines. The dynamics of four special symmetry lines when the Stormer parameter ₁ changes is presented, and we obtain a clear global view of the structure of the simple periodic orbits and their bifurcations, including the asymmetrical ones. New asymmetrical multiple periodic orbits are obtained.     

Eta carinae nebulosities in 1963

The purpose of this note is to give further information regarding the positions of some condensations around Carinae in 1963, an epoch not yet considered in the literature. The new information is unable to confirm the deceleration hypothesis of theeir motion.     

The behavior of trace elements during schwertmannite precipitation and subsequent transformation into goethite and jarosite

Schwertmannite is a ubiquitous mineral formed from acid rock drainage (ARD), and plays a major role in controlling the water chemistry of many acid streams. The formation of schwertmannite was investigated in the acid discharge of the Monte Romero abandoned mine (Iberian Pyrite Belt, SW, Spain). Schwertmannite precipitated from supersaturated solutions mainly owing to the oxidation of Fe(II) to Fe(III) and transformed with time into goethite and jarosite. In a few hours, schwertmannite precipitation removed more than half of the arsenic load from solution, whereas the concentration of divalent trace metals (Zn, Cu, Pb, Cd, Ni, and Co) remained almost unchanged. In the laboratory, natural schwertmannite was kept in contact with its coexisting acid water in a flask with a solid-liquid mass ratio of 1:5 for 353 days. During this time, the pH of the solution dropped from 3.07 to 1.74 and the concentrations of sulfate and Fe increased. During the first 164 days, schwertmannite transformed into goethite plus H₃O-jarosite but, subsequently, goethite was the only mineral to form. Some of the trace elements, such as Al, Cu, Pb, and As were depleted in solution during the first stage as schwertmannite transformed into goethite plus H₃O-jarosite. On the contrary, the transformation of schwertmannite to goethite (with no jarosite) during the second stage released Al, Cu, and As to the solution. Despite the variation in their concentrations in solution, approximately 80% of the total Al and Cu inventories and more than 99% As and Pb remained in the solid phase throughout the entire aging process.     

The “El Pilote” fluorite skarn: A crucial deposit in the understanding and interpretation of the origin and mobilization of F from northern Mexico deposits

Fluorite deposits are widespread in northern Mexico and those deposits have traditionally been categorized as exclusively hydrothermal–magmatic in origin. Recently, two different fluorite-bearing type models have been proposed for the Northern Mexican deposits: (1) MVT-like deposits formed from basinal brines mobilized during the Laramide Orogeny (La Encantada deposit, Gonzalez-Partida et al., [Gonzalez-Partida, E., Carrillo-Chavez, A., Grimmer, J.O.W., Pironon, J., 2002. Petroleum-rich fluid inclusions in fluorite, Purisima mine, Coahuila, Mexico. International Geological Review 44 (8), 751–763.]; Tritlla et al., [Tritlla, J., Gonzalez-Partida, E., Levresse, G., Banks, D., Pironon, J., 2004. Fluorite deposits at Encantada-Buenavista, Mexico: products of Mississippi Valley type processes — a reply. Ore Geology Reviews 25, 329–332.]); and (2) fluorite-bearing skarns in close contact with rhyolite intrusives (Levinson, [Levinson, A.A., 1962. Beryllium–fluorine mineralization at Aguachile Mountain, Coahuila, Mexico. American Mineralogist 47, 67–75.]). The El Pilote fluorite deposit falls into the second category, and is the only known example of a magmatic-related fluorite deposit in the area. The fluorite trace-element patterns from both the El Pilote skarn and La Encantada MVT deposits display comparable and very low relative abundances as well as comparable chondrite-normalized REE patterns; this would suggest that the skarn F-source comes from the remobilization of a MVT fluorite manto.     

Modeling nonlinear seagrass clonal growth: Assessing the efficiency of space occupation across the seagrass flora

The clonal growth of 9 seagrass species was modeled using a simulation model based on observed clonal growth rules (i.e., spacer length, rhizome elongation rates, branching rates, branching angle) and shoot mortality rates for seagrass species. The results of the model confirmed the occurrence of complex, nonlinear growth of seagrass clones derived from internal dynamics of space occupation. The modeled clones progressed from a diffuse-limited aggregation (DLA), dendritic growth, identified with a guerrilla strategy of space occupation, to a compact (Eden) growth, comparable to the phalanx strategy of space occupation, once internal recolonization of gaps, left by dead shoots within the clone, begins. The time at which seagrass clones shifted from diffuse limited to compact growth was predictable from the branching angle and frequency of the species and varied from 1 yr to several decades among species. As a consequence the growth behavior and the apparent growth strategy of the species changes with the development of the clones. The results of the model demonstrate that the emergent complexity of seagrass clonal growth is contained within the simple set of growth rules that can be used to represent clonal growth.     

Daily Meteorological Observations in Cádiz – San Fernando. Analysis of the Documentary Sources and the Instrumental Data Content (1786–1996)

Meteorological observations in the city of Cádiz are acknowledged as having been made from the middle of the 18th century onwards although they were only recorded and preserved in documentary form from 1789 onwards. Data readings were taken at the new Naval Observatory in San Fernando, ten kilometres from Cádiz, from 1797 onwards. Continuous series for temperature and atmospheric pressure at a daily resolution have been compiled and constructed from 1817 until 1996. The data series is composed of thrice daily observations made at Cádiz (1821–1880) by local observers and hourly data from Naval Observatory at San Fernando (1870–1996).     

Spatial and temporal variation of the nekton and hyperbenthos from a temperate European estuary with regulated freshwater inflow

The aquatic macrofauna of the Guadalquivir estuary were sampled (1 mm mesh persiana net) at 5 sampling sites located along the entire (except the tidal freshwater region) estuarine gradient of salinity (outer 50 km). A total of 134 fish and macroinvertebrate species was collected but only 62 were considered common or regularly present in the estuary. Univariate measures of the community structure showed statistically significant differences among sampling sites: species richness, abundance, and biomass decreased in the upstream direction, being positively correlated with the salinity. Temporal differences of these three variables were also statistically significant. While a clear seasonal pattern (minimum densities in winter and maximum in spring-summer) was observed for abundance and biomass, no such pattern existed for the number of species. Mysids was the most dominant group throughout the estuary (96% to 99% of abundance; 49% to 85% of biomass), although fish biomass was also important at the outer estuary (36% to 38%). Multivariate analyses indicated highly significant spatial variation in the macrofaunal communities observed along the salinity gradient. These analyses suggest that the underlying structure was a continuum with more or less overlapping distributions of the species dependent on their ability to tolerate different physicochemical conditions. There were also significant temporal (intermonthly + interannual) variation of the estuarine community; the relative multivariate dispersion indicated that monthly variation was more considerable (relative multivariate dispersion >1) at the outer part of the estuary during the wet year (last 20 km) and was higher in the inner stations during the dry year (32 to 50 km from the river mouth). Since a clear negative exponential relationship was observed between the freshwater input (from a dam located 110 km upstream) and water salinity at all sampling stations, it is concluded that the human freshwater management is probably affecting the studied estuarine communities. While the higher seasonal (long-term) stability of the salinity gradient, due to the human control of the freshwater input, may facilitate the recruitment of marine species juveniles during the meteorologically unstable early-spring, the additional (short-term) salinity fluctuations during the warm period may negatively affect species that complete their lifecycle within the estuary.     

Alpujarride attribution of the supposed ‘Almagride Complex’ (Betic Internal Zone,Almerı́a Province,Spain)Appartenance Alpujarride du prétendu « Complexe almagride » (Zones internes bétiques,province d'Almeria,Espagne)

The differentiation of units in the Sierra de Almagro has been a source of controversy. There were defined the Almagride and Ballabona–Cucharón complexes, the former considered by several authors as part of a Subbetic metamorphosed and outcropping in a tectonic window. In this study, the units of Ballabona, Almagro and Cucharón are integrated into a single one, that of Tres Pacos, because they correspond to different parts of the same stratigraphic series. This unit is tectonically over the Nevado–Filabride Complex. The existence of the Almagride and Ballabona–Cucharón complexes is discarded and their units form part of the Alpujarride Complex. To cite this article: C. Sanz de Galdeano, F.J. Garc??a Tortosa, C. R. Geoscience 334 (2002) 355–362.