Growth of Neogene Andes linked to changes in plate convergence using high-resolution kinematic models.

The Andean cordillera was constructed during compressive tectonic events, whose causes and controls remain unclear. Exploring a possible link to plate convergence has been impeded by the coarse temporal resolution of existing plate kinematic models. Here we show that the Neogene evolution of the Andean margin is primarily related to changes in convergence as observed in new high-resolution plate reconstructions. Building on a compilation of plate finite rotations spanning the last 30 million years and using noise-mitigation techniques, we predict several short-term convergence changes that were unresolved in previous models. These changes are related to main tectono-magmatic events and require forces that are compatible with a range of geodynamic processes. These results allow to revise models of ongoing subduction orogeny at its type locality, emphasizing the role of upper plate deformation in the balance between kinematic energy associated with plate motion and gravitational potential energy stored in orogenic crustal roots.

Metal concentrations and source identification in Chilean public children's playgrounds.

This study is focused on four Biobio region cities, Concepcion, Talcahuano, Los Ángeles, and Tomé; these cities flourished very close to different industrial activities. We determined a pseudo total concentration of seven heavy metals (Cr, Ni, Cu, Zn, As, Cd, and Pb) in playground soils through inductively coupled plasma-mass spectrometry (ICP-MS). Principal components analysis (PCA) revealed that contamination in soils comes from three principal sources. Firstly, industrial and burning activities; secondly, the use of phytosanitary and chemical products; and thirdly, vehicular traffic emissions. Zn and Cu are the most abundant analyzed elements in all the playground's soils. Concepción reflected the lowest values of pollutants and Talcahuano the highest, reflecting the industrial effects. The average values of the analyzed elements were Cr = 32.90 mg kg-1; Ni = 23.76 mg kg-1; Cu = 31.51 mg kg-1; Zn = 63.69 mg kg-1; As = 19.51 mg kg-1; Cd = 0.50 mg kg-1; and Pb = 17.59 mg kg-1. Anomalously high values of some elements were found Cu = 462.73 mg kg-1, Zn = 364.39 mg kg-1, As = 34.7 mg kg-1 in Talcahuano, Cd = 1.6 mg kg-1 in Tome, and Pb = 55.59 mg kg-1 in Los Ángeles. Nevertheless, according to international guideline values of pollutants (VROM 2000 and ADEC 2010) there is no risk for children in any playground studied but all playgrounds are a potential risk for the environment. It points out the necessity to continue studying and monitoring Chilean urban playground to prevent health problems in the population. Graphical abstract.