Major Element Composition of Sediments in Terms of Weathering and Provenance: Implications for Crustal Recycling

The elemental composition of a sediment is set by the composition of its protolithand modified by weathering, sorting, and diagenesis. An important problem is deconvolving these contributions to a sediment’s composition to arrive at information about processesthat operate on the Earth’s surface. We approach this problem by developing a predictive andinvertible model of sedimentary major-element composition. We compile a dataset of sedimentary rock, river sediment, soil, and igneous rock compositions. Principal componentanalysis of the dataset shows that most variation can be simplified to a small number of variables. We thus show that any sediment’s composition can be described with just two vectorsof igneous evolution and weathering. We hence define a model for sedimentary compositionas a combination of these processes. A 1:1 correspondence is observed between predictionsand independent data. The log-ratios ln(K 2 O/MgO) and ln(Al 2 O 3 /Na 2 O) are found to besimple proxies for respectively the model’s protolith and weathering indices. Significant deviations from the model can be explained by sodium-calcium exchange. Using this approach,we show that the major-element composition of the upper continental crust has been modified by weathering and we calculate the amount of each element that it must have lost tomodify it to its present composition. By extrapolating modern weathering rates over the ageof the crust we conclude that it has not retained a significant amount of the necessarily produced weathering restite. This restite has likely been subducted into the mantle, indicating acrust-to-mantle recycling rate of 1.33 ± 0.89 × 10 13 kg yr −1 .</p

Scale‐dependent flow directions of rivers and the importance of subplate support

Large rivers play crucial roles in determining locations of civilization, biodiversity, and efflux to the oceans. The paths they take across Earth's surface vary with scale. At long‐wavelengths rivers can have simple flow paths. At smaller scales, in meanders for example, their paths change rapidly as a consequence of lithology, biota, and other environmental variables. It is not straightforward to identify the scales at which river planforms are set. We overcome these issues by developing a spectral (wavelet) methodology to map flow‐directions as a function of distance and scale. This methodology allows short‐wavelength features (e.g., meanders) to be filtered from river flow‐paths. With short‐wavelength structure removed, the flow‐directions of rivers in Western USA correlate with long‐wavelength gravity anomalies suggesting control by subplate support. This relationship is replicated by an ensemble of landscape evolution models. These results combined suggest that drainage at large scales, O(103) km, is set by subplate support

Multidimensional Scaling of Varietal Data in Sedimentary Provenance Analysis

Varietal studies of sedimentary provenance use the properties of individual minerals or mineral groups. These are recorded as lists of numerical tables that can be difficult to interpret. Multidimensional Scaling (MDS) is a popular multivariate ordination technique for analyzing other types of provenance data based on, for example, detrital geochronology or petrography. Applying MDS to varietal data would allow them to be treated on an equal footing with those other provenance proxies. MDS requires a method to quantify the dissimilarity between two samples. This paper introduces three ways to do so. The first method (“treatment-by-row”) turns lists of (compositional) data tables into lists of vectors, using principal component analysis. These lists of vectors can then be treated as “distributional” data and subjected to MDS analysis using dissimilarity measures such as the Kolmogorov-Smirnov statistic. The second method (“treatment-by-column”) turns lists of compositional data tables into multiple lists of vectors, each representing a single component of the varietal data. These multiple distributional data sets are subsequently subjected to Procrustes analysis or 3-way MDS. The third method uses the Wasserstein-2 distance to jointly compare the rows and columns of varietal data. This arguably makes the best use of the data but acts more like a “black box” than the other two methods. Applying the three methods to a detrital titanite data set from Colombia yields similar results. After converting varietal data to dissimilarity matrices, they can be combined with other types of provenance data, again using Procrustes analysis or 3-way MDS

The composition and weathering of the continents over geologic time

The composition of continental crust records the balance between construction by tectonics and destruction by physical and chemical erosion. Quantitative constraints on how igneous addition and chemical weathering have modified the continents’ bulk composition are essential for understanding the evolution of geodynamics and climate. Using novel data-analytic techniques we have extracted temporal trends in sediments’ protolith composition and weathering intensity from the largest available compilation of sedimentary major-element compositions: ∼ 15,000 samples from 4.0 Ga to the present. We find that the average Archean upper continental crust was silica rich and had a similar compositional diversity to modern continents. This is consistent with an early-Archean, or earlier, onset of plate tectonics. In the Archean, chemical weathering sequestered ∼ 25 % more CO2 per mass eroded for the same weathering intensity than in subsequent time periods, consistent with carbon mass-balance despite higher Archean outgassing rates and more limited continental exposure. Since 2.0 Ga, over long (> 0.5 Ga) timescales, crustal weathering intensity has remained relatively constant. On shorter timescales over the Phanerozoic, weathering intensity is correlated to global climate state, consistent with a weathering feedback acting in response to changes in CO2 sources or sinks

Comprehensive molecular characterization of the hippo signaling pathway in cancer

Hippo signaling has been recognized as a key tumor suppressor pathway. Here, we perform a comprehensive molecular characterization of 19 Hippo core genes in 9,125 tumor samples across 33 cancer types using multidimensional “omic” data from The Cancer Genome Atlas. We identify somatic drivers among Hippo genes and the related microRNA (miRNA) regulators, and using functional genomic approaches, we experimentally characterize YAP and TAZ mutation effects and miR-590 and miR-200a regulation for TAZ. Hippo pathway activity is best characterized by a YAP/TAZ transcriptional target signature of 22 genes, which shows robust prognostic power across cancer types. Our elastic-net integrated modeling further reveals cancer-type-specific pathway regulators and associated cancer drivers. Our results highlight the importance of Hippo signaling in squamous cell cancers, characterized by frequent amplification of YAP/TAZ, high expression heterogeneity, and significant prognostic patterns. This study represents a systems-biology approach to characterizing key cancer signaling pathways in the post-genomic era

Major Element Composition of Sediments in Terms of Weathering and Provenance: Implications for Crustal Recycling

The elemental composition of a sediment is set by the composition of its protolithand modified by weathering, sorting, and diagenesis. An important problem is deconvolving these contributions to a sediment’s composition to arrive at information about processesthat operate on the Earth’s surface. We approach this problem by developing a predictive andinvertible model of sedimentary major-element composition. We compile a dataset of sedimentary rock, river sediment, soil, and igneous rock compositions. Principal componentanalysis of the dataset shows that most variation can be simplified to a small number of variables. We thus show that any sediment’s composition can be described with just two vectorsof igneous evolution and weathering. We hence define a model for sedimentary compositionas a combination of these processes. A 1:1 correspondence is observed between predictionsand independent data. The log-ratios ln(K 2 O/MgO) and ln(Al 2 O 3 /Na 2 O) are found to besimple proxies for respectively the model’s protolith and weathering indices. Significant deviations from the model can be explained by sodium-calcium exchange. Using this approach,we show that the major-element composition of the upper continental crust has been modified by weathering and we calculate the amount of each element that it must have lost tomodify it to its present composition. By extrapolating modern weathering rates over the ageof the crust we conclude that it has not retained a significant amount of the necessarily produced weathering restite. This restite has likely been subducted into the mantle, indicating acrust-to-mantle recycling rate of 1.33 ± 0.89 × 10 13 kg yr −1 .</p

Entwicklung eines thermischen Verfahrens (Wirbelschichtverbrennung) zur umweltvertraeglichen Entsorgung von militaerischen Treibladungsmitteln

A thermal process for environmentally acceptable disposal of cartridge propellant powders on the basis of circulating fluidized bed combustion was developed and tested in the course of a state-funded project. The process, including preparation and feeding of the powders and underwater processing, was found to be reliable and safe. Experiments showed that emission ratings below the legal limiting value of 200 mg of nitrogen per cubic metre are possible with up to 20 per cent of cartridge propellant powder in the total fuel charge in optimized conditions with a solution of urea as fuel additive; no downstream catalytic denitrification system is required. (orig.)SIGLEAvailable from TIB Hannover: F95B800+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman