Marine accumulations of terrigenous sediment are widely assumed to accurately record climatic- and tectonic-controlled mountain denudation and play an important role in understanding late Cenozoic mountain uplift and global cooling. Underpinning this is the assumption that the majority of sediment eroded from hinterland orogenic belts is transported to and ultimately stored in marine basins with little lag between erosion and deposition. Here we use a detailed and multi-technique sedimentary provenance dataset from the Yellow River to show that substantial amounts of sediment eroded from Northeast Tibet and carried by the river's upper reach are stored in the Chinese Loess Plateau and the western Mu Us desert. This finding revises our understanding of the origin of the Chinese Loess Plateau and provides a potential solution for mismatches between late Cenozoic terrestrial sedimentation and marine geochemistry records, as well as between global CO2 and erosion records.

The increase in detrital geochronological data presents challenges to existing approaches to data visualization and comparison, and highlights the need for quantitative techniques able to evaluate and compare multiple large data sets. We test five metrics commonly used as quantitative descriptors of sample similarity in detrital geochronology: the Kolmogorov-Smirnov (K-S) and Kuiper tests, as well as Cross-correlation, Likeness, and Similarity coefficients of probability density plots (PDPs), kernel density estimates (KDEs), and locally adaptive, variable-bandwidth KDEs (LA-KDEs). We assess these metrics by applying them to 20 large synthetic data sets and one large empirical data set, and evaluate their utility in terms of sample similarity based on the following three criteria. (1) Similarity of samples from the same population should systematically increase with increasing sample size. (2) Metrics should maximize sensitivity by using the full range of possible coefficients. (3) Metrics should minimize artifacts resulting from sample-specific complexity. K-S and Kuiper test p-values passed only one criterion, indicating that they are poorly suited as quantitative descriptors of sample similarity. Likeness and Similarity coefficients of PDPs, as well as K-S and Kuiper test D and V values, performed better by passing two of the criteria. Cross-correlation of PDPs passed all three criteria. All coefficients calculated from KDEs and LA-KDEs failed at least two of the criteria. As hypothesis tests of derivation from a common source, individual K-S and Kuiper p-values too frequently reject the null hypothesis that samples come from a common source when they are identical. However, mean p-values calculated by repeated subsampling and comparison (minimum of 4 trials) consistently yield a binary discrimination of identical versus different source populations. Cross-correlation and Likeness of PDPs and Cross-correlation of KDEs yield the widest divergence in coefficients and thus a consistent discrimination between identical and different source populations, with Cross-correlation of PDPs requiring the smallest sample size. In light of this, we recommend acquisition of large detrital geochronology data sets for quantitative comparison. We also recommend repeated subsampling of detrital geochronology data sets and calculation of the mean and standard deviation of the comparison metric in order to capture the variability inherent in sampling a multimodal population. These statistical tools are implemented using DZstats, a MATLAB-based code that can be accessed via an executable file graphical user interface. It implements all of the statistical tests discussed in this paper, and exports the results both as spreadsheets and as graphic files.

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of 29 samples from the EasternCordillera of Colombia reveal the origin of northern Andean basement and patterns of sedimentation during Paleozoic subsidence, Jurassic-Early Cretaceous extension, Late Cretaceous postrift subsidence, and Cenozoic shortening and foreland-basin evolution. U-Pb geochronological results indicate that presumed Precambrian basement is mainly a product of early Paleozoic magmatism (520-420 Ma) potentially linked to subduction and possible collision. Inherited zircons provide evidence for Mesoproterozoic tectonomagmatic events at 1200-1000 Ma during Grenville-age orogenesis. Detrital zircon U-Pb ages for Paleozoic strata show derivation from Andean basement, syn depositional magmatic sources (420-380 Ma), and distal sources of chiefl y Mesoproterozoic basement (1650-900 Ma) in the Amazonian craton (Guyana shield) to the east or in possible continental terranes along the western margin of South America. Sedimentation during Jurassic-Early Cretaceous rifting is expressed in detrital zircon age spectra as Andean basement sources, recycled Paleozoic contributions, and igneous sources of Carboniferous-Permian (310-250 Ma) and Late Triassic-Early Jurassic (220-180 Ma) origin. Detrital zircon provenance during continued Cretaceous extension and postrift thermal subsidence recorded the elimination of Andean basement sources and increased infl uence of craton-derived drainage systems providing mainly Paleoproterozoic and Mesoproterozoic (2050-950 Ma) grains. By Eocene time, zircons from the Guyana shield (1850-1350 Ma) dominated the detrital signal in the easternmost Eastern Cordillera. In contrast, coeval Eocene deposits in the axial Eastern Cordillera contain Late Cretaceous-Paleocene (90-55 Ma), Jurassic (190-150 Ma), and limited Permian-Triassic (280-220 Ma) zircons recording initial uplift and exhumation of principally Mesozoic magmatic-arc rocks to the west in the Central Cordillera. Oligocene-Miocene sandstones of the proximal Llanos foreland basin document uplift-induced exhumation of the Eastern Cordillera fold-thrust belt and recycling of the Paleogene cover succession rich in both arc-derived detritus (dominantly 180-40 Ma) and shield-derived sediments (mostly 1850-950 Ma). Late Miocene-Pliocene erosion into the underlying Cretaceous section is evidenced by elimination of Mesozoic-Cenozoic zircons and increased proportions of 1650-900 Ma zircons emblematic of Cretaceous strata.

Despite recent advances in quantitative methods of detrital provenance analysis, there is currently no widely accepted method of unmixing detrital geochronology age distributions. We developed a model that determines mixing proportions for source samples through inverse Monte Carlo modeling, wherein mixed samples are compared to randomly generated combinations of source distributions, and a range of best mixing proportions are retained. Results may then be used to constrain a forward optimization routine to find a single best‐fit mixture. Quantitative comparison is based on the Kolmogorov‐Smirnov (KS) test D statistic and Kuiper test V statistic for cumulative distribution functions, and the Cross‐correlation coefficient for finite mixture distributions (probability density plots or kernel density estimates). We demonstrate the capacity of this model through a series of tests on synthetic data, and published empirical data from North America mixed in known proportions; this proof‐of‐concept testing shows the model is capable of accurately unmixing highly complex distributions. We apply the model to two published empirical data sets mixed in unknown proportions from Colombia and central China. Neither example yields perfect model fits, which provides a cautionary note of potentially inadequate characterization of source and/or mixed samples, and highlights the importance of such characterization for accurate interpretation of sediment provenance. Sample size appears to be a major control on mixture model results; small (n < 100) samples may lead to misinterpretation. The model is available as a MATLAB‐based stand‐alone executable (.exe file) graphical user interface.

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