scholarly journals Interpreting large detrital geochronology data sets in retroarc foreland basins: An example from the Magallanes-Austral Basin, southernmost Patagonia

Lithosphere ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 620-642 ◽  
Author(s):  
Zachary T. Sickmann ◽  
Theresa M. Schwartz ◽  
Matthew A. Malkowski ◽  
Stephen C. Dobbs ◽  
Stephan A. Graham
Keyword(s):  
Multidimensional Scaling ◽  
Detrital Zircon ◽  
Foreland Basin ◽  
Data Sets ◽  
Foreland Basins ◽  
Dispersal Patterns ◽  
Data Set ◽  
Sediment Dispersal ◽  
Source Regions ◽  
Provenance Data

Abstract The Magallanes-Austral retroarc foreland basin of southernmost South America presents an excellent setting in which to examine interpretive methods for large detrital zircon data sets. The source regions for retroarc foreland basins generally, and the Magallanes-Austral Basin specifically, can be broadly divided into (1) the magmatic arc, (2) the fold-and-thrust belt, and (3) sources around the periphery of foreland flexural subsidence. In this study, we used an extensive detrital zircon data set (30 new, 87 previously published samples) that is complemented by a large modal provenance data set of 183 sandstone petrography samples (32 new, 151 previously published) and rare earth element geochemical analyses (130 previously published samples) to compare the results of empirical (multidimensional scaling) and interpretive (age binning based on source regions) treatments of detrital zircon data, ultimately to interpret the detailed evolution of sediment dispersal patterns and their tectonic controls in the Magallanes-Austral Basin. Detrital zircon sample groupings based on both a priori age binning and multidimensional scaling are required to maximize the potential of the Magallanes-Austral Basin data set. Multidimensional scaling results are sensitive to differences in major unimodal arc-related U-Pb detrital zircon ages and less sensitive to differences in multimodal, thrust belt–related age peaks. These sensitivities complicate basin-scale interpretations when data from poorly understood, less densely sampled sectors are compared to data from better-understood, more densely sampled sectors. Source region age binning alleviates these biases and compares well with multidimensional scaling results when samples from the less well-understood southern basin sector are excluded. Sample groupings generated by both multidimensional scaling and interpretive methods are also compatible with compositional provenance data. Together, this integration of provenance data and methods facilitates a detailed interpretation of sediment dispersal patterns and their tectonic controls for the Late Cretaceous to Eocene fill of the Magallanes-Austral retroarc foreland basin. We interpret that provenance signatures and dispersal patterns during the retroarc foreland phase were fundamentally controlled by conditions set by a predecessor extensional basin phase, including (1) variable magnitude of extension with latitude, (2) the composition of lithologies emplaced on the antecedent western flank, and (3) long-lasting structural discontinuities associated with early rifting that may have partitioned dispersal systems or controlled the location of long-lived drainage networks.

DETRITAL ZIRCON PROVENANCE OF THE DENVER BASIN: EVOLVING SEDIMENT DISPERSAL PATTERNS DURING THE LARAMIDE OROGENY

2016 ◽  
Author(s):  
Viridis M. Miranda Berrocales ◽  
◽  
Glenn R. Sharman ◽  
Jacob A. Covault ◽  
Daniel F. Stockli
Keyword(s):  
Detrital Zircon ◽  
Denver Basin ◽  
Dispersal Patterns ◽  
Sediment Dispersal ◽  
Laramide Orogeny

scholarly journals Tectonic influence on axial-transverse sediment routing in the Denver Basin

2022 ◽  
Author(s):  
Glenn R. Sharman ◽  
Daniel F. Stockli ◽  
Peter Flaig ◽  
Robert G. Raynolds ◽  
Marieke Dechesne ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Detrital Zircon ◽  
Foreland Basin ◽  
The Other ◽  
Front Range ◽  
Denver Basin ◽  
Dispersal Patterns ◽  
Magmatic Arc ◽  
Sedimentary Sequences ◽  
Basin Fill

ABSTRACT Detrital zircon U-Pb and (U-Th)/He ages from latest Cretaceous–Eocene strata of the Denver Basin provide novel insights into evolving sediment sourcing, recycling, and dispersal patterns during deposition in an intracontinental foreland basin. In total, 2464 U-Pb and 78 (U-Th)/He analyses of detrital zircons from 21 sandstone samples are presented from outcrop and drill core in the proximal and distal portions of the Denver Basin. Upper Cretaceous samples that predate uplift of the southern Front Range during the Laramide orogeny (Pierre Shale, Fox Hills Sandstone, and Laramie Formation) contain prominent Late Cretaceous (84–77 Ma), Jurassic (169–163 Ma), and Proterozoic (1.69–1.68 Ga) U-Pb ages, along with less abundant Paleozoic through Archean zircon grain ages. These grain ages are consistent with sources in the western U.S. Cordillera, including the Mesozoic Cordilleran magmatic arc and Yavapai-Mazatzal basement, with lesser contributions of Grenville and Appalachian zircon recycled from older sedimentary sequences. Mesozoic zircon (U-Th)/He ages confirm Cordilleran sources and/or recycling from the Sevier orogenic hinterland. Five of the 11 samples from syn-Laramide basin fill (latest Cretaceous–Paleocene D1 Sequence) and all five samples from the overlying Eocene D2 Sequence are dominated by 1.1–1.05 Ga zircon ages that are interpreted to reflect local derivation from the ca. 1.1 Ga Pikes Peak batholith. Corresponding late Mesoproterozoic to early Neoproterozoic zircon (U-Th)/He ages are consistent with local sourcing from the southern Front Range that underwent limited Mesozoic–Cenozoic unroofing. The other six samples from the D1 Sequence yielded detrital zircon U-Pb ages similar to pre-Laramide units, with major U-Pb age peaks at ca. 1.7 and 1.4 Ga but lacking the 1.1 Ga age peak found in the other syn-Laramide samples. One of these samples yielded abundant Mesozoic and Paleozoic (U-Th)/He ages, including prominent Early and Late Cretaceous peaks. We propose that fill of the Denver Basin represents the interplay between locally derived sediment delivered by transverse drainages that emanated from the southern Front Range and a previously unrecognized, possibly extraregional, axial-fluvial system. Transverse alluvial-fluvial fans, preserved in proximal basin fill, record progressive unroofing of southern Front Range basement during D1 and D2 Sequence deposition. Deposits of the upper and lower D1 Sequence across the basin were derived from these fans that emanated from the southern Front Range. However, the finer-grained, middle portion of the D1 Sequence that spans the Cretaceous-Paleogene boundary was deposited by both transverse (proximal basin fill) and axial (distal basin fill) fluvial systems that exhibit contrasting provenance signatures. Although both tectonic and climatic controls likely influenced the stratigraphic development of the Denver Basin, the migration of locally derived fans toward and then away from the thrust front suggests that uplift of the southern Front Range may have peaked at approximately the Cretaceous-Paleogene boundary.

Weber's Ratio, Multidimensional Scaling and Incomplete Data Sets: New Light on an Old Problem

1988 ◽  
Vol 32 (17) ◽  
pp. 1183-1187
Author(s):  
J. G. Kreifeldt ◽  
S. H. Levine ◽  
M. C. Chuang
Keyword(s):  
Multidimensional Scaling ◽  
Incomplete Data ◽  
Data Sets ◽  
Observation Data ◽  
Data Set ◽  
New Approach ◽  
Sensory Modalities ◽  
Minimal Difference ◽  
Typical Measurement ◽  
Measurement Context

Sensory modalities exhibit a characteristic known as Weber's ratio which remarks that when two stimuli are compared for a difference: (1) there is some minimal nonzero difference which can be differentiated and (2) this minimal difference is a nearly constant proportion of the magnitude of the stimuli. Both of these would, in a typical measurement context, appear to be system defects. We have found through simulation explorations that in fact these are apparently the characteristics required by a system designed to extract an adequate amount of information from an incomplete observation data set according to a new approach to measurement.

scholarly journals Detrital zircon provenance record of the Zagros mountain building from the Neotethys obduction to the Arabia-Eurasia collision, NW Zagros fold-thrust belt, Kurdistan region of Iraq

2021 ◽  
Author(s):  
Renas I. Koshnaw ◽  
Fritz Schlunegger ◽  
Daniel F. Stockli
Keyword(s):  
Detrital Zircon ◽  
Upper Cretaceous ◽  
Foreland Basin ◽  
Source Area ◽  
Late Eocene ◽  
Thrust Belt ◽  
Kurdistan Region ◽  
Angular Unconformity ◽  
Tectonic Processes ◽  
Provenance Data

Abstract. Recognition of new angular unconformity and synthesizing of new detrital zircon U-Pb and (U-Th)/He provenance records, including zircon (U-Th)/(He-Pb) double dating, from the NW Zagros elucidate the basin dynamics of the foreland wedge-top and intermontane units, as well as the tectonic processes in the source terranes in response to different geodynamic phases. In this contribution, we present field observations and detrital zircon provenance data from hinterland basins to reconstruct the basin dynamics and the underlying tectonic controls in the NW Zagros in the Kurdistan region of Iraq. Results reveal that the deposition of the suture zone units of the Red Beds Series (RBS; Suwais Group, Govanda Formation, Merga Group) occurred in an intermontane basin on top of folded Upper Cretaceous units with an angular unconformity. The RBS provenance data point at the Paleogene Walash-Naopurdan-Kamyaran (WNK) arc-related complex as a source area and show substantial decrease of magmatism by ~ 36 Ma, as reflected by the youngest ages peaks. New detrital zircon provenance data from the hinterland wedge-top units of the proto-Zagros foreland basin (the Tanjero, Kolosh, and Gercus Formations) exhibit exclusive derivation from the Upper Cretaceous Neotethys ophiolitic terranes, different from the provenance of the older Lower Cretaceous and Paleozoic units that are dominated by the Paleozoic and Neoproterozoic age spectra. These shifts in provenance between different tectonostratigraphic units argue for sediment route reversal from E to W in response to ophiolite obduction, arrival of the WNK complex and commencement of the continental collision during the late Eocene, followed by deposition of the RBS in the hinterland of the proto-Zagros fold-thrust belt, and paleodrainage connection with the post-collisional Neogene foreland basin.

scholarly journals Along-strike variations in sediment provenance within the Nanaimo basin reveal mechanisms of forearc basin sediment influx events

Lithosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 180-197 ◽  
Author(s):  
Daniel S. Coutts ◽  
William A. Matthews ◽  
Rebecca G. Englert ◽  
Morgan D. Brooks ◽  
Marie-Pier Boivin ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Coarse Grained ◽  
Sediment Provenance ◽  
Data Set ◽  
Coast Mountains ◽  
The North ◽  
Provenance Data ◽  
Thrust System ◽  
Spatio Temporal ◽  
Forearc Basins

Abstract The along-strike variability in sediment provenance within the Nanaimo basin is important for understanding the tectonic evolution of North America’s Late Cretaceous Pacific margin, providing context for paleogeographic reconstructions. Here, we provide 35 point-counted sandstone samples and 22 new detrital zircon samples from the Nanaimo basin. These new detrital zircon samples compose a portion of a basin-wide data set (N = 49, n = 10,942) that is leveraged to discern spatio-temporal changes in sediment provenance. Provenance data demonstrates that the majority of Nanaimo basin strata were sourced from regions within and east of the Coast Mountains Batholith, while only the southernmost Nanaimo basin, exposed in the San Juan Islands, was supplied sediment from the North Cascade thrust system. Additionally, near-identical age modes and synchronous changes in detrital zircon facies are used to hypothesize a correlation between the Nanaimo Group and the protolith of the Swakane Gneiss. These observations, along with previously identified events in the Cordillera, are used to define two basin-wide events that affected the Nanaimo basin: the first at 84 Ma and the second at 72 Ma. The first event is correlated to the onset of Kula-Farallon spreading, which affected basin subsidence, introduced Proterozoic detrital zircon to the central and southern Nanaimo basin, and uplifted the North Cascade thrust system. The second basin-wide event, which is speculated to have been driven by increased rates of subduction and obliquity, resulted in localized high-flux events in the arc, increased exhumation of the Cascade Crystalline Core, underplating of the Swakane Gneiss, and coarse-grained sedimentation across the basin. The data presented here provides added context for the evolution of the basin and provides insight into the protracted geodynamics of forearc basins undergoing oblique subduction.

scholarly journals Application of spectral analysis techniques to the intercomparison of aerosol data – Part 4: Synthesized analysis of multisensor satellite and ground-based AOD measurements using combined maximum covariance analysis

2014 ◽  
Vol 7 (8) ◽  
pp. 2531-2549 ◽  
Author(s):  
J. Li ◽  
B. E. Carlson ◽  
A. A. Lacis
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Satellite Data ◽  
Covariance Analysis ◽  
Data Sets ◽  
Data Set ◽  
Maximum Covariance Analysis ◽  
Source Regions ◽  
Cross Covariance ◽  
Aerosol Source

Abstract. In this paper, we introduce the usage of a newly developed spectral decomposition technique – combined maximum covariance analysis (CMCA) – in the spatiotemporal comparison of four satellite data sets and ground-based observations of aerosol optical depth (AOD). This technique is based on commonly used principal component analysis (PCA) and maximum covariance analysis (MCA). By decomposing the cross-covariance matrix between the joint satellite data field and Aerosol Robotic Network (AERONET) station data, both parallel comparison across different satellite data sets and the evaluation of the satellite data against the AERONET measurements are simultaneously realized. We show that this new method not only confirms the seasonal and interannual variability of aerosol optical depth, aerosol-source regions and events represented by different satellite data sets, but also identifies the strengths and weaknesses of each data set in capturing the variability associated with sources, events or aerosol types. Furthermore, by examining the spread of the spatial modes of different satellite fields, regions with the largest uncertainties in aerosol observation are identified. We also present two regional case studies that respectively demonstrate the capability of the CMCA technique in assessing the representation of an extreme event in different data sets, and in evaluating the performance of different data sets on seasonal and interannual timescales. Global results indicate that different data sets agree qualitatively for major aerosol-source regions. Discrepancies are mostly found over the Sahel, India, eastern and southeastern Asia. Results for eastern Europe suggest that the intense wildfire event in Russia during summer 2010 was less well-represented by SeaWiFS (Sea-viewing Wide Field-of-view Sensor) and OMI (Ozone Monitoring Instrument), which might be due to misclassification of smoke plumes as clouds. Analysis for the Indian subcontinent shows that here SeaWiFS agrees best with AERONET in terms of seasonality for both the Gangetic Basin and southern India, while on interannual timescales it has the poorest agreement.

scholarly journals Mesoproterozoic−Early Cretaceous provenance and paleogeographic evolution of the Northern Rocky Mountains: Insights from the detrital zircon record of the Bridger Range, Montana, USA

2020 ◽  
Author(s):  
Chance B. Ronemus ◽  
Devon A. Orme ◽  
Saré Campbell ◽  
Sophie R. Black ◽  
John Cook
Keyword(s):  
Early Cretaceous ◽  
Detrital Zircon ◽  
Foreland Basin ◽  
Mountain Range ◽  
Thrust Belt ◽  
Sediment Sources ◽  
Middle Cambrian ◽  
Sediment Dispersal ◽  
Northern Rocky Mountains ◽  
Basin System

The Bridger Range of southwest Montana, USA, preserves one of the most temporally extensive sedimentary sections in North America, with strata ranging from Mesoproterozoic to Cretaceous in age. This study presents new detrital zircon geochronologic data from eight samples collected across this mountain range. Multidimensional scaling and non-negative matrix factorization statistical analyses are used to quantitatively unmix potential sediment sources from these and 54 samples compiled from previous studies on regional correlative strata. We interpret these sources based on reference data from preserved strata with detrital zircon signatures likely representative of ancient sediment sources. We link these sources to their sinks along sediment dispersal pathways interpreted using available paleogeographic constraints. Our results show that Mesoproterozoic strata in southwest Montana contain detritus derived from the nearby craton exposed along the southern margin of the fault-bounded Helena Embayment. Middle Cambrian strata were dominated by the recycling of local sources eroded during the development of the Great Unconformity. In Devonian−Pennsylvanian time, provenance in southwest Montana shifted to more distal sources along the northeastern to southeastern margins of Laurentia, but more western basins received detritus from outboard sources along a tectonically complicated margin. By the Late Jurassic, provenance in the developing retroarc foreland basin system was dominated by Cordilleran magmatic arcs and fold-thrust belt sources to the west. Eastward propagation of the fold-thrust belt caused recycling of Paleozoic and Jurassic detritus into the foreland basin to dominate by the Early Cretaceous.

scholarly journals Detrital Zircon Provenance and Lithofacies Associations of Montmorillonitic Sands in the Maastrichtian Ripley Formation: Implications for Mississippi Embayment Paleodrainage Patterns and Paleogeography

Geosciences ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 80
Author(s):  
Jennifer N. Gifford ◽  
Elizabeth J. Vitale ◽  
Brian F. Platt ◽  
David H. Malone ◽  
Inoka H. Widanagamage
Keyword(s):  
Mississippi River ◽  
Detrital Zircon ◽  
Drainage System ◽  
Clay Mineralogy ◽  
Foreland Basin ◽  
Mississippi Embayment ◽  
Fluvial Systems ◽  
Source Regions ◽  
Cretaceous Volcanism ◽  
Appalachian Foreland

We provide new detrital zircon evidence to support a Maastrichtian age for the establishment of the present-day Mississippi River drainage system. Fieldwork conducted in Pontotoc County, Mississippi, targeted two sites containing montmorillonitic sand in the Maastrichtian Ripley Formation. U-Pb detrital zircon (DZ) ages from these sands (n = 649) ranged from Mesoarchean (~2870 Ma) to Pennsylvanian (~305 Ma) and contained ~91% Appalachian-derived grains, including Appalachian–Ouachita, Gondwanan Terranes, and Grenville source terranes. Other minor source regions include the Mid-Continent Granite–Rhyolite Province, Yavapai–Mazatzal, Trans-Hudson/Penokean, and Superior. This indicates that sediment sourced from the Appalachian Foreland Basin (with very minor input from a northern or northwestern source) was being routed through the Mississippi Embayment (MSE) in the Maastrichtian. We recognize six lithofacies in the field areas interpreted as barrier island to shelf environments. Statistically significant differences between DZ populations and clay mineralogy from both sites indicate that two distinct fluvial systems emptied into a shared back-barrier setting, which experienced volcanic ash input. The stratigraphic positions of the montmorillonitic sands suggest that these deposits represent some of the youngest Late Cretaceous volcanism in the MSE.

scholarly journals A visual approach for analysis and inference of molecular activity spaces

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Samina Kausar ◽  
Andre O. Falcao
Keyword(s):  
Multidimensional Scaling ◽  
Dimensionality Reduction ◽  
Biological Evaluation ◽  
Classification Model ◽  
Data Sets ◽  
Similarity Matrix ◽  
Data Set ◽  
Structure Activity ◽  
Reference Space ◽  
Sammon Mapping

Abstract Background Molecular space visualization can help to explore the diversity of large heterogeneous chemical data, which ultimately may increase the understanding of structure-activity relationships (SAR) in drug discovery projects. Visual SAR analysis can therefore be useful for library design, chemical classification for their biological evaluation and virtual screening for the selection of compounds for synthesis or in vitro testing. As such, computational approaches for molecular space visualization have become an important issue in cheminformatics research. The proposed approach uses molecular similarity as the sole input for computing a probabilistic surface of molecular activity (PSMA). This similarity matrix is transformed in 2D using different dimension reduction algorithms (Principal Coordinates Analysis ( PCooA), Kruskal multidimensional scaling, Sammon mapping and t-SNE). From this projection, a kernel density function is applied to compute the probability of activity for each coordinate in the new projected space. Results This methodology was tested over four different quantitative structure-activity relationship (QSAR) binary classification data sets and the PSMAs were computed for each. The generated maps showed internal consistency with active molecules grouped together for all data sets and all dimensionality reduction algorithms. To validate the quality of the generated maps, the 2D coordinates of test molecules were computed into the new reference space using a data transformation matrix. In total sixteen PSMAs were built, and their performance was assessed using the Area Under Curve (AUC) and the Matthews Coefficient Correlation (MCC). For the best projections for each data set, AUC testing results ranged from 0.87 to 0.98 and the MCC scores ranged from 0.33 to 0.77, suggesting this methodology can validly capture the complexities of the molecular activity space. All four mapping functions provided generally good results yet the overall performance of PCooA and t-SNE was slightly better than Sammon mapping and Kruskal multidimensional scaling. Conclusions Our result showed that by using an appropriate combination of metric space representation and dimensionality reduction applied over metric spaces it is possible to produce a visual PSMA for which its consistency has been validated by using this map as a classification model. The produced maps can be used as prediction tools as it is simple to project any molecule into this new reference space as long as the similarities to the molecules used to compute the initial similarity matrix can be computed.

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