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Shaded relief map, created from light detection and ranging (LiDAR) digital elevation models (DEMs), of an area 12.6 km (7.8 mi) southeast of DeQuincy in Beauregard Parish, Louisiana, showing fault-line scarps (f1 and f2) displacing the surface of the Lissie Alloformation (Pil) and Prairie Allogroup (Pp), where f1 is an 8-m-high fault-line scarp displacing the dissected surface of the Lissie Alloformation, and f2 is a 1-m-high fault-line scarp displacing terrace surfaces of the Prairie Allogroup. Hua-Holocene alluvium.
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Prior to the early 1990s, nearly all surface faults recognized in south Louisiana were faults of the Baton Rouge system. Since then, the number of surface fault traces interpreted in the region has increased dramatically, owing to a combination of (1) application of traditional analysis of cues on topographic maps and aerial- photographic imagery o...
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... include those of Gagliano (2005), Gagliano et al. (2003aGagliano et al. ( , 2003b, Van Biersel (2006), and McCulloh (2008) (Fig. 7). As observed in southeast- ern Louisiana, LiDAR images show that in many parts of south- western Louisiana where faults transect adjacent younger and older Pleistocene units, younger units are displaced less ( Fig. 8; Heinrich, 2005c, his fi gures 2 and ...
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... There is visual evidence of building and road displacements along the BRF and other coastal faults with measured rate estimates of ∼3 mm/y (Hopkins et al., 2021;McCulloh, 2001). The BRF and DSF reactivated during the Pleistocene due to depositional loading (McCulloh & Heinrich, 2013). Shen et al. (2017) calculated mean fault throw rates in the eastern portion of the BRF using optically stimulated luminescence dating. ...
The Coast of Louisiana is affected by accelerating sea level rise compounded by land subsidence, leading to land loss. Vertical crustal motions in the region are caused by natural and anthropogenic processes that vary temporally and spatially across the Gulf of Mexico. We investigate the role of growth faulting contributions to subsidence in a case study of Baton Rouge, where two E‐W striking, down‐to‐the‐south normal faults, the Denham Springs and Baton Rouge faults, cut compacted Pleistocene strata, and where sediment compaction should be minimal. We used InSAR time series and LiDAR differencing data spanning 1999–2020 to quantify modern vertical and horizontal displacements. After calibration with GNSS data, both methods reveal similar spatial patterns in ground motion, with the faults delimiting areas with different absolute rates. On average the area north of the Baton Rouge fault is subsiding faster than the south, opposite to the long‐term sense of fault slip. LiDAR mean vertical rates range between −5 to −11 mm/y and −2.4 to −7 mm/y. InSAR time‐series mean rates in the LOS direction range between −10.9 to −13.6 mm/y and −8 to −10.6 mm/y, respectively, for the north and south areas. Subsidence in the northern area likely is controlled by groundwater level changes caused by pumping as indicated by groundwater extraction models. The southern area average is likely influenced by the injection of fluids. Our results suggest volumetric changes caused by fluid extraction and injection in regions separated by growth faults that are creeping to accommodate the spatial variations in subsidence.
... There is visual evidence of building and road displacements along the BRF and other coastal faults with measured rate estimates of ∼3 mm/y (Hopkins et al., 2021;McCulloh, 2001). The BRF and DSF reactivated during the Pleistocene due to depositional loading (McCulloh & Heinrich, 2013). Shen et al. (2017) calculated mean fault throw rates in the eastern portion of the BRF using optically stimulated luminescence dating. ...
The Coast of Louisiana is affected by accelerating sea level rise compounded by land subsidence, leading to land loss. Vertical crustal motions in the region are caused by natural and anthropogenic processes that vary temporally and spatially across the Gulf of Mexico. We investigate the role of growth faulting contributions to subsidence in a case study of Baton Rouge, where two E-W striking, down-to-the-south normal faults, the Denham Springs and Baton Rouge faults, cut compacted Pleistocene strata, and where sediment compaction should be minimal. We used InSAR time series and LiDAR differencing data spanning 1999-2020 to quantify modern vertical and horizontal displacements. After calibration with GNSS data, both methods reveal similar spatial patterns in ground motion, with the faults delimiting areas with different absolute rates. On average the area north of the Baton Rouge fault is subsiding faster than the south, opposite to the long-term sense of fault slip. LiDAR mean vertical rates range between -5 to -11 mm/y and -2.4 to -7 mm/y. InSAR time-series mean rates in the LOS direction range between -10.9 to -13.6 mm/y and -8 to -10.6 mm/y, respectively, for the north and south areas. Subsidence in the northern area likely is controlled by groundwater level changes caused by pumping as indicated by groundwater extraction models. The southern area average is likely influenced by the injection of fluids. Our results suggest volumetric changes caused by fluid extraction and injection in regions separated by growth faults that are creeping to accommodate the spatial variations in subsidence.
... We obtained Holocene succession thickness values ( Figure 1) from Heinrich et al. (2015) to examine their relationship to subsidence. Whether listric growth faults, which are widespread across the Mississippi Delta (e.g., Fisk, 1944;McCulloh & Heinrich, 2012), have been sufficiently active throughout the late Holocene to drive extensive land loss in the Mississippi Delta is currently a subject of much debate (Dokka et al., 2006;Frederick et al., 2019;Shen et al., 2017). The Lafourche bayhead delta is crosscut by several fault zones and growth faults including the Golden Meadow and Lake Hatch faults (Gagliano et al., 2003;Kuecher et al., 2001); we consider their potential contributions to subsidence by comparing subsidence at locations landward and seaward of the faults (Figure 1). ...
The ability of deltas to persist by building new land is critical to maintaining these vital ecologic environments that are often home to major economic and population centers. However, the deposition of land‐building sediment triggers load‐induced shallow subsidence which may undermine the effectiveness of natural and engineered emergent landforms. Here, we present a new method to quantify shallow subsidence in a 6,000–8,000 km² relict bayhead delta of the Mississippi Delta using the mouth bar to overbank stratigraphic boundary that formed near sea level, temporally constrained by optically stimulated luminescence dating. Vertical displacement rates at this boundary, averaged over 750–1,500 years, are on the order of a few mm/yr. Total subsidence scales to ∼50% of the thickness of overlying deposits, significantly greater than the 28%–35% loss estimated for inland localities underlain by peat, indicating that bay muds in the study area are more compaction‐prone than terrestrial organic‐rich deposits. Modeling shows a modest reduction of ∼13% in deltaic land‐area gain under a realistic compaction scenario for 1,000 years of simulated delta progradation, compared to a no‐compaction scenario. Our findings indicate that load‐driven compaction does not majorly hinder land‐area gain and may in fact promote long‐term growth at engineered sediment diversions through channel maintenance driven by compaction, thereby adding further support to this restoration strategy.
... Figure 2 displays the location of well logs and geological fault traces. The fault traces are part of the Tepetate fault system (McCulloh and Heinrich, 2013). Well log data include 29,107 drillers' logs and 811 electrical logs that were collected from the Louisiana Department of Natural Resources (LDNR) and the USGS. ...
This study identifies hydrogeologic characteristics of complex aquifers based on constructing stratigraphic structure with large, non-uniform well log data. The approach was validated through a modeling study of the irrigation-intensive Chicot aquifer system, which is an important Pleistocene-Holocene aquifer of the Coastal Lowlands aquifer system in the southwestern Louisiana. Various well log types were unified into the same data structure, prioritized based on data sources, and interpolated to generate a detailed stratigraphic structure. More than 29,000 well logs were integrated to construct a stratigraphy model of 56 model layers for the Chicot aquifer system. The stratigraphy model revealed interconnections of various sands in the system, where 90% of the model domain is covered by fine-grained sediments. Although the groundwater model estimated a slight groundwater storage gain during 2005–2014 for the entire region, groundwater storage in the agricultural area was depleted. Nevertheless, the quick groundwater storage recovery during the non-irrigation seasons suggests that the Chicot aquifer system is a prolific aquifer system. The groundwater modeling result shows that the gulfward groundwater flow direction prior to pumping has been reversed toward inland pumping areas. The large upward vertical flow from the deeper sands indicates potential saltwater migration from the base of the Chicot aquifer system.
... Increased sediment loading on the underlying Louann Salt intensified halokinesis, contributing to the development of growth faults (Bruce, 1973). Growth faults generally have an east-west trending strike parallel to subparallel with the shoreline of the Louisiana Gulf Coast (Culpepper et al., 2019;McCulloh and Heinrich, 2012;Murray, 1961). ...
... Some studies attribute subsidence to compaction of Holocene sediments and argue that the Louisiana coast is stable in a vertical sense, and restoration efforts will offset the natural compaction of Holocene sediments (Gonzá lez and Törnqvist et al., 2006). However, recent studies conducted in the Mississippi River delta plain suggest that subsidence affects not just Holocene sediments but also extends deeper to the Pleistocene sediments (e.g., Armstrong et al., 2014;Dokka, 2011;McCulloh and Heinrich, 2012;Yeager et al., 2012). In the Chenier Plain, the Pleistocene surface lies only 33 ft (10 m) below the surface, whereas the Mississippi River Delta's Pleistocene surface is 984 ft (300 m) deep (Fisk, 1948;Kulp, 2000). ...
This study investigates the relationship between faulting, subsidence, and land loss in coastal Louisiana. A methodology that integrates three-dimensional (3D) seismic data, well logs, high-resolution topographic mapping (LIDAR), and historical aerial photography is successfully developed to identify fault-related geomorphic changes in southwestern Louisiana’s Chenier Plain. Analysis of a 3D seismic survey and well logs reveals the presence of 10 normal faults that
form an east-west graben in the middle of the study area. Well logs were used to further constrain the geometry of the faults. Shallow water well logs were used to map the faults at shallow depth, below the resolution of the seismic survey. Fault traces were extrapolated to the surface by maintaining constant dip and projected on LIDAR data. Elevation profiles derived from the LIDAR were conducted across the different faults, and results show that a distinct difference between the upthrown and downthrown sides of the faults occurs. Historical aerial photographs were used to investigate any change in geomorphology from 1953 to 2017 within the study area. Results reveal the occurrence of water bodies on the immediate downthrown sides of suspected fault traces. These findings suggest that faulting influences and focuses areas where subsidence is happening and subsequent land loss may occur, and detailed understanding of active shallow faulting in coastal areas can be used to identify regions that are at risk of land loss.
... Longer term geologic processes operating below the Pleistocene-Holocene stratal contact are inherent to the Mississippi deltaic depocentre and represent the primary driver for regional deep-seated subsidence including pre-Holocene compaction, glacio-isostatic forebulge collapse, Holocene sedimentary isostatic adjustment, and growth fault movement. In particular, there has been~200 km of north-to-south Neogene and Quaternary deltaic and shelfmargin progradation, extending east-to-west from F I G U R E 1 Extent of study region and generalized geologic map of lower Mississippi River valley, delta region, and Gulf of Mexico coast illustrating shelf-margins positions and mapped growth faults (McCulloh & Heinrich, 2013;Murray, 1961). Pleistocene alluvial-deltaic deposits are shown in orange, whereas Holocene strata are shown in yellow. ...
... Fault symbols ( ) represent locations where the data extraction line crosses regional growth faults as mapped in Murray (1961). Letters represent sea-level data sampling locations: A = Rodriguez et al. (2004Rodriguez et al. ( , 2005 (McCulloh & Heinrich, 2013;Murray, 1961) ...
... Farther downdip, on the southern margins of the subaerial delta plain (29.4-29°N), a series of growth faults have long been recognised (e.g., Murray, 1961): these include the Empire, Golden Meadow and other faults (e.g., Armstrong, Mohrig, Hess, George, & Straub, 2014;Chan & Zoback, 2007;Gagliano, Kemp, Wicker, Wiltenmuth, & Sabate, 2008;Kuecher, Roberts, Thompson, & Matthews, 2001;Roberts, Morton, & Freeman, 2008), which show T A B L E 3 Calculated percentage of throw rate relative to deep-seated subsidence rate along dip line sections at the intersection of fault planes and Chronosequence 1, 3, & 7 boundaries (McCulloh & Heinrich, 2013;Murray, 1961) Due to oblique nature of longitudinal dip line extraction relative to the true dip of the fault, the above-referenced throw estimates and rates are conservative. Consistent with Shen et al. (2017) fault throw was measured as the vertical offset of facies boundaries originally horizontal. ...
To date, quantification of individual components that contribute to shallow and deep‐seated subsidence in passive margin deltas worldwide has proven problematic. A new, regional gridded chronostratigraphic dataset for the Lower Mississippi Delta region, derived from 80,928 well reports across the northern Gulf of Mexico (GOM), has bridged the disparity between geodetic mean rates measuring total land surface subsidence across annual‐to‐decadal time scales and the deep‐seated stratigraphic subsidence rates that record isostatic response over time scales of >10⁴ years. Through a quantitative assessment of gridded chronostratigraphic surfaces, sections, and subsidence rates extending from the Middle Pleistocene (0.58 Ma) to the Late Pliocene (3.85 Ma), we identify both temporal and spatial variability in deep‐seated subsidence across the northern GOM. Targeted deep‐seated subsidence data extracted across prior GOM Holocene sea‐level sample locations have revealed more than an order of magnitude greater rates of isostatic compensation in the Mississippi depocenter versus similar GOM sea‐level control sites in Florida and Alabama, casting doubt on efforts toward a representative Holocene sea‐level curve. Spatial variability in subsidence was also assessed locally in both the strike and dip directions to assess the contributions of growth faults. Fault throw displacement magnitude was discovered to decrease with depth, accounting for less than half of the total deep‐seated subsidence record of the Middle Pleistocene. Temporal subsidence complexities were also revealed including a direct, inverse logarithmic relationship between subsidence rate and time indicating variable subsidence component controls across different time scales. Despite the spatial and temporal complexities, this dataset serves as the first regional baseline for deep‐seated subsidence rates across the northern GOM.
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... First, climate-change driven shifts of the late Quaternary depocenter of the Mississippi River are relatively well-known (e.g., Coleman & Roberts, 1988). Second, there is a well-mapped major fault system in this area that has known late Quaternary activity (Fisk, 1944; McCulloh & Heinrich, 2013; Gasparini et al., 2015). Third, OSL dating has a proven potential here to date sediments that record fault motion (Rittenour et al., 2007;). ...
... Rowan et al. (2000) suggested that the quiescence was caused by a reversal of the slope of the basal detachment due to isostatic subsidence caused by sediment loading. Many faults, especially those in the TBRFZ, were reactivated during the Pleistocene (Hanor, 1982; McCulloh & Heinrich, 2013), which may be related to acceleration of Pleistocene sedimentation rates ...
Quaternary sea-level cycles have caused dramatic depocentre shifts near the mouths of major rivers. The effects of these shifts on fault activity in passive margin settings is poorly known, as no studies have constrained passive margin fault throw-rate variability over 10^3 to 10^5 year time scales. Here we present 11 mean throw rates for the Tepetate-Baton Rouge fault zone along the northern Gulf of Mexico coast in southern Louisiana. These data were obtained by optically stimulated luminescence dating over time scales spanning the last interglacial to the late Holocene. The mean throw rate is ca. 0.22 mm year-1 during the late Holocene, ca. 0.03 mm year-1 during the last glacial and at least 0.07 mm year-1 during the last interglacial. Throw rates averaged over the late Pleistocene to present are spatially uniform within our study area. The temporal variability of throw rates suggests that shifts of the Mississippi River depocentre relative to this fault zone, driven by Quaternary sea-level cycles, may have imposed a significant control on fault activity. The late Holocene throw rate is at least in the order of magnitude smaller than the rates of land-surface subsidence in the Mississippi Delta, indicating that this fault zone is not a dominant contributor to subsidence in this region.
... Pleistocene fault scarps are on the order of a few meters in height, traces of the fault segments can be difficult to identify in the field, especially because much of the area is heavily vegetated. However, a publically available digital elevation model (DEM) derived from an airborne light detection and ranging (LiDAR) survey has removed any doubt that this landscape has been affected by fault activity through Late Pleistocene-Holocene time (Gagliano et al., 2003;Dokka, 2011;Shen et al., 2011;McCulloh and Heinrich, 2013) (Fig. 2). Many of the smaller fault segments were identified only after the release of the LiDAR derived DEM (data distributed by "Atlas: ...
We explore the fluvial response to faulting in three low-gradient, sand-bed rivers in southeastern Louisiana, USA, that flow across active normal faults from footwall (upstream) to hangingwall (downstream). We calculate sinuosity, migration rate and migration direction in order to identify anomalies spatially associated with fault scarps. In two of the rivers we model 1-D steady water flow to identify anomalies in surface water slope, width-to-depth ratio, and shear stress. In each of these rivers there is one location where flow modeling suggests potential channel incision through the footwall, as indicated by relatively high surface water slopes and shear stress values. In one of these footwall locations, the river straightens and width-to-depth ratios decrease, likely contributing to higher surface water slopes and shear stress. This is in contrast to previous studies that have proposed increased sinuosity across fault footwalls and decreased sinuosity across hangingwalls. However, in two hangingwall locations we also observe relatively less sinuous channels. Other planform changes on the hangingwall include topographic steering of channels along and towards the fault and one example of an avulsion. The most notable anomaly in migration rate occurs on the hangingwall of a fault where a river has cut off a meander loop. Although fluvial response to faulting varies here, comparatively large and small channels exhibit similar responses. Further, Pleistocene fault slip rates are orders of magnitude lower than the channel migration rates, suggesting that faulting should not be a major influence on the fluvial evolution. Nonetheless, notable channel anomalies exist near faults, suggesting that recent fault slip rates are higher than Pleistocene rates, and/or that low-gradient alluvial channels are more sensitive to faulting than previous studies have suggested. Rivers appear to be influenced by faulting in this setting, however background rates of meander loop cut-off may be just as influential as faulting. This article is protected by copyright. All rights reserved.
... [45] The Baton Rouge fault system consists of the Baton Rouge fault and the Denham Springs-Scotlandville fault (Tepetate fault) [McCulloh and Heinrich, 2012]. This eastwest trending fault system crosscuts the aquifer/aquiclude sequences in the study area as shown in Figure 2. The low permeable Baton Rouge fault is important from a resource point of view since it separates the sequence of freshwater and brackish aquifers at the north and south of the fault, respectively. ...
[1] Analysts are often faced with competing propositions for each uncertain model component. How can we judge that we select a correct proposition(s) for an uncertain model component out of numerous possible propositions? We introduce the hierarchical Bayesian model averaging (HBMA) method as a multimodel framework for uncertainty analysis. The HBMA allows for segregating, prioritizing, and evaluating different sources of uncertainty and their corresponding competing propositions through a hierarchy of BMA models that forms a BMA tree. We apply the HBMA to conduct uncertainty analysis on the reconstructed hydrostratigraphic architectures of the Baton Rouge aquifer-fault system, Louisiana. Due to uncertainty in model data, structure, and parameters, multiple possible hydrostratigraphic models are produced and calibrated as base models. The study considers four sources of uncertainty. With respect to data uncertainty, the study considers two calibration data sets. With respect to model structure, the study considers three different variogram models, two geological stationarity assumptions and two fault conceptualizations. The base models are produced following a combinatorial design to allow for uncertainty segregation. Thus, these four uncertain model components with their corresponding competing model propositions result in 24 base models. The results show that the systematic dissection of the uncertain model components along with their corresponding competing propositions allows for detecting the robust model propositions and the major sources of uncertainty.
... The study area occupies 2.88 square kilometers next to the Mississippi River and between Denham Springs-Scotlandville Fault (DSS) and Baton Rouge (BR) Fault (McCulloh, 2008;McCulloh & Heinrich, 2013); 16 electrical logs in the study area were collected, interpreted, and used to estimate the hydrostratigraphy of the Industrial District as shown in Figure 13. The log length is from 125 to 796 m. ...
Developing a three‐dimensional (3D) lithofacies model from boreholes is critical for providing a coherent understanding of complex subsurface geology, which is essential for groundwater studies. This study aims to introduce a new geostatistical method—interval kriging—to efficiently conduct 3D borehole‐based lithological modeling with sand/non‐sand binary indicators. Interval kriging is a best linear unbiased estimator for irregular interval supports. Interval kriging considers 3D anisotropies between two orthogonal components—a horizontal plane and a vertical axis. A new 3D interval semivariogram is developed. To cope with the nonconvexity of estimation variance, the minimization of estimation variance is regulated with an additional regularization term. The minimization problem is solved by a global‐local genetic algorithm embedded with quadratic programming and Brent's method to obtain kriging weights and kriging length. Four numerical and real‐world case studies demonstrate that interval kriging is more computationally efficient than 3D kriging because the covariance matrix is largely reduced without sacrificing borehole data. Moreover, interval kriging produces more realistic geologic characteristics than 2.5D kriging, while conditional to spatial borehole data. Compared to the multiple‐point statistics (MPS) algorithm—SNESIM, interval kriging can reproduce the geological architecture and spatial connectivity of channel‐type features, meanwhile producing tabular‐type features with better connectivity. Because the regularization term constrains kriged value toward 0 or 1, interval kriging produces more certainty in sand/non‐sand classification than 2.5D kriging, 3D kriging, and SNESIM. In conclusion, interval kriging is an effective and efficient 3D geostatistical algorithm that can capture the 3D structural complexity while significantly reducing computational time.
