Growth Faults Research Articles

Contrasting Geomorphic and Stratigraphic Responses to Normal Fault Development During Single and Multi-Phase Rifting

Understanding the impact of tectonics on surface processes and the resultant stratigraphic evolution in multi-phase rifts is challenging, as patterns of erosion and deposition related to older phases of extension are overprinted by the subsequent extensional phases. In this study, we use a one-way coupled numerical modelling approach between a tectonic and a surface processes model to investigate topographic evolution, erosion and basin stratigraphy during single and multi-phase rifting. We compare the results from the single and the multi-phase rift experiments for a 5 Myr period during which they experience equal amounts of extension, but with the multi-phase experiment experiencing fault topography inherited from a previous phase of extension. Our results demonstrate a very dynamic evolution of the drainage network that occurs in response to fault growth and linkage and to depocentre overfilling and overspilling. We observe profound differences between topographic and depocenter development during single and multi-phase rifting with implications for sedimentary facies architecture. Our quantitative approach, enables us to better understand the impact of changing extension direction on the distribution of sediment source areas and the syn-rift stratigraphic development through time and space.

Study on Segmental Growth Characteristics of Main Faults in Southern Aer Sag

The segmental growth of faults plays an important role in controlling oil and gas. This time, the southern part of the Aer sag is taken as the main research object to analyze the growth process of the faults. This paper uses the fault distance-distance curve, the fault distance-buried depth curve and the growth index to study the active stage of the segmental growth of the fault. The maximum fault distance subtraction method is used to strip back the faults, restore the ancient faults, and clarify the development characteristics of the main faults in each period. It is concluded that the Altala fault is a three-segment growth fault, and the fault continued to act during the depositional period of the A3 to Teng2 members, and the activity of the A4 was the most intense. The Hanwula fault is a two-segment growth fault. The faults continued to move during the depositional period of the A4 to Teng2 members, and the fault activity was most intense in the upper Teng1 sub-member. Hanwu Ladong belongs to a two-stage segmental growth fault, and the faults continued to be active during the strata depositional period from the first sub-member of Teng 1 to the second member of Teng 2, and the fault activity was most intense in the first sub-member of Teng. This study enriches the theory of the structure of the Erlian Basin's Aer sag and supports further breakthroughs in oil and gas exploration.

Study on the controlling effect of Nanpu No. 2 Fault growth connection on buried hill evolution

Nanpu fault 2 has an important control action of buried hill, in order to study the growth of Nanpu fault 2 connection process and Nanpu no. 2 the control function of buried hill through the application of slip - distance curve and slip back stripping method to study the growth of the Nanpu fault 2 connection process, and the use of equilibrium profile to analyze its effect on the tectonic evolution of the buried hill. The results show that the Nanpu No. 2 fault is characterized by segmentalized growth, caledonian quiet structure, and widely distributed carbonate deposits. After the middle-late Caledonian uplift, the strata suffered from denudation. Strong folding occurred in The Indochinese period, and in the Himalayan Period, the Nanpu no. 2 fault was weakly active in the Shahejie sedimentary period and developed only in the north, forming the prototype of buried hill at this time. During the sedimentary period of Dongying Formation, the structure reversed slightly, which is also known as the Dongying Movement. At this time, fault no. 2 strongly extended southward, and buried-hill was formed and basically formed. The research results have certain reference value for oil and gas exploration in Nanpu sag.

Emergence and Growth of Faults During Earthquakes: Insights from a Dynamic Elasto-Plastic Continuum Model

Emergence and Growth of Faults During Earthquakes: Insights from a Dynamic Elasto-Plastic Continuum Model

Land Subsidence in the Texas Coastal Bend: Locations, Rates, Triggers, and Consequences

Land subsidence and sea level rise are well-known, ongoing problems that are negatively impacting the entire Texas coast. Although ground-based monitoring techniques using long-term global navigation satellite systems (GNSS) records provide accurate subsidence rates, they are labor intensive, expensive, time-consuming, and spatially limited. In this study, interferometric synthetic aperture radar (InSAR) data and techniques were used to map the locations and quantify rates of land subsidence in the Texas Coastal Bend region during the period from October 2016 to July 2019. InSAR-derived land subsidence rates were then validated and calibrated against GNSS-derived rates. The factors controlling the observed land subsidence rates and locations were investigated. The consequences of spatial variability in land subsidence rates in Coastal Bend were also examined. The results indicated that: (1) land subsidence rates in the Texas Coastal Bend exhibited spatial variability, (2) InSAR-derived land subsidence rates were consistent with GNSS-derived deformation rates, (3) land subsidence in the Texas Coastal Bend could be attributed mainly to hydrocarbon and groundwater extraction as well as vertical movements along growth faults, and (4) land subsidence increased both flood frequency and severity in the Texas Coastal Bend. Our results provide valuable information regarding not only land deformation rates in the Texas Coastal Bend region, but also the effectiveness of interferometric techniques for other coastal rural areas around the globe.

Turbidite System Controlled by Fault Growth and Linkage on a Slope Belt of Rift Basin: Zhanhua Depression, Bohai Bay Basin, China

Turbidite System Controlled by Fault Growth and Linkage on a Slope Belt of Rift Basin: Zhanhua Depression, Bohai Bay Basin, China

INTEGRATION OF LOGS AND SEISMIC DATA FOR DELINEATION OF DEPOSITIONAL ENVIRONMENT OF CLASTIC SEDIMENTS IN TOMBOY FIELD, NIGER DELTA

The depositional environment of Clastic sediments in Tomboy Field Onshore Niger Delta were delineated using 3D Seismic and lithological logs. Well log suites from 5 wells comprising Spontaneous potential, Gamma ray, Sonic, Resistivity, Density, and Neutron logs were obtained and analyzed. Reverse estimation was done for the Neutron log and Bulk Density log using volumetric method. Gamma-ray log were used to calibrate Log motifs and correlate sand bodies TMB-01, TMB-02, TMB-03, TMB-04, and TMB-06. Prediction of depositional environment was made through the usage of wireline log shapes of facies combined with result from seismic data. Results of correlation across the five wells showed that. there was continuity at depth interval of 4000-5000ft across the wells as well 3 did not have any gamma information to correlate accros it. The seismic section showed two major growth faults and a channel fill on seismic (inline 5940, crossline1660) between 3.3-3.6ms. According to the paleo-reconstruction from the correlated wells within the tomboy field, the reservoir is made up of sands from fluvial and tidal channels, barrier, and barrier bar. These sand bodies are likely to contain hydrocarbons because of the rollover anticline, which is found at the fault’s downthrown block. This study has revealed that the Clastic sediments in Tomboy Field Onshore Niger Delta were deposited within a predominantly deltaic environment (transitional).

South Tethyan passive margin paleoslope orientation inferred from soft-sediment deformation and fault kinematic analysis: a case study from the Cretaceous of Borj Cedria area, Tunisia

The Cretaceous outcrops of Borj Cedria-Bou Kournine area belongs to the NE-trending Atlas system of northern Tunisia. This area exposes sub-meridian folds associated with numerous N- to NW-trending major fault systems. This study together with previous surveys reveals that this N-trending folding is believed to be related to the inversion of the Jurassic and Early Cretaceous pre-existing fault zones and generated in response to the late compressive deformations. In addition, the study area provides evidence of soft-sediment deformations by good exposures of Cretaceous-aged slump sheets. Slump folds are usually associated with several meso-scale syn-sedimentary normal faulting together with frequent reworked blocs and occasional conglomeratic horizons. All these features indicate sedimentation on irregular seafloor topography. The aim of the present study is to investigate slump folds by applying techniques to reconstruct the contemporaneous slope gradient which has triggered soft-sediment deformations. Moreover, the brittle deformation is quantified using fault kinematic analysis together with the analysis of lithostratigraphic correlation and syn-sedimentary structures. Considerable thickness variations of Cretaceous deposits are interpreted as controlled by normal faulting activities. Likewise, fault kinematic analysis typifies a regional pure extension that trends NNW during Barremain, NNE during Albian, and probably NW during Cenomanian time. Based on slump folds analysis, the inferred sub-marine paleoslope is believed to have a northward dipping during Barremian and a NNE-dipping during Albian time. On the light of the over-mentioned interpretations, it is believed that Cretaceous sedimentation of the study area is highly controlled by major syn-depositional normal faults associated with intra basin growth faulting. These fault systems seem to be related to the Southern Tethyan expansion of the rifted continental passive margin.

Drainage Development in the Dunhuang Basin, NE Tibet, Controlled by Multi-Segment Fault Growth

The Dongbatu Shan (DBTS, also known as the Nanjie Shan), which interrupts the northern Tibetan foreland in the Dunhuang basin, is an active anticline. It has accommodated the northwestern growth of the eastern Altyn Tagh fault system (ATF). Although several thrust faults have been identified around the DBTS, their evolution history and influence on regional landscape have received little attention during the late-Quaternary. In this study, several geomorphic methods are used to investigate the interaction between drainage development and tectonic movement around DBTS. Based on high-resolution satellite images, field investigation, and cosmogenic nuclide 10Be dating method, the fluvial landform sequences around DBTS were constructed. Using quantitative geomorphology methods including landscape relief profile, asymmetry factor (AF), and transverse topographic symmetry factor (T), we hypothesize that drainage deflection is controlled by multi-segment fault growth. Combining the results of the above-mentioned methods, we propose that Yulin He, flowing across the DBTS, had gone through several abandonments since the late mid-Pleistocene due to the lateral propagation of DBTS. Affected by the discharge of channel and multi-segment fault growth, our research confirms that the direction of river abandonment may have decoupled with the mountain range propagation trend. Based on the chronology dating, the DBTS has gone through two severe uplifts since ∼208 ka and the shortening rate across the central DBTS is constrained to be ∼1.47 mm/yr since ∼83 ka. Given the fact that thrust faults are widely developed around DBTS, we propose that the flower-like structure formed by the northward growth of the eastern ATF could better explain the development of the secondary subparallel faults.

Growth and linkage of normal faults experiencing multiple non‐coaxial extension: A case from the Qikou Sag, Bohai Bay Basin, East China

AbstractOblique‐slip faults, which are essentially reactivated pre‐existing fault caused by non‐coaxial stress, are common in rift basins. Large faults with lengths exceeding thousands of kilometres are mostly rooted faults and would have experienced numerous reactivations. Using 3D seismic and drilling data, we investigated the geometry, kinematic features, growth and linkage, and three‐dimensional evolution of the Nandagang fault system (NDGFS) on the Qinan Slope in the Qikou Sag, Bohai Bay Basin. A hybrid fault model incorporating a lengthening stage and a displacement accrual stage was used to analyse the growth and linkage of NDGFS. By using the throw/displacement backstripping approach, ratios of maximum displacement to fault length (Dmax/L) of the evolving NDGFS were also obtained to delineate faulting stages of the hybrid fault model. From the pre‐Cenozoic basement to the Quaternary strata, NDGFS comprises three fault systems separated vertically by two unconformities, namely the lower, the middle and the upper systems. On planar view, NDGFS encompasses three structural trending zones with variable vertical growth styles. The E–W and NEE–SWW trending zones are mainly dominated by growth faults, while the NE–SW zones are characterised by dip‐linkage faults. For NDGFS, both the middle and deeper fault segments experienced a two‐stage hybrid faulting and reached their final lengths in ca. 20%–30% less time than the usual faulting lifetime proposed by previous researchers. In contrast, the upper faults, especially the segments within the Neogene Guantao (Ng) and Minghuazhen (Nm) formations, only experienced a lengthening stage. The slip rates and the pre‐existing faults have strong influences on the duration that faults accomplished their lengthening stages. A Dmax/L ratio of 0.015 obtained from the evolving NDGFS is determined to be effective in delineating between the lengthening stage and the displacement accrual stage, which may have a broad application for normal faults in similar geological settings.

Characteristics of continental rifting in rotational systems: New findings from spatiotemporal high resolution quantified crustal scale analogue models

Continental rifts are the expression of regional horizontal stretching and are in modelling studies often assumed to be the result of orthogonal or oblique extension. However, naturally occurring V-shaped rift geometries infer an underlying rotational component, resulting in a divergence velocity gradient. Here we use such analogue models of rifting in rotational settings to investigate and quantify the effect of such a divergence velocity gradient on normal fault growth and rift propagation towards a rotation pole. Particularly, we apply different divergence velocities and use different brittle-ductile ratios to simulate different crustal configurations and analyse its effect on rift propagation and surface deformation. Surface deformation is captured using stereoscopic 3D Digital Image Correlation, which allows for quantifying topographic evolution and surface displacement including vertical displacement. In combination with X-Ray computed tomography, we gain insights into the three-dimensional structures in our two-layer models. Based on our models, we present a novel characterisation of normal fault growth under rotational extension which is described by 1) an early stage of bidirectional stepwise growth in length by fault linkage with pulses of high growth rates followed by a longer and continuous stage of unidirectional linear fault growth; 2) segmented rifting activity which promotes strain partitioning among competing conjugate faults and 3) along-strike segmented migration of active faulting from boundary faults inwards to intra-rift faults allowing different fault generations to be simultaneously active over the entire rift length. For models with higher divergence velocities, inward migration is delayed but other first-order observations are similar to models with lower divergence velocities. Our quantitative analysis provides insights on spatiotemporal fault growth and rift propagation in analogue models of rotational rifting. Although natural rifts present complex systems, our models may contribute to a better understanding of natural rift evolution with a rotational component.

Tectonic and stratigraphic evolution of the central Exmouth Plateau, NW Shelf of Australia

A detailed tectono-stratigraphic analysis of the Mesozoic through Present-day structures and sedimentary sequences has been carried-out on a very large merged 3-D seismic survey that covers the great part of the central Exmouth Plateau, northern Carnarvon Basin, NW Shelf of Australia. Four main megasequences bounded by regional unconformities have been delineated. They are; (1) Megasequence-I - Early-Late Triassic pre-extension, (2) Megasequence-II - Latest Triassic (Rhaetian)-earliest Late Jurassic (Oxfordian) syn-extension; (3) Megasequence-III - Late Jurassic-Early Cretaceous post-extension; and (4) Megasequence-IV - Early Cretaceous-Present-day passive margin strata. Three populations of extensional faults and a previously unrecognised compressional phase of folding have been identified. The main Mesozoic (Rhaetian-Oxfordian) WNW-directed extension produced domino-style planar extensional faults (Fault System 1) with two principle fault sets; (i) large N–S to NNE-SSW-trending, west-dipping faults and (ii) smaller-scale, largely antithetic east-dipping faults. The large faults are possibly reactivated pre-existing deeper and older faults (possibly related to listric growth faults of the large Lower-to Mid-Triassic Mungaroo delta) as well as completely new faults developed in the upper part of the Triassic Mungaroo Formation. Synclinal hangingwall basins of this system are strongly segmented and underfilled with little (<450 m) syn-extensional sedimentation.Fault System 1 was reactivated during the Early Cretaceous-Neogene post-extension stage and strongly influenced the development of the segmented NNE-SSW-trending Fault System 2 in the Cenozoic strata. Two stacked polygonal non-tectonic fault tiers (Fault System 3) separated by little deformed stratigraphy occur within the Berriasian to Pliocene post-extension sequences. In the early post-extension phase, Late Jurassic to Early Cretaceous NNE-SSW-directed minor contraction event produced broad WNW-ESE-striking folds in the Triassic-Early Cretaceous strata. This study documents the development of the extensional fault systems and proposes new 4-D tectono-stratigraphic evolutionary models for the central Exmouth Plateau. The results of this study have wider implications for the tectono-stratigraphy of the northern Carnarvon Basin and future exploration.

3-D Seismic Structural Interpretation of High Field Offshore Western Niger Delta

Seismic Structural interpretation of subsurface system is a vital tool in mapping source rocks and good trapping system which enhances good understanding of the subsurface system for productive drilling operation. This study is geared towards mapping the structural traps available within the hydrocarbon bearing zones of the “High field” with the use of well log and 3D seismic data. Seven horizons (H1, H2, H3, H4, H5, H6 and H7) were identified on well logs using gamma ray log and resistivity logs. Nine (9) faults were mapped on seismic sections across the field, two (2) of which are major growth faults (F1 and F2), two (2) synthetic faults (F3 and F7) and five (5) antithetic faults (F4, F5, F6, F8 and F9). Rollover anticlines which are structural closure and displayed on the depth structural maps suggest probable hydrocarbon accumulation at the down throw side of the fault F1. Structural interpretation of high field has revealed a highly fault assisted reservoir which depicts the tectonic setting of Niger Delta basin.

Ocean crust accretion along a high-temperature detachment fault in the Oman ophiolite: A structural and petrological study of the Bahla massif

The Bahla massif exposes the lower crustal section of the Oman ophiolite located close to the thrust front of the Semail nappe. It is affected by intense faulting previously attributed to tectonic events that dismembered a classical ophiolitic sequence during or after the obduction. Here we show that most of this complexity is primary, inherited from syn-accretion tectonics. The crustal section is exposed in a 15 by 8 km tectonic enclave surrounded by mantle peridotite. Its northern boundary corresponds to a major, steeply dipping normal fault striking WNW-ESE, at low angle to the paleo-ridge axis. Movement along this fault was accommodated by intense plastic deformation of the crustal cumulates and adjacent mantle peridotites at temperature conditions ≥900 °C. The thickness of the deformed zone reaches several hundred meters. The flattening of the cumulate layering away from the fault is correlated to a decrease in the deformation intensity. Undeformed olivine-gabbro dykes cross-cut this “tectonic Moho” indicating that the tilting occurred before the end of the igneous activity. To the southwest, the crustal enclave is bounded by a NW-SE trending transtentional shear zone that was active in the amphibolite to greenschist facies and was intensely injected by syn- to post-kinematic gabbronorite and tonalite/trondhjemite dykes and plugs. The age of one felsic sample (95.214 ± 0.032 Ma, high-precision UPb zircon dating) is within error of the age of intrusive felsic intrusions into the mantle and lowermost axial crust from the length of the Oman ophiolite, which slightly post-dates the mean crystallization age of the Semail crust (V1 magmatism; 96.1–95.6 Ma). Other contacts are low temperature features including cataclastic faults, serpentine‑carbonate breccias and flat-lying décollements.Parent melts of the Bahla crustal cumulates were more siliceous and hydrous, i.e. more andesitic, than typical mid-ocean ridge basalt (MORB) as deduced from the frequent occurrence of early crystallizing orthopyroxene (opx) and late crystallizing amphibole. Some facies such as cumulate harzburgite and opx-troctolite have not been documented elsewhere in the Oman ophiolite and may be specific to the tectonic context in which the frontal massifs accreted. The chemical composition of the lower crustal cumulates can be accounted for by the hybridization in various proportions between MORB and a primitive andesite from a depleted source whose origin can be looked for in melts from a nascent subduction zone or from high temperature hydrothermal processes.The structure of the Bahla lower crustal section is reminiscent of the plutonic growth faults documented along present-day slow-spreading centres in both mid-ocean ridge and back arc settings. The distinctive characteristics of the Moho and lower crustal section in the Bahla massif are tentatively related to their position at the leading edge of the ophiolite, i.e. closer to the Arabian continental margin at the time of accretion than the massifs from the internal part of the ophiolite that have a more continuous and less deformed lower crust. It indicates that the style of crustal accretion may have changed during the opening of the oceanic basin from which the Oman ophiolite issued.

The geometric and temporal evolution of fault‐related folds constrain normal fault growth patterns, Barents Sea, offshore Norway

AbstractExtensional growth folds form ahead of the tips of propagating normal faults. These folds can accommodate a considerable amount of extensional strain and they may control rift geometry. Fold‐related surface deformation may also control the sedimentary evolution of syn‐rift depositional systems. Thus, by examining the stratigraphic record, we can constrain the four‐dimensional evolution of extensional growth folds, which in turn provides a record of fault growth and broader rift history. Here, we use high‐quality 3D seismic reflection and borehole data from the SW Barents Sea, offshore northern Norway to determine the geometric and temporal evolution of extensional growth folds associated with a large, long‐lived, basement‐rooted fault. We show that the fault grew via the linkage of four segments, and that fault growth was associated with the formation of fault‐parallel and fault‐perpendicular folds that accommodated a substantial portion (10%–40%) of the total extensional strain. Several periods of fault‐propagation folding occurred in response to the periodic burial of the fault, with individual folding events (ca. 25 and 32 Myr) lasting a considered part of the ca. 130 Myr rift period. Our study supports previous suggestions that continuous (i.e. folding) as well as discontinuous (i.e. faulting) deformation must be explicitly considered when assessing total strain in an extensional setting. We also show that changes in the architecture of growth strata record alternating periods of folding and faulting and that the margins of rift‐related depocentres may be characterised by basinward‐dipping monoclines as opposed to fault‐bound scarps. Our findings have broader implications for our understanding of the structural, physiographic and tectonostratigraphic evolution of rift basins.

New onshore insights into the role of structural inheritance during Mesozoic opening of the Inner Moray Firth Basin, Scotland

The Inner Moray Firth Basin (IMFB) forms the western arm of the North Sea trilete rift system that initiated mainly during the Late Jurassic–Early Cretaceous with the widespread development of major NE–SW-trending dip-slip growth faults. The IMFB is superimposed over the southern part of the older Devonian Orcadian Basin. The potential influence of older rift-related faults on the kinematics of later Mesozoic basin opening has received little attention, partly owing to the poor resolution of offshore seismic reflection data at depth. New field observations augmented by drone photography and photogrammetry, coupled with U–Pb geochronology, have been used to explore the kinematic history of faulting in onshore exposures along the southern IMFB margin. Dip-slip north–south- to NNE–SSW-striking Devonian growth faults are recognized that have undergone later dextral reactivation during NNW–SSE extension. The U–Pb calcite dating of a sample from the synkinematic calcite veins associated with this later episode shows that the age of fault reactivation is 130.99 ± 4.60 Ma (Hauterivian). The recognition of dextral-oblique Early Cretaceous reactivation of faults related to the underlying and older Orcadian Basin highlights the importance of structural inheritance in controlling basin- to sub-basin-scale architectures and how this influences the kinematics of IMFB rifting. Supplementary material: Analytical protocols and analysed sample details are available at https://doi.org/10.6084/m9.figshare.c.5635432

Deformation of soft sediments and evaporites in a tectonically active basin: Bay St. George sub-basin, Newfoundland, Canada

The Bay St. George sub-basin of SW Newfoundland, part of the larger late Paleozoic Maritimes basin, formed under the influence of strike-slip faulting and the movement of evaporites. New stratigraphic correlations between Newfoundland and other late Paleozoic sub-basins illustrate the effects of both basement and salt movement. Coastal outcrops show complex combinations of synsedimentary, salt-related, and tectonic structures. Map relationships and dramatic thickness contrasts in the Tournaisian Anguille Group indicate that a large, concealed, NE–striking normal growth fault (Ship Cove fault) controlled sedimentation; the exposed Snakes Bight fault originated as a hanging-wall splay. Structures formed during, or soon after deposition include soft-sediment folds, boudins, clastic dykes, and millimetre-scale diapiric bulb structures, formed by overpressuring and liquidization of sediment. These suggest that the sub-basin was tectonically active throughout deposition. Evaporite-related deformation is recorded in the Visean Codroy Group and overlying strata. Comparisons between outcrop and subsurface suggests that significant amounts of evaporite were removed from exposed sections by halokinesis and solution. Complex outcrop relationships indicate salt welds, and suggest that units of the upper Codroy and overlying Barachois groups represent fills of minibasins that subsided into thick evaporites. Field relationships suggest tectonic inversion deposition related to E-W dextral strike slip motion that affected the entire Maritimes basin in the Serpukhovian, producing reverse-sense offsets and contractional folds. Many of the structures in the Bay St. George sub-basin, previously interpreted as post-depositional and purely tectonic, were formed by deformation of unlithified sediment and ductile evaporites during basin development.

Can sea level rise help us restore coastal wetlands? The hydrologic restoration of the Slop Bowl, Brazoria National Wildlife Refuge, Texas

The Slop Bowl marsh in the Brazoria National Wildlife Refuge provides extraordinarily high quality, heavily used bird habitat. Much of this habitat has experienced hypersaline conditions due to both hydrologic alteration by humans and a rapidly and changing physical environment over the past several decades. Oil and natural gas extraction activities have resulted in excavation and channelization along pipelines and hydrologic obstruction by an access road. In addition, subsidence along growth faults has altered hydrologic pathways and lowered surface elevations in the center of the marsh. Our objective was to understand the underlying processes that contribute to hypersaline conditions and to evaluate possible restoration alternatives to reduce the severity of those conditions. Accordingly, we conducted extensive field and hydrologic modeling efforts, and identified the past, present, and future of this marsh habitat under a baseline scenario. We then compared various restoration action scenarios against this baseline. We found that, beginning in about 15 years, relative sea level rise will improve the hydrologic conditions by enhancing tidal flushing. However, if fill material is continually added to elevate the obstructing road as the sea rises, this hydrologic relief may never be realized. Moreover, we found that if a drought occurs during this critical period, a difference of only a few centimeters in the relative water level and road elevation, or changes in marsh surface elevations driven by fault motion and subsidence, may have catastrophic consequences. The modeling also suggests that several potential interventions can bridge this gap over the next 15 years and beyond. Actions that improve tidal circulation, reduce salinity, and enhance marsh accretion are being developed by the project team to enhance and restore habitat in the near term. The most optimal approaches evaluated thus far include the installation of culverts at critical locations, the excavation of a small channel, the modification of flow pathways, and the beneficial use of sediments and vegetative plantings. We conclude that, under specific circumstances or at unique locations such as the Slop Bowl marsh, sea level rise can be leveraged to improve coastal wetland health.

Research on sedimentary facies of Guantao Formation in Shanjiasi area of Dongying depression, China

Alluvial fan and Fluvial facies sand bodies are important reservoirs for oil and gas resources. In this study, the sedimentary characteristics and evolutionary patterns of Alluvial fan and fluvial deposits in the Neogene Guantao Formation of the Dongying Sag, Bohai Bay Basin were analyzed using cores, well logs and three-dimensional seismic data, and the quantitative information of the sand bodies in different deposits were characterized with dense well-net constraints. Through the calibration between the core and wireline logging data, the developmental characteristics of the sand bodies in the Alluvial fan and fluvial deposits were clearly defined base on sedimentary microfacies and seismic facies interpretation. Using the RMS amplitude attribute and reconstructed Wave Impedance Inversion, the sand bodies of Guantao Formation in this area were carefully described and studied, and the effective reservoir range was predicted on the basis of fully understanding the oil test data. Results: The top and bottom interface of Guantao Formation are characterized by strong continuous reflection on seismic section, exist within the guantao on seismic section three continuous or intermittent peaks, from bottom to top respectively represent the interface between Ng4 and Ng3 sand group, the interface between Ng3 and Ng2 sand group,the interface between Ng2 and Ng1 of the Guantao Formation, and Ng4 sand group of the Guantao Formation is the key layer; The boundary Growth Fault and Binxian high jointly controlled the deposition of Guantao Formation. The sedimentary thickness of the strata decreased on the north and west sides of the sag, and increased from the core to the edge of the Binxian high; The sedimentary facies of Guantao Formation in the study area can be divided into three types: alluvial fan facies, braided river facies and meandering river facies, and various corresponding subfacies and microfacies can be subdivided into different types. Ng4 sand group of the Guantao Formation is identified as alluvial fan-braided river model; Based on the analysis of the distribution and physical properties of alluvial and fluvial facies sand bodies in the study area, it is considered that the effective reservoir of Ng4 sand group of the Guantao Formation is mainly developed in the nose structure around Binxian high, and is semicircular in distribution.

Beaufort–Mackenzie Tectono-Sedimentary Element

Abstract The Beaufort–Mackenzie Tectono-Sedimentary Element (TSE) is a post-rift sequence of the Canada Basin that consists of Late Cretaceous–Pleistocene sedimentary strata with a maximum thickness of over 12 km. The tectonics of the Canada Basin formation and the Cenozoic contractional deformation associated with the Cordilleran Orogeny jointly shaped and controlled the architecture and the depositional systems of the TSE. In the west, contractional deformation prevails, whereas in the east extensional deformation dominates, and gravitational deformation associated with growth faults is prominent in the far north. Early successions of Cenomanian–Early Maastrichtian age are composed of thin but commonly organic-rich muds (Boundary Creek, Smoking Hills and Mason River sequences) that were deposited on the continental margin. The main phase of sedimentation started in the Late Maastrichtian with the deposition of a series of large progradational delta complexes, which migrated oceanwards from the SW margin in the Paleogene to the central part of the TSE in the Pliocene in response to the rising Cordilleran orogen in the SW. Coal seams and gas-prone terrestrial-derived organic-rich interbeds in the Cenozoic sequences are the main source rocks for gas generation, whereas organic-rich marine shales in Cretaceous sequences are probably the source rocks for oil generation. The Beaufort–Mackenzie TSE is a proven petroleum province with many significant discoveries and a large undiscovered resource potential in oil, gas and methane hydrate.