Article

Sedimentology and Paleontology of the Upper Cretaceous Wahweap Formation sag ponds adjacent to syndepositional normal faults, Grand Staircase-Escalante National Monument, Utah

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Abstract

During the development of the East Kaibab monocline, listric normal faulting related to outer arc influenced the sedimentation style of the Upper Cretaceous Wahweap Formation. The initiation of the Laramide Orogeny was therefore recorded in the sedimentary record of south-central Utah. Evidence for this includes the preservation of sag ponds adjacent to two of the normal faults in our study area, which developed when fault movement created topographic features. Ancient sag-pond deposits are likely under-identified in the rock record. This study demonstrates their significance and potential for unraveling fault histories. The northern, younger, sag-pond deposit is located at the boundary between the upper and capping sandstone members of the Wahweap Formation, and consists of sandstone dikes and sills hosted in gray mudstones and siltstones with no discernable invertebrate fauna, but some small macerated flora. The second southern sag-pond fill, is located at the base of the upper member. The sag pond is older, larger in area, and contains a thicker deposit. In contrast to the northern sag-pond deposit siltstones and mudstones are gray and visiblity structureless. Within the southern sag pond there are a series of fossil horizons consisting mainly of juvenile unionid bivalves, a lesser number of gastropods, and macerated plants. Comparison of the two preserved Upper Cretaceous sag-pond deposits suggests two distinct responses to fault movement, perhaps governed by fault kinematics, manifested in sedimentation style and type; the impact of faunal invertebrate invasion; and post-sedimentation deformation.

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... Laramidestyle, basement-involved uplifts exist on the margins of the SWHP, including the Kanarra Fold to the west, and the East Kaibab monocline and Circle Cliffs uplifts to the east (Fig. 1). The earliest evidence of this foreland break-up in southern Utah includes growth faults in the Campanian Wahweap Formation in the northern Kaiparowits Plateau (e.g., Hilbert-Wolf et al., 2009;Simpson et al., 2014). One of the main drivers for Laramide tectonism is flat-slab subduction, which is thought to have initiated at the latitude of southern Utah during the earliest Campanian (Simpson et al., 2014). ...
... The earliest evidence of this foreland break-up in southern Utah includes growth faults in the Campanian Wahweap Formation in the northern Kaiparowits Plateau (e.g., Hilbert-Wolf et al., 2009;Simpson et al., 2014). One of the main drivers for Laramide tectonism is flat-slab subduction, which is thought to have initiated at the latitude of southern Utah during the earliest Campanian (Simpson et al., 2014). Inverse mantle convection models show the flat-slab segment, likely the conjugate of the Shatsky Rise, entering the subduction zone along the Mojave area of California at ca. 90 Ma, followed by northeast underthrusting beneath Arizona to Wyoming during the latest Cretaceous Liu and Currie, 2016). ...
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Anomalous features of Upper Cretaceous strata in southern Utah challenge existing tectonic and depositional models of the Cordilleran foreland basin. Extreme thickness variations, net to gross changes, and facies distributions of nonmarine to marginal marine strata of the Turonian−early Campanian Straight Cliffs Formation are documented across the Southwestern High Plateaus. Contrary to most traditional models of foreland basin architecture, regional correlations demonstrate abrupt stepwise thickening, with a punctuated increase in average grain size of key intervals from west to east, i.e., proximal to distal relative to the fold-thrust belt. Except in the most proximal sections, fluvial drainage systems were oriented predominantly subparallel to the fold-thrust belt. Combined, these results suggest that modern plateau-bounding faults may have had topographic expressions as early as Cenomanian time, and influenced the position of the main axial river system by creating northeast-trending paleotopography and sub-basins. Laramide-style tectonism (e.g., basement-involved faults) is already cited as a driver for sub-basin development in latest Cretaceous−Cenozoic time, but new data presented here suggest that this part of the foredeep was “broken” into distinct sub-basins from its earliest stages. We suggest that flexural foundering of the lithosphere may have caused early stage normal faulting in the foredeep. Regional implications of these new data indicate that both detachment-style and basement-involved structures were simultaneously active in southern Utah earlier than previously recognized. These structures were likely influenced by inherited Proterozoic basement heterogeneities along the edge of the Colorado Plateau. This interpretation suggests that tectonic models for the region should be reevaluated and has broader implications for understanding variability and geodynamics of foreland basin evolution.
... Laramidestyle, basement-involved uplifts exist on the margins of the SWHP, including the Kanarra Fold to the west, and the East Kaibab monocline and Circle Cliffs uplifts to the east (Fig. 1). The earliest evidence of this foreland break-up in southern Utah includes growth faults in the Campanian Wahweap Formation in the northern Kaiparowits Plateau (e.g., Hilbert-Wolf et al., 2009;Simpson et al., 2014). One of the main drivers for Laramide tectonism is flat-slab subduction, which is thought to have initiated at the latitude of southern Utah during the earliest Campanian (Simpson et al., 2014). ...
... The earliest evidence of this foreland break-up in southern Utah includes growth faults in the Campanian Wahweap Formation in the northern Kaiparowits Plateau (e.g., Hilbert-Wolf et al., 2009;Simpson et al., 2014). One of the main drivers for Laramide tectonism is flat-slab subduction, which is thought to have initiated at the latitude of southern Utah during the earliest Campanian (Simpson et al., 2014). Inverse mantle convection models show the flat-slab segment, likely the conjugate of the Shatsky Rise, entering the subduction zone along the Mojave area of California at ca. 90 Ma, followed by northeast underthrusting beneath Arizona to Wyoming during the latest Cretaceous Liu and Currie, 2016). ...
... A series of Late Cretaceous syndepositional, listric normal faults, linked to the onset of the Laramide orogeny, are exposed in the east-dipping limb of the East Kaibab monocline in Grand Staircase-Escalante National Monument, southern Utah ( Fig. 1; Tindall et al., 2010). These faults were seismically active during deposition of the upper and capping sandstone members, and evidence includes growth strata (significantly thicker sequences on the downthrown side of the fault), colluvial breccia of recycled Wahweap sediment, distribution and intensity of soft-sediment deformation (seismites) and sag pond deposits (Fig. 2;Hilbert-Wolf et al., 2009;Simpson et al., 2009;Tindall et al., 2010;Simpson et al., 2013Simpson et al., , 2014 At Bull Flat, the metre-scale load structures are found over an area greater than a thousand square metres, adjacent to the fault and along the sandstone-sandstone contact of the upper and capping sandstone members. The contact dips about 25°and is well-exposed along a dipparallel slope (Fig. 2). ...
... Bull Flat is located along the tip line of the fault and later fault activity may have propagated the fault through the load. Numerous lines of evidence indicate multiple phases of fault movement, including multiple stratigraphic intervals of seismites that can be attributed to the normal faults , growth faults and synorogenic strata (Tindall et al., 2010), and sediment fill within sag pond deposits (Simpson et al., , 2014. ...
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Large-scale soft-sediment deformation structures occur within fluvial sandstone bodies of the Upper Cretaceous Wahweap Formation in the Kaiparowits basin, southern Utah, USA. These structures represent an exceptional example of metre-scale fault-proximal, seismogenic load structures in nearly homogenous sandstones. The load structures consist of two types: large-scale load casts and wedge-shaped load structures. Large-scale load casts penetrate up to 4.5 m into the underlying sandstone bed. Wedge-shaped load structures include metre-scale, parallel, sub-vertical features, and decimetre-scale features along the periphery of the large-scale load casts or other wedge-shaped load structures. Wedge-shaped load structures contain well-developed, medial cataclastic shear deformation bands. All load structures contain pervasive well-defined millimetre-thick to centimetre-thick internal laminae, oriented parallel to the outside form of the load structures and asymptotic to deformation bands. Both types of load structures formed because of an inverted density profile, earthquake-triggered liquefaction, and growth of irregularities (a Rayleigh-Taylor instability) on the sandstone–sandstone erosional contact. The internal laminae and deformation bands formed during deformation, and clearly demonstrate polyphase deformation, recording a transition from liquefied to hydroplastic to brittle modes of deformation. Decimetre-scale wedge-shaped load structures on the edge of the large-scale load casts probably formed towards the end of a seismic event after the sediment dewatered and increased the frictional contact of grains enough to impart strength to the sands. Metre-scale wedge-shaped load structures were created as the tips of downward foundering sediments were driven into fractures, which widened incrementally with seismic pulsation. With each widening of the fracture, gravity and a suction effect would draw additional sediment into the fracture. Superimposed laminae indicate a secondary syndeformational origin for internal laminae, probably by flow-generated shearing and vibrofluidization mechanisms. Large-scale and wedge-shaped load structures, polyphase deformation and secondary laminae may characterize soft-sediment deformation in certain fault-proximal settings. This article is protected by copyright. All rights reserved.
... Danau Bandung yang ada di Cekungan Bandung memiliki bagian yang disebut sag pond, merupakan suatu kolam relatif kecil yang pembentukannya pada daerah Bandung dipengaruhi oleh adanya Sesar Lembang (Hidayat, 2010;Hubert-Ferrari, Avsar, Ouahabi, & Lepoint, 2012;Rasmid, 2014;Simpson et al., 2014;Ghassemi et al., 2014). Sag pond pada Cekungan Bandung terletak di sebelah utara berdampingan dengan kehadiran Sesar Lembang (Hidayat, 2010). ...
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... The Wahweap Formation, first described by Gregory and Moore (1931) as the Wahweap Sandstone, is a 360 to 460-m-thick fluvial succession comprising interbedded floodplain mudstones and channel sandstones. Peterson and Waldrop (1965) formally defined the unit as the Wahweap Formation, which was followed by more detailed sedimentological investigation by Peterson (1969), Eaton (1991), Little (1995), Pollock (1999), Simpson et al. (2008Simpson et al. ( , 2014 and Jinnah and Roberts (2011). The Wahweap Formation is exposed in southern Utah, U.S.A., along the margins of the Markagunt and Paunsaugunt plateaus (Biek et al., 2015) and extensively throughout the Kaiparowits Plateau ( Fig. 1) and is also correlated to the Masuk and Tarantula Mesa Sandstone formations to the northeast in the nearby Henry Basin (Eaton, 1990;Corbett et al., 2011;Jinnah, 2013;Lawton et al., 2014a). ...
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Late Holocene marsh deposits composing a terrace about 55 km northeast of Los Angeles, California, contain geologic evidence of many large seismic events produced by slip on the San Andreas fault since the sixth centrury A.D. I excavated several trenches into the deposits in order to study this evidence. The principal indicators of past events are (1) sandblows and other effects of liquefaction, (2) the termination of secondary faults at distinct levels within the stratigraphic section, and (3) sedimentary deposits and faulted relationships along the main fault. The effects upon the marsh deposits of six of the eight prehistoric events are comparable to those of the great (Ms=81/4+) 1857 event, which is the youngest of the nine events disturbing the strata and is associated with about 41/2 m of right lateral slip nearby. Two large events may be smaller than this. Radiocarbon dates indicate that the events occurred in the nineteenth, eighteenth, fifteenth, thirteenth, late twelfth, tenth, ninth, seventh, and sixth centuries A.D. Recurrence intervals average 160 years but vary from 1/2 century to about 3 centuries. The dates may indicate a fairly systematic pattern of occurrence of large earthquakes.
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Sand dikes and sills in glaciomarine sediments record two liquefaction events in Newbury, Massachusetts, the meizoseismal area of the A.D. 1727, felt-area magnitude 5.0, earthquake. During the 1727 earthquake, Newbury experienced ground shaking on the order of modified Mercalli intensity VII and underwent ground failure typical of liquefaction. According to accounts of the earthquake, ground cracks with separations of up to 0.6 m formed; sand and water vented through at least ten ground cracks; land was locally elevated; and firm ground was changed to quagmire. Crosscutting relations and radiocarbon dating of woody material associated with liquefaction features exposed by trenching indicate that at least two moderate to large earthquakes have occurred in the Newbury area in the past 4 ka. The relatively unweathered, younger features are consistent in style and location with ground failure described for the 1727 earthquake. The more weathered, older features probably formed during a prehistoric earthquake. Glaciomarine and other deposits that may be prone to liquefaction are widely distributed in northeastern North America; they provide the opportunity to develop criteria for identifying paleoliquefaction events and to better determine earthquake hazard in the region.
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Petrographic and dispersal data are essential to correct interpretation of mechanisms that create continental sequence-stratigraphic architecture. A case study from southern Utah demonstrates that Upper Cretaceous (upper Santonian-Campanian) alluvial successions in the southernmost part of the Cordilleran foreland basin were deposited by fluvial systems of contrasting drainage directions and provenance, and suggests that different mechanisms governed their sequence architecture. Most of the rivers flowed northeast, subparallel to the basin foredeep. Less common fluvial systems flowed to the east-southeast. The fluvial sandstones fall naturally into four petrofacies: (1) quartzofeldspatholithic (mean Qt(61)F(19)L(20)); (2) feldspatholithic (Qt(29)F(19)L(52)); (3) quartzolithic (Qt(75)F(6)L(20)); and (4) quartzose (Qt(99)F(1)L(1)). Petrofacies 1 and 2 were derived from mixed supracrustal and basement sources to the southwest and south, respectively, whereas petrofacies 3 and 4 were derived from uplifted thrust sheets of the Sevier orogenic belt to the southwest and west, respectively. Only the east-southeast-flowing rivers transported the quartzose petrofacies. The fluvial strata, which include the uppermost Straight Cliffs, Wah-weap, and Kaiparowits formations, form two large-scale stratigraphic successions typically interpreted as continental stratigraphic sequences hundreds of meters thick. Each succession begins with an amalgamated braided-fluvial deposit, grades to mudstone-rich strata with low sandstone-body connectivity, and culminates in highly connected sandstone bodies with multistory stacking. The basal amalgamated deposits of each succession are architecturally similar, but their compositional and dispersal characteristics are different. Quartzofeldspatholithic, quartzolithic, and quartzose sandstones above the lower base-level shift are variable, but generally similar in compositional and dispersal characteristics to both underlying and overlying strata, a phenomenon termed here congruence. In contrast, quartzose amalgamated fluvial sandstone above the upper base-level shift differs sharply in composition and dispersal direction from underlying and overlying lithic-rich strata. The foredeep aids controlled the progradation direction of the congruent shift, which was likely driven by climatically induced sediment influx, a eustatic fall, or both. In the case of the incongruent shift, increased sediment supply permitted the rivers to cross the foredeep. Temporal association of the upper amalgamated deposit with active structures in the thrust belt and foreland basin indicates that syntectonic thrust uplift, not isostatic uplift or climate, caused the influx of quartz.
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Paleoseismic investigations of the Lavic Lake fault at Lavic Lake playa place constraints on the timing of a possible earlier earthquake along the 1999 Hector Mine rupture trace and reveal evidence of the timing of the penultimate earthquake on a strand of the Lavic Lake fault that did not rupture in 1999. Three of our four trenches, trenches A, B, and C, were excavated across the 1999 Hector Mine rupture; a fourth trench, D, was excavated across a vegetation lineament that had only minor slip at its southern end in 1999. Trenches A–C exposed strata that are broken only by the 1999 rupture; trench D exposed horizontal bedding that is locally warped and offset by faults. Stratigraphic evidence for the timing of an earlier earthquake along the 1999 rupture across Lavic Lake playa was not exposed. Thus, an earlier event, if there was one along that rupture trace, predates the lowest stratigraphic level exposed in our trenches. Radiocarbon dating of strata near the bottom of trenches constrains a possible earlier event to some time earlier than about 4950 B.C. Buried faults revealed in trench D are below a vegetation lineament at the ground surface. A depositional contact about 80 cm below the ground surface acts as the upward termination of fault breaks in trench D. Thus, this contact may be the event horizon for a surface-rupturing earthquake prior to 1999—the penultimate earthquake on the Lavic Lake fault. Radiocarbon ages of detrital charcoal samples from immediately below the event horizon indicate that the earthquake associated with the faulting occurred later than A.D. 260. An approximately 1300-year age difference between two samples at about the same stratigraphic level below the event horizon suggests the potential for a long residence time of detrital charcoal in the area. Coupled with a lack of bioturbation that could introduce young organic material into the stratigraphic section, the charcoal ages provide only a maximum bounding age; thus, the recognized event may be younger. There is abundant, subtle evidence for pre-1999 activity of the Lavic Lake fault in the playa area, even though the fault was not mapped near the playa prior to the Hector Mine earthquake. The most notable indicators for long-term presence of the fault are pronounced, persistent vegetation lineaments and uplifted basalt exposures. Primary and secondary slip occurred in 1999 on two southern vegetation lineaments, and minor slip locally formed on a northern lineament; trench exposures across the northern vegetation lineament revealed the post-A.D. 260 earthquake, and a geomorphic trough extends northward into alluvial fan deposits in line with this lineament. The presence of two basalt exposures in Lavic Lake playa indicates the presence of persistent compressional steps and uplift along the fault. Fault-line scarps are additional geomorphic markers of repeated slip events in basalt exposures.
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The burrowing behaviour and rates of burrowing on sand, clay, mud, and gravel were determined for three species of freshwater mussels, Lampsilis radiata (Barnes), Anodonta grandis Say, and Elliptio complanata (Solander). Burrowing is achieved by a series of probing and digging movements by the foot, alternating with adduction or closing of the valves, and foot contraction, which cause the valves to be forced downwards into the substratum. Overall burrowing abilities were superior in sand in comparison to gravel in all three species, and E. complanata burrowed more rapidly than the other species in clay, sand, and gravel. Righting was not accomplished in soft liquid mud but burrowing was achieved by frequent, rapid adduction of the valves. Although righting by both E. complanata and A. grandis in a clay substratum was slower than in either sand or gravel, both species burrowed more rapidly in clay. Although there were differences in burrowing abilities between species and in the four substrata tested, the ultimate success in burrowing by all three species suggests that substrate is not the direct causal factor affecting local distribution of freshwater mussels.
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Mean seasonal species composition of living molluscan communities was compared with the composition of current dead assemblages in the sediments of three sites located in the Delta Marsh of southern Lake Manitoba. Dead shells were more numerous in vegetated than in bare areas, resulting primarily from the affinities of living molluscs for vegetated areas. Redistribution patterns of empty shells were not significantly different for vegetated and bare areas, as judged from distributions of passively transported land shells in the sediments. Significant differences were observed at all sites between species frequencies in living and corresponding dead assemblages averaged for the season. Proportions of living to dead individuals per unit bottom area indicated higher attrition rates with increasing energy conditions as well as with increasing shell size. Differential attrition may result in overrepresentation of small species in fossil assemblages.