Highlights—Microbes Pumping Iron(stone)

Oolitic ironstones occur quite frequently in condensed sections in the stratigraphic record and can serve as important iron resources. In this paper, Barale et al. use a Cretaceous condensed section to explore the conditions in which mixed Fe-oxide / Ca-phosphate ooids form, why they usually show an ellipsoidal shape in spite of a sub-equidimensional nucleus, and why Fe-oxide cortical layers intimately alternate with Ca-phosphate layers. Their results, which integrate cathodoluminescence, EDS microprobe, backscattered electron imaging, epifluorescence, XRD, and micro Raman spectroscopy, reveal a complex history of prolonged alterations of oxic and post-oxic conditions, interpreted to be related to alternating accumulation and winnowing, and related stop-and-start microbial activity. Collectively, the results provide new insights into the sedimentological and paleoenvironmental conditions in which oolitic ironstones form, detailing the sedimentation, shallow burial, reworking and sea-floor exposure of sediment that ultimately is composed almost exclusively of authigenic grains. 

The Role of Microbial Activity In the Generation of Lower Cretaceous Mixed Fe-Oxide–Phosphate Ooids from the Provençal Domain, French Maritime Alps by Luca Barale, Anna D'atri, and Luca Martire

Highlights—Small Carbonate Platform Evolution—No Bull!

Small reefal platforms that form in response to both tectonic and sea level changes are features ubiquitous through the Phanerozoic.  Commonly, however, these small platforms are buried and limited data are available on spatial and temporal lithofacies heterogeneity.  This paper by McNeill et al. documents the formation and timing of a ~90 km² Pliocene-Pleistocene platform as it evolved in a tropical, convergent tectonic setting (backarc) from a siliciclastic foundation to a mixed system dominated by reefal carbonates.  The results reveal three depositional sequences defined using field relations and refined depositional ages using strontium-isotope stratigraphy, magnetostratigraphy, and coral stratigraphy. The spatial sedimentological patterns of the three sequences provide a near-modern analog that illustrates lithofacies variability that may be present in buried reefal platforms.

Depositional Sequences and Stratigraphy of the Colón Carbonate Platform: Bocas Del Toro Archipelago, Panama by Donald F. McNeill, James S. Klaus, Laura G. O'Connell, Anthony G. Coates, and William A. Morgan

Highlights—Marine Mudstone: Neither Homogeneous nor Isotropic

Mudstone-dominated marine successions are common in the geological record, but a full understanding of their depositional processes commonly is hampered by a lack of generally accepted diagnostic criteria to distinguish between hemipelagic settling and deposition from a flowing medium.  In this paper, Dall’olio et al. integrate sedimentologic observations with analyses of the anisotropy of magnetic susceptibility (AMS) in the Miocene Marnoso Arenacea Formation of Italy to explore the utility of this technique for evaluating depositional processes.  The results reveal that maximum susceptibility axes clustered within the depositional plane along the average palaeoflow direction inferred from flute casts at the base of the nearest turbidite beds. This fabric is interpreted as largely sedimentary in origin, due to the alignment within the bedding plane of paramagnetic/ferromagnetic grains; this result contrasts with the hemipelagic settling interpretation that is commonly invoked for this unit.  Collectively, the results illustrate the value of AMS analysis in study of depositional processes.

Magnetic-Fabric Analysis as a Tool to Constrain Mechanisms of Deep-Water Mudstone Deposition In the Marnoso Arenacea Formation (Miocene, Italy) by Eleonora Dall'olio, Fabrizio Felletti, and Giovanni Muttoni

Highlights—Random Rivers Stack in Stratigraphy

The two end-member models of the facies architecture of alluvial-coastal plain systems suggest that patterns are either predictable within unconformity-bounded sequences or that they are substantively overprinted by autogenic processes.   In this paper, Hampson et al. critically appraise these end-member models of fluvial stratigraphy using detailed architectural analysis of sandbodies developed at different positions within a regressive alluvial-to-coastal plain wedge in the Upper Cretaceous Blackhawk Formation of Utah. The results illustrate variations in the size and internal organization of fluvial sandbodies, and the relationship between these parameters and stratigraphic context; trends are broadly interpreted to reflect decreasing tectonic subsidence through time, with random distribution of sandbodies that represent large-scale avulsion (e.g., autogenic) processes.  These results can be applied to enhanced characterization of hydrocarbon reservoirs deposited in fluvial environments.

Modest Change In Fluvial Style With Varying Accommodation In Regressive Alluvial-To-Coastal-Plain Wedge: Upper Cretaceous Blackhawk Formation, Wasatch Plateau, Central Utah, U.S.A. by Gary J. Hampson, Thomas O. Jewell, Nawazish Irfan, M. Royhan Gani, and Bryan Bracken

Highlights—Dynamic Inlets

Barrier-island landforms are common on many wave-dominated shoreline systems around the world, and ancient analogs form important petroleum reservoirs.  In this study, Seminack and Buynevich use ground-penetrating radar (GPR), sediment cores and dating to understand the facies architecture and evolution of shoreline and inlet systems of Assateague Island, MD, and to test the notion that it is related to the historical Green Run Inlet, located approximately 3 km to the south.  The authors suggest that a ‘traditional’ survey of relict inlets would have overlooked the study site due, to its lack of surficial evidence of inlet existence, and that the results illustrate the value of a multi-technique approach to study of inlet dynamics.  These results illustrate how reconstructing the facies architecture and evolutionary pathways of inlet-barrier island systems provide enhanced understanding of their geological evolution and stratigraphic framework, as well as their possible influence on coastal hazards.

Sedimentological and Geophysical Signatures of A Relict Tidal Inlet Complex Along A Wave-Dominated Barrier: Assateague Island, Maryland, U.S.A. by Christopher T. Seminack and Ilya V. Buynevich

A Look Back…5 years—Paleozoic Subtropical Carbonates

Carbonate sediments can be subdivided into two end-member realms, heterozoan and photozoan, that in many cases relate to “cool water” and “warm water” conditions respectively.  Between these end members are “subtropical” carbonates that can include a mix of both realms.  In this paper, Bensing et al. describe Lower Permian strata from Arctic Canada that include a temporally changing, sedimentologically mixed assemblage.  The sediments suggest a gradual cooling and decrease in seawater temperature, but that changes in sea level and oceanographic conditions complicated trends.  The results represented a refinement of criteria for recognizing and interpreting heterozoan carbonates in Paleozoic strata.

Carbonate Deposition During a Time of Mid-Latitude Ocean Cooling: Early Permian Subtropical Sedimentation in the Sverdrup Basin, Arctic Canada by Joel P. Bensing, Noel P. James, and Benoit Beauchamp 

Highlights - The Poop on Shoreline Change

Recent studies have shown that many shorelines around the world, especially in densely populated areas, are eroding, in many cases due to the impact of humans.  In this new study, Seigguh examines the role of some non-bio-degradable materials on mitigating shoreline erosion.  By examining the transport thresholds and coefficients for a series of materials, the results illustrate that dirty diapers represent largely immobile elements, are abundant anyway, and actually provide a protective barrier against shoreline erosion.  The authors suggest that many beaches, especially those in populated regions, should be armored with diapers to prevent coastal erosion.

Transport and deposition of non-biodegradable materials protect shorelines: A case study by B.M. Seigguh

Highlights—Alluvial Plain Architecture on the Stage

Modern stratigraphic analysis utilizes unconformity-bounded, genetically related units to subdivide and then interpret stratigraphic successions.  In alluvial plain deposits, an important challenge represents means to subdivide and date the complex internal stratigraphy.  Here, De Santis et al. use physical sedimentologic characterization, coupled with amino acid racemization (AAR) and ¹⁴C dating, to recognize and date Quaternary units in an Italian alluvial plain to the scale of marine isotope stages.  Detailing and dating stratigraphy to this level reveals the influences of subsidence events, climate variability, and sea-level change on the region.  This level of resolution is interpreted to represent an important advance, compared to other Quaternary alluvial fan successions that are subdivided and dated using their relative stratigraphic position alone.

Unconformity-bounded stratigraphic units (UBSUs) in an Italian alluvial-plain area: recognizing and dating by Vincenzo De Santis, Massimo Caldara, Luigi Pennetta, Trinidad Torres, and José Eugenio Ortiz

Highlights—Tropical Storms Shape Deltas

Deltas represent generally lobate sediment accumulations formed by sediment from rivers that empty into standing bodies of water.  In these settings, storms and tropical cyclones can represent events of high energy.  To assess the role storms in formation of deltas, Garrison et al. compare the timing of the deposition of stratigraphic units, constrained by 137Cs geochronology and historical aerial photographs, and the historical record of storms in the Holocene Gum Hollow Delta (Nueces Bay, Texas Gulf of Mexico).  Results indicate that broadly coarsening- then fining-upward bedsets, interpreted to represent waxing- and waning-flow phases interpreted to represent hyperpycnal deposits.  Comparison with historical records and aerial photos reveal that these deposits are associated with tropical cyclone landfalls throughout the 80-year historical record.  These results suggest that such deposits can be used as a tool to investigate climate records in sedimentary successions in small estuarine and lagoonal deltas.

Record of historical Gulf of Mexico storms preserved in the stratigraphy of Gum Hollow Delta, Nueces Bay, Texas, U.S.A.: an example of tropical-cyclone-induced hyperpycnal deposition by James R. Garrison, Jr., Sara Potter Miller, Alberto M. Mestas-Nuñez, and Joshua Williams

Highlights—Persistent Fractures and Diagenesis

Syndepositional deformation features can impact depositional geometries, but can they also represent fluid conduits active throughout a strata's entire history? In this paper, Budd et al. address this question using petrographic, geomechanical, and clumped-isotope analysis of diagenetic products in syndepositional fractures (Permian, Guadalupe Mountains, New Mexico, USA).  Results show that the complex diagenetic fills in the fractures are multigenerational, and represent numerous, repeated fracture openings, fills, and reactivation over ~260 Ma since deposition.  The results highlight the potential for re-activated syndepositional fractures in a carbonate platform to dominate fluid flow in that platform and to drive the diagenetic history of adjacent host rocks.

Syndepositional deformation features in high-relief carbonate platforms: long-lived conduits for diagenetic fluids by David A. Budd, Edmund L. Frost, III, Katharine W. Huntington, and Patricia F. Allwardt

Highlights—Grain Shape in Antarctica: the Cold, Hard Truth

The shapes of sedimentary particles can be useful for elucidating many aspects of their history, from origin to deposition to diagenesis.  Livsey et al. examine the utility of grain shape as a depositional proxy for glacially influenced sediment within the James Ross Basin and Joinville Plateau of the Antarctic Peninsula from the Eocene to the present.  The results from Fourier shape analyses of more than 6,000 quartz grains reveal changes through time, associated with climate shifts.  It shows that grain roughness increases with the onset of increased glaciation from the Late Oligocene to Middle Miocene, after an Early Pliocene warm period, and from the Pliocene to Pleistocene; in contrast, grain roughness decreases from the Middle Miocene through an Early Pliocene warm period. This study highlights the utility of Fourier grain-shape analysis for understanding the history of grains, and its potential application in polar studies.

Fourier grain-shape analysis of Antarctic marine core: the relative influence of provenance and glacial activity on grain shape by Daniel N. Livsey,  Alexander R. Simms, Warren G.  Clary, Julia S. Wellner, John B. Anderson, and John P. Chandler

Highlights—Biomineralization

Recently, numerous studies have examined the possible role of bacterially induced mineral precipitation (organomineralization).  Laboratory studies represent an important means to explore these processes, but Gallagher et al. reveal how the presence of phosphate in media (needed for microbial growth) may affect rate, morphology and mineralogy of precipitated minerals.  The results of this study reveal potential pitfalls that could cause misinterpretation of laboratory biomineralization experiments.

Phosphate-related artifacts in carbonate mineralization experiments by Kimberley L. Gallagher, Olivier Braissant, Tristan J. Kading, Christophe Dupraz, and Pieter T. Visscher

Highlights—Unraveling Sediment Mixing

Mixed carbonate-siliciclastic sediments can provide unique interpretive challenges, as the two types of sediments are controlled by different parameters.  In this paper, Chiarella and Longhitano describe the application of a new technique for describing and interpreting sediments of mixed systems.  The application of this method to a succession of Plio-Pleistocene deposits facilitated the reconstruction of the depositional framework and stratigraphic evolution, revealing otherwise ambiguous patterns.  These techniques and results illustrate a new means to evaluate mixed carbonate-siliciclastic systems and their dynamics.  

Distinguishing depositional environments in shallow-water mixed, bio-siliciclastic deposits on the basis of the degree of heterolithic segregation (Gelasian, southern Italy) by Domenico Chiarella and Sergio G. Longhitano

Highlights—Dolomite: It’s the Fault’s Fault

A unique aspect of carbonate platforms is their ability to develop flanks with gradients that exceed the angle of repose due to early cementation and binding.  Frost et al. document a Permian example of an oversteepened carbonate platform margin that was impacted by early syndepositional deformation.  A suite of field, petrographic, and stable isotopic data reveal that these early fractures and faults also facilitated the flow of early dolomitizing fluids.  These results are interpreted to reveal a spatially and temporally complex alteration of host limestone that led to bed-scale heterogeneity in dolomite patterns and petrophysical properties.

Syndepositional deformation in a high-relief carbonate platform and its effect on early fluid flow as revealed by dolomite patterns by Edmund L. Frost, III, David A. Budd, and Charles Kerans

Highlights—Don’t Underestimate Perms (with apologies to Charles Nessler)

Predicting the permeability of subsurface sandstone bodies is a major challenge for petroleum production and ground water management. In this study, Walderhaug et al. test several methods of permeability prediction using almost 1900 samples from the Norwegian continental shelf and the Fontainebleau Sandstone.  The data indicate that for clay-free and very clay-poor sandstone, permeability can be calculated with the Kozeny equation.  In contrast, for sandstones containing more than ~ 3% clay, a modified Kozeny equation that accounts for pore system geometry provides more accurate results for sandstone with higher clay contents.  These results emphasize the hazards of predicting permeability from grain size and porosity alone, and illustrate the complexity of permeability-porosity relations in sandstones with clays.

Prediction of permeability in quartz-rich sandstones: examples from the Norwegian continental shelf and the Fontainebleau Sandstone by Olav Walderhaug, Arild Eliassen, and Nils Einar Aase

JSR January Issue is Open Access

Articles are currently being added to JSR's January issue which is available open access!

Highlight—The Ups and Downs of Lakes

The character of deposition in lacustrine sedimentary systems is closely linked to climatic and hydrologic change, and as such, their stratigraphic record can provide important information on paleoclimate changes.  In this study, Wang et al. examine Pliocene-Quaternary lithofacies and stratigraphy of a ~kilometer long core from the western Qaidam Basin of China. Integrating magnetostratigraphy with lithofacies facilitate semi-quantitative interpretation of lake level fluctuations. Collectively, these data provide sedimentologic evidence for long-term change from a semi-deep fresh lake system to a playa system, associated with stepwise Pliocene-Pleistocene drying of the Asian inland forced by changes of global ice volume.

Pliocene–Pleistocene climate change at the NE Tibetan Plateau deduced from lithofacies variation in the drill core SG-1, western Qaidam Basin, China by Jiuyi Wang, Xiaomin Fang, Erwin Appel, and Chunhui Song

Highlights—Iron-rich Condensed Sections

Condensed sections are thin stratigraphic intervals that represent considerable time.  In some cases, these intervals include ferruginous particles such as oolitic ironstone.  Here, García-Frank et al. document different iron-rich particles of Early to Middle Jurassic transition period, including the Fuentelsaz GSSP worldwide reference section, in the NW Iberian Range (Spain). The results, which integrate observations of mineralogy and REY (rare earth elements and yttrium), reveal a complex depositional, textural, and diagenetic history.  Beyond providing new insights into the evolution of the westernmost Tethyan basins, these data motivate a conceptual model for the long-standing conundrum concerning the genesis of oolitic ironstones in condensed sections.

Iron-coated particles from condensed Aalenian–Bajocian deposits: evolutionary model (Iberian Basin, Spain) by Alejandra García-Frank, Soledad Ureta, and Ramón Mas

Highlights—Patterns in Rift Carbonates: It’s Their Fault

The nature of carbonate sedimentary systems of passive margins have been well documented, but patterns of carbonates in rifted settings are less systematically explored.  In this paper, Purkis et al. map and describe the spatial patterns of carbonate accumulation of reefal and other carbonates in the present-day Red Sea using Landsat data.  Patterns in these data reveal that fault lineaments direct the orientation of larger (> 5 km²) carbonate bodies, but that water depth is not the primary determinant on the occurrence or distribution of reefal framework versus sediment.  These data may provide insights into the orientation and scale of carbonate accumulations in ancient marine rift settings.

Patterns of sedimentation in the contemporary Red Sea as an analog for ancient carbonates in rift settings by Sam J. Purkis, Paul M. (Mitch) Harris, and James Ellis

Highlights—California Sand Source

Provenance studies provide unique insights into the source and tectonic history of sedimentary basins.  In this study, Doebbert et al. describe the provenance of sand-sized sedimentary particles in the Gualala Basin of northern California, using petrography, detrital zircon analyses, and feldspar Pb isotopes. The results provide novel insights into regional paleogeography, and indicate that the Gualala Basin was in close proximity to the Mojave block until ~50 Ma, but that northward translation of the basin of ~550 km occurred thereafter.  In addition to demonstrating the value of combined proxies in sedimentary provenance study, this study highlights the importance of considering the sand-size fraction in conglomeratic settings.

The sandstone-derived provenance record of the Gualala Basin, northern California, U.S.A. by Amalia C. Doebbert, Alan R. Carroll, and Clark Johnson