Friday, July 21, 2017

Highlights: Cambrian Cratonic Carbonates

What sediments are preserved during sea-level falls on cratonic passive margins? Raine and Smith explore the concept that on many carbonate platforms, sequence boundaries are represented by a zone of shallower facies and it is difficult to identify a single surface as a sequence boundary. To do so, they start by describing facies that provide evidence of a coastal sabkha, a sedimentary environment commonly not well preserved in Palaeozoic carbonates. At a larger scale, they document stacking patterns and physical features (e.g., karst, sandstone) that record a falling stage systems tract and a well-defined type 1 sequence boundary in a Cambrian succession in Scotland, interpreted to be consistent with the idea that the Sauk II-III boundary represents a major sea-level fall associated with progradation of sabkhas.



Wednesday, July 12, 2017

Highlights: Seismic Expression of Fluvial Channels

Fluvial channels are inherently three-dimensional features; although challenging to study on two-dimensional outcrops, seismic data provide unique perspectives on their architecture. Alqahtani and others evaluate the geometry, dimensions, distribution and evolution of fluvial channel systems from a humid-tropical climatic setting through detailed analysis of high-resolution 3D seismic reflection data from the Malay Basin. The interpretations reveal eight depositional units that include systematic changes in six types of fluvial channels defined based on cross-sectional and planform geometries. The data provide input for reconstructions of the palaeo-hydrological conditions during Pleistocene sea-level cycles that affected the Sunda Shelf Sea. The manuscript further evaluates the roles that sea-level variations, climate, and sediment supply play on controlling the formation and evolution of fluvial systems, including incised valleys and associated tributary channels.


Thursday, June 29, 2017

Highlights: Enhanced Pictures of Tidal Cycles

Geoscientists love repeated themes, and have identified cycles at scales from tectonic to Milankovitch to tidal. A key component to identifying cyclic processes is identification of some sort of duplicated motif. To provide an enhanced means for identifying tidal cycles, Hayes et al. explore dune foreset thickness measurement errors from images, and suggest a quick, easy alternative to reduce these errors using 3D photogrammetry. The new method allows improved measurement accuracy by remaining orthogonal to the outcrop face while collecting data. In doing so, the final results are less noisy and more precise, allowing for a stronger interpretation of the data.  After all, we know there are indeed some really bad dune pictures.

Analyzingdune foreset cyclicity in outcrop with photogrammetry by Derek A. Hayes, Eric R. Timmer, Jared L. Deutsch, Michael J. Ranger, and Murray K. Gingras


Monday, May 29, 2017

Highlights: The Shape of Sand

Interpreting depositional setting is a fundamental task of many sedimentary geologists.  Existing analytical techniques using sediment properties to characterize depositional setting and related mechanism of transport can produce results with varying accuracy or can be cost prohibitive. Here, Eamer and co-workers describe a new method that uses freely available software and an optical microscope to differentiate coastal sands transported by eolian and littoral processes. The method is based on the principle of eolian sand sorting, in which wind preferentially transports rounded grains to angular grains. The software was used to classify grain solidity. Results from application of this method are promising, with correct identification of the transport mechanism of 76% of nearly 6000 tested sand grains. Determining the depositional setting of sand grains provides important information for paleoenvironmental reconstruction, stratigraphic interpretation, and applied sciences (e.g., hydrogeology).

Distinguishing depositional setting for sandy deposits in coastal landscapes using grain shape by Jordan Blair Reglin Eamer, Dan Hirsh Shugar, Ian James Walker, Olav B. Lian, and Christina M. Neudorf

Friday, May 26, 2017

Highlights: Good (Tidal) Beach Reading

Tide-dominated beaches are widespread in today's world, and coastal researchers have recently begun to address their sedimentary character, finding that they differ notably from the more familiar, purely wave-dominated beaches. Nonetheless, ancient tide-dominated beaches are infrequently recognized, perhaps for want of suitable sedimentological criteria and facies models. Smosna and Bruner present the facies reconstruction of The Cambro-Ordovician Cabos Formation of northern Spain, a system interpreted to represent an ancient tide-dominated beach system. In describing sedimentologic observations and the criteria on which the interpretation is based, this analysis constitutes a beginning step in constructing the sedimentological framework for a virtually unknown (or at least poorly documented) paleoenvironment. 



Friday, May 19, 2017

Highlights: Sources in the Chaco

Foreland basins are the ultimate sink for much of the sediment derived from erosion of fold-and-thrust belts in convergent margins. To better understand the evolution of the Andean cordillera, and convergent-margin syn-orogenic sediments in general, McGlue and others integrate geomorphological observations with analyses of composition, texture, and U-Pb ages of modern detrital sediments of the Río Bermejo megafan in the Chaco foreland basin, northern Argentina. The results document that provenance reflects the lithology of the parent material and the transport distance, with maturity increasing farther from the thrust front and sediment fining towards the forebulge. These data enhance understanding of distributive fluvial systems in overfilled retroarc foreland basins, and may improve interpretation of ancient analogs that have been the source of critical information on the history of convergent orogenic belts. [Editor’s note: other Chacos are interesting as well.]

An integrated sedimentary systems analysis of the Río Bermejo (Argentina): megafan character in the overfilled southern Chaco foreland basin by Michael M. McGlue, Preston H. Smith, Hiran Zani, Aguinaldo Silva, Barbara Carrapa, Andrew S. Cohen, and Martin B. Pepper

Tuesday, May 16, 2017

Highlights: Unraveling Unroofing in the Piceance

As numerous JSR papers have illustrated, sediment provenance can provide key insights for interpreting climatic controls on stratigraphy, estimating paleoaltimetry, and reconstructing the timing and mechanisms of tectonic processes; after all, there are various causes for unroofing. Here, Foreman and Rasmussen examine the provenance of sediment the Wasatch Formation exposed in the Piceance Basin of Colorado to explore the unroofing history of surrounding uplifts. Integrating new and compiled paleocurrent measurements, sandstone petrographic compositions, and U-Pb detrital-zircon ages, the results refine unroofing history and revised age constraint for the Sawatch (Laramide) Range.  The data provide new perspectives on mechanisms behind the shift from Sevier to Laramide tectonism, and at a finer scale, implicate major shifts in deposition within the Wasatch Formation related to fluctuations in tectonics and climate.


Tuesday, May 9, 2017

Highlights: JSR: Jammin’ Speedy Results

Although most authors (ultimately) appreciate of the rigorous editorial process at JSR, many may not realize that JSR currently has no backlog for getting accepted manuscripts to publication

What exactly does that mean for authors?  In short: Quicker publication. 

To provide perspective: your humble blogger and a student had a manuscript that was accepted for publication in another well-respected society journal in September, 2016.  We were told it would appear in press in May 2017 (!!)...but we just heard that “oops we meant August 2017...maybe.”  That’s a year delay!  Likewise, another competitor journal lists dates of acceptance online. Their most recent issue (April 2017) shows that some manuscripts that were accepted in August 2016 just now have their official final version published.

In marked contrast, manuscripts at the Journal of Sedimentary Research accepted for publication in April 2017  will appear in their final published version online in May 2017!  A matter of a few weeks!  Yowzah – Speedy Gonzales!  

Now to be fair, faster is not always better, and sometimes fast can be “too fast” and get you in trouble. And of course, there are some different (eh?) and interesting ways to speed up things. Some other journals post accepted manuscripts online early, but that’s “kind of” a pre-publication, but, as savvy JSR PaperClip readers know, you can see a lot of fake stuff on the internet.

But wouldn’t you just rather see your accepted manuscript published for real sooner than later?!  Submit it to JSR.



Thursday, May 4, 2017

Highlights: Zany Zircons Mix It Up

Provenance data from sand-sized sediment is an important tool in sedimentology, tectonics and structural geology. To understand the role of sedimentary process in controlling provenance signatures in sand-sized sediment at the scale of entire sediment dispersal systems, Sickmann and others explore U-Pb detrital-zircon data from a series of modern second-order river-to-deep-marine depositional systems in central California. The results illustrate that changes in provenance signatures from sand-sized sediment across dispersal systems and between dispersal systems potentially are influenced by sedimentary processes - and not by tectonic evolution of sources or the evolution and expansion of drainage basins as commonly assumed. These data emphasize understanding the potentially important role of sediment mixing in the marine realm, systems with changes in sediment pathways that can create variable pathways.




Monday, May 1, 2017

JSR Outstanding Paper 2015

This April at AAPG, SEPM announced the winner of the Outstanding Paper Award for JSR. The award is determined through a combination of nominations and votes from the editorial board and a metric of citations from GeoScienceWorld. We are very happy to present the OP award for 2015 (yes, we know we are behind a year) to three papers!


Gary J. Hampson, Robert A. Duller, Andrew L. Petter, Ruth Robinson, and Philip A. Allen


and

Ted E. Playton and Charlie Kerans


Congratulations to our winners!

Wednesday, April 26, 2017

Highlights: Continental Carbonate Conditions

Continental carbonates are distinct from their marine cousins, but like them, contain numerous proxies for the environment in which they formed. Yet, continental carbonates can be of two general types: those formed ambient temperature from calcium bicarbonate–enriched waters and those associated with hyperalkaline thermal springs, from fluids commonly depleted in dissolved inorganic carbon. Both are favored under distinct conditions, yet how closely they each reflect their environment is unclear. To better understand these complexities, Leleu and others examined travertine forming at DIC-depleted hyper-alkaline springs with pH up to 12. Their multi-disciplinary approach ranged from macroscopic to microscopic scale, analyzing travertine samples to assess the relationship between the petrologic features and fabrics and the geochemical and isotopic signatures. The results illustrate the potential of these deposits as proxies of past climatic record and atmospheric CO2 sequestration.

Travertines associated with hyperalkaline springs: evaluation as a proxy for paleoenvironmental conditions and sequestration of atmospheric CO2 by Thomas Leleu, Valérie Chavagnac, Adélie Delacour, Catherine Noiriel, Georges Ceuleneer, Markus Aretz, Céline Rommevaux, and Sandra Ventalon


Friday, April 21, 2017

Highlights: Appalachian Sand Sources

In providing clues of since-leveled landscapes, the stratigraphic record records tectonic evolution. In this study, Uddin et al. integrate petrographic, detrital-geochronologic, and mineral-chemistry analyses of detrital minerals and lithic clasts of the Pennsylvanian Pottsville Formation, part of a clastic wedge in the foreland basin in Alabama and Mississippi.  This manuscript illustrates that this part of the foreland basins received detritus mostly from the Appalachians, rather than the Oucahitas, and draws an analogy to the modern Himalayan-Bengal system. The mineralogy and dates suggest an initial Blue Ridge Piedmont source, followed by a migrating steep erosional front that buried previously eroded terrains; alternatively, some of the variations may result from along-strike transport of detrital material in the foreland basin.



Tuesday, April 18, 2017

Highlights: Quality Deep-Water Sand

Porten and others show how reservoir quality of deep-marine sandstones is controlled by sediment composition, transport, and depositional histories in a range of sediment-gravity-flow deposits in a Maastrichtian submarine-fan in the Vøring Basin (Norwegian Sea, Norwegian continental shelf). In these strata, porosity increases with decreasing clay content, and permeability increases with increasing grain size, decreasing clay volume, and increasing porosity. Porosities of the different depositional bed types are similar, whereas permeabilities are distinct, with high-density turbidites having permeabilities approximately two orders of magnitude higher than clay-rich hybrid event beds. The results of this study emphasize the importance of the transport and depositional processes responsible for producing different bed types with characteristic composition and texture. This step is essential in reservoir evaluation, necessary for predicting most likely porosity and permeability evolution with sediment burial and for understanding reservoir quality distribution in potential deep-marine siliciclastic hydrocarbon reservoir targets.



Thursday, April 13, 2017

Highlights: Ode to Sand o Green

To expl're the genesis of the Gosp'rt Sand, an Eocene greensand deposit from the U.S. Gulf coastal plain, Pietsch and co-auth’rs integrateth sedimentology, the min'ralogy, taxonomic and ecological analysis, and taphonomic hist'ry o’ the mollusk fauna. The results bewray yond this glauconite-rich sand enwheels hyp'r-div'rse mollusk fauna, int'rpret'd to representeth deltaic inn'r shallow shelf to ope soundeth environments. Although glauconite-rich shell beds art int'rpret'd to beest fav'r'd by transgression, the ov'rall stratigraphy wast influenc'd by delta progradation, subsidence, and shifting sea-level. This w'rk may representeth analogs to oth'r glauconitic and fossil bearing h'rizons throughout the paleogene gulf and atlantic coastal plain, and oth'r greensand h'rizons throughout the geologic rec'rd.



Monday, April 10, 2017

Highlights: Alluvial Sand Bodies Can Cluster

Alluvial architecture includes describing stacking patterns, spatial density of fluvial channel-belt sandstone bodies, and connectivity, aspects shaped by influences of autogenic and allogenic processes. This study by Benhallam et al. attempts to understand the relative roles of allogenic and autogenic factors on the fluvial John Henry Member of the Straight Cliffs Formation (Cretaceous) of the southwestern Kaiparowits Plateau of Utah. To attempt to discriminate between local and regional controls, this study uses a suite of spatial algorithms to quantify and statistically discriminate clustered, uniform, or random channel-belt bodies in several outcrops. By comparison with predictions from various experimental and numerical models of alluvial architecture, the existence of different patterns at different spatial scales implicates avulsion reoccupation at the small scale, and avulsion-driven compensational stacking at a larger scale. This study suggests that specific types of channel stacking patterns provide insights into the underlying controls and depositional processes, such as compensational stacking and avulsion reoccupation.



Thursday, April 6, 2017

Highlights: On Sand and Sequences

Although that dastardly diagenesis plays a role, many of the same depositional factors that control sequence stratigraphy also influence the composition of sandy sediment within those sequences. Taking this concept as a starting point, Tentori and others unravel relationships between siliciclastic sediment composition (petrofacies) and sequence stratigraphic systems tracts of the Quaternary sedimentary succession of the Roman Basin. The results document different quartz/feldspar and quartz/lithic ratios, and textural changes, among systems tracts. These changes are interpreted to represent the influences of hydraulic sorting (by various processes among systems tracts) and post-depositional in situ weathering, and are linked to tectonics, volcanism, and relative changes in sea level. The data show how a sedimentary petrographic approach can be used to derive information on the stage evolution of a sedimentary succession through time. These results might be directly applicable to petroleum exploration and production in wave-dominated deltaic succession.



Saturday, April 1, 2017

Highlights: The Future of Carbonate Sedimentology(?)


Although recently some have lamented the “demise” of carbonate geology, practictioners in the field are not ones to let it die. Instead of re-hashing what he considers to be more mundane aspects of carbonate depositional systems, or argumentative aspects of cyclostratigraphy, Bruce Wilkinson starts from the premise that “so much of carbonate sedimentology is crap” to develop the concepts and applications of the future of carbonate geology—peloids and pelotherapy. The Medical Subject Headings (MeSH) database of the MEDLINE/PubMed defines pelotherapy as “The therapeutic use of mud in packs or baths taking advantage of the absorptive qualities of the mud. It has been used for rheumatism and skin problems.” Building on efforts of clay mineralogists, Wilkinson argues that pelotherapy can take three approaches: 1) Geophagy, which utilizes the healing power of the calcium carbonate-organic mix, but which can become addictive; 2) Psammotherapy (sand baths) useful for muscular-skeletal diseases; and 3) Cosmetics, providing for a strong skrabiruyuschy effect. The manuscript notes a niche (but growing) peloid travel destination, clear relevance for modeling, and a strong and growing market – after all, who doesn’t love a good peloidal mud bath?




Monday, March 27, 2017

Highlights: Differences between the EARSs

The East African Rift System (EARS) includes a northern segment that is more volcanically influenced than regions to the south. To explore the roles of climate, tectonism, and volcanism and the architecture of sedimentary deposits in rift basins, this manuscript by Mtelela and others provides a sedimentologic investigation of the Pleistocene–Holocene upper Lake Beds, the uppermost stratigraphic unit exposed throughout the Rukwa Rift Basin in southwestern Tanzania. Integrating geologic mapping, lithofacies analysis, petrographic microscopy, scanning electron microscopy, and radiocarbon dating reveal alternating stacking patterns of landward- and basinward-stepping alluvial to fluvial channel, deltaic, and profundal lacustrine strata, bounded by unconformities. Sequence development in this rift basin is interpreted to be controlled largely by base-level changes drive by interplay between climate change and sediment supply, but was influenced by episodic volcanism in the Rungwe Volcanic Province.  Understanding these types of linkages is central to efforts in evaluating the resource potential of rift basins; in this basin, it also provides a foundational context for interpretation of regional paleoclimate and paleoenvironmental setting of vertebrate fossils.