Wednesday, January 30, 2013

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.

Tuesday, January 22, 2013

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.

Tuesday, January 15, 2013

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.

Tuesday, January 8, 2013

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.