Friday, April 1, 2016

Highlights—Sequence Stratigraphy Review

Following up on his recent magnum opus that considered universal sequence stratigraphy, Burgess explores the depth of “what we really know” about the fundamental controls on sequence stratigraphy in his most recent contribution.  Wasting no words, with nary a flaw in style or content, he lucidly and simply describes his perspective on this question, and in doing so, illuminates gaps in understanding. His unusually succinct style carefully avoids the jargon common in sequence stratigraphy, so even beginners can grasp his points. [Ed. Note: We appreciate Dr. Burgess’ brief abstract, shorter than even many physics articles, which are notoriously curt.  Even though it is a review paper, it is the early favorite to win the Outstanding Paper Award.]

Wednesday, February 24, 2016

Highlights—Muddy Coastal Systems

Mud-dominated coastal systems play by their own rules. Many of the generalizations derived from years of study of sandy shoreline systems appear to not apply to shaley successions, or at least apply in unique ways. To better understand spatial changes and proximal-to-distal facies relationships of muddy systems, Harazim and McIlroy describe sedimentological, ichnological, and geochemical characteristics of the Lower Ordovician (Tremadocian) Beach Formation, Bell Island Group, Newfoundland. The results demonstrate that ancient fine-grained coastal systems are incompletely incorporated into sequence stratigraphic models owing to their atypical proximal-to-distal facies relationships, unique physical sedimentologic properties, and burial efficiency. The interpretations highlight the importance of 1) frequency of sediment supply events, 2) direction of mud transport, 3) diagenetic reactivity of minerals and bioavailable organic carbon, and (4) residence time of mineral grains and organic matter close to the sediment–water interface on facies architecture of this non-uniformitarian paleoenvironment, deposited prior to the evolution of soils. Face it, mud is complicated.

Wednesday, January 20, 2016

Highlights—The Poop on the Cretaceous–Paleogene Boundary, OR, Did the K–Pg Event Scare the Crap Out of Echinoids?

The Cretaceous–Paleogene boundary (K–Pg) represents a major event in earth history that impacted both terrestrial and marine realms. To explore the nature of sea-level and biologic change, Esmeray-Senletet al. explore strata straddling the Cretaceous–Paleogene boundary event in the Haymana Basin, Turkey, using planktonic foraminiferal biostratigraphy, a comprehensive microfacies analysis, and a sequence stratigraphy. The results illustrate a catastrophic and abrupt extinction of planktonic foraminifera in the Haymana Basin at the boundary. Immediately above the boundary is an enrichment of authigenic clay minerals and an extraordinary increase in abundance of echinoid fecal pellets, interpreted to represent low sedimentation rates; this signal may provide a criteria for identifying this horizon regionally. Comparing the interpreted relative sea-level curve of the Haymana Basin with sections in Europe, North Africa, and New Jersey, suggests similar trends in sea-level change, and indicate that the K–Pg boundary occurred during a global sea-level rise.

Monday, January 11, 2016

Highlights—Tilting the Table in the Book Cliffs

Many sequence stratigraphic studies have emphasized the important role of eustatic change on sequence architecture, led to large extent by studies in the Book Cliffs region of Utah and Colorado. This paper by Madof et al. tests the hypothesis that deposition within the late Cretaceous western interior foreland basin was modulated by the interaction of eustatic change and regional patterns of flexural subsidence—and suggest that it fails. The paper describes new insights concerning relationships among deposition (shallow marine, marginal marine, nonmarine facies), thickness trends, and geometrical relationships. The data suggest syndepositional tilting markedly influenced patterns, and cast doubt on the flexure-eustatic conceptual model for the origin of sequences in this area. Instead, the authors explain the patterns of deposition within the Book Cliffs in terms of an actively deforming basin, and propose that stratigraphic architecture can be fully understood only in three dimensions.

Tectonically controlled nearshore deposition: Cozzette Sandstone, Book Cliffs, Colorado, U.S.A. by Andrew S. Madof, Nicholas Christie-Blick, and Mark H. Anders