REEVALUATING CLAWED ARTHROPODA FROM UPPER DEVONIAN BLACK SHALES: IS THE “FIRST SHRIMP” REALLY A SHRIMP?

2016 ◽  
Author(s):  
Joseph T. Hannibal ◽  
Keyword(s):  
2004 ◽  
Vol 52 (3) ◽  
pp. 234-255 ◽  
Author(s):  
L.D. Stasiuk ◽  
M.G. Fowler

Abstract Petrographic analyses of dispersed organic matter (including macerals and palynomorphs), siliceous and calcareous microfossil assemblages and microtextures (e.g. stromatolitic) have been used to define and interpret five organic facies and regionally map their distribution for the following informal groupings of potential hydrocarbon source rocks in the Western Canada Sedimentary Basin: Upper Devonian Woodbend group, Upper Devonian Winterburn group and Upper Devonian to Lower Mississippian black shales of the Exshaw and Bakken formations. Five petrographic organic facies (A–E) are defined for the potential source rocks based on assemblages of alginites, acritarchs, sporinites, siliceous microfossils and algal mat microtextures. Organic facies A, B (prasinophyte alginites and acritarchs) and C (coccoidal alginite), represent accumulation in relatively deep (basin), intermediate (shelf-platform), and shallow water depths (bank-reef margin to lagoonal). Organic facies D is defined by siliceous microfossils (e.g. Radiolaria) and accumulated in deep basinal to outer shelf settings immediately east of an ancient Pacific Ocean, or south of an ancient Arctic Ocean. This facies may reflect regions of upwelling which extended into intracratonic and epicontinental settings. Organic facies E, characterized by stromatolitic microtextures with or without coccoidal alginite, only occur within Upper Devonian Winterburn Group shallow water, restricted shelf to lagoonal dolostones associated with evaporites. As a whole, the regional distribution of organic facies is related to paleogeography, paleobathymetry or paleostructure in the source rocks. Surprisingly, petrographic organic facies do not show strong positive correlation with kerogen type as defined by Hydrogen-Oxygen indices or TOC-S2 plots.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Man Lu ◽  
YueHan Lu ◽  
Takehito Ikejiri ◽  
Nicholas Hogancamp ◽  
Yongge Sun ◽  
...  

2019 ◽  
Vol 8 (2) ◽  
pp. 35
Author(s):  
Michael Iannicelli

Stratigraphic “displacements or dislocations” are coarse clasts and / or objects (such as unaltered remains or conodont-elements) slowly mobilizing or migrating vertically upward through a fine-grained matrix by a cryogenetic process known as “upfreezing” due to freezing temperatures. The process was originally established by periglaciologists and cold-climate geomorphologists who applied it only to unconsolidated, sedimentary deposits. In this study, the process is applied to the marine, pre-lithified, black shales of the Upper Devonian, Chattanooga Shale Formation, specifically in Tennessee, USA. The importance of this recognition is to alert paleontologists and stratigraphers about the strong possibility of inaccurate age-determinations made concerning coarse objects such as a conodont-element (denticles) (but not fossilized molds) because of their fossilized presence in age-determined, stratigraphic, rock levels when the apatite-composed denticles may have instead been initially deposited at a lower stratigraphic level during pre-lithification of the fine-grained, host-rock (shale) before the paleo-upfreezing process mobilized the denticles upwards. Many lines of evidences are given in this study towards apparent, predominant, freezing temperatures in the pre-existing, Chattanooga Sea of the Appalachian Basin, including particular, supposed, bioturbated, pre-lithified, organic black shale that is reinterpreted here as cryoturbated, pre-lithified, organic, black shale.


Author(s):  
IRVING A. BREGER ◽  
PATRICK G. HATCHER ◽  
LISA A. ROMANKIW ◽  
FRANCIS P. MIKNIS ◽  
GARY E. MACIEL

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