scholarly journals Supplemental Material: Suprasubduction zone ophiolite fragments in the central Appalachian orogen: Evidence for mantle and Moho in the Baltimore Mafic Complex (Maryland, USA)

2020 ◽  
Author(s):  
G.L. Guice ◽  
et al.

<div>Excel file containing bulk-rock and mineral chemical data, including standard data and precision calculations.<br></div>

2020 ◽  
Author(s):  
G.L. Guice ◽  
et al.

<div>Excel file containing bulk-rock and mineral chemical data, including standard data and precision calculations.<br></div>


Geosphere ◽  
2021 ◽  
Author(s):  
George L. Guice ◽  
Michael R. Ackerson ◽  
Robert M. Holder ◽  
Freya R. George ◽  
Joseph F. Browning-Hanson ◽  
...  

Suprasubduction zone (SSZ) ophiolites of the northern Appalachians (eastern North America) have provided key constraints on the fundamental tectonic processes responsible for the evolution of the Appalachian orogen. The central and southern Appalachians, which extend from southern New York to Alabama (USA), also contain numerous ultra- mafic-mafic bodies that have been interpreted as ophiolite fragments; however, this interpretation is a matter of debate, with the origin(s) of such occurrences also attributed to layered intrusions. These disparate proposed origins, alongside the range of possible magmatic affinities, have varied potential implications for the magmatic and tectonic evolution of the central and southern Appalachian orogen and its relationship with the northern Appalachian orogen. We present the results of field observations, petrography, bulk-rock geochemistry, and spinel mineral chemistry for ultramafic portions of the Baltimore Mafic Complex, which refers to a series of ultramafic-mafic bodies that are discontinuously exposed in Maryland and southern Pennsylvania (USA). Our data indicate that the Baltimore Mafic Complex comprises SSZ ophiolite fragments. The Soldiers Delight Ultramafite displays geochemical characteristics—including highly depleted bulk-rock trace element patterns and high Cr# of spinel—characteristic of subduction-related mantle peridotites and serpentinites. The Hollofield Ultramafite likely represents the “layered ultramafics” that form the Moho. Interpretation of the Baltimore Mafic Complex as an Iapetus Ocean–derived SSZ ophiolite in the central Appalachian orogen raises the possibility that a broadly coeval suite of ophiolites is preserved along thousands of kilometers of orogenic strike.


Geosphere ◽  
2021 ◽  
Author(s):  
George L. Guice ◽  
Michael R. Ackerson ◽  
Robert M. Holder ◽  
Freya R. George ◽  
Joseph F. Browning-Hanson ◽  
...  

In the Table 3 note and captions of Figures 8 and 9, the equation Fe2+# = molar Fe2+/[Mg+Fe2++Fe3+] is incorrect. It should instead be Fe2+# = molar Fe2+/[Mg+Fe2+].


1991 ◽  
Vol 28 (10) ◽  
pp. 1635-1652 ◽  
Author(s):  
G. A. Jenner ◽  
G. R. Dunning ◽  
J. Malpas ◽  
M. Brown ◽  
T. Brace

The Bay of Islands Complex of the Humber Arm allochthon, west Newfoundland, contains the best-exposed ophiolite in the Appalachian Orogen. Associated structural slices, the Little Port and Skinner Cove complexes, also contain rocks formed in an oceanic domain, although their relationship to the Bay of Islands Complex remains controversial.To constrain the origin of the complexes and obtain a better understanding of the geology of the Humber Arm allochthon, we have undertaken an integrated geochronological, geochemical, and isotopic study. A U/Pb zircon age of [Formula: see text] Ma for the Little Port Complex and a zircon and baddeleyite age of 484 ± 5 Ma for the Bay of Islands Complex have been obtained. Geochemical and isotopic data on trondhjemitic rocks from the two complexes indicate that petrogenetic models for these rocks must account for fundamental differences in source materials and mineralogy during differentiation. The Little Port Complex trondhjemites are characterized by initial εNd of −1 to +1, whereas those in the Bay of Islands have εNd of +6.5. Geochemical signatures in mafic and felsic volcanics of the complexes are diverse, and show a complete gradation between arc and non-arc.The Bay of Islands and Little Port complexes are not related by any form of a major mid-ocean-ridge – transform-fault model. An alternative model to explain the relationships between the two complexes interprets the Little Port as arc-related and the Bay of Islands as a suprasubduction-zone ophiolite.


2020 ◽  
Author(s):  
George Guice ◽  
◽  
Michael R. Ackerson ◽  
Robert Holder ◽  
Freya George ◽  
...  

1982 ◽  
Vol 46 (341) ◽  
pp. 411-420 ◽  
Author(s):  
N. S. Angus ◽  
R. Kanaris-Sotiriou

AbstractThe Currywongaun and Doughruagh masses of northern Connemara represent a section through a syntectonic, partially layered intrusion formed of ultrabasic cumulates all having plagioclase of around An94. Differentiation and contamination of the magma from which these cumulates were precipitated ultimately produced an acid residuum which was responsible for the hydrous metasomatism of the earlier formed ultrabasic rocks resulting in the extensive formation of quartz-amphibole-anorthite gneisses in the petrogenetically ‘upper’ parts of the intrusion. Coexisting Ca-rich and Ca-poor amphiboles in the gneisses are interpreted as ‘frozen’ reaction intermediates that were in local equilibrium. The bulk-rock chemical data presented confirm that the compositions of the quartz-rich gneisses can be attributed almost entirely to the addition of Si to the ultrabasic rocks, coupled with the removal of Mg and Ca. The data also suggest that Zr, which reaches around 1000 ppm in some of the gneisses, may have been ‘mobile’ under these conditions of hydrothermal metasomatism.


Author(s):  
Karen A. Katrinak ◽  
David W. Brekke ◽  
John P. Hurley

Individual-particle analysis is well established as an alternative to bulk analysis of airborne particulates. It yields size and chemical data on a particle-by-particle basis, information that is critical in predicting the behavior of air pollutants. Individual-particle analysis is especially important for particles with diameter < 1 μm, because particles in this size range have a disproportionately large effect on atmospheric visibility and health.


2013 ◽  
Vol 18 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Emmanuel Kuntsche ◽  
Florian Labhart

Ecological Momentary Assessment (EMA) is a way of collecting data in people’s natural environments in real time and has become very popular in social and health sciences. The emergence of personal digital assistants has led to more complex and sophisticated EMA protocols but has also highlighted some important drawbacks. Modern cell phones combine the functionalities of advanced communication systems with those of a handheld computer and offer various additional features to capture and record sound, pictures, locations, and movements. Moreover, most people own a cell phone, are familiar with the different functions, and always carry it with them. This paper describes ways in which cell phones have been used for data collection purposes in the field of social sciences. This includes automated data capture techniques, for example, geolocation for the study of mobility patterns and the use of external sensors for remote health-monitoring research. The paper also describes cell phones as efficient and user-friendly tools for prompt manual data collection, that is, by asking participants to produce or to provide data. This can either be done by means of dedicated applications or by simply using the web browser. We conclude that cell phones offer a variety of advantages and have a great deal of potential for innovative research designs, suggesting they will be among the standard data collection devices for EMA in the coming years.


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