James A. Walker

The rocks of the TCZ are interpreted to have erupted in a transtensional continental rifting environment in the Late Siiurian to Middle Devonian. In this tectonic environment A-type granites are expected, and indeed the reiativeiy high Zr, Nb, and Y content in these rocks support this. However, many other geochemicai aspects of these rocks, i.e., high Ba, Rb, Th and K, are more typical of the I-type magmas that commonly occur in collisional settings. 

The Siluro-Devonian Tobique-Chaleurs Zone (TCZ) of New Brunswick is host to several relatively small Zn-Pb Cu-Ag sulfide deposits and occurrences that are all spatially associated with Early Devonian felsic volcanic and related sedimentary rocks (Fig. 1). The sulfide mineralization occurs as veins, veinlets and replacements of rock units that had high primary permeability (e.g., flow top breccias). Massive bedded sulfides that are typical of many modern and ancient VMS deposits are not present however, their absence is not surprising given the relatively shallow oxidizing marine conditions at that time therefore, the TCZ deposits belong to that part of the VMS family formed beneath the seafloor. This study was undertaken to assess the nature of the felsic volcanic host rocks and their control on mineralization. 

The TCZ extends from the Gaspe Peninsula of Quebec in the northeast to the State of Maine (USA) in the 

In the northern part of the TCZ, the Chaleurs Group comprises subaerially deposited. Late Silurian bimodal volcanic rocks that overlie early Silurian shallow marine fine- to coarse-grained clastic and carbonate sedimentary rocks. The Chaleurs Group is overlain disconformably by bimodal volcanic rocks and interlayered sandstones and siltstones of the Dalhousie Group. 

In the southern TCZ only Early Devonian rocks are exposed, and all of them are assigned to the Tobique Group. The Tobique and Dalhousie groups are in part coeval and are similar in terms of rock types. The depositional environment for the Tobique Group is, for the most part, thought to be outer shelf or slope based on sedimentary bed forms and ichnofauna and the presence of abundant pillow lava and hyaloclastite in mafic volcanic units. In 

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Joseph D.S Zulu David. R. Lentz James A.Walker ... 

WALKER, A.R., DAVISON, P.A., BOLOGNESI-WINFIELD, A.C., JAMES, C.M., SRINIVASAN, N., BLUNDELL, T.L., ESCH, J.J., MARKS, M.D., GRAY, J.C., The TRANSPARENT TESTA GLABRA1 locus, which regulates trichome differentiation and anthocyanin biosynthesis in Arabidopsis, encodes a WD40 repeat protein, Plant Cell,... 

Fifteen prominent chemical engineers first met in New York more than 60 years ago to plan a continuing literature for their rapidly growing profession. From industry came such pioneer practitioners as Leo H. Baekeland, Arthur D. Litde, Charles L. Reese, John V. N. Dorr, M. C. Whitaker, and R. S. McBride. From the universities came such eminent educators as William H. Walker, Allred H. White, D. D. Jackson, J. H. James, Warren K. Lewis, and Harry A. Curtis. H. C. Parmelee, then editor of Chemical and Metallurgical Engineering, served as chairman and was joined subsequently by S. D. Kukpatrick as consulting editor. 

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