Book Chapters

The chemical character of mafic rocks from the Arctic Alaska–Chukotka terrane records rifting of continental crust during the early Paleozoic, possibly during the Ordovician. The mafic rocks are part of a metamorphosed Neoproterozoic to Devonian continental margin sequence preserved in a Mesozoic metamorphic terrane, the Nome Complex, of Seward Peninsula, Alaska. Protoliths of the mafic rocks incl

The Arctic Alaska–Chukotka terrane is a microcontinent with an origin exotic to Laurentia. We used a sensitive high-resolution ion microprobe (SHRIMP) to date nine samples of Neoproterozoic rock and five samples of Devonian rock from the Brooks Range and Seward Peninsula of Alaska and from the Chukotka Peninsula of northeastern Russia. Felsic magmatism occurred at 968 Ma and 742 Ma in the Brooks R

Detrital zircons from the Nome Complex, a metamorphic terrane in northern Alaska, reveal important constraints on the early Paleozoic history of the Arctic Alaska–Chukotka terrane, a microcontinental block with an origin exotic to Laurentia.Twenty-two samples (17 in this study, five previously published) produce three detrital zircon population patterns (called themes), indicating that at least th

Both instrument design and capabilities of fluorescence spectroscopy have greatly advanced over the last several decades. Advancements include solid-state excitation sources, integration of fiber optic technology, highly sensitive multichannel detectors, rapid-scan monochromators, sensitive spectral correction techniques, and improve data manipulation software (Christian et al., 1981, Lochmuller a

The tectonic evolution of the Arctic realm, particularly in the Mesozoic, remains a subject of considerable uncertainty. The nature of the crustal entities involved, their origins, and the nature, location, and age of major tectonic boundaries are incompletely studied and understood (Pease, 2011). The largest piece of continental crust of uncertain origin that plays a role in Arctic tectonics is t

A detailed study of the Pb isotope geochemistry of Zn-Pb(-Ag-Au-Ba-F) stratabound sulfide deposits within metasedimentary rocks of the Neoproterozoic to Mississippian(?) Nome Complex provides key information for understanding deposit genesis and crustal evolution. A total of 106 new analyses of galena (and other sulfi des) and metasedimentary rocks hosting the deposits shows that (1) Pb isotope si

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This chapter provides an overview of geochemical modeling that applies to water–rock interactions under ambient conditions of temperature and pressure. Topics include modeling definitions, historical background, issues of activity coefficients, popular codes and databases, examples of modeling common types of water–rock interactions, and issues of model reliability. Examples include speciation, mi

Rural landscapes in the Andes are characterized by an impressive diversity of natural environments and by multiple resource assets. This is particularly the case in the tropical realm where the ecological altitudinal zones of the tierra caliente, the tierra templada, the tierra fria and the tierra heladaoffer a remarkable range of agricultural potential. This is complemented by a multitude of topo

Lampreys typically spawn in riffle habitats during the spring. Spawning activity and diel (i.e., during daylight and at night) behavioral patterns are initiated when spring water temperatures increase to levels that coincide with optimal embryologic development. Nests are constructed in gravel substrate using the oral disc to move stones and the tail to fan sediment out of the nest. Spawning habit

Tidal wetlands are some of the most dynamic areas of the Earth and are found at the interface between the land and sea. Salinity, regular tidal flooding, and infrequent catastrophic flooding due to storm events result in complex interactions among biotic and abiotic factors. The complexity of these interactions, along with the uncertainty of where one draws the line between tidal and nontidal, mak

The English chemistry pioneer Sir Humphry Davy first combined gas and water to produce a solid substance in his lab in 1810. For more than a century after that landmark moment, a small number of scientists catalogued various solid “hydrates” formed by combining water with an assortment of gases and liquids. Sloan and Koh (2007) review this early research, which was aimed at discerning the chemical