The end-Permian extinction is typically ascribed to massive volcanic eruptions, but direct geochemical evidence linking the two independent events is generally lacking. Zinc is an important micronutrient of marine phytoplanktons, and Zn isotope (d66Zn) ratios of seawater are markedly higher than those of volcanic rocks and riverine waters. We conducted high-resolution Zn concentration and Zn is...

Certain alteration minerals are used to identify the hydrothermally altered rocks. In volcanic rocks, mainly potassic, phyllic (sericitic), propylitic, argillic alteration and silicification are observed. The role of remote sensing in alteration mapping is the differentiation of the minerals that are unique for different alteration types. In this study, Landsat TM 5 images are used. General alt...

Rifted continental margins are the product of stretching, thinning and ultimate break-up of a continental plate into smaller fragments, and the rocks lying beneath them store a record of this rifting process. Earth scientists can read this record by careful sampling and with remote geophysical techniques. These experimental studies have been complemented by theoretical analyses of continental e...

We examined the potential use of lead (Pb) isotopes to source archaeological materials from the Maya region of Mesoamerica. The main objectives were to determine if: 1) geologic terrains throughout the Maya area exhibit distinct lead isotope ratios (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb), and 2) a combination of lead and strontium ratios can enhance sourcing procedures in the Mesoamerica re...

New geochemical data including Sm/Nd isotopic data show evidence for an early Paleozoic arc/back-arc complex in the Nashoba terrane of southeastern New England. The Nashoba terrane lies between rocks of Ganderian affinity to the northwest and Avalonian affinity to the southeast. It consists of early Paleozoic mafic to felsic metavolcanic and metasedimentary rocks that were intruded by intermedi...

•80 data have been obtained on 7 of the 17 intrusive centers of diorite and granodiorite (Miocene?) that lie along a N-S belt about 50 km west of the High Cascades. Whole-rock $ values (per mil relative to SMOW) in the intrusive stocks are: -[-2.3 to -t-4.9 (South Umpqua River), -0.7 to -t-3.8 (Bohemia mining district), -t-4.3 to -t-4.6 (Vida stock), -0.2 to -t-5.5 (Nimrod stock), --1.7 to -}-0...

Discussions continue about whether Middle Eocene magmatism in the Eastern Pontides is associated with collision or subduction. This paper presents new whole-rock geochemistry, Sr-Nd isotopic and 40Ar-39Ar age data for volcanic rocks from Bayburt area of (NE Turkey) to investigate their sources evolutionary history. The 40Ar–39Ar ages reveal that these erupted between 44.6 ± 0.1 Ma 43.5 Ma, with...

Maars are monogenic volcanic edifices of peculiar morphology with a wide circular crater surrounded by a low gentle rim of erupted pyroclastic material. Craters of maars are deeply incised into underlying rocks (frequently down to the aquifer), which explains their frequent partial or complete water infill. Owing to their morphological peculiarities, maars are easily identifiable in air photos.

A bidimensional empirical mode decomposition (BEMD) program on a MATLAB platform was effectively used to handle gravity signals for the Tongshi gold field. This yielded a two-dimensional intrinsic mode function (IMF3) image that meticulously depicts the spatial distribution relationship between various gold deposits and the different geological units of the gold field. By combining the IMF3 ima...