Isotope Geology

Allègre, Claude J.; Sutcliffe, Christopher

doi:10.1017/cbo9780511809323

Cited by 111 publications

(114 citation statements)

References 257 publications

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“…It can be considered that Sr and Nd isotopes keep a record of geological evolution (e.g. Allègre 2008) and thus, the isotopic compositions of the studied volcanic and subvolcanic basic rocks could contribute to the interpretation of the magma genesis, the position of the magma chamber in relation to the continental crust and upper mantle. Consequently, they can solve the relationships between individual phases of volcanism in relation to basin evolution and individual phases of rifting.…”

Section: Introductionmentioning

confidence: 99%

Geochemistry and Sr, Nd isotopic composition of the Hronic Upper Paleozoic basic rocks (Western Carpathians, Slovakia)

Vozár¹,

Spišiak²,

Vozárová³

et al. 2015

Geologica Carpathica

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The paper presents new major and trace element and first Sr-Nd isotope data from selected lavas among the Permian basaltic andesite and basalts of the Hronicum Unit and the dolerite dykes cutting mainly the Pennsylvanian strata. The basic rocks are characterized by small to moderate mg # numbers (30 to 54) and high SiO 2 contents (51-57 wt. %). Low values of TiO 2 (1.07-1.76 wt. %) span the low-Ti basalts. Ti/Y ratios in the dolerite dykes as well as the basaltic andesite and basalt of the 1 st eruption phase are close to the recommended boundary 500 between high-Ti and low-Ti basalts. Ti/Y value from the 2 nd eruption phase basalt is higher and inclined to the high-Ti basalts. In spite of this fact, in all studied Hronicum basic rocks Fe 2 O 3 * is lower than 12 wt. % and Nb/La ratios (0.3-0.6) are low, which is more characteristic of low-Ti basalts. The basic rocks are characterized by Nb/La ratios (0.56 to 0.33), and negative correlations between Nb/La and SiO 2 , which point to crustal assimilation and fraction crystallization. The intercept for Sr evolution lines of the 1 st intrusive phase basalt is closest to the expected extrusions age (about 290 Ma) with an initial 87 Sr/ 86 Sr ratio of about 0.7054. Small differences in calculated values I Sr document a partial Sr isotopic heterogeneity source (0.70435-0.70566), or possible contamination of the original magma by crustal material. For Nd analyses of the three samples, the calculated values εCHUR (285 Ma) are positive (from 1.75 to 3.97) for all samples with only subtle variation. Chemical and isotopic data permit us to assume that the parental magma for the Hronicum basic rocks was generated from an enriched heterogeneous source in the subcontinental lithospheric mantle.

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Section: Introductionmentioning

confidence: 99%

Geochemistry and Sr, Nd isotopic composition of the Hronic Upper Paleozoic basic rocks (Western Carpathians, Slovakia)

Vozár¹,

Spišiak²,

Vozárová³

et al. 2015

Geologica Carpathica

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“…In addition, geochronology studies using isotopes, magnetostratigraphy, fission tracks, cosmogenic nuclides, and so on (e.g. Vance & Müller 2003;Allègre 2008;Lisker et al 2009;Dunai 2010) have enabled estimates to be derived for both the timing and the short-and long-term rates of motion of single structures and larger-scale tectonic processes. These have demonstrated, for instance, that synchronous movement of different thrusts is a significant feature in the kinematic evolution of FAT belts, which, in turn, has important implications for thrust sequences and the balancing/ restoration of cross-sections and forward modelling of thrust terrains.…”

mentioning

confidence: 99%

Kinematic evolution and structural styles of fold-and-thrust belts

Poblet

Lisle

2011

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Fold-and-thrust (FAT) belts occur worldwide and have long been the focus of research of structural geologists who have devised a variety of techniques to image, characterize and model their main structural features. This introductory chapter reviews the principal geological features of FAT belts formed in different settings, emphasizing aspects related to their kinematic evolution and structural styles. Despite great advances, challenges remain, particularly in the understanding of the spatial and temporal evolution (4D) of FAT belts and their controlling factors. These research efforts are being assisted by the growing availability to researchers of relatively new tools to collect field data, high quality 3D seismic data, and computer and laboratory modelling tools. This volume includes technical papers presented in the conference 'International Meeting of Young Researchers in Structural Geology and Tectonics (YORSGET-08)' held in Oviedo (Spain), together with other papers on the same theme. These papers deal with FAT belts in different parts of the world and cover a broad range of different aspects, from detailed structural analysis of single structures to regional issues, and from studies based on classical field structural geology to modelling.

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“…This process can be analyzed by the comparison of the 87 Sr/ 86 Sr ratio of the primary rock minerals, the secondary minerals located in fractures pores and the groundwater (Allègre, 2008).…”

Section: Discussionmentioning

confidence: 99%

Relationships of stable isotopes, water-rock interaction and salinization in fractured aquifers, Petrolina region, Pernambuco State, Brazil

et al. 2018

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Relationships of stable isotopes, water-rock interaction and salinization in fractured aquifers, Petrolina region, Pernambuco State, Brazil AbstractThe Petrolina County, Pernambuco State, Brazil, presents specificities that make it unique from a hydrogeological point of view. Water resource scarcity is both a quantitative and qualitative issue. The climate is classified as semiarid, having low precipitation, along with high temperatures and evapotranspiration rates. Aquifer zones are related to low connected fractures resulting in a restricted water flow in the aquifer. The recharge is limited and the groundwater salinity is high. Stable isotope analyses of H and O were developed in groundwater samples (with different electrical conductivity) and surface water collected in a bypass channel flowing from the São Francisco River. The results were plotted in a δD ‰ versus δ 18 O ‰ graph along with the curves of the global and local meteoric water line. Groundwater samples showed unexpected results showing a lighter sign pattern when compared to the meteoric waters. More negative δD and δ 18 O values indicate an enrichment in light isotopes, which show that this process is not influenced by surface processes, where the enrichment occurs in heavy isotopes due to evaporation. The isotopic signature observed is interpreted either as resulting from the water-rock interaction, or as resulting from recharge from paleo rains. The waters are old and show restricted flow. So the water-rock contact time is extended. In the rock weathering processes, through the hydration of feldspars, there is preferential assimilation of heavy isotopes at the expense of the lighter ones that remain in the water. Analyses of the 87 Sr/ 86 Sr ratio and isotopic groundwater dating assist in the interpretations.

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Isotope Geology

Cited by 111 publications

References 257 publications

Geochemistry and Sr, Nd isotopic composition of the Hronic Upper Paleozoic basic rocks (Western Carpathians, Slovakia)

Geochemistry and Sr, Nd isotopic composition of the Hronic Upper Paleozoic basic rocks (Western Carpathians, Slovakia)

Kinematic evolution and structural styles of fold-and-thrust belts

Relationships of stable isotopes, water-rock interaction and salinization in fractured aquifers, Petrolina region, Pernambuco State, Brazil

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