Large igneous provinces (LIPs) are intraplate magmatic events, involving volumes of mainly mafic magma upwards of 100,000 km3, and often above 1 million km3. They are linked to continental break-up, global environmental catastrophes, regional uplift and a variety of ore deposit types. In this up-to-date, fascinating book, leading expert Richard E. Ernst explores all aspects of LIPs, beginning by introducing their definition and essential characteristics. Topics covered include continental and oceanic LIPs; their origins, structures, and geochemistry; geological and environmental effects; association with silicic, carbonatite and kimberlite magmatism; and analogues of LIPs in the Archean, and on other planets. The book concludes with an assessment of LIPs' influence on natural resources such as mineral deposits, petroleum and aquifers. This is a one-stop resource for researchers and graduate students in a wide range of disciplines, including tectonics, igneous petrology, geochemistry, geophysics, Earth history, and planetary geology, and for mining industry professionals.

Large Igneous Provinces

Evaporites through time: Tectonic, climatic and eustatic controls in marine and nonmarine deposits

The “chessboard” classification scheme of mineral deposits: Mineralogy and geology from aluminum to zirconium

On the causes of mass extinctions

Constraints of C-O-S-Pb isotope compositions and Rb-Sr isotopic age on the origin of the Tianqiao carbonate-hosted Pb-Zn deposit, SW China

Hydrothermal events in the Valle de Tena (Spanish Western Pyrenees) as evidenced by fluid inclusions and trace-element distribution from fluorite deposits

The Cambrian Drumian Carbon Isotope Excursion (DICE) and the Steptoean Positive Carbon Isotope Excursion (SPICE) have been so far reported in subtropical platforms: the DICE event is a large negative excursion in δ13Ccarb record that nearly coincides with the beginning of the Drumian (Cambrian Series 3), whereas the SPICE event is a large positive shift in δ13Ccarb identified close to the base of the Paibian (Furongian Series). The chemostratigraphic excursions have been recognized in carbonate-dominated platforms, and their application to mid- and high-latitude, siliciclastic-dominated platforms has been problematic. This paper offers, for the first time, a high-resolution stratigraphic analysis of this time span in a temperate-water platform (Montagne Noire, France) that recorded episodes of carbonate productivity in nearshore environments. Two sections were analyzed in detail: a complete Cambrian Series 3–Tremadocian succession, devoid of carbonate interbeds and paleogeographically located in the distal part of the platform (Pardailhan nappe), and a Furongian-Tremadocian succession, which has limestone interbeds and represents the proximal part of the platform (Minervois nappe).

The lower part of the La Gardie Formation in the Pardailhan nappe displays background δ13Corg values of −22‰ punctuated by a large negative, middle Languedocian (regional substage) shift, peaking at −24.5‰. This negative excursion is similar to the DICE event reported close to the base of the Drumian, although the latter is exclusively based on δ13Ccarb values. Stable isotopes of δ13Ccarb and δ13Corg from both sections also indicate a common chemostratigraphic shift at the onset of the Furongian. In nearshore deposits of the Minervois nappe, the δ13Ccarb background values for the interbedded limestone strata of the Val d'Homs Formation gradually increase from −3‰ to −1‰ and are punctuated by a sharp increase in δ13Ccarb values to >3.0‰. By contrast, in basinal shales of the La Gardie Formation in the Pardailhan nappe, the δ13Corg background values decrease from −22‰ to −27.1‰. This trend is directly controlled by total organic carbon (TOC) contents and is interpreted to have been initiated by changes in the degree of biodegradation of organic matter, sulfate reduction, and methanogenesis before or soon after burial. Despite this overprinting and the very low degree of metamorphism reached by the shales, the δ13Corg background trend is also punctuated by a sharp positive shift in δ13Corg values to >4.0‰, similar to the SPICE event. In addition, the asymmetric shape of the SPICE excursion in the Montagne Noire shows evidence for the HERB event, a late Furongian negative carbon isotope excursion not yet accepted as a worldwide chemostratigraphic anomaly.

The recognition of both chemostratigraphic shifts in mixed and clayey strata opens new possibilities of chemostratigraphic correlation in mid- and high-latitude platforms, where carbonate factories did not widely develop, and strata only contain endemic fauna. This implication has a major consequence because the Global Stratotype Section and Point (GSSP) of the Drumian and Paibian stages occurs near the base of both excursions.

Carbon chemostratigraphy of the Cambrian-Ordovician transition in a midlatitude mixed platform, Montagne Noire, France

The San Juan de Plan deposit, in the central Pyrenees of Spain, is situated in an ankeritic horizon in Silurian black shales. The main association consists of pyrite, sulfarsenides, diarsenides, and Co triarsenides (skutterudite), as well as a late stage consisting of cobaltite, Fe, Cu and Bi sulfides and native Bi. The sulfarsenides are arsenopyrite, alloclasite, members of the gersdorffite‐ cobaltite solid-solution series, arsenic-rich gersdorffite and cobaltite, whereas the diarsenides range from rammelsbergite to safflorite. Rammelsbergite is characterized by a composition within the range (Ni0.71‐0.97Co0.02‐0.29Fe0.00‐0.02)As1.75‐2.01S0.00‐0.26, exceeding the theoretical value (As1.93S0.07) given by Yund (1962). Two generations of the gersdorffite‐cobaltite solid-solution series have been found on the basis of textural features and chemical composition; the first, (Co0.10‐0.77Ni0.07‐0.80Fe0.03‐0.58)As0.95‐ 1.27S0.75‐1.06, shows a positive correlation between S and Fe contents, and between Co and As contents, whereas the second one, (Co0.02‐0.91Ni0.02‐0.96Fe0.00‐0.28)As0.99‐1.38 S0.67‐1.01, exhibits a considerable compositional field in the Fe-poor region of the system CoAsS‐NiAsS‐FeAsS , providing evidence of extensive substitution of Co by Ni, with a positive correlation between As and Ni contents. Arsenic-rich gersdorffite displays a broad range of As and S mutual substitution, (Ni0.65‐0.98Co0.02‐0.27Fe0.00‐0.06)As1.37‐ 1.83S0.22‐0.64, exceeding the experimental value of NiAs1.77S0.23 reported by Yund (1962). The presence of alloclasite and the extent of the solid-solution fields of the cobaltite‐gersdorffite series suggest that the main assemblage of minerals at the San Juan de Plan deposit formed at temperatures as high as 600°C. Preliminary geothermometric data obtained on graphite support such a high temperature.

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THE COMPOSITION OF Co–Ni–Fe SULFARSENIDES, DIARSENIDES AND TRIARSENIDES FROM THE SAN JUAN DE PLAN DEPOSIT, CENTRAL PYRENEES, SPAIN

The formation of Parzan fluorite-lead «extension-type» vein (Spanish Central Pyrenees) is related to the post-Hercynian hydrothermal activity widespread not only in the Pyrenees but in Western Europe as well. The lode was later strongly deformed during the Alpine orogeny with textural modifications and destruction of primary fluid inclusions. In order to determine if geochemical signatures of the vein were disturbed during Alpine deformation, post-ore fluid inclusions and quartz oxygen-isotopes have been addressed. Microthermometry and X-ray microanalysis of frozen inclusions confirm the Na-Ca-Cl character of post-ore fluid circulations and indicate that they were originally derived from a single source: Triassic connate waters. Oxygen isotope data on quartz formed during deformation along with trace element geochemistry suggest that the geochemical signatures of the vein (mainly REE and 87Sr/86Sr) were apparently not reset during deformation. The REE content of fluorites is very high (up to 0.12%); the chondrite normalized REE patterns display a continuous decrease from La to Lu. Sulphur isotope data for the Parzan vein is outside the typical “deep seated” range, suggesting dominantly crustal sources of sulphur for sulphides, while formation waters may be proposed for barite. Parzan fluorites have the most radiogenic Sr values of all the investigated fluorite deposits in Central Pyrenees. They scatter in the range of both the igneous rocks and the Cambrian-Ordovician and Triassic detrital sequences of the Parzan area. If REE contents and 87Sr/86Sr ratios reflect the primary stage of vein filling as suggested by the good correlation between both geochemical signatures, the linear array between 87Sr/86Sr and 1/ΣREE is suggestive of a mixing process. The δ34S, δ18O and 87Sr/86Sr parameters in barite, which postdates the fluorite, also provide strong evidence that barite deposition is a result of fluid mixing. Such an interpretation is in line with present-day ideas for the genesis of many of the F-Ba-Pb-Zn vein deposits in the Hercynian belt of Iberia.

Geochemical patterns of a sheared fluorite vein, Parzan, Spanish Central Pyrenees

The fluorite deposits of the Valle de Tena, Central Pyrenees, include stratabound (Portalet) and vein (Lanuza and Tebarray) deposits the formation of which are linked to a Namurian-Westfalian emersion episode and to post-Hercynian hydrothermal systems similar to those occurring elsewhere in Hercynian Europe. In this study, strontium isotopes were used to determine the source(s) of strontium, and by inference calcium, of the fluorite mineralizations, as well as the nature of the ore-forming fluids. Fluorite and calcite from each deposit have similar 87Sr/86Sr ratios (Portalet 0.7085–0.7108; Lanuza 0.7086–0.7104 and Tebarray 0.7086–0.7101). In all deposits, the Sr isotope composition of most of the Ca-minerals is more radiogenic than that of the host limestones. This indicates that the Ca-minerals contain a mixture of Sr derived locally from the host limestones and 87 Sr-enriched Sr leached from silicate minerals in the siliciclastic portion of the basement sequence and in granites from the study area. Volcanic rocks are ruled out as a significant Sr source for the fluorite deposits. The observed trend in 87Sr/86Sr versus 1/Sr support a fluid-rock interaction model which satisfactorily reproduces the marked 87Sr-enrichment in the fluorites and calcites from the deposits.

/pdf/isotopic-composition-of-strontium-in-the-valle-de-tena-3xhzuu0oiq.pdf

Isotopic composition of strontium in the Valle de Tena (Spanish Central Pyrenees) fluorite deposits: relevance for the source of elements and genetic significance

I. Subías

Papers

Hydrothermal events in the Valle de Tena (Spanish Western Pyrenees) as evidenced by fluid inclusions and trace-element distribution from fluorite deposits

Carbon chemostratigraphy of the Cambrian-Ordovician transition in a midlatitude mixed platform, Montagne Noire, France

THE COMPOSITION OF Co–Ni–Fe SULFARSENIDES, DIARSENIDES AND TRIARSENIDES FROM THE SAN JUAN DE PLAN DEPOSIT, CENTRAL PYRENEES, SPAIN

Geochemical patterns of a sheared fluorite vein, Parzan, Spanish Central Pyrenees

Isotopic composition of strontium in the Valle de Tena (Spanish Central Pyrenees) fluorite deposits: relevance for the source of elements and genetic significance