Christophe Galerne

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Verified

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• PhD
• Researcher at University of Bremen

Magma emplacement in the top unconsolidated sediments of rift basins is poorly understood. We compare two shallow sills from the Guaymas Basin (Gulf of California) using core data and analyses from IODP Expedition 385, and high‐resolution 2D seismic data. We show that magma stalling in the top uncemented sediment layer is controlled by the transiti...

Igneous basaltic intrusions into young organic-rich sedimentary basins have a major impact not only on the carbon cycle but also on major and trace element transfers between deep and superficial geological reservoirs. The actively rifting Guaymas Basin in the Gulf of California, which was drilled by the International Ocean Discovery Program during...

he intrusion of magmatic sills into sedimentary basins plays an important role in fluid circulation and element transfer (carbon, sulfur, major/minor elements) between deep and shallow reservoirs. The Guaymas Basin represents the nascent stage of an oceanic basin characterized by the sedimentation of siliceous sediments (diatom oozes) rich in organ...

Les intrusions magmatiques dans les bassins sédimentaires jouent un rôle essentiel dans le transfert d'éléments chimiques tels que le soufre et les métaux entre les réservoirs profonds et superficiels. Le Bassin de Guaymas représente le stade précoce d'ouverture d'un bassin océanique, caractérisé par la mise en place d'un important réseau de sills...

Sills emplaced in organic-rich sedimentary rocks trigger the generation and migration of hydrocarbons in volcanic sedimentary basins. Based on seismic and geological observations, numerical modeling studies of hydrothermal flow around sills show that thermogenic methane is channeled below the intrusion towards its tip, where hydrothermal vents nucl...

Igneous sill intrusions into young organic-rich sedimentary basins have major impact on the carbon cycle but also on the transfer of major and trace element between deep and superficial geological reservoirs. The Guaymas Basin in the Gulf of California represents the nascent stage of an ocean characterized by siliceous organic-rich sediments (diato...

Heat flow is estimated at eight sites drilled during the International Ocean Discovery Program Expedition 385 into the Guaymas Basin, Gulf of California. The expedition sought to understand the thermal regime of the basin and heat transfer between off‐axis sills intruding the organic‐rich sediments of the Guaymas Basin, and the basin floor. The dis...

The igneous intrusions of the Karoo Large Igneous Province (LIP) provide critical information on the magma plumbing system, which served as source rock maturation agent for organic-rich sedimentary rocks of the Main Karoo Basin as well as pathway and barrier to subsurface fluid flow. Here, we present results from the research borehole KWV-01 drille...

Sill intrusions emplaced in organic-rich sedimentary rocks trigger the generation and migration of hydrocarbons in volcanic sedimentary basins. Based on seismic and geological observations, numerical modeling studies of hydrothermal flow around sills have shown that thermogenic methane is channeled towards the intrusion tip, where it rises to the s...

Seafloor heat flow provides information about the thermal evolution of the lithosphere, the magnitude and timing of volcanic activity, and hydrothermal circulation patterns. In the central Gulf of California, the Guaymas Basin is part of a young marginal spreading rift system that experiences high sedimentation (1–5 km/Myr) and widespread magmatic...

We document the geometry of a massive sill at the root of an approximately 20-m high and 800 m wide ring of hydrothermal formations, termed Ringvent, located 28.5 km off-axis on the northwestern flanking regions of the actively rifting Guaymas Basin (Gulf of California). Using petrophysical data collected during the IODP Expedition 385 and processe...

Magmatism in sedimentary basins caused global mass extinctions and it is the closest analogue to present-day anthropogenic climate change. Studying these natural processes is often difficult because the magma plumbing systems remain buried with little surface expression. At GEOMAR, we examine these systems with the help of marine seismic imaging du...

This paper presents major, trace element and Sr-Nd isotope data on two large, east-west trending dolerite dykes in the southeastern part of the Karoo Basin, the South Gap (155 km long, ≤275 m wide) and the North Gap (150 km long, ≤190 m wide) dykes. The Gap dykes represent a rare case in the Karoo Large Igneous Province (LIP) where low-Ti (Gap1: <1...

Magma emplacement in organic‐rich sedimentary basins is a main driver of past environmental crises. Using a 2‐D numerical model, we investigate the process of thermal cracking in contact aureoles of cooling sills and subsequent transport and emission of thermogenic methane by hydrothermal fluids. Our model includes a Mohr‐Coulomb failure criterion...

Subvolcanic systems are characterized by complex combinations of intrusive units (dykes, sills, saucer-shaped sills, cone sheets, etc.) for which genetic relationships are unclear. This chapter explains how whole-rock geochemistry may be used to resolve the genetic relationships of such subvolcanic (and volcanic) systems. We start with a short intr...

Volcanism in organic-rich sedimentary basins leading to thermogenic greenhouse gas generation has been documented as a strong forcing factor of past mass extinctions. However, quantitative studies fail to provide degassing rate estimates that would allow a direct comparison with anthropogenic warming. We are investigating different sill-emplacement...

Subvolcanic systems are characterized by complex combinations of intrusive units (dykes, sills, saucer-shaped sills, cone sheets, etc.) for which genetic relationships are unclear. This chapter explains how whole-rock geochemistry may be used to resolve the genetic relationships of such subvolcanic (and volcanic) systems. We start with a short intr...

[1] Large volumes of magma emplaced within sedimentary basins have been linked to multiple climate change events due to release of greenhouse gases such as CH4. Basin-scale estimates of thermogenic methane generation show that this process alone could generate enough greenhouse gases to trigger global incidents. However, the rates at which these ga...

Continental Flood Basalts (CFB) occur worldwide and represent an important part of intra-plate magmatism in the continents. CFBs are characterized by the emplacement of large volumes of magma (on the order of several million km 3) within time periods of only a few million years or less. Extrusion of lavas is accompanied by extensive intrusion of si...

Saucer shaped sills are tabular intrusions observed worldwide on volcanic margins and in sedimentary basins (e.g., offshore Norway, Karoo Basin). Although they are common, their feeding mechanisms are still poorly known mainly because the relationships between sills and their feeders are (1) rarely exposed, and (2) difficult to image on seismic dat...

In this paper, we address sill emplacement mechanisms through the three-dimensional relationships between sills and their potential feeders (dykes or sills) in the well-exposed Golden Valley Sill Complex (GVSC), Karoo Basin, South Africa. New field observations combined with existing chemical analyses show that: 1) the contacts between sills in the...

RECEIVED JANUARY 15, 2010; ACCEPTED FEBRUARY 25, 2011 Early Jurassic sheet-like intrusions (sills and dykes) are abundant in the Karoo Basin in South Africa, and were emplaced as a part of the Karoo Large Igneous Province. Here we discuss the evolutionary history of dolerite sills and dykes in different parts of the basin on the basis of new major...

Analysis of compositional variations along profiles from tholeiitic sills provides insights into syn- and post-emplacement magmatic differentiation processes. We present here 18 whole-rock compositional profi les sampled from a saucer-shaped sill emplaced in the Karoo Basin (South Africa), the Golden Valley Sill. We show that different compositiona...

The structural relationships between sills and their feeders are poorly documented because they are rarely observed in the field and difficult to image on seismic data. For instance, it is unclear whether sills are fed by pipes, dikes or other sills. Nevertheless, the geometrical relationships between sills and their feeders provide first-order con...

Modeling of multi-component multi-phase porous systems is fundamental to the study of geological processes. Recipes of continuum mechanics and thermodynamics are employed here in order to derive a closed system of equations. We start from a set of balance equations for mass, momentum, energy, and entropy written for a general multi-phase multi-comp...

The well-exposed Golden Valley Sill Complex, Karoo basin, South Africa, consists of four large sills (ca. 100 m thick; long axes: 13–24 km), one small sill (55–80 m thick; long axis: 4 km; forming an appendix to one of the large sills), and two large dykes (15–20 m thick; 25 and 70 km long), plus some minor intrusions. Field mapping shows physical...

Basic-ultrabasic sills are recognized as features whose study can provide important insight into processes that lead to the differentiation of natural silicate magmas. The detailed geochemical study of the Golden Valley Sill Complex (GVSC) shows a wide range of compositions and typical fractional crystallization trends. Vertical composi-tional vari...

Basic-ultrabasic sills present a unique opportunity to study processes controlling the differentiation of natural silicate magmas. The detailed geochemical study of the Golden Valley Sill Complex (GVSC) shows a wide range of compositions and fractional crystallization trends. Vertical compositional variations detected by the Mg-number in the GVSC r...

Saucer-shaped sills and dykes are common features in sedimentary basins worldwide and represent important parts of the plumbing system in such areas. In spite their common occurrence, the emplacement mechanisms that lead to the formation of sill complexes are poorly understood. Two main emplacement models have been proposed, based on field observat...

The Plouézec–Plourivo Basin (PPB), Armorican Massif, is an Ordovician half-graben filled with red-bed deposits lying on a Cadomian metamorphic basement. Peperites crop out along its northeast coastal sector, in connection with diverse magmatic and hydrothermal products. Combining field structural observations and geochemical analyses of magmatic ro...

The plumbing system of large igneous provinces (LIPs) consists largely of sheet-like intrusions that are vertical (dykes) and sub-horizontal (sills). Detailed seismic mapping in the NE Atlantic and field work in the Karoo basin, South Africa, show that the magma tends to develop into interconnected 3D networks of saucer-shaped sills in undeformed b...