Froukje M. Van der Zwan

King Abdullah University of Science and Technology | KAUST · Department of Earth Science and Engineering (ErSE)

Quantitative textural analysis of crystals, including their number density, shapes, sizes, overall abundance and size distribution can be used to shed light on magmatic processes and the timescales over which they operate. At Merapi, textural analysis of phenocrysts in dome lavas, lava flows, tephra, and in plutonic cumulates has revealed that open...

Basalts from high flux intra-plate volcanism (Iceland, Hawaii, Samoa) are characterised by 3He/4He that are significantly higher than those from the upper mantle sampled at mid-ocean ridges. The prevailing paradigm requires that a largely undegassed deep Earth is enriched in primordial noble gases (3He, 20Ne) relative to degassed convecting upper m...

The processes of plate rupturing and transition from rifting continental lithosphere to an oceanic spreading center are important to understand the formation of oceanic basins but details remain unclear. Hydrothermal samples provide information about cooling of a young lithosphere and element redistribution but have so far not been recovered from r...

Plutonic rocks such as gabbros provide information on magmatic and tectonic processes which occur beneath a mid-ocean rift axis as well as on the formation of the oceanic crust. Igneous rocks, reported from the Red Sea Rift valley, have been limited to extrusive basalts so far. The only deeper crustal rocks found in the Red Sea area are from the ri...

The crustal and tectonic structure of the Red Sea and especially the maximum northward extent of the (ultra)slow Red Sea spreading centre has been debated—mainly due to a lack of detailed data. Here, we use a compilation of earthquake and vertical gravity gradient data together with high-resolution bathymetry to show that ocean spreading is occurri...

Unlike the well-studied narrow hotspot tracks, the origin of broadly distributed seamount provinces remains a topic of conjecture. Here we present major and trace element and Sr-Nd-Hf-Pb double spike isotope data of a comprehensive sample suite from the Bathymetrists Seamount Province (a broad belt of submarine volcanoes in the eastern equatorial A...

Hydrothermal circulation at mid-ocean ridges and assimilation of hydrothermally altered crust or hydrothermal fluids by rising magma can be traced by measuring chlorine (Cl) excess in erupted lavas. The Red Sea Rift provides a unique opportunity to study assimilation of hydrothermally altered crust at an ultra-slow spreading ridge (maximum 1.6 cm y...

Continental rifting and ocean basin formation can be observed at the present day in the Red Sea, which is used as the modern analogue for the formation of mid-ocean ridges. Competing theories for how spreading begins—either by quasi-instantaneous formation of a whole spreading segment or by initiation of spreading at multiple discrete “nodes” separ...

Continental breakup represents the successful process of rifting and thinning of the continental lithosphere, leading to plate rupture and initiation of oceanic crust formation. Magmatism during breakup seems to follow a path of either excessive, transient magmatism (magma-rich margins) or of igneous starvation (magma-poor margins). The latter type...

Hydrothermal circulation at slow-spreading ridges is important for cooling the newly formed lithosphere, but the depth to which it occurs is uncertain. Magmas which stagnate and partially crystallize during their rise from the mantle provide a means to constrain the depth of circulation because assimilation of hydrothermal fluids or hydrothermally...

Debunscha Maar is a monogenetic volcano forming part of the Mt. Cameroon volcanic field, located within the Cameroon Volcanic Line (CVL). Partly glassy cauliflower bombs have primitive basanite-picrobasalt compositions and contain abundant normally and reversely zoned olivine (Fo 77–87) and clinopyroxene phenocrysts. Naturally quenched melt inclusi...

Continental rifting and ocean basin formation is occurring today in the Red Sea, providing a possible modern analogue for the creation of mid-ocean ridges. Yet many of the seafloor features observed along the axis of the Red Sea appear anomalous compared to ancient and modern examples of mid-ocean ridges in other parts of the world, making it uncle...

The slow- to ultra-slow spreading Red Sea Rift (<1 – 1.6 cm/yr spreading rate), was the target of two research cruises performed within the framework of the multidisciplinary “Jeddah Transect Project” carried out in cooperation between the Helmholtz Centre for Ocean Research Kiel (GEOMAR) and King Abdulaziz University in Jeddah, Saudi-Arabia (www.j...

The transition from continental rifting to seafloor spreading is presently occurring at only a few places on Earth, such as the Red Sea or the Woodlark Basin. Competing theories for how spreading begins (either by quasi-instantaneous formation of a whole spreading segment or by initiation of spreading at multiple discrete “nodes” separated by thinn...

Hydrothermal activity can be traced by the chlorine (Cl) concentrations of erupted mid-ocean ridge basalts, if their magmas assimilated hydrothermally altered, Cl-rich crust. In contrast to fast-spreading ridges, this process is not observed so far at slow-spreading ridges, due to their intrinsically lower basaltic Cl contents (<200 ppm). This stud...

Mt. Merapi in Central Java is one of the most active stratovolcanoes on Earth and is underlain by a multistage plumbing system. Crystal size distribution analyses (CSD) were carried out on recent Merapi basaltic-andesites and co-eruptive magmatic and plutonic inclusions to characterise the crystallisation processes that operate during storage and a...

Only little is known on the geological context of the Mabahiss Deep, located in the northern Red Sea at 25°29´N, 36°04´E. In comparison to the central Red Sea, the flat-bottomed morphology of this deep does not depict organized seafloor spreading (Martinez & Cochran 1988). Previous low resolution bathymetric (>100 m grid cell size) and crude geophy...

The Red Sea is one of the few places on Earth where rifting and splitting of a continent by the formation of an ocean basin is presently occurring. Continental rifting takes place in the northernmost Red Sea and ocean floor is continuously created from at least 23°N to the vicinity of the strait of Bab al-Mandab in the south. Here we present a uniq...

Recent basaltic-andesite lavas from Merapi volcano contain abundant and varied igneous inclusions suggesting a complex sub-volcanic magmatic system for Merapi volcano. In order to better understand the processes occurring beneath Merapi, we have studied this suite of inclusions by petrography, geochemistry and geobarometric calculations. The inclus...

There is a 2–3 order of magnitude difference between the chlorine concentrations of seawater and the magmas making up the oceanic crust. For this reason, chlorine is a key element for tracing present and past water–rock interactions. In order to trace processes such as assimilation of hydrothermally altered oceanic crust by mid-ocean ridge magmas,...

The Mg- and Si-rich nature of the sub-cratonic lithospheric mantle (SCLM) beneath the Kaapvaal Craton indicates extensive melt depletion, followed by a Si-enrichment process. Six highly silica enriched peridotites from Kimberley containing high amounts of orthopyroxene (Opx) or garnet (Grt) that are locally concentrated in clots, were investigated...