Oxidation of Iron-Titanium Oxides in Igneous Rocks

Verhoogen, John

doi:10.1086/626806

Cited by 124 publications

(45 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…McCall (op.cit) has inferred that explosive behaviour is related primarily to high volatile content and that the lack of explosive activity when the ring graben of Mount Suswa was formed is due to the low volatile content of the magma. However, as stated by Verhoogen (1951), and 152. -as emphasised earlier in section 3.2., explosive volcanic activity is a kinetic effect related to several variables of which volatile content is only one.…”

Section: The Origin Of Potentially Explosive Magmasmentioning

confidence: 80%

“…Verhoogen (1951), in emphasising the similarities between the principles of crystal nucleation and growth and those of bubble formation, has stated that, depending on the rate of oversaturation, "incubation" effects may exist which will cause nucleation of gas bubbles to "lag behind oversaturation". Magma may therefore be extruded as lava before vesiculation takes place.…”

Section: Fragmentation Of Lava Flows Resulting From Vesiculationmentioning

confidence: 99%

“…Verhoogen (1962) and Buddington and Lindsley (1964) record the presence of "quench" crystAls of titanomagnetite in rapidlycooled glassy lavas. Abundant titanomagnetite grains are found in all the glassy crustal rocks of the Mount Suswa flows, while in those from the more slowly-cooled, totally-crystalline central parts they are completely absent.…”

Section: Felspathoidsmentioning

confidence: 99%

See 2 more Smart Citations

Volcanic geology of Mount Suswa, Kenya

Johnson

1969

Phil. Trans. R. Soc. Lond. A

View full text Add to dashboard Cite

This thesis describes the geological history of Mount Suswa, a Quaternary, central-type volcano in the Rift Valley of Kenya.Four major eruptive episodes are distinguished, the earliest of which gave rise to quartz-bearing, flood, trachyte lavas; these constitute a plateau foundation onto which the later, felspathoid-bearing, phonolite lavas of Mount Suswa were erupted.The first eruptive episode of the volcano produced a primitive shieldshaped cone consisting mainly of lava flows. The significance of an unusual fragmental rock occurring at the surfaces of these flows is discussed with reference to the recent controversy on froth flows. The second episode accompanied the formation of a caldera in the summit of the early cone; it gave rise to thick pumice deposits and to lava flows which originated at a ring-fracture zone lying concentrically outside the caldera escarpment. The significance of the depositional relationships of these rocks is discussed with reference to the origin of calderas. The third, post-caldera episode produced phonolite lavas with a different flow morphology, petrography and chemistry to those of the earlier periods. Two post-caldera groups are distinguished; these are thought to have been derived from different phonolite magmas which entered the magma chamber on successive occasions. The origin of a later ring graben which lies within the older caldera is also discussed.-3 -Contents page (Fig. 1). The position of the cone relative to other volcanoes of central-type within the East African Tertiary to Recent alkaline volcanic field is shown in Fig. 2.Willis (1936) diVides the volcanic field into two major areas, both of which consist of contrasting volcanic sequences resting on "Basement System" rocks of probable Pre-Cambrian age (Baker 1965). Of these two areas, a southern sector in Tanzania includes the "Crater Highlands" and Kilimanjaro, and a northern sector in Kenya straddles a "super-elevated dome, (Willis op. cit). This dome is described as "...an oval area of high-land centred on Nakuru an area of upwarping which was uplifted repeatedly in Mount Suswa is one of a series of Quaternary central-type cones confined to the Rift Valley floor (Fig. 2), which includes Longonot, Menengai, Kilombe and Lopokino. In all these volcanoes cauldron collapse structures occur in the summits of primitive cones that are composed of phonolitesand trachytes. TOPOGRAPHY AND GEOGRAPHYMount Suswa is the largest and most complex member of the group, with products extending across almost the whole width of the Rift Valley floor and probably covering a total area of the order of 1000 sq. km. It forms an asymmetric, low-lying, shield-shaped cone, and rises from the floor of the Rift Valley (between 1525 m and 1615 m above sea level) to a maximum altitude of 2357 mat 01 Doinyo Nyukie trignometric point (Fig. 1).The asymmftry of the volcano is due mainly to the southerly dip of the Rift Valley floor on which the cone has grown. This is best exemplified by the lavas erupted down the eastern flank-of the vol...

show abstract

Section: The Origin Of Potentially Explosive Magmasmentioning

confidence: 80%

Section: Fragmentation Of Lava Flows Resulting From Vesiculationmentioning

confidence: 99%

Section: Felspathoidsmentioning

confidence: 99%

See 1 more Smart Citation

Volcanic geology of Mount Suswa, Kenya

Johnson

1969

Phil. Trans. R. Soc. Lond. A

View full text Add to dashboard Cite

show abstract

“…Verhoogen (1962) suggested the mineralogic basis of the TCRM process. Ade Hall (1963) suggested that TCRM might be responsible for the anomalous increase in saturation magnetization (js) and Curie point (Ta) observed in some oceanic basalts.…”

Section: Introductionmentioning

confidence: 99%

“…lA illustrates results of the basic experiment of Nagata and Kobayashi (1963) used to define the TCRM process. They considered the process to be due to the oxidation of titanomagnetite to titanomaghemite (see also Verhoogen, 1962). This may be correct for synthetic specimens, but it most certainly does not explain the changes in all rocks.…”

Section: Introductionmentioning

confidence: 99%

Thermochemical Remanent Magnetization (TCRM) in Basaltic Rocks

Wasilewski¹

1969

J. geomagn. geoelec

View full text Add to dashboard Cite

Continental or oceanic basaltic rocks which contain optically homogeneous titanomagnetites are defined as magnetic class I rocks and exhibit thermochemical remanent magnetization (TCRM) behavior when heated. Heating of magnetic class I rocks results in an increase in:(a) Curie point (Ta) (b) susceptibility (X) (c) coercive force (HI) (d) remanent magnetization (Jr) (e) demagnetization stability (f) saturation magnetization (Js). Though the titanomagnetites are optically homogeneous, they are chemically heterogeneous, and may contain textures which cannot be optically resolved. The extent of optically unresolved textures and degree of chemical heterogeneity will depend on the previous history of the sample. The development of iron-oxide textures and correlative magnetization behavior can be understood through experimental studies of magnetic class I rocks. The magnetic characteristics of rocks which exhibit the TCRM behavior are presented and discussed. Three processes can be operative in the development of TCRM in basaltic rocks :(a) thermal process (b) thermochemical process (c) oxidation process.

show abstract

Raman spectroscopy of laser‐induced oxidation of titanomagnetites

Bauer

Davydovskaya

Janko

et al. 2011

J Raman Spectroscopy

View full text Add to dashboard Cite

Titanomagnetites are important carriers of magnetic remanence in nature and can track redox conditions in magma. The titanium concentration in magnetite bears heavily on its magnetic properties, such as saturation moment and Curie temperature. On land and in the deep ocean, however, these minerals are prone to alteration which can mask the primary magnetic signals they once recorded. Thus, it is essential to characterize the cation composition and oxidation state of titanomagnetites that record the paleomagnetic field. Raman spectroscopy provides a unique tool for both purposes. Nonetheless, the heat generated by the excitation laser can itself induce oxidation. We show that the laser power threshold to produce oxidation decreases with increasing titanium content. With confocal Raman spectroscopy and magnetic force microscopy (MFM) on natural and synthetic titanomagnetites, a non-destructive Raman imaging protocol was established. We applied this protocol to map out the composition and magnetization state within a single ex-solved titanomagnetite grain in a deep-sea basalt.

show abstract

Oxidation of Iron-Titanium Oxides in Igneous Rocks

Cited by 124 publications

References 21 publications

Volcanic geology of Mount Suswa, Kenya

Volcanic geology of Mount Suswa, Kenya

Thermochemical Remanent Magnetization (TCRM) in Basaltic Rocks

Raman spectroscopy of laser‐induced oxidation of titanomagnetites

Contact Info

Product

Resources

About