Crust sequences of the Xigaze ophiolite in South Tibet: The water effect on crust accretion at a slow-spreading oceanic ridge and its implications

Dikes in which two different liquids flowed simultaneously, usually called composite dikes, naturally fall into two classes depending on which lithology forms the contact with the country rock, and hence, which liquid was the first to enter the fracture. In these two kinds of dikes, the structures formed by the mingling of the two liquids differ. Dikes in which the more basic liquid entered first have contacts between the two lithologies that are nearly planar, and parallel to the dike walls, whereas the more basic lithology forms discrete pillows in those dikes in which the more silicic liquid entered first. Experiments indicate that these pillows probably form from a flow-front instability that develops when a liquid invades another of higher viscosity between two parallel rigid walls. We provide scalings for the critical flow rate for the onset of this instability, the time required for the instability to develop, and the wavelength that is selected. These scalings are consistent with field observations.

Sill

Dike

10.2307/30079886

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Citations (7)

Emplacement of shallow dikes and sills beneath a small basaltic volcanic center – The role of pre-existing structure (Paiute Ridge, southern Nevada, USA)

Earth and Planetary Science Letters (2006)

Greg A. Valentine K.E. Carter Krogh

Dike

Sill

10.1016/j.epsl.2006.04.031

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Citations (175)

Petrological and geochemical characteristics of the diabase and metasomatised dikes from the Tekirova ophiolite (SW Anatolia, Turkey): Tectonomagmatic evolution of the southern Neotethys

Geochemistry (2021)

Alper Güneş Nurdane İlbeyli Sabir Rasimgil Mehmet Demirbilek

Dike

10.1016/j.chemer.2021.125767

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Citations (2)

Supplemental Material: Large-scale Permo-Triassic back-arc extensions of the Mongol- Okhotsk Ocean

Mingshuai Zhu Laicheng Miao et al.

<p>Figure S1: Discrimination diagrams for the granite dikes in the Monhhan ophiolite. Table S1: Major and trace element compositions of the Monhhan ophiolite and intruding granite. Table S2: LA-ICP-MS zircon U-Pb analytical data for the gabbro, intruding granite, and associated sandstone in the Monhhan ophiolite. Table S3: Lu–Hf data for zircons from the gabbro and intruding granite in the Monhhan ophiolite.</p>

Dike

Table (database)

Trace element

10.1130/gsab.s.21448209

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Intrusive Rocks of the Leeward Slope of the Koolau Range, Oahu

The Journal of Geology (1940)

Chester K. Wentworth Austin E. Jones

The Koolau dome, forming the east half of the island of Oahu, is notably elongate, built about a linear rift zone in which numerous feeder dikes occur in a dike complex over 30 miles long. Scattered dikes and sills occur in the leeward parts of the dome, the concentration being progressively reduced with the distance away from the dike complex. There are secondary rift zones and subcomplexes with increased concentrations of dikes and sills, which trend at right angles to the main rift zone. The dikes and sills show three stages and patterns of columnar jointing which are related to the cooling history. Shallow intrusives are vesicular and banded but not columnar jointed. Dikes with a thickness of about 2 feet are preponderant to such an extent as to suggest that this is an optimum determined by the amount of lateral crowding-together of contracted lava formations which can be achieved by the pressures of invading lava.

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Dome (geology)

Rift zone

10.1086/624933

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Citations (23)

Cracking the lid: Sill-fed dikes are the likely feeders of flood basalt eruptions

Earth and Planetary Science Letters (2014)

James D. Muirhead Giulia Airoldi James D. L. White J. V. Rowland

Dike

Sill