نتایج جستجو برای: island arc
تعداد نتایج: 91659 فیلتر نتایج به سال:
Abstract Mountain building and the rock cycle often involve large vertical crustal motions, but their rates timescales in unmetamorphosed rocks remain poorly understood. We utilize high-resolution magneto-biostratigraphy backstripping analysis of marine deposits an active arc-continent suture zone eastern Taiwan to document short cycles oscillations. A basal unconformity formed on Miocene volca...
From Oligocene to Recent times a series of tectomcally controlled coastal embayments fonned on the Pacific fore-arc side of the southern Central American island-arc system. Each of these basins shows characteristic stratal geometries and facies distributIOns reflecting the complex interaction of changes of sea level. volcaniclastic input. and tectonic activity (subsidence, uplift). Sequential s...
Wrangellia consists largely of an oceanic plateau, a vast outpouring of basalt and more Mg-rich magma that erupted onto the ocean floor and was subsequently accreted to the western margin of the North American plate. Flood basalts form extensive sequences on Vancouver Island and are believed to have formed by melting in a mantle plume (an upwelling zone of hot mantle rock). They form the oceani...
The islands of northeast Fiji studied are all the emergent parts of the northern end of the Lau^Colville Ridge, a remnant island arc which has been rising for most of the Quaternary. Within the study area, investigations of coastal landforms (primarily emerged notches and shore platforms) and emerged coral reefs allow rates of tectonic movements to be calculated. The Vanuabalavu Island group is...
We have measured the major and trace element compositions of a suite of olivine-hosted melt inclusions in basaltic lavas from the islands of Agrigan and Guguan (one sample each) from the Mariana arc, part of the larger Izu–Bonin–Mariana system. The two lava samples examined show distinctly different chemical signatures that are considered to represent the dominance of sediment melt (Agrigan) or...
New high resolution seismic data (Subbottom Chirp) coupled to high resolution Multibeam bathymetry collected in the frame of the Stromboli geophysical experiment aimed at recording active seismic data and tomography of the Stromboli Island are here presented. The Stromboli geophysical experiment has been already carried out based on onshore and offshore data acquisition in order to investigate ...
[1] We present major, volatile, and trace elements for quenched glasses from the Fonualei Spreading Center, a nascent spreading system situated very close to the Tofua Volcanic Arc (20 km at the closest), in the northeast Lau Basin. The glasses are basalts and basaltic andesites and are inferred to have originated from a relatively hot and depleted mantle wedge. The Fonualei Spreading Center sh...
The Early Paleozoic Lachlan Fold Belt of eastern Australia is widely regarded as an ancient convergent plate margin beneath which paleo-Pacific (Panthalassic) oceanic lithosphere was continuously subducted. It is cited as the type example of a retreating accretionary orogeny. However, sandstone compositions, the sedimentological nature and timing of chert accumulation and overall stratigraphic ...
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