KOHISTAN ISLAND ARC EBOOK

We have found from analysis of paleomagnetic data that in Late Cretaceous–early Paleocene times, the Kohistan-Ladakh island arc could not  ‎Abstract · ‎INTRODUCTION · ‎GEOLOGICAL · ‎RESULTS. We have found from analysis of paleomagnetic data that in Late Cretaceous– early Paleocene times, the Kohistan- Ladakh island arc could not. The Kohistan arc terrane of the western Trans-Himalaya exposes a remarkable cross-section through an island arc sequence which developed as a result of the.


KOHISTAN ISLAND ARC EBOOK

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KOHISTAN ISLAND ARC EBOOK


Thermobarometry calculations indicate that garnet cores formed at kohistan island arc temperatures, followed by progressively higher temperatures and pressures for subsequent garnet generations.

These P-T estimates show that paragneisses of the Lower Swat terrane developed during two stages of prograde metamorphic growth under amphibolite to upper amphibolite facies conditions.

kohistan island arc The second phase of garnet growth was followed by retrograde metamorphism to greenschist facies conditions. Correlation of the structural-tectonic history with the P-T estimates and garnet growth history suggest that during the initial collision of India and Asia around Ma, the Lower Swat terrane was subducted underneath the Kohistan island arc terrane to a depth of km, forming the first generation of kohistan island arc.

Dynamic Earth - Subduction zones - Kohistan - an island arc turned on its side!

Most felsic volcanics rhyolites, dacites have REE systematics that are consistent with the hypothesis that they formed by fractional crystallization of more mafic basaltic andesites. Magma-mixing of low-MgO basalt with rhyolite or dacite does not seem to be important in this volcanic series, although this process appears to be kohistan island arc in the southern Andes.

KOHISTAN ISLAND ARC EBOOK

The REE pattern for one of these andesites crosses the chondrite-normalized patterns kohistan island arc dacites and rhyolites, showing that these rocks cannot be related by fractional crystallization, assimilation, or magma-mixing.

The REE systematics of these andesites are compatible with an origin by crustal anatexis, leaving a refractory residue mineralogically similar to high pressure mafic and ultramafic granulites of the Jijal complex.

Dynamic Earth - Subduction zones - Kohistan - an island arc turned on its side!

Kohistan island arc was close to the equator, but the southern margin of Asia was more than km to the north. Because the Kohistan-Ladakh block now lies within the Asian continent, it is important to know how and when it became sandwiched between India and the rest of Asia.

Further confirmation of the collision of the Kohistan arc with India in early Paleocene times comes from evidence of the timing of obduction of ophiolites and from the unconformity of postcollisional sedimentary rocks onto the Indian continental margin in northwestern and western Pakistan.

The scarcity of more kohistan island arc felsic volcanics dacite, rhyolite can be explained by the nature of the underlying crust, which consists of accreted intra-oceanic arc volcanic and plutonic rocks, and is mafic relative to normal continental margins.

Dynamic Earth - Subduction zones - Kohistan - an island arc turned on its side!

Most felsic volcanics rhyolites, dacites have REE kohistan island arc that are consistent with the hypothesis that they formed by fractional crystallization kohistan island arc more mafic basaltic andesites.

Magma-mixing of low-MgO basalt with rhyolite or dacite does not seem to be important in this volcanic series, although this process appears to be common in the southern Andes. The REE pattern for one of these andesites crosses the chondrite-normalized patterns of dacites and rhyolites, showing that these rocks cannot be related by fractional crystallization, assimilation, or magma-mixing.

KOHISTAN ISLAND ARC EBOOK

Advanced Search Abstract The Kohistan-Ladakh block occupies the northwestern corner of the Himalayan mountains and has long been recognized to represent an island arc constructed on ocean floor during Jurassic and Kohistan island arc times.