TY - CHAP

T1 - Axial Melt-Lens Dynamics at Fast Spreading Midocean Ridges

AU - Koepke, Jürgen

AU - Zhang, Chao

N1 - Funding Information: This research used samples and/or data provided by the International Ocean Drilling Program (IODP). The IODP is sponsored by the United States National Science Foundation (NSF) and participating countries under management of the Consortium for Ocean Leadership (COL). Funding for this research was provided by grants from the Deutsche Forschungsgemeinschaft (DFG) in the framework of the SPP “International Ocean Discovery Program (IODP)” (SPP 527).

PY - 2020/10/1

Y1 - 2020/10/1

N2 - Multichannel seismic studies performed at fast spreading midocean ridges revealed the presence of a thin (tens to hundreds of meters high), narrow (< 1–2 km wide) axial melt lens (AML) in the midcrust, which is underlain by crystal–melt mush that is in turn laterally surrounded by a transition zone of mostly solidified material. In this chapter we shed light on the complexity of magmatic and metamorphic processes ongoing within and at the roof of axial melt lenses, with a focus on the petrological and geochemical record provided by fossilized AMLs. Of particular significance is Hole 1256D in the equatorial Pacific drilled by the International Ocean Discovery Program, where for the first time the transition between sheeted dikes and gabbros in intact fast spreading crust was penetrated, providing a drill core with a more or less continuous record of the upper part of an AML. This can be regarded as a Rosetta Stone to answer long-standing questions on the complex magmatic evolution within an AML, as well as on metamorphic and anatectic processes ongoing at the roof of a dynamic AML, rising upward in the midcrust as a consequence of a replenishment event.

AB - Multichannel seismic studies performed at fast spreading midocean ridges revealed the presence of a thin (tens to hundreds of meters high), narrow (< 1–2 km wide) axial melt lens (AML) in the midcrust, which is underlain by crystal–melt mush that is in turn laterally surrounded by a transition zone of mostly solidified material. In this chapter we shed light on the complexity of magmatic and metamorphic processes ongoing within and at the roof of axial melt lenses, with a focus on the petrological and geochemical record provided by fossilized AMLs. Of particular significance is Hole 1256D in the equatorial Pacific drilled by the International Ocean Discovery Program, where for the first time the transition between sheeted dikes and gabbros in intact fast spreading crust was penetrated, providing a drill core with a more or less continuous record of the upper part of an AML. This can be regarded as a Rosetta Stone to answer long-standing questions on the complex magmatic evolution within an AML, as well as on metamorphic and anatectic processes ongoing at the roof of a dynamic AML, rising upward in the midcrust as a consequence of a replenishment event.

UR - http://www.scopus.com/inward/record.url?scp=85135347922&partnerID=8YFLogxK

U2 - 10.1002/9781119521143.ch9

DO - 10.1002/9781119521143.ch9

M3 - Contribution to book/anthology

AN - SCOPUS:85135347922

SN - 9781119521136

T3 - Geophysical Monograph Series

SP - 179

EP - 206

BT - Dynamic Magma Evolution

ER -