scholarly journals Geodynamic nature of magmatic sources of North-West Pacific: an interpretation data on isotope composition of Sr and Nd in rocks dredged at Stalemate ridge, Ingenstrem depression, and Shirshov Rise

2019 ◽  
Vol 27 (6) ◽  
pp. 715-736
Author(s):  
S. A. Silantyev ◽  
Yu. A. Kostitsyn ◽  
V. V. Shabykova ◽  
E. A. Krasnova ◽  
Ya. Yu. Ermakov ◽  
...  
Keyword(s):  
Bering Sea ◽  
Isotope Composition ◽  
Spreading Center ◽  
Aleutian Island ◽  
Adjacent Segment ◽  
North West ◽  
Volcanic Chain ◽  
Aleutian Arc ◽  
Back Arc ◽  
Geochemical Heterogeneity

First data on isotope composition of Sr and Nd in rocks dredged at different areas belong to lithosphere of the NW Pacific are present. All samples examined were obtained from NW termination of Stalemate Ridge (NW Pacific) and Central part of Shirshov Rise (Western Bering Sea). Results of conducted study allow sure enough to judge on geodynamic affinity of the central segment of Shirshov Rise. Mafic-ultramafic rocks dredged here originated due evolution of magmatic melt formed by partial melting of source parental for MORB belongs to mantle wedge perhaps. Thus, this interpretation means that Shirshov Rise is remnant Back-Arc Spreading Center. Data on petrology and isotope chemistry of rocks from Stalemate magmatic assemblage demonstrate geochemical heterogeneity of their possible magmatic sources. The presented data allow to assume participation in magmatism of this region of NW Pacific source that responsible for formation of most older volcanic seamounts from NW Termination of Hawaiian-Emperor volcanic chain. There is petrographic similarity between rock assemblage recovered at NW Stalemate and plutonic rocks composed of xenoliths from volcanic effusions of Aleutian Island Arc exists. Considering the scarcity of existing information about the structure of the lithosphere in the NW Pacific it is possible to assume with caution the participation in the construction of the oceanic slope of the Aleutian Trench and the adjacent segment of the Stelmate Ridge fragments of Aleutian Arc basement.

scholarly journals Geochemical characteristics of back-arc basin lower crust and upper mantle at final spreading stage of Shikoku Basin: an example of Mado Megamullion

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Norikatsu Akizawa ◽  
Yasuhiko Ohara ◽  
Kyoko Okino ◽  
Osamu Ishizuka ◽  
Hiroyuki Yamashita ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Spreading Center ◽  
Chemical Compositions ◽  
Olivine Gabbro ◽  
Pb Isotope ◽  
Shikoku Basin ◽  
Source Mantle ◽  
Evolutional Process ◽  
Back Arc

AbstractThis paper explores the evolutional process of back-arc basin (BAB) magma system at final spreading stage of extinct BAB, Shikoku Basin (Philippine Sea) and assesses its tectonic evolution using a newly discovered oceanic core complex, the Mado Megamullion. Bulk and in-situ chemical compositions together with in-situ Pb isotope composition of dolerite, oxide gabbro, gabbro, olivine gabbro, dunite, and peridotite are presented. Compositional ranges and trends of the igneous and peridotitic rocks from the Mado Megamullion are similar to those from the slow- to ultraslow-spreading mid-ocean ridges (MOR). Since the timing of the Mado Megamullion exhumation corresponds to the very end of the Shikoku Basin opening, the magma supply was subdued and highly episodic, leading to extreme magma differentiation to form ferrobasaltic, hydrous magmas. In-situ Pb isotope composition of magmatic brown amphibole in the oxide gabbro is identical to that of depleted source mantle for mid-ocean ridge basalt (MORB). In the context of hydrous BAB magma genesis, the magmatic water was derived solely from the MORB source mantle. The distance from the back-arc spreading center to the arc front increased away through maturing of the Shikoku Basin to cause MORB-like magmatism. After the exhumation of Mado Megamullion along detachment faults, dolerite dikes intruded as a post-spreading magmatism. The final magmatism along with post-spreading Kinan Seamount Chain volcanism were introduced around the extinct back-arc spreading center after the opening of Shikoku Basin by residual mantle upwelling.

Author response for "Neodymium isotope composition of Palaeoproterozoic Birimian shales from the Wa‐Lawra Belt, north‐west Ghana: Constraints on provenance"

2020 ◽  
Author(s):  
Marian S. Sapah ◽  
Jennifer E. Agbetsoamedo ◽  
Prince O. Amponsah ◽  
Samuel B. Dampare ◽  
Daniel K. Asiedu
Keyword(s):  
Isotope Composition ◽  
Author Response ◽  
North West

Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland

1999 ◽  
pp. 65-78
Author(s):  
Henrik Rasmussen ◽  
Lars Frimodt Pedersen
Keyword(s):  
Tectonic Setting ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
West Greenland ◽  
North West ◽  
North East ◽  
Metavolcanic Rocks ◽  
Arc Setting ◽  
Area North ◽  
Back Arc

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Frimodt Pedersen, L. (1999). Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 65-78. https://doi.org/10.34194/ggub.v181.5114 _______________ Two Archaean supracrustal sequences in the area north-east of Disko Bugt, c. 1950 and c. 800 m in thickness, are dominated by pelitic and semipelitic mica schists, interlayered with basic metavolcanic rocks. A polymict conglomerate occurs locally at the base of one of the sequences. One of the supracrustal sequences has undergone four phases of deformation; the other three phases. In both sequences an early phase, now represented by isoclinal folds, was followed by north-west-directed thrusting. A penetrative deformation represented by upright to steeply inclined folds is only recognised in one of the sequences. Steep, brittle N–S and NW–SE striking faults transect all rock units including late stage dolerites and lamprophyres. Investigation of major- and trace-element geochemistry based on discrimination diagrams for tectonic setting suggests that both metasediments and metavolcanic rocks were deposited in an environment similar to a modern back-arc setting.

scholarly journals Geological interpretation of volcanism and segmentation of the Mariana back-arc spreading center between 12.7°N and 18.3°N

2017 ◽  
Vol 18 (6) ◽  
pp. 2240-2274 ◽  
Author(s):  
Melissa O. Anderson ◽  
William W. Chadwick ◽  
Mark D. Hannington ◽  
Susan G. Merle ◽  
Joseph A. Resing ◽  
...  
Keyword(s):  
Spreading Center ◽  
Geological Interpretation ◽  
Back Arc

scholarly journals Origins of chemical diversity of back-arc basin basalts: A segment-scale study of the Eastern Lau Spreading Center

2009 ◽  
Vol 114 (B6) ◽  
Author(s):  
Antoine Bézos ◽  
Stéphane Escrig ◽  
Charles H. Langmuir ◽  
Peter J. Michael ◽  
Paul D. Asimow
Keyword(s):  
Chemical Diversity ◽  
Spreading Center ◽  
Back Arc

A fission track thermochronological study of King George and Livingston islands, South Shetland Islands (West Antarctica)

2004 ◽  
Vol 16 (2) ◽  
pp. 191-197 ◽  
Author(s):  
I. SELL ◽  
G. POUPEAU ◽  
J.M. GONZÁLEZ-CASADO ◽  
J. LÓPEZ-MARTÍNEZ
Keyword(s):  
South Shetland Islands ◽  
West Antarctica ◽  
The South ◽  
North West ◽  
The North ◽  
Early Oligocene ◽  
Barton Peninsula ◽  
Bransfield Basin ◽  
Back Arc ◽  
The Antarctic

This paper reports the dating of apatite fission tracks in eleven rock samples from the South Shetland Archipelago, an island arc located to the north-west of the Antarctic Peninsula. Apatites from Livingston Island were dated as belonging to the Oligocene (25.8 Ma: metasediments, Miers Bluff Formation, Hurd Peninsula) through to the Miocene (18.8 Ma: tonalites, Barnard Point). Those from King George Island were slightly older, belonging to the Early Oligocene (32.5 Ma: granodiorites, Barton Peninsula). Towards the back-arc basin (Bransfield Basin), the apatite appears to be younger. This allows an opening rate of approximately 1.1 km Ma−1 (during the Miocene–Oligocene interval) to be calculated for Bransfield Basin. Optimization of the apatite data suggests cooling to 100 ± 10°C was coeval with the end of the main magmatic event in the South Shetland Arc (Oligocene), and indicates slightly different tectonic-exhumation histories for the different tectonic blocks.

Sign in / Sign up

Export Citation Format

Share Document