Part 5. Plate boundary evolution in the New Guinea region: Subdivision and geochemistry of tertiary intrusive complexes from part of the New Guinea Mobile Belt

1975 ◽  
Vol 6 (2-3) ◽  
pp. 69-71 ◽  
Author(s):  
D.R. Mason
Keyword(s):  
Plate Boundary ◽  
New Guinea ◽  
Mobile Belt

A possible Proterozoic plate boundary in North America

1977 ◽  
Vol 14 (6) ◽  
pp. 1229-1238 ◽  
Author(s):  
P. A. Camfield ◽  
D. I. Gough
Keyword(s):  
Electrical Conductivity ◽  
North America ◽  
Fracture Zone ◽  
Plate Boundary ◽  
Mobile Belt ◽  
Hudson Bay ◽  
Precambrian Geology ◽  
Collision Zone ◽  
Narrow Belt ◽  
Very High

A long, narrow belt of rocks of very high electrical conductivity has been discovered and mapped by means of large arrays of recording magnetometers, over a distance of 1400 km from southeastern Wyoming to the edge of the Canadian Shield in Saskatchewan. Evidence that the conductive belt might be associated with conductive minerals in metamorphosed and fractured rocks in the basement has been discussed in earlier papers. Recent results on the Precambrian geology at both ends of the conductor, in the Churchill Province of the Shield and in southeastern Wyoming, support the hypothesis that the anomaly in electrical conductivity traces a major fracture zone in the lithosphere of Precambrian North America. This paper presents and relates various lines of evidence which together tend to substantiate such a fracture zone or mobile belt. From the age and composition of rocks near the southern end of the structure, Hills and others suggest that a Proterozoic subduction zone is located there. It is possible that the entire fracture zone from the Southern Rockies to the vicinity of Hudson Bay is a Proterozoic continental collision zone or geosuture.

Contribution of an Eastern Indochina-derived fragment to the formation of island arc systems in the Philippine Mobile Belt

2021 ◽  
Author(s):  
Lin Gong ◽  
Pete Hollings ◽  
Yu Zhang ◽  
Jing Tian ◽  
Dengfeng Li ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Plate Boundary ◽  
Philippine Sea Plate ◽  
Geochemical Data ◽  
Mobile Belt ◽  
Potential Contribution ◽  
Northern Margin ◽  
Early Oligocene ◽  
Arc Setting ◽  
T Values

The Philippine Mobile Belt is a complex plate boundary with multiple terranes in Southeast Asia, yet its early tectonic evolution is still not fully understood due to a scarcity of solid evidence. Here we report new whole rock geochemical, Sr-Nd isotopic, and zircon U-Pb-Hf isotopic data for Cretaceous-Miocene arc magmatic rocks from the Cebu and Bohol Islands, Philippine Mobile Belt. Bulk geochemical data display arc affinities with enriched large ion lithophile elements (e.g., Sr and Ba) and depleted high field strength elements (e.g., Nb, Ta, and Ti). The high positive εNd(t) (+4.6 to +9.1) values and low initial 87Sr/86Sr ratios (0.7032−0.7048) suggest that these igneous rocks were generated by partial melting of mantle wedge in an arc setting. U-Pb dating of zircons revealed Cretaceous (ca. 120−90 Ma), middle Eocene to early Oligocene (ca. 43−30 Ma), and middle Miocene (ca. 14 Ma) crystallization ages for the arc magmatism with abundant Permian-Triassic zircon xenocrysts clustering at ca. 250 Ma. The Permian-Triassic grains show dominantly negative εHf(t) values ranging from −16.2 to −6.6, which are similar to those of coeval rocks in Eastern Indochina. Combined with previous paleomagnetic studies, we propose that an Eastern Indochina-derived continental fragment was involved during the formation of arcs in the Cebu and Bohol Islands, which highlights the potential contribution of ancient continental materials in the formation of intra-oceanic arcs. This scenario does not support the previously proposed model that the Cretaceous arc in the Philippine Mobile Belt formed in the northern margin of the proto-Philippine Sea Plate and Australian margin.

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