scholarly journals The formation of Neoarchean continental crust in the south-east Superior Craton by two distinct geodynamic processes

2021 ◽  
Vol 356 ◽  
pp. 106104
Author(s):  
D.R. Mole ◽  
P.C. Thurston ◽  
J.H. Marsh ◽  
R.A. Stern ◽  
J.A. Ayer ◽  
...  
Keyword(s):  
Continental Crust ◽  
The South ◽  
Geodynamic Processes ◽  
Superior Craton

Chapter 3.2b Bransfield Strait and James Ross Island: petrology

2021 ◽  
pp. M55-2018-37 ◽  
Author(s):  
Karsten M. Haase ◽  
Christoph Beier
Keyword(s):  
Antarctic Peninsula ◽  
South Shetland Island ◽  
The South ◽  
Bransfield Strait ◽  
Geodynamic Processes ◽  
James Ross Island ◽  
South Shetland Trench ◽  
Low Degrees ◽  
Back Arc ◽  
The Antarctic

AbstractYoung volcanic centres of the Bransfield Strait and James Ross Island occur along back-arc extensional structures parallel to the South Shetland island arc. Back-arc extension was caused by slab rollback at the South Shetland Trench during the past 4 myr. The variability of lava compositions along the Bransfield Strait results from varying degrees of mantle depletion and input of a slab component. The mantle underneath the Bransfield Strait is heterogeneous on a scale of approximately tens of kilometres with portions in the mantle wedge not affected by slab fluids. Lavas from James Ross Island east of the Antarctic Peninsula differ in composition from those of the Bransfield Strait in that they are alkaline without evidence for a component from a subducted slab. Alkaline lavas from the volcanic centres east of the Antarctic Peninsula imply variably low degrees of partial melting in the presence of residual garnet, suggesting variable thinning of the lithosphere by extension. Magmas in the Bransfield Strait form by relatively high degrees of melting in the shallow mantle, whereas the magmas some 150 km further east form by low degrees of melting deeper in the mantle, reflecting the diversity of mantle geodynamic processes related to subduction along the South Shetland Trench.

A study on tectonic and sedimentary development in the rifted northern continental margin of the South China Sea near Taiwan

2016 ◽  
Vol 4 (3) ◽  
pp. SP47-SP65 ◽  
Author(s):  
Wei-Zhi Liao ◽  
Andrew T. Lin ◽  
Char-Shine Liu ◽  
Jung-Nan Oung ◽  
Yunshuen Wang
Keyword(s):  
South China Sea ◽  
Continental Crust ◽  
South China ◽  
Seismic Data ◽  
The South China Sea ◽  
Seismic Facies ◽  
The South ◽  
Northern Margin ◽  
China Sea ◽  
Breakup Unconformity

A series of Cenozoic rifted basins developed in the northern margin of the South China Sea (SCS). Tainan Basin is one of these rifted basins near Taiwan, lying in the outer margin. We have used reflection seismic data in the deepwater areas and boreholes drilled in the shelf of the Tainan Basin to understand the tectonic and sedimentary development in the northern SCS margin near Taiwan. Four key stratal surfaces (i.e., the base of the Pleistocene Series, the base of the Pliocene Series, the 17 Ma maximum flooding surface [MFS], and a breakup unconformity of approximately 30 Ma in age) and seven seismic facies (i.e., continuous- and parallel-layer seismic facies, wavy seismic facies, chaotic seismic facies, U-shaped canyon-cut seismic facies, imbricated-layer seismic facies, high-amplitude reflector package seismic facies, and extrusive volcanism seismic facies) are recognized from seismic data with ages constrained by borehole stratigraphy drilled in the shelf. We have established a model for Cenozoic tectonic and sedimentary development in the rifted northern margin of the SCS near Taiwan. The occurrence of Paleogene fault-bounded grabens/half-grabens topped by a breakup unconformity and draped by postrift sediments indicates that these deepwater rifted basins developed on the continental crust, attesting that a thinned continental crust underlies the deepwater study area, rather than oceanic crust as reported in some literature. Postbreakup extrusive volcanic bodies, of early Miocene age, were buried by thick deepwater sediments. Fairly continuous stratal surfaces of 17 Ma MFS reveal that volcanic activities ceased to be active since middle Miocene. A series of channel cut-and-fills is observed in late Miocene, Pliocene, and Pleistocene strata beneath and to the south of the modern Formosa Canyon. Two distinct fields of deepwater sediment waves developed since middle Pleistocene are found lying to the west of modern deformation front/Manila Trench and to the north and south of the Formosa Canyon, respectively.

Mapping the continent-ocean transition in the Eastern Black Sea Basin

2020 ◽  
Author(s):  
Tim Minshull ◽  
Vanessa Monteleone ◽  
Hector Marin Moreno ◽  
Donna Shillington
Keyword(s):  
Continental Crust ◽  
Oceanic Crust ◽  
Black Sea ◽  
Seismic Data ◽  
Wide Angle ◽  
Seismic Velocities ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Rifted Margins ◽  
Geodynamic Processes

<p>The transition from continental to oceanic crust at rifted margins is characterised by changes in a variety of parameters including crustal thickness, basement morphology and magnetisation. Rifted margins also vary significantly in the degree of magmatism that is associated with breakup. The Eastern Black Sea Basin formed by backarc extension in late Cretaceous to early Cenozoic times, by the rotation of Shatsky Ridge relative to the Mid Black Sea High. Wide-angle seismic data show that anomalously thick oceanic crust is present in the southeast of the basin, while further to the northwest the crust is thinner in the centre of the basin. This thinner crust has seismic velocities that are anomalously low for oceanic crust, but is significantly magnetised and has a similar basement morphology to the thicker crust to the southeast. We synthesise constraints from wide-angle seismic data, magnetic anomaly data and new long-offset seismic reflection data into an integrated interpretation of the location and nature of the continent-ocean transition within the basin. Northwest to southeast along the axis of the basin, we infer a series of transitions from mildly stretched continental crust at the Mid Black Sea High to hyper-thinned continental crust, then to thin oceanic crust, and finally to anomalously thick oceanic crust. We explore the geodynamic processes that may have led to this configuration.</p>

Growth of Cratons and their Post-Stabilization Histories

2004 ◽  
Author(s):  
John J. W. Rogers ◽  
M. Santosh
Keyword(s):  
Continental Crust ◽  
Evolutionary Process ◽  
Major Elements ◽  
Tectonic Activity ◽  
Crustal Recycling ◽  
The Earth ◽  
History Of ◽  
Superior Craton ◽  
The Relationship ◽  
Comparative Stability

As we have seen in chapter 3, continental crust evolved from regions of the mantle that contained higher concentrations of LIL elements than regions that underlie typical ocean basins. The most complete record of this evolutionary process is in cratons, which passed through periods of rapid crust production to times of comparative stability over intervals of several hundred million years. After the cratons became stable enough to accumulate sequences of undeformed platform sediments, they moved about the earth without being subjected to further compressive tectonic activity. Because many of the cratons are also partly covered by sediments that are unmetamorphosed or only slightly metamorphosed, they appear to have undergone very little erosion since the sediments were deposited. Thus, a craton may be considered as a large block of continental crust that has been permanently removed from the crustal recycling process. This chapter starts with a discussion of the history of cratons as interpreted from studies of the upper part of the crust. We describe the Superior craton of the Canadian shield and the Western Dharwar craton of southern India within the chapter and use appendix E for brief summaries of other typical cratons. These cratons and numerous others elsewhere developed at different times during earth history, and we look for similarities and differences that may have been caused by progressive cooling of the earth (chapter 2). This section concludes with a summary of the general evolution of cratons and the meaning of the terms “Archean” and “Proterozoic.” The following section is an investigation of processes that occurred following stabilization, all of which take place in the presence of fluids that permeate the crust. We include a summary of these fluids and their effects on anorogenic magmatism and separation of the lower and upper crust. The final section discusses the relationship between cratons and their underlying subcontinental lithospheric mantle (SCLM). Continual metasomatism and metamorphism of the SCLM after cratons develop above it apparently has not destroyed the relationship between the ages of the cratons and the concentrations of major elements in the SCLM. This provides us with an opportunity to determine whether cratons evolved from the mantle beneath them or by depletion of much larger volumes of mantle. The discussions in this chapter are based partly on information summarized in appendices B (heat flow) and D (isotopes).

Sign in / Sign up

Export Citation Format

Share Document