The Dabie Orogen as the early Jurassic sedimentary provenance: Constraints from the detrital zircon SHRIMP U-Pb dating

2005 ◽  
Vol 48 (2) ◽  
pp. 145 ◽  
Author(s):  
Renwei LI
Geosphere ◽  
2021 ◽  
Vol 17 (5) ◽  
pp. 1422-1453
Author(s):  
Snir Attia ◽  
Scott R. Paterson ◽  
Jason Saleeby ◽  
Wenrong Cao

Abstract A compilation of new and published detrital zircon U-Pb age data from Permo-Triassic to Cretaceous intra-arc strata of the Sierra Nevada (eastern California, USA) reveals consistent sedimentary provenance and depositional trends across the entire Sierra Nevada arc. Detrital zircon age distributions of Sierra Nevada intra-arc strata are dominated by Mesozoic age peaks corresponding to coeval or just preceding arc activity. Many samples display a spread of pre-300 Ma ages that is indistinguishable from the detrital age distributions of pre-Mesozoic prebatholithic framework strata and southwestern Laurentian continental margin deposits. Synthesis of detrital zircon age data with tectonostratigraphic constraints indicates that a marine to subaerial arc was established in Triassic time, giving way to widespread shallow- to deep-marine deposition in latest Triassic to Early Jurassic time that continued until the emergence of the arc surface in the Early Cretaceous. No data presented herein require the existence of Mesozoic exotic terranes and/or outboard arcs that were previously hypothesized to have been accreted to the Sierra Nevada. We conclude that Sierra Nevada intra-arc strata formed within a coherent depositional network that was intimately linked to the southwestern United States Cordilleran margin throughout the span of Mesozoic arc activity.


2004 ◽  
Vol 41 (1) ◽  
pp. 103-125 ◽  
Author(s):  
Nathan T Petersen ◽  
Paul L Smith ◽  
James K Mortensen ◽  
Robert A Creaser ◽  
Howard W Tipper

Jurassic sedimentary rocks of southern to central Quesnellia record the history of the Quesnellian magmatic arc and reflect increasing continental influence throughout the Jurassic history of the terrane. Standard petrographic point counts, geochemistry, Sm–Nd isotopes and detrital zircon geochronology, were employed to study provenance of rocks obtained from three areas of the terrane. Lower Jurassic sedimentary rocks, classified by inferred proximity to their source areas as proximal or proximal basin are derived from an arc source area. Sandstones of this age are immature. The rocks are geochemically and isotopically primitive. Detrital zircon populations, based on a limited number of analyses, have homogeneous Late Triassic or Early Jurassic ages, reflecting local derivation from Quesnellian arc sources. Middle Jurassic proximal and proximal basin sedimentary rocks show a trend toward more evolved mature sediments and evolved geochemical characteristics. The sandstones show a change to more mature grain components when compared with Lower Jurassic sedimentary rocks. There is a decrease in εNdT values of the sedimentary rocks and Proterozoic detrital zircon grains are present. This change is probably due to a combination of two factors: (1) pre-Middle Jurassic erosion of the Late Triassic – Early Jurassic arc of Quesnellia, making it a less dominant source, and (2) the increase in importance of the eastern parts of Quesnellia and the pericratonic terranes, such as Kootenay Terrane, both with characteristically more evolved isotopic values. Basin shale environments throughout the Jurassic show continental influence that is reflected in the evolved geochemistry and Sm–Nd isotopes of the sedimentary rocks. The data suggest southern Quesnellia received material from the North American continent throughout the Jurassic but that this continental influence was diluted by proximal arc sources in the rocks of proximal derivation. The presence of continent-derived material in the distal sedimentary rocks of this study suggests that southern Quesnellia is comparable to known pericratonic terranes.


2015 ◽  
Vol 52 (12) ◽  
pp. 1182-1190 ◽  
Author(s):  
Amanda Labrado ◽  
Terry L. Pavlis ◽  
Jeffrey M. Amato ◽  
Erik M. Day

A complex array of faulted arc rocks and variably metamorphosed forearc accretionary complex rocks form a mappable arc–forearc boundary in southern Alaska known as the Border Ranges fault (BRF). We use detrital U–Pb zircon dating of metasedimentary rocks within the Knik River terrane in the western Chugach Mountains to show that a belt of Early Cretaceous amphibolite-facies metamorphic rocks along the BRF was formed when older mélange rocks of the Chugach accretionary complex were reworked in a sinistral-oblique thrust reactivation of the BRF during a period of forearc plutonism. The metamorphic subterrane of the Knik River terrane has a maximum depositional age (MDA) of 156.5 ± 1.5 Ma and a detrital zircon age spectrum that is indistinguishable from the Potter Creek assemblage of the Chugach accretionary complex, supporting correlation of these units. These ages contrast strongly with new and existing data that show Triassic to earliest Jurassic detrital zircon ages from metamorphic screens in the plutonic subterrane of the Knik River terrane, a fragmented Early Jurassic plutonic assemblage generally interpreted as the basement of the Peninsular terrane. Based on these findings, we propose the following new terminology for the Knik River terrane: (1) “Carpenter Creek metamorphic complex” for the Early Cretaceous “metamorphic subterrane”, (2) “western Chugach trondhjemite suite” for the Early Cretaceous forearc plutons within the belt, (3) “Friday Creek assemblage” for a transitional mélange unit that contains blocks of the Carpenter Creek complex in a chert–argillite matrix, and (4) “Knik River metamorphic complex” in reference to metamorphic rocks engulfed by Early Jurassic plutons of the Peninsular terrane that represent the roots of the Talkeetna arc. The correlation of the Carpenter Creek metamorphic complex with the Chugach mélange indicates that the trace of the BRF lies ∼1–5 km north of the map trace shown on geologic maps, although, like other segments of the BRF, this boundary is blurred by local complexities within the BRF system. Ductile deformation of the mélange is sufficiently intense that few vestiges of its original mélange fabric exist, suggesting the scarcity of rocks described as mélange in the cores of many orogens may result from misidentification of rocks that have been intensely overprinted by younger, ductile deformation.


Author(s):  
Bingshuang Zhao ◽  
Xiaoping Long ◽  
Jin Luo ◽  
Yunpeng Dong ◽  
Caiyun Lan ◽  
...  

The crustal evolution of the Yangtze block and its tectonic affinity to other continents of Rodinia and subsequent Gondwana have not been well constrained. Here, we present new U-Pb ages and Hf isotopes of detrital zircons from the late Neoproterozoic to early Paleozoic sedimentary rocks in the northwestern margin of the Yangtze block to provide critical constraints on their provenance and tectonic settings. The detrital zircons of two late Neoproterozoic samples have a small range of ages (0.87−0.67 Ga) with a dominant age peak at 0.73 Ga, which were likely derived from the Hannan-Micangshan arc in the northwestern margin of the Yangtze block. In addition, the cumulative distribution curves from the difference between the depositional age and the crystalline age (CA−DA) together with the mostly positive εHf(t) values of these zircon crystals (−6.8 to +10.7, ∼90% zircon grains with εHf[t] > 0) suggest these samples were deposited in a convergent setting during the late Neoproterozoic. In contrast, the Cambrian−Silurian sediments share a similar detrital zircon age spectrum that is dominated by Grenvillian ages (1.11−0.72 Ga), with minor late Paleoproterozoic (ca. 2.31−1.71 Ga), Mesoarchean to Neoarchean (3.16−2.69 Ga), and latest Archean to early Paleoproterozoic (2.57−2.38 Ga) populations, suggesting a significant change in the sedimentary provenance and tectonic setting from a convergent setting after the breakup of Rodinia to an extensional setting during the assembly of Gondwana. However, the presence of abundant Grenvillian and Neoarchean ages, along with their moderately to highly rounded shapes, indicates a possible sedimentary provenance from exotic continental terrane(s). Considering the potential source areas around the Yangtze block when it was a part of Rodinia or Gondwana, we suggest that the source of these early Paleozoic sediments had typical Gondwana affinities, such as the Himalaya, north India, and Tarim, which is also supported by their stratigraphic similarity, newly published paleomagnetic data, and tectono-thermal events in the northern fragments of Gondwana. This implies that after prolonged subduction in the Neoproterozoic, the northwestern margin of the Yangtze block began to be incorporated into the assembly of Gondwana and then accept sediments from the northern margin of Gondwanaland in a passive continental margin setting.


2020 ◽  
Vol 63 (7) ◽  
pp. 954-968
Author(s):  
Yongsheng Wang ◽  
Qiao Bai ◽  
Ziqiang Tian ◽  
Hui Du

Sign in / Sign up

Export Citation Format

Share Document