scholarly journals Sedimentary provenance study of the post-Early Permian to pre-Early Cretaceous metasedimentary Duque de York Complex, Chile

2010 ◽  
Vol 33 (2) ◽  
pp. 199
Author(s):  
Juan Pablo Lacassie ◽  
Francisco Herve ◽  
Barry Roser
Keyword(s):  
Early Cretaceous ◽  
Continental Margin ◽  
Active Continental Margin ◽  
Source Area ◽  
Mineralogical Composition ◽  
Late Triassic ◽  
Low Grade ◽  
Early Permian ◽  
Magmatic Arc ◽  
Geochemical Analyses

The Duque de York Complex constitutes a post-Early Permian to pre-Early Cretaceous metasedimentary succession that crops out at the Madre de Dios and Diego de Almagro archipelagos along the Chilean Patagonian Andes. The petrography and geochemistry of sandstones and mudstones of this complex have been analyzed to characterize its source and depositional tectonic regime. Sandstone modal compositions are dominated by feldspar and, in similar but smaller proportions, by quartz. The mineralogical composition of the sandstones and mudstones is compatible with a low-grade sub-greenschist facies metamorphism. This did not affect significantly the geochemical compositions of these rocks. Nevertheless, the geochemical analyses reveal variable K+ enrichment, especially in the mudstones. Chemical Index of Alteration values of the sandstones and mudstones range between 58 and 71, indicating that the sediment underwent moderate chemical alteration in the source area or during transportation. Sandstone modal compositions are consistent with erosion of the plutonic roots of a magmatic arc. Geochemical provenance indices suggest a relatively evolved source, close in composition to typical continental magmatic arc granodiorite. Deposition of the detritus is most likely to have occurred within an active continental margin. Geochronological, petrographic, and geochemical similarities between the metasediments of the Duke de York Complex, the LeMay Group (Western Antarctica) and the Permian-Late Triassic Rakaia terrane (New Zealand) suggest a common geodynamic set-up for these three successions. This likely constituted an extensive late Paleozoic-early Mesozoic active continental margin, possibly along the Antarctic sector of Gondwana.

Andesite Geochemistry Features of Late Triassic Tumugou Formation, in Zhongdian, Yunnan Province

2012 ◽  
Vol 524-527 ◽  
pp. 16-23
Author(s):  
Jian Guo Huang ◽  
Run Sheng Han ◽  
Ren Tao ◽  
Zhi Qiang Li
Keyword(s):  
Trace Element ◽  
Volcanic Rock ◽  
Continental Margin ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Distribution Patterns ◽  
Island Arc ◽  
Late Triassic ◽  
Magma Source ◽  
Volcanic Arc

The Late Triassic Tumugou Formation volcanic rocks which belongs to typical island arc volcanic rocks in southern end of Yidun island arc belt is located at the eastern of the Zhongdian ,NW Yunnan, SW China. The volcanic rocks can be divided into three categories:andesitic basalt, andesite, quartz andesite, etc. Through geochemical analysis the major elements, rare earth ele and trace element in volcanic rocks, SiO255.18-57.59×10-2,TiO21.16-1.45×10-2,Na2O+K2O5.11-8.05×10-2.consider it is calc-alkaline- alkaline Series of high-K andesite, volcanic may be controlled by the crystal fractionation of magma.Rb31.50-101×10-6,Ba1310-12300×10-6,Nb/Ta11.4-15.5,REE166.07-240.78×10-6,δEu0.74-1.00,REE distribution patterns show oblique to the HREE side and enrichment in LREE .Eu anomaly is not obvious. It is can see from the relevant figure about trace element, it is very similar in magmatic distribution patterns between volcanic rock and Volcanic-arc rock, indicating that the volcanic in this area may be formed in volcanic-arc environment. From east to west, Magma source depth have regular change with the really thickness of mainland shell. Explain that Tumugou Formation volcanic rock is subduction by Ganzi- Litang Ocean basin from east to west. Hongshan-Ousaila region of eastern edge of Zhongdian is the volcanic island arc system during the passive continental margin into an active continental margin.

Petrogenesis of Tertiary granitoid rocks from east of the Bidhand fault, Urumieh-Dokhtar Magmatic Arc, Iran: Implication for an active continental margin setting

Lithos ◽  
2021 ◽  
Vol 400-401 ◽  
pp. 106422
Author(s):  
Sakine Moradi ◽  
Shao-Yong Jiang ◽  
Eric H. Christiansen ◽  
Mohammad Reza Ghorbani
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Magmatic Arc ◽  
Margin Setting ◽  
Granitoid Rocks

scholarly journals Supplemental Material: Syn-exhumation magmatism in an active continental margin above a continental subduction zone: Evidence from Late Triassic mafic igneous rocks in the southeastern North China Block

2020 ◽  
Author(s):  
Wei Fang ◽  
Li-Qun Dai
Keyword(s):  
Trace Element ◽  
Subduction Zone ◽  
Continental Margin ◽  
North China ◽  
Active Continental Margin ◽  
Hf Isotope ◽  
Igneous Rocks ◽  
Late Triassic ◽  
North China Block ◽  
Pb Isotope

Table S1: Major and trace element compositions of mafic igneous rocks from the southeastern North China Block; Table S2: Whole-rock Rb-Sr, Sm-Nd, and Lu-Hf isotope compositions of mafic igneous rocks from the southeastern North China Block; Table S3: LA-ICPMS zircon U-Pb isotope compositions of mafic igneous rocks from the southeastern North China Block; Table S4: Zircon LA-MC-ICPMS Lu-Hf and SIMS O isotopic compositions of mafic igneous rocks from the southeastern North China Block.

scholarly journals Geochemistry and mineralogy of the Truc Thon Clay, Hai Duong Province, North Vietnam: implication for paleoclimatic and provenance analysis

2021 ◽  
Author(s):  
Tha Hoang Van ◽  
Shahid Iqbal ◽  
Urszula Czarniecka ◽  
Anna Wysocka ◽  
Pha Phan Dong ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Clay Mineralogy ◽  
Source Area ◽  
Mineralogical Composition ◽  
Provenance Analysis ◽  
Geological Investigation ◽  
Basement Rocks ◽  
Chemical Index Of Alteration ◽  
Geochemical Analyses ◽  
North Vietnam

During the Miocene-Pleistocene, generally sub-tropical to tropical warm and humid paleoclimate prevailed in Southeast Asia with a gradual cooling trend. The Truc Thon clay (TTC) mine presents interesting outcrops for sedimentological and provenance analysis. The present study uses results of geological investigation in 16 outcrops and wells at the clay mine Truc Thon. The TTC has lens-shaped geometry, filled with two clay bodies, including grey-white clay and multicolor clay. Bulk mineralogy indicates the predominance of quartz and a relatively high amount of pyrophyllite. Clay mineralogy shows the presence of main kaolinite, followed by illite and mixed-layer illite-smectite. These may interpret a warm, humid paleoclimatic condition in the source areas. Illite may be inherited from basement rocks. The bulk rock geochemistry supports intense chemical weathering with the Chemical Index of Alteration (CIA) in the TTC ranged ca. 80.6-98 (average = 90.4). In combination with the geochemical proxies and the mineralogical composition of the TTC, the chemical weathering intensity indicated warm/hot, semi-humid/humid tropical paleoclimate in the source area. A combination of mineralogical and geochemical analyses with regional geological features show that the Hon Gai Triassic rocks are the main source for the TTC. Source materials are originally related to silicic rocks of granitic-granodioritic composition. Paleoclimatic conditions favored intense chemical weathering of the Hon Gai Triassic rocks and surrounding rocks, creating a ceramic mine of great industrial value.

scholarly journals The Geology of Basement Rocks in the Southeastern Tararua Range, North Island, New Zealand

2021 ◽  
Author(s):  
◽  
Lisa Ann Foley
Keyword(s):  
New Zealand ◽  
Early Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Depositional Environment ◽  
Active Continental Margin ◽  
Turbidity Currents ◽  
High Angle ◽  
Basement Rocks ◽  
Geochemical Analyses

<p>Basement rocks within the southeastern Tararua Range belong to two associations: a sedimentary association (greywacke, argillite, calcareous siltstone, conglomerate and olistostrome) and a volcanogenic association (metabasite, chert, red argillite and limestone). Rocks of the sedimentary association are more abundant and have been deposited by turbidity currents and debris flows in a deep water, marine environment. Three turbidite and two intercalated non-turbidite lithofacies are recognized. Sedimentological data suggest that the sediment was deposited in a submarine fan system (mid-fan environment), probably in a trench. The alternating greywacke-argillite beds have detrital compositions which are essentially quartzo-feldspathic. Framework mode and geochemical analyses indicate that the sediment was derived from an active continental margin that was shedding detritus of mainly acid-volcanic and metamorphic origin. Rocks of the volcanogenic association, although volumetrically minor, are widely distributed. Geochemical analyses of metabasites suggest that they were erupted in an oceanic environment, both at a mid-ocean ridge and an intra-plate setting. The presence of radiolaria skeletons in red argillite and chert indicates a hemiplagic depositional environment for these rocks. Rocks of the volcanogenic association often have conformable contacts. These rocks have a related depositional environment and represent seafloor material. Where observed, contacts between rocks of the two associations are always faulted. Deformation in the field area is characterized by development of the following types of structures: several generations of folds, faults at both a low angle and high angle to bedding, shear foliation and melange. The region has undergone the following deformational events, outlined from oldest to youngest: 1) folding with at least two fold generations present. 2) fragmentation and disruption of the beds by faults. Low-angle to bedding faults and high-angle to bedding faults have disrupted the bedding. Where these structures have occurred to a great extent, a chaotically disrupted unit, melange, has formed. 3) post-melange folding. 4) recent faulting related to the present strike-slip regime in New Zealand. Rocks have undergone prehnite-pumpellyite facies metamorphism. The rock types, their field relationships and the deformation that the area has undergone is consistent with accretion at a convergent plate margin. Radiolaria were extracted from two red chert samples. In the study the radiolaria define a Middle Jurassic age, which indicates that the sediments in the southeastern Tararua Range must be of Middle Jurassic in age or younger (possibly Cretaceous). A similar sample from the Manawatu Gorge to the north of the study area contained radiolaria of Late Jurassic-Early Cretaceous age. Sediments in both areas therefore belong to fossil zone 5 (Late Jurassic-Early Cretaceous) of MacKinnon (1983).</p>

scholarly journals Supplemental Material: Syn-exhumation magmatism in an active continental margin above a continental subduction zone: Evidence from Late Triassic mafic igneous rocks in the southeastern North China Block

2020 ◽  
Author(s):  
Wei Fang ◽  
Li-Qun Dai
Keyword(s):  
Trace Element ◽  
Subduction Zone ◽  
Continental Margin ◽  
North China ◽  
Active Continental Margin ◽  
Hf Isotope ◽  
Igneous Rocks ◽  
Late Triassic ◽  
North China Block ◽  
Pb Isotope

Table S1: Major and trace element compositions of mafic igneous rocks from the southeastern North China Block; Table S2: Whole-rock Rb-Sr, Sm-Nd, and Lu-Hf isotope compositions of mafic igneous rocks from the southeastern North China Block; Table S3: LA-ICPMS zircon U-Pb isotope compositions of mafic igneous rocks from the southeastern North China Block; Table S4: Zircon LA-MC-ICPMS Lu-Hf and SIMS O isotopic compositions of mafic igneous rocks from the southeastern North China Block.

scholarly journals LATERAL ZONALITY OF THE ANYUI SEGMENT OF THE CHUKCHI PLUTONIC BELT (WESTERN CHUKOTKA)

2021 ◽  
pp. 117-125
Author(s):  
VASILY EGOROVICH STRIKHA ◽  
Keyword(s):  
Early Cretaceous ◽  
Continental Margin ◽  
Active Continental Margin ◽  
Primitive Mantle ◽  
Southwestern Part ◽  
Mantle Enrichment ◽  
Plutonic Belt ◽  
Gold Bearing

Early Cretaceous granitoids of the Anyui segment of the Chukchi plutonic belt are represented by associations: gabbro-granite, monzodiorite-granite and granite-leucogranite. For the rocks of gabbro-granite and monzonite-granite associations with respect to the primitive mantle, enrichment of Cs, Rb, K was established, with depletion of Nb, Hf, Ti. Granitoids of the granite-leucogranite association are characterized by the most contrasting ratios of enriched and depleted elements, with deep lows of Ba, Nb, Sr, P, Ti against the background of high Cs, Rb, K, Th, U, as well as the absence of a minimum of Hf. Along with the presence of lateral zonality in the placement of granitoids in relation to the southwestern border of the Anyuy Terrain, these data suggest the subductive nature of the formation of gold-bearing gabbro-granite and monzonite-granite associations in the conditions of an active continental margin that arose in the southwestern part of the Chukchi Terrain in Early Cretaceous time due to subduction.

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