Petrographical, geochemical characteristics and ironmineralization of mafic massif at Tan Hoa area of Tan Chau, Tay Ninh

The mafic massif at Tan Hoa area, Tan Chau, Tay Ninh (Hill 95) was detected in 1986 and was classified as Tay Ninh complex (K1tn, Nguyen Ngoc Hoa et al, 1995). Petrographical composition of this complex was clarified through the bores in 2013. It included gabbrodiorite, gabbronorite, gabbro, gabbropyroxenite and pyroxenite. The main mineral components were plagioclase, clinopyroxene, orthopyroxene and green hornblende. The secondary mineral was biotite. The accessory minerals are apatite, sphene, magnetite, pyrrhotite. Tay Ninh complex was in high content of titanium, rich in elements of Fe, Ti, V but low content of Rb, Sr, Y, Cs, Ba, Sm, Eu, Nd. The rare and trace elements standardized with primitive mantle and chondrite showed that their origin was from the deep, clear mantle and classified in rift on active continental margin pattern. Tay Ninh complex was characterized by its high anomalies in geophysics. The results of chemical and spectroscopic analysis, grinding and ore selection offered prospect of iron and titanium mineralization for complex.

Download Full-text

U-Pb Detrital Zircon Ages and Geochemical Features of the Jingxing Formation, (Qamdo Basin, Tibet: Implications): Inferences for the Metallogenic Model of the East Tethys Evaporite

Minerals ◽

10.3390/min11070745 ◽

2021 ◽

Vol 11 (7) ◽

pp. 745

Author(s):

Wenhua Han ◽

Haizhou Ma ◽

Weixuan Fang ◽

Huaide Cheng ◽

Yongshou Li ◽

...

Keyword(s):

Trace Elements ◽

Continental Margin ◽

Detrital Zircon ◽

Tectonic Setting ◽

Active Continental Margin ◽

Age Distribution ◽

Major And Trace Elements ◽

Jinsha River ◽

The North ◽

Detrital Zircon Ages

Qamdo basin is located between the suture zone of Jinsha River (Ailao Mountains) and that of Ban Gong Lake (Nujiang) in the eastern Tethys. Part of the Jingxing Formation is deposited in the southwest of the basin. In this study, two profiles were investigated from the north and south of Qamdo basin. The characteristics of detrital zircon LA-ICP-MS U-Pb age, and the main and trace elements of sandstone were analyzed. The characteristics of major and trace elements showed that the tectonic setting of the study area is mainly composed of a relatively stable active continental margin and a passive continental margin, showing characteristics of a continental island arc. The weathering degree of Jingxing Formation in the Qamdo area is lower than that in the Lanping-Simao area, which may be closer to the origin. The age distribution characteristics of detrital zircon grains indicate that the Qiangtang Block, Youjiang basin, and Yangtze area jointly constitute the provenance of the Qamdo-Lanping-Simao basin. Both basins may be part of a large marine basin with unified water conservancy connection before evaporite deposition. Metamorphic seawater from the Qamdo basin may migrate to the Lanping-Simao basin and even the Khorat basin, where evaporite was deposited.

Download Full-text

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

Messenger AmSU ◽

10.22250/jasu.93.25 ◽

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.

Download Full-text

Plutonic rocks of the 1985 Tibet Geotraverse, Lhasa to Golmud

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1988.0124 ◽

1988 ◽

Vol 327 (1594) ◽

pp. 145-168 ◽

Cited By ~ 90

Keyword(s):

Trace Elements ◽

Continental Margin ◽

Upper Mantle ◽

Active Continental Margin ◽

Upper Crust ◽

Calc Alkaline ◽

The South ◽

Lhasa Terrane ◽

Northern Edge ◽

Central Tibet

Two large east-trending granitic batholiths are exposed on the plateau of Central Tibet. In the southern Lhasa Terrane , north of the Zangbo Suture, the Gangdise Belt is a calc-alkaline composite batholith dominated by monzodiorites, tonalites, granodiorites and monzo granites. Trace elements indicate that strongly fractionated melts were emplaced at an active continental margin; deeper crustal levels of the batholith are exposed in the crustally -derived Nyainqentanglha orthogneiss. A long the northern edge o f the plateau , a syn-tectonic calcic to calc-alkaline suite of tonalites, granodiorites and monzo granites forms the Kunlun batholith with post-tectonic granites emplaced to the south. The Kunlun intrusions are derived from anatexis of a garnet-bearing source at in termediate crustal depths above an active or recently active continental margin . Between these two batholiths, a bimodal suite of metaluminous tonalite -grano-diorite and peraluminous two-mica granite is exposed in the northern Lhasa Terrane, indicative of melting both in the upper crust and at deeper levels in the crust or upper mantle. This association suggests a post-collision setting.

Download Full-text

Geochemical Characteristics, Palaeoenvironment and Provenance of Uranium-Bearing Sandstone in the Sifangtai Formation, Northern Songliao Basin, Northeast China

Minerals ◽

10.3390/min11091019 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1019

Author(s):

Yan Li ◽

Feng-Jun Nie ◽

Li-Cheng Jia ◽

Sheng-Jun Lu ◽

Zhao-Bin Yan

Keyword(s):

Continental Margin ◽

Tectonic Setting ◽

Active Continental Margin ◽

Thick Layer ◽

Songliao Basin ◽

Geochemical Characteristics ◽

Source Rocks ◽

Geochemical Data ◽

Water Medium ◽

Semi Arid

During the Cretaceous period of the northern Songliao Basin (northeast of China), a 100 m thick layer of fluvial-phase sandstone (Sifangtai Formation) with uranium potential was widely deposited, but its geochemical characteristics, paleoenvironment, and provenance remain unknown. This research proposes a new set of relevant geochemical data for sandstones to investigate their paleoenvironment, provenance and tectonic setting. The results revealed that: (1) The sandstone of the Sifangtai Formation was dominated by feldspar lithic sandstone. Geochemical signatures demonstrate that these sandstones have a high silicon content (SiO2 = 68.30~83.60 wt%) and total alkali content, but are poor in magnesium and calcium. They are also enriched in Rb, Th, U, K and LREE, and depleted HFSE (e.g., Nb, Ta), with crustal magmatic source. (2) The paleoclimate discriminant indicated that the rocks of the Sifangtai Formation might that the climate of Sifangtai Formation is semi-arid, and the chemical weathering of the source rocks is weak under the semi-arid climate environment. (3) The combination of element Sr/Ba, 100 MgO/Al2O3 and the combination of v/v + Ni, V/Cr, Ni/Co, and Sr/Cu indicated that the paleo-water medium was deposited in an oxygen-rich freshwater environment when the Sifangtai Formation was deposited. (4) The discriminate diagrams showed that almost all the sandstones of the Sifangtai Formation fell in the range of the active continental margin, indicating that the source area of the sandstones of Sifangtai Formations is an active continental margin tectonic environment, and the source is a felsic rock developed in the Xiaoxing’an Ridge and Zhangguangcailing area.

Download Full-text

Nature and origin of the volcanic ash beds near the Permian–Triassic boundary in South China: new data and their geological implications

Geological Magazine ◽

10.1017/s001675681900133x ◽

2019 ◽

Vol 157 (4) ◽

pp. 677-689 ◽

Cited By ~ 3

Author(s):

Binsong Zheng ◽

Chuanlong Mou ◽

Renjie Zhou ◽

Xiuping Wang ◽

Zhaohui Xiao ◽

...

Keyword(s):

Trace Element ◽

Continental Margin ◽

South China ◽

Volcanic Ash ◽

Active Continental Margin ◽

Main Body ◽

Early Triassic ◽

Late Permian ◽

Triassic Boundary ◽

Permian Triassic Boundary

AbstractPermian–Triassic boundary (PTB) volcanic ash beds are widely distributed in South China and were proposed to have a connection with the PTB mass extinction and the assemblage of Pangea. However, their source and tectonic affinity have been highly debated. We present zircon U–Pb ages, trace-element and Hf isotopic data on three new-found PTB volcanic ash beds in the western Hubei area, South China. Laser ablation inductively coupled plasma mass spectrometry U–Pb dating of zircons yields ages of 252.2 ± 3.6 Ma, 251.6 ± 4.9 Ma and 250.4 ± 2.4 Ma for these three volcanic ash beds. Zircons of age c. 240–270 Ma zircons have negative εHf(t) values (–18.17 to –3.91) and Mesoproterozoic–Palaeoproterozoic two-stage Hf model ages (THf2) (1.33–2.23 Ga). Integrated with other PTB ash beds in South China, zircon trace-element signatures and Hf isotopes indicate that they were likely sourced from intermediate to felsic volcanic centres along the Simao–Indochina convergent continental margin. The Qinling convergent continental margin might be another possible source but needs further investigation. Our data support the model that strong convergent margin volcanism took place around South China during late Permian – Early Triassic time, especially in the Simao–Indochina active continental margin and possibly the Qinling active continental margin. These volcanisms overlap temporally with the PTB biocrisis triggered by the Siberian Large Igneous Province. In addition, our data argue that the South China Craton and the Simao–Indochina block had not been amalgamated with the main body of Pangea by late Permian – Early Triassic time.

Download Full-text