Paleozoic structural deformation of Bachu uplift, Tarim basin of Northwest China: Implications for plate drifting

Despite the crucial role of epibenthic primary producers (cyanobacteria, green and red algae), no diversity curves for calcimicrobes and calcareous algae are available to assess the pyramiding paleoecology characterizing the Ordovician biodiversification episode. A total of 24 taxa of calcimicrobes and calcareous algae are identified from a Dapingian to lower Katian succession of carbonate sedimentary rocks exposed at the Leyayilitag ridge, Bachu Uplift, Tarim Basin, northwest China. Calcimicrobes (14 taxa), Dasycladales (seven taxa), Bryopsidales (one taxon), and Cyclocrinales (two taxa) contribute to five distinct taphocoenoses characterizing a suite of carbonate mounds. In stratigraphic order, these are calathid sponge mounds, algal calcimicrobial mounds, algal mounds, algal reefs, and calcimicrobial mounds. Within the lower Katian Belodina confluens Zone, the diversity increases substantially from around 5 to more than 20 taxa per 2 Ma. This increase in diversity is based on new calcimicrobes (Bija, Ortonella, Garwoodia, Hedstroemia, Rothpletzella, Phacelophyton, Rauserina) and the diversification of Dasycladales and Cyclocrinales. By comparison, the global diversity of calcimicrobes and calcareous algae (derived from literature data) started to increase earlier, namely within the late Darriwilian Pygodus serra Zone (offset of about 4 Ma). This offset might be due to the peculiar lithology of the Sandbian Tumuxiuke Formation (condensed section of red nodular limestones bounded by disconformities). However, a similar temporal offset is recorded for calathid sponge mounds; therefore, the Tarim tectonic microplate (Tarim Block) might display an endemic–anachronistic character. The diversity curves of Ordovician benthic primary producers (calcimicrobes, calcareous algae) are similar to those recorded by some fossil groups, in particular eleutherozoan echinoderms.

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DIFFERENTIAL PETROLEUM CHARGING CONTROLLED BY ACTIVITIES OF TWO CONJUGATE STRIKE-SLIP FAULTS IN SHUNBEI AREA, TARIM BASIN, NORTHWEST CHINA

10.1130/abs/2019am-340508 ◽

2019 ◽

Author(s):

Fuyun Cong ◽

◽

Jinqiang Tian ◽

Fang Hao ◽

Qi Wang ◽

...

Keyword(s):

Tarim Basin ◽

Northwest China ◽

Strike Slip

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Forced Fold Amplitude and Sill Thickness Constrained by Wireline and 3-D Seismic Data Suggest an Elastic Magma-Induced Deformation in Tarim Basin, NW China

Minerals ◽

10.3390/min11030293 ◽

2021 ◽

Vol 11 (3) ◽

pp. 293

Author(s):

Wei Tian ◽

Xiaomin Li ◽

Lei Wang

Keyword(s):

Tarim Basin ◽

Seismic Data ◽

Inelastic Deformation ◽

Northwest China ◽

Well Log ◽

Total Thickness ◽

Nw China ◽

Seismic Method ◽

Two Parameters ◽

Outer Area

Disparities between fold amplitude (A) and intrusion thickness (Hsill) are critical in identifying elastic or inelastic deformation in a forced fold. However, accurate measurements of these two parameters are challenging because of the limit in separability and detectability of the seismic data. We combined wireline data and 3-D seismic data from the TZ-47 exploring area in the Tarim Basin, Northwest China, to accurately constrain the fold amplitude and total thickness of sills that induced roof uplift in the terrain. Results from the measurement show that the forced fold amplitude is 155.0 m. After decompaction, the original forced fold amplitude in the area penetrated by the well T47 ranged from 159.9 to 225.8 m, which overlaps the total thickness of the stack of sills recovered by seismic method (171.4 m) and well log method (181.0 m). Therefore, the fold amplitude at T47 area is likely to be elastic. In contrast, the outer area of the TZ-47 forced fold is characterized by shear-style deformation, indicating inelastic deformation at the marginal area. It is suggested that interbedded limestone layers would play an important role in strengthening the roof layers, preventing inelastic deformation during the emplacement of intrusive magma.

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Geochemical characteristics of different kinds of crude oils in the Tarim Basin, Northwest China

Chinese Journal of Geochemistry ◽

10.1007/bf03166851 ◽

2001 ◽

Vol 20 (1) ◽

pp. 73-87 ◽

Cited By ~ 5

Author(s):

Yangming Zhu

Keyword(s):

Tarim Basin ◽

Northwest China ◽

Geochemical Characteristics ◽

Crude Oils

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Major unconformities, tectonostratigraphic frameword, and evolution of the superimposed Tarim basin, Northwest China

Journal of Earth Science ◽

10.1007/s12583-012-0263-4 ◽

2012 ◽

Vol 23 (4) ◽

pp. 395-407 ◽

Cited By ~ 21

Author(s):

Changsong Lin ◽

Hao Li ◽

Jingyan Liu

Keyword(s):

Tarim Basin ◽

Northwest China

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Fluid geochemistry of the Jurassic Ahe Formation and implications for reservoir formation in the Dibei area, Tarim Basin, northwest China

Energy Exploration & Exploitation ◽

10.1177/0144598718759560 ◽

2018 ◽

Vol 36 (4) ◽

pp. 801-819 ◽

Cited By ~ 1

Author(s):

Shuangfeng Zhao ◽

Wen Chen ◽

Zhenhong Wang ◽

Ting Li ◽

Hongxing Wei ◽

...

Keyword(s):

Natural Gas ◽

Tarim Basin ◽

Oil And Gas ◽

Northwest China ◽

Source Rocks ◽

Coal Measure ◽

Hydrocarbon Generation ◽

Gas Reservoirs ◽

Isotopic Analyses ◽

Jurassic Coal

The condensate gas reservoirs of the Jurassic Ahe Formation in the Dibei area of the Tarim Basin, northwest China are typical tight sandstone gas reservoirs and contain abundant resources. However, the hydrocarbon sources and reservoir accumulation mechanism remain debated. Here the distribution and geochemistry of fluids in the Ahe gas reservoirs are used to investigate the formation of the hydrocarbon reservoirs, including the history of hydrocarbon generation, trap development, and reservoir evolution. Carbon isotopic analyses show that the oil and natural gas of the Ahe Formation originated from different sources. The natural gas was derived from Jurassic coal measure source rocks, whereas the oil has mixed sources of Lower Triassic lacustrine source rocks and minor amounts of coal-derived oil from Jurassic coal measure source rocks. The geochemistry of light hydrocarbon components and n-alkanes shows that the early accumulated oil was later altered by infilling gas due to gas washing. Consequently, n-alkanes in the oil are scarce, whereas naphthenic and aromatic hydrocarbons with the same carbon numbers are relatively abundant. The fluids in the Ahe Formation gas reservoirs have an unusual distribution, where oil is distributed above gas and water is locally produced from the middle of some gas reservoirs. The geochemical characteristics of the fluids show that this anomalous distribution was closely related to the dynamic accumulation of oil and gas. The period of reservoir densiﬁcation occurred between the two stages of oil and gas accumulation, which led to the early accumulated oil and part of the residual formation water being trapped in the tight reservoir. After later gas filling into the reservoir, the fluids could not undergo gravity differentiation, which accounts for the anomalous distribution of fluids in the Ahe Formation.

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