Reservoir properties and controlling factors of contact metamorphic zones of the diabase in the northern slope of the Gaoyou Sag, Subei Basin, eastern China

Liu, Chao; Xie, Qingbin; Wang, Guiwen; Chujun, Zhang; Wang, Lvli; Qi, Kening

doi:10.1016/j.jngse.2016.08.070

Cited by 17 publications

(5 citation statements)

References 34 publications

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“…The origin of the dubiofossils is suggested by the observed distribution of the needles only close to the contact and prior to the filled veins linked to the intrusion. Formation through the thermal effect is chemically plausible since ions and acids are produced by thermal degradation of organic matter (microbial C found in the matrix) and by magma degassing capable of crystallizing these carbonates (Saxby and Stephenson, 1987;Aarnes et al, 2010;Agirrezabala et al, 2014;Liu et al, 2016). Nevertheless, the morphology of the needles is different from products of contact metamorphism in mudstones: (1) usually these carbonates are cements or pore fillers, occupying the available space and gen-erally amorphous-subhedral and unbranched (e.g., Finkelman et al, 1998;Huntington et al, 2011;Fig. 10c and s); (2) they occur as fractures breaking the sedimentary layers, forming irregular, sharp to serrated branches, which are features missing from needles (e.g., Golab et al, 2007;Huntington et al, 2011); (3) dendrites, as a branched radial growth structure from a point, usually have more than one order of branches (see Jones, 2017).…”

Section: Comparison With Similar Objectsmentioning

confidence: 99%

“…This reaction, by mineral dehydration as well as organic matter decarbonization and decomposition, produces inorganic and organic acids such as CO, CO 2 , CH 4 , HCO 3− , and water, and the intrusion adds alkali cations (Fe 2+ , Mg 2+ , and Ca 2+ ), which together can circulate the sedimentary package by hydrothermal convection (Finkelman et al, 1998;Agirrezabala et al, 2014;. This highly acidic environment can cause the dissolution of pre-existing carbonates and the precipitation of new ones (generally cementing the pores) by decreasing hydrothermal flow, overpressure buildup, and ion concentration (Zekri et al, 2009;Liu et al, 2016). The conditions presented above support the presence of needles only in this thermal aureole but do not justify their morphological diversity, pattern of distribution between layers, and packing.…”

Section: Thermal Effectmentioning

confidence: 99%

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Deciphering the origin of dubiofossils from the Pennsylvanian of the Paraná Basin, Brazil

Saldanha,

Cagliari,

Scalise Horodyski

et al. 2023

Biogeosciences

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Abstract. Minerals are the fundamental record of abiotic processes over time, while biominerals are one of the most common records of life due to their easy preservation and abundance. However, distinguishing between biominerals and abiotic minerals is challenging due to the superimposition and repetition of geologic processes and the interference of ubiquitous and diverse life on Earth's surface and crust. Mineral dubiofossils, being potential outcomes of both abiotic and biotic environments, emerge as valuable entities that can contribute significantly to the understanding of this issue, facilitating the testing and refinement of biogenicity criteria. The aim of this contribution is to decipher the origin and history of branched mineralized structures that were previously considered mineral dubiofossils from the Pennsylvanian of the Paraná Basin, Brazil. While this material has different forms and refers to biological aspects, it is challenging to associate it with any known fossil group due to the overlapping geological processes occurring in a transitional deposit of Rio do Sul Formation (Itararé Group of the Paraná Basin), particularly in close proximity to a sill from the Serra Geral Group (Lower Cretaceous), which has undergone thermal effects. Given the absence of attributes essential for supporting the initial hypotheses proposing the material as a potential set of sponge spicules or a result of contact metamorphism in Pennsylvanian turbidites, the objects are now investigated as mineral dubiofossils. To address this challenge, we have developed a descriptive protocol for dubiofossils, building upon prior research in the field. This protocol evaluates the following aspects: (1) morphology, texture, and structure; (2) relationship with the matrix; (3) composition; and (4) context. This is done by assessing indigeneity and syngenicity and comparing the specimens with abiotic and biotic products. Applying this protocol to our samples revealed a wide range of morphologies with internal organization, predominantly composed of calcite with impurities such as iron, magnesium, aluminum, and oxygen. The inferred indigeneity suggests the presence of these minerals concurrently with or prior to the intrusion of the sill. Extensive comparisons were made between the studied samples and a broad spectrum of abiotic minerals, as well as controlled, induced, and influenced biominerals from similar contexts. These comparative analyses encompassed sponge spicules; sea urchin and algae skeletons; minerals induced or influenced by fungi, bacteria, and microbial mats; and inorganic pre- and synsedimentary–eodiagenetic minerals like evaporites, springs, and other precipitates, and mesodiagenetic–metamorphic crystals. Despite this comprehensive analysis, no hypothesis emerged as significantly more likely than others. The comparative analysis did allow us to exclude the possibility of the samples being controlled biominerals due to their patternless diversity of morphologies, as well as purely thermometamorphic in origin due to their branched elongated forms. The occurrence of these structures suggests a complex history: a syn-depositional or eodiagenetic origin of some carbonate or sulfate (gypsum, ikaite, dolomite, calcite, aragonite, siderite), potentially associated with the presence of microbial mats, which may have served as templates for mineralization and mediated mineral growth. Mesodiagenesis could have further modified the occurrence through processes such as mineral stabilization, agglutination, aging, and growth. However, the primary agent responsible for the formation of the dubiofossil was the Cretaceous intrusion, which dissolved and replaced the initial minerals, resulting in the precipitation of calcite. Throughout these steps, a combination of physical–chemical and biological reactions, influenced by intrinsic matrix characteristics, organic matter content, and distance from the intrusive body, may have contributed to the heightened morphological complexity observed, thus corroborating the origin of the material becomes even more challenging. Consequently, both the hypotheses pertaining to the formation of biotic and abiotic sulfates and carbonates remain plausible explanations, hence sustaining the classification of the material as a dubiofossil. This material illustrates how dubiofossils can be a result of a complex history and overlapping geological processes. It also highlights the difficulty in differentiating biominerals from abiotic minerals due to the scarcity of biogenicity arguments.

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Section: Comparison With Similar Objectsmentioning

confidence: 99%

Section: Thermal Effectmentioning

confidence: 99%

Deciphering the origin of dubiofossils from the Pennsylvanian of the Paraná Basin, Brazil

Saldanha,

Cagliari,

Scalise Horodyski

et al. 2023

Biogeosciences

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“…3-c) and mylonite (Fig. 3h), and the scales are small; thus, they can be considered scaly spalling (a typical characteristic of chemical dissolution effects 21 ). Irregular dissolution pits are also observed, so the mica schist was mainly chemically dissolved during the process of rock formation.…”

Section: Microscopic Pore Types and Morphological Characteristicsmentioning

confidence: 99%

Semiquantitative Characterizations And Controlling Factors of Microscopic Pore Characteristics of The Metamorphic Rock Reservoir In The Central Paleo-Uplift Belt, Songliao Basin

Zeng

Shan

Hao

et al. 2021

Preprint

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Currently, metamorphic rock is a common target for oil and gas exploration, and reservoirs are the key factors restricting hydrocarbon exploration and development in metamorphic rocks. The deep metamorphic rock gas reservoir in the central paleo-uplift of the northern Songliao Basin has good exploration and development potential. In this study, we use a combination of qualitative descriptions and quantitative analysis to comprehensively analyze the pore characteristics of the reservoir and explore the factors controlling the pore characteristics of the metamorphic rock reservoir in the central paleo-uplift belt of the Songliao Basin. The metamorphic rock reservoir in the central paleo-uplift belt contains three types of lithologies: chlorite schist, mylonite, and mica schist, each with different protoliths and metamorphic histories. The reservoir space can be divided into 4 pore types, and the reservoir space of each lithology is quite different. The results of high-pressure mercury intrusion and nitrogen adsorption indicate that the pore size distributions of the schist and mylonite differ. Compared with the schist, the mylonite has less reservoir space, stronger homogeneity, larger pore size, smaller specific surface area, more natural gas reservoir space and stronger natural gas adsorption capacity. This paper also studies the formation process of the reservoir and divides it into four stages. Finally, this article discusses in detail the factors controlling the microscopic pore characteristics of metamorphic rock reservoirs in the central paleo-uplift belt; the metamorphic rock protolith is the most important controlling factor.

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“…Under the same tectonic stress, rocks with smaller particles and rich in brittle minerals such as felsic are more likely to break and develop fractures (Ye et al, 2021). Weathering and eluviation can cause irregular fractures of different scales near the rocks surface, high rupture degree and well-development fractures were developed (Salah and Alsharhan, 1998;Liu et al, 2016;Yin et al, 2016). The stress concentration degree of fracture tip in different rock stratum thickness is different.…”

Section: Introductionmentioning

confidence: 99%

Characteristics and controlling factors of tectonic fractures within the buried hill reservoirs from the Archaean metamorphic basement: a case study in the Bozhong 19–6 condensate gas field, Bohai Bay Basin

Liu,

Cheng,

Liao

et al. 2024

Front. Energy Res.

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The Bozhong 19–6 Condensate gas field is the first giant gas field discovered in the Bohai Bay Basin in recent years. The gas field reservoir has diverse reservoir space and strong heterogeneity.In this paper, we systematically summarize tectonic fractures development patterns and explore the main factors controlling fractures development and clarify the influence of fractures on reservoir quality through core and microscopic thin section observations, physical property data, imaging logging data. The results show that the major types of tectonic fractures in study area are shear fractures, followed by tensile fractures. Study area mainly developed high-angle fractures and completely filled fractures, fractures are commonly filled with carbonate and clay cement. Four groups of tectonic fractures were found in the study area, which corresponds to the four fracture formation period. Tectonic movement controls the fractures development in study area, the multi-stage tectonic movement had caused a complex fractures network system. The faults control the development of associated fractures formation in the fractures zone, different faults control the fractures formation and orientations in the vicinity. Rock type and minrals content is the basis of forming different fractures, such as the high felsic content is the basis of developed fractures in metamorphic rocks, and rock layer thickness, reservoir porosity and permeability are important factors of the fractures development heterogeneity longitudinally.

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Reservoir properties and controlling factors of contact metamorphic zones of the diabase in the northern slope of the Gaoyou Sag, Subei Basin, eastern China

Cited by 17 publications

References 34 publications

Deciphering the origin of dubiofossils from the Pennsylvanian of the Paraná Basin, Brazil

Deciphering the origin of dubiofossils from the Pennsylvanian of the Paraná Basin, Brazil

Semiquantitative Characterizations And Controlling Factors of Microscopic Pore Characteristics of The Metamorphic Rock Reservoir In The Central Paleo-Uplift Belt, Songliao Basin

Characteristics and controlling factors of tectonic fractures within the buried hill reservoirs from the Archaean metamorphic basement: a case study in the Bozhong 19–6 condensate gas field, Bohai Bay Basin

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