scholarly journals Geochemical Significance of Clay Minerals and Elements in Paleogene Sandstones in the Center of the Northern Margin of the Qaidam Basin, China

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 505 ◽  
Author(s):  
Guoqiang Sun ◽  
Meng Wang ◽  
Jiajia Guo ◽  
Yetong Wang ◽  
Yongheng Yang
Keyword(s):  
Clay Minerals ◽  
Chemical Weathering ◽  
Qaidam Basin ◽  
Sedimentary Environment ◽  
Climatic Conditions ◽  
Northern Margin ◽  
Magmatic Arc ◽  
Average Value ◽  
Geochemical Significance ◽  
Continental Magmatic Arc

The average thickness of Paleogene sandstones reaches about 3000–4000 m at the northern margin of the Qaidam Basin. However, the provenance and sedimentary environment of these sandstones are uncertain; thus, more comprehensive research is needed. Integrated research is conducted on the provenance and weathering process based on petrographic characteristics, clay minerals, and geochemical compositions of sandstones in the center of the northern Qaidam Basin. The results of lithofacies analysis show that the Paleogene sandstones were mainly derived from an active continental magmatic arc, subduction accretion, or a fold-thrust belt. The average illite content in the Paleogene clay minerals is more than 50%, followed by chlorite and smectite, which reflect climatic and environmental characteristics that were arid to semi-arid, whereas the characteristics of carbon–oxygen isotopes reveal a mainly freshwater sedimentary environment. The corrected chemical index of alteration (CIAcorr) is between 56.3 and 75.7, with an average value of 66.5. These results indicate that the provenance of the Paleogene sandstones in the center of the northern Qaidam Basin mainly formed under cold and dry climatic conditions and experienced limited chemical weathering with a small amount that underwent intermediate chemical weathering under warm and humid conditions.

scholarly journals Clay Minerals and Element Geochemistry of Clastic Reservoirs in the Xiaganchaigou Formation of the Lenghuqi Area, Northern Qaidam Basin, China

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 678 ◽  
Author(s):  
Sun ◽  
Wang ◽  
Guo ◽  
Wang ◽  
Jiang ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Chemical Weathering ◽  
Qaidam Basin ◽  
Global Climate ◽  
Sedimentary Environment ◽  
Clay Mineralogy ◽  
Late Eocene ◽  
Element Geochemistry ◽  
Humid Climate ◽  
Climate Conditions

We performed mineralogical and geochemical analyses of core samples from the Lenghuqi area in the northern marginal tectonic belt of the Qaidam Basin. The clay mineralogy of the Xiaganchaigou Formation sandstone is dominated by I + I/S + C types and characterized by high illite, a higher mixed-layer illite/smectite and chlorite, lesser smectite, and an absence of kaolinite. The clay minerals reflect that the Oligocene sedimentary basin formed in an arid-semi-arid climate with weak leaching and chemical weathering, and that diagenesis occurred in a K+- and Mg2+-rich alkaline environment. Measured major oxide concentrations show clear correlations. The lower Xiaganchaigou Formation is representative of a dry and cold freshwater sedimentary environment, whereas the upper Xiaganchaigou Formation is warmer and more humid. Trace element and rare earth element variations indicate that the paleoclimate conditions of the lower Xiaganchaigou Formation sedimentary period were relatively cold and dry, while the upper Xiaganchaigou Formation formed under warmer and more humid climate conditions. These findings reflect a global climate of a cold and dry period from the late Eocene to early Oligocene, and a short warming period in the late Oligocene.

scholarly journals Sedimentary Environment Analysis of Eocene in Pingtai Area of Qaidam Basin, China

2021 ◽  
Author(s):  
Jiang yun ◽  
Sun Guoqiang ◽  
Pan Shile ◽  
Wang yetong ◽  
Zhang shuncong
Keyword(s):  
Clay Minerals ◽  
Chemical Weathering ◽  
Oil And Gas ◽  
Qaidam Basin ◽  
Sedimentary Environment ◽  
Element Geochemistry ◽  
Freshwater Environment ◽  
Environment Analysis ◽  
Oil And Gas Exploration ◽  
Exploration Area

Abstract The Pingtai area is a relatively new oil and gas exploration area in Qaidam Basin, China. As one of the most important sandstone reservoir in the Qaidam Basin, Eocene Lulehe Formation and Xiaganchaigou Formation. Based on the petrological characteristics and element geochemistry of core samples, the paleosalinity and paleoclimate changes are discussed. The results show that the clay mineral assemblage of the Lulehe Formation consists of smectite, chlorite, and illite; while the clay minerals in the Xiaganchaigou Formation consist of illite/smectite mixed layer, chlorite, and illite. The paleosalinity calculated using the B content and Sr/Ba and Rb/Sr ratios indicates that the Lulehe Formation was formed in a freshwater environment, and the Xiaganchaigou Formation was formed in alternating brackish water and fresh water environments. The chemical weathering index (CIA), La/Th ratio, and Eu anomaly index indicate that the overall chemical weathering in the Pingtai area was weak, the provenance was relatively stable, and the influence of diagenesis on the clay minerals and the trace element contents was negligible. From the Lulehe Formation to the Xiaganchaigou Formation, the paleoclimate gradually changed from warm and humid to cold with humid-dry seasonal changes, which is consistent with the global decrease in temperature in the Eocene. Moreover, because of the uplift of the Altun Mountain and the global cooling, the rainfall decreased, resulting in the Xiaganchaigou Formation being formed in a higher salinity environment.

Clay-Mineral Assemblages from Late Quaternary Deposits on Vancouver Island, Southwestern British Columbia, Canada

1989 ◽  
Vol 31 (1) ◽  
pp. 41-56 ◽  
Author(s):  
Bertrand Blaise
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Late Quaternary ◽  
Sedimentary Environment ◽  
Volcanic Rocks ◽  
Clay Mineralogy ◽  
Vancouver Island ◽  
Climatic Conditions ◽  
Glacial Deposits ◽  
Mineral Contents

AbstractOn Vancouver Island, the Dashwood Drift, Cowichan Head Formation, Quadra Sand, and Vashon Drift were deposited during late Pleistocene glacial and interstadial periods and show large variations in clay-mineral contents partly related to changing climatic conditions. Glacial deposits are characterized by iron-rich chlorite, illite (both well crystallized), and smectite with a morphology reflecting rapid derivation from volcanic rocks. The clay mineralogy of nonglacial deposits is more complex, and is marked by the presence of vermiculite, kaolinite, halloysite, and irregular mixed-layer minerals. Nonglacial clay minerals are poorly preserved and show a higher state of alteration due to pedogenesis. Large variations in nonglacial deposits compared to glacial deposits are also due to secondary factors such as selective sorting, soil and rock source variations, differences in sedimentary environment, and diagenesis. These secondary factors do not seem to obliterate significantly the climatic imprint on the clay minerals. These studies also permit the recognition of glacially reworked sediments, the determination of relationships between two units in the same section, and the establishment of the conditions of clay-mineral formation.

Cambrian-Ordovician continental magmatic arc at the northern margin of Gondwana: Insights from the Schladming Complex, Eastern Alps

Lithos ◽  
2021 ◽  
Vol 388-389 ◽  
pp. 106064
Author(s):  
Qianwen Huang ◽  
Johann Genser ◽  
Yongjiang Liu ◽  
Franz Neubauer ◽  
Sihua Yuan ◽  
...  
Keyword(s):  
Eastern Alps ◽  
Northern Margin ◽  
Magmatic Arc ◽  
Continental Magmatic Arc

Characteristics and genesis of clay minerals in the northern margin of the Qaidam Basin

2011 ◽  
Vol 21 (1) ◽  
pp. 141-145
Author(s):  
Wang Linlin ◽  
Jiang Bo ◽  
Peng Dehua ◽  
Yin Chengming ◽  
Zeng Chunlin
Keyword(s):  
Clay Minerals ◽  
Qaidam Basin ◽  
Northern Margin

scholarly journals Clay mineralogical evidence for mid-latitude terrestrial climate change from the latest Cretaceous through the earliest Paleogene in the Songliao Basin, NE China

2020 ◽  
Author(s):  
Yuan Gao ◽  
Youfeng Gao ◽  
Daniel E. Ibarra ◽  
Xiaojing Du ◽  
Tian Dong ◽  
...  
Keyword(s):  
High Resolution ◽  
Clay Minerals ◽  
Chemical Weathering ◽  
Sedimentary Environment ◽  
Relative Weight ◽  
Songliao Basin ◽  
Basin Scale ◽  
Stable Isotopic ◽  
Weathering Intensity ◽  
Percentage Ratio

Abstract. From the latest Cretaceous (late Campanian to Maastrichtian, ~ 76−66 Ma) through the earliest Paleogene, a fluctuating greenhouse climate prevailed and climatic changes were linked to catastrophic geological events and massive biotic extinction. Paleoclimate reconstructions during this time period primarily rely on marine sediments, with limited high-resolution terrestrial records. Here we present a high-resolution clay mineralogical record from the Sifangtai Formation and the Mingshui Formation of the Songliao Basin, northeast China, which are continuously deposited fluvial to lacustrine strata, and have been tightly age constrained as late Campanian to early Danian. Smectite and illite are the dominant clay species, whereas kaolinite and chlorite are minor components. Clay minerals are derived from the weathering of parent rocks and/or paleosols, and their relative weight percentages are primarily controlled by regional paleoclimate and sedimentary environment. We use three clay mineralogical proxies, including the percentage ratio of smectite and illite, illite chemistry index and the percentage ratio of phyllosilicate clay minerals and quartz in clay fractions, for paleoclimatic reconstruction. We correlate these proxy timeseries with basin-scale and global paleoclimate timeseries. Our results show that from the latest Cretaceous through the earliest Paleogene, values of all three clay mineralogical proxies in the Songliao Basin are generally higher during warming intervals than those during cooling intervals. We interpret this dataset to suggest that warming caused strengthened moisture delivery from the Pacific, increasing precipitation and intensified chemical weathering, whereas cooling was accompanied by increasing dryness and physical weathering. Before the Cretaceous-Paleogene (K-Pg) boundary (approximately 66.4 Ma to 66.0 Ma), the warming likely related to Deccan volcanism and the transient cooling afterwards are characterized by paleosol carbonate stable isotopic excursions and changes in the illite chemistry index recorded in the Songliao Basin sediments, reflecting fluctuations in precipitation and weathering intensity. However, changes in clay mineral assemblages are not clear before and at the K-Pg boundary. This is probably due to the relatively long-response time of terrestrial weathering regimes (up to 500 kyrs) to the short duration of the K-Pg boundary impact and the degassing by the preceding Deccan Traps volcanism (~ 200 kyrs). In the earliest Paleogene, after the K-Pg boundary, all clay mineralogical and stable isotopic proxies indicate a warmer and more humid climate with stronger chemical weathering. Our work demonstrates that terrestrial climate and weathering intensity in the mid-latitude Songliao Basin fluctuated during the latest Cretaceous through the earliest Paleogene and sensitively responded to global climate changes.

scholarly journals Origin and occurrence of clay minerals in the Ariyalur Group of sedimentary rocks, Cauvery basin, Tamil Nadu, India

1999 ◽  
Vol 19 ◽  
Author(s):  
J. Madhavaraju ◽  
S. Ramasamy
Keyword(s):  
Clay Minerals ◽  
Tamil Nadu ◽  
Chemical Weathering ◽  
Sedimentary Rocks ◽  
Climatic Conditions ◽  
Temperate Climate ◽  
X Ray Diffraction ◽  
Mineral Assemblages ◽  
Lower Maastrichtian ◽  
Climatic Transition

Clay mineral assemblages in the Ariyalur Group of sedimentary rocks were studied by X-ray diffraction analysis. The results of the study indicate that illite and smectite are the predominant clay minerals whereas kaolinite and chlorite occur in minor amounts. The Campanian-Lower Maastrichtian rocks (i.e., Sillakkudi and Kallankurichchi Formations) contain a large amount of illite. The study reveals that these sediments were derived from the continental erosion of pre-existing rocks that were subjected to low intensity chemical weathering associated with a temperate climate. A significant decrease in illite content is observed in the Ottakkovil Formation. It implies a climatic transition (from temperate to warm) during the Middle Maastrichtian time. On the other hand, a high content of pedogenic smectite in the Kallamedu Formation is indicative of warm climatic conditions with alternating dry and wet periods during the formation of this mineral.

scholarly journals CLAY MINERALS AND GAMMA-RAY SPECTROMETRY AS PALEOCLIMATIC INDICATORS IN THE GONDWANA’S SEDIMENTARY SEQUENCES, SANTA CATARINA, BRAZIL

2018 ◽  
Vol 36 (3) ◽  
pp. 1
Author(s):  
Hérlon da Silva Costa ◽  
Marivaldo dos Santos Nascimento ◽  
Francisco José Fonseca Ferreira
Keyword(s):  
Clay Minerals ◽  
Chemical Weathering ◽  
Gamma Ray ◽  
Climatic Conditions ◽  
Gamma Ray Spectrometry ◽  
Sedimentary Sequences ◽  
Chemical Index ◽  
Paraná Basin ◽  
Parana Basin ◽  
Eastern Edge

ABSTRACT. This work presents clay minerals data and gamma-spectrometry to accesses the paleoclimatic signature during the depositional transition from Taciba to the Rio Bonito Formation in the eastern edge of the Paraná Basin. Detrital illite content (50 to 60%) and chemical index alteration indicates low-influence of chemical weathering. The eTh/K and eTh/eU ratios and detrital illite in the Rio Bonito Formation indicate a cold and dry climate during deposition. The contrast between the increase in eTh/K and eTh/eU ratios and the decrease in the illite content toward the top of the Rio Bonito Formation suggests progressively warmer and humid climatic conditions. The cycling in the eTh/K and eTh/eU ratios clearly indicate seasonal variations in temperature and leaching of K and eU.Keywords: Paleoclimate, Rio do Sul Formation and Rio Bonito Formation, Paraná Basin. RESUMO. Este trabalho apresenta dados de argilominerais e gamaespectrometria para acessar a assinatura paleoclimática durante a transição deposicional da Formação Taciba para a Formação Rio Bonito na borda leste da Bacia do Paraná. O conteúdo de ilita detrítica (50 a 60%) e a alteração do índice químico indicam baixa influência do intemperismo químico. As relações eTh/K e eTh/eU e ilita detrítica na Formação Rio Bonito indicam um clima frio e seco durante a deposição. O contraste entre o aumento das razões eTh/K e eTh/eU e a diminuição do conteúdo de ilitas em direção ao topo da Formação Rio Bonito sugerem condições climáticas progressivamente mais quentes e úmidas. A ciclagem nas razões eTh/K e eTh/eU indica claramente variações sazonais na temperatura e lixiviação de K e eU. Palavras-chave: Paleoclima, Formação Rio do Sul e Formação Rio Bonito, Bacia do Paraná. 1Federal

scholarly journals Impact of Diagenesis on the Low Permeability Sandstone Reservoir: Case Study of the Lower Jurassic Reservoir in the Niudong Area, Northern Margin of Qaidam Basin

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 453
Author(s):  
Wenhuan Li ◽  
Tailiang Fan ◽  
Zhiqian Gao ◽  
Zhixiong Wu ◽  
Ya’nan Li ◽  
...  
Keyword(s):  
Physical Properties ◽  
Oil And Gas ◽  
Qaidam Basin ◽  
Isotope Analysis ◽  
Lower Jurassic ◽  
Low Permeability ◽  
Hydrocarbon Generation ◽  
Northern Margin ◽  
Pore Evolution ◽  
Sandstone Reservoir

The Lower Jurassic reservoir in the Niudong area of the northern margin of Qaidam Basin is a typical low permeability sandstone reservoir and an important target for oil and gas exploration in the northern margin of the Qaidam Basin. In this paper, casting thin section analysis, scanning electron microscopy, X-ray diffraction, and stable isotope analysis among other methods were used to identify the diagenetic characteristics and evolution as well as the main factors influencing reservoir quality in the study area. The predominant types of sandstone in the study area are mainly feldspathic lithic sandstone and lithic arkose, followed by feldspathic sandstone and lithic sandstone. Reservoir porosity ranges from 0.01% to 19.5% (average of 9.9%), and permeability ranges from 0.01 to 32.4 mD (average of 3.8 mD). The reservoir exhibits robust heterogeneity and its quality is mainly influenced by diagenesis. The Lower Jurassic reservoir in the study area has undergone complex diagenesis and reached the middle diagenesis stage (A–B). The quantitative analysis of pore evolution showed that the porosity loss rate caused by compaction and cementation was 69.0% and 25.7% on average, and the porosity increase via dissolution was 4.8% on average. Compaction was the main cause of the reduction in the physical property of the reservoir in the study area, while cementation and dissolution were the main causes of reservoir heterogeneity. Cementation can reduce reservoir space by filling primary intergranular pores and secondary dissolved pores via cementation such as a calcite and illite/smectite mixed layer, whereas high cement content increased the compaction resistance of particles to preserve certain primary pores. δ13C and δ18O isotopes showed that the carbonate cement in the study area was the product of hydrocarbon generation by organic matter. The study area has conditions that are conductive to strong dissolution and mainly occur in feldspar dissolution, which produces a large number of secondary pores. It is important to improve the physical properties of the reservoir. Structurally, the Niudong area is a large nose uplift structure with developed fractures, which can be used as an effective oil and gas reservoir space and migration channel. In addition, the existence of fractures provides favorable conditions for the uninterrupted entry of acid fluid into the reservoir, promoting the occurrence of dissolution, and ultimately improves the physical properties of reservoirs, which is mainly manifested in improving the reservoir permeability.

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