scholarly journals Chemically Oscillating Reactions during the Diagenetic Formation of Ediacaran Siliceous and Carbonate Botryoids

Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1060
Author(s):  
Dominic Papineau ◽  
Jiayu Yin ◽  
Kevin Devine ◽  
Deng Liu ◽  
Zhenbing She

Chemically oscillating reactions are abiotic reactions that produce characteristic, periodic patterns during the oxidation of carboxylic acids. They have been proposed to occur during the early diagenesis of sediments that contain organic matter and to partly explain the patterns of some enigmatic spheroids in malachite, phosphorite, jasper chert, and stromatolitic chert from the rock record. In this work, circularly concentric self-similar patterns are shown to form in new chemically oscillating reaction experiments with variable mixtures of carboxylic acids and colloidal silica. This is carried out to best simulate in vitro the diagenetic formation of botryoidal quartz and carbonate in two Ediacaran-age geological formations deposited after the Marinoan–Nantuo snowball Earth event in South China. Experiments performed with alkaline colloidal silica (pH of 12) show that this compound directly participates in pattern formation, whereas those with humic acid particles did not. These experiments are particularly noteworthy since they show that pattern formation is not inhibited by strong pH gradients, since the classical Belousov–Zhabotinsky reaction occurs in solution with a pH around 2. Our documentation of hundreds of classical Belousov–Zhabotinsky experiments yields a number of self-similar patterns akin to those in concretionary structures after the Marinoan–Nantuo snowball Earth event. Morphological, compositional, and size dimensional comparisons are thus established between patterns from these experiments and in botryoidal quartz and carbonate from the Doushantuo and Denying formations. Selected specimens exhibit circularly concentric layers and disseminations of organic matter in quartz and carbonate, which also occurs in association with sub-micron-size pyrite and sub-millimetre iron oxides within these patterns. X-ray absorption near edge structure (XANES) analyses of organic matter extracted from dolomite concretions in slightly younger, early Cambrian Niutitang Formation reveal the presence of carboxylic and N-bearing molecular functional groups. Such mineral assemblages, patterns, and compositions collectively suggest that diagenetic redox reactions take place during the abiotic decay of biomass, and that they involve Fe, sulphate, and organic matter, similarly to the pattern-forming experiments. It is concluded that chemically oscillating reactions are at least partly responsible for the formation of diagenetic siliceous spheroids and concretionary carbonate, which can relate to various other persistent problems in Earth and planetary sciences.

2020 ◽  
Vol 105 (4) ◽  
pp. 447-454 ◽  
Author(s):  
Dominic Papineau

Abstract The origin of banding patterns in malachite [Cu2CO3(OH)2] is an enduring problem in geology. While the bright green, vivid colors of this mineral have been attributed to the presence of Cu, no specific process has been proposed that can explain the perfect circularly concentric banding and geometrical shapes in botryoidal malachite. These patterns of concentric equidistant laminations are comparable to those arising from chemically oscillating experiments using the classical reactants of the Belousov-Zhabotinsky (B-Z) reaction. Through optical microscopy and micro-Raman imaging, this contribution documents that the geometric centers of the self-similar geometric patterns are often composed of organic matter. Carbon isotopes and trace elements further suggest that non-biological decarboxylation reactions of biological organic matter took place during diagenesis. Hence, the morphological and chemical characteristics of chemically oscillating reactions offer a plausible explanation for the formation of botryoidal malachite and abiotic environmental decarboxylation reactions.


RSC Advances ◽  
2017 ◽  
Vol 7 (55) ◽  
pp. 34339-34347 ◽  
Author(s):  
Xin Zhong ◽  
Chongwei Cui ◽  
Shuili Yu

The reaction between ozone and natural organic matter (NOM) generates a certain amount of aromatic carboxylic acids (ACAs).


2002 ◽  
Vol 2 (5-6) ◽  
pp. 515-521 ◽  
Author(s):  
W. Liu ◽  
S.A. Andrews ◽  
J.R. Bolton ◽  
K.G. Linden ◽  
C. Sharpless ◽  
...  

The impact of UV irradiation on disinfection byproduct (DBP) formation was investigated for low pressure, medium pressure and pulsed UV technologies using a broad range of UV doses. Four classes of DBPs (THMs, HAAs, aldehydes and carboxylic acids) were examined. This enabled the determination of effects resulting from the direct action of UV irradiation on natural organic matter (aldehydes, carboxylic acids) as well as effects on the ultimate formation of chlorinated DBPs (THMs and HAAs) from secondary chlorination. For doses of less than 1,000 mJ/cm2, UV irradiation did not affect THM and HAA formation in subsequent chlorination processes, however higher UV doses resulted in lower ultimate concentrations of THMs and HAAs. UV irradiation also resulted in the formation of aldehydes and carboxylic acids at UV doses above 500 mJ/cm2, compounds that are known to adversely effect drinking water biostability.


1983 ◽  
Vol 20 (5) ◽  
pp. 859-866 ◽  
Author(s):  
J. F. Dormaar

In southern Alberta, a buried Ah horizon is frequently present beneath Mazama tephra (ca. 6600 years BP). Drainage conditions during the formation of such buried Ah horizons may determine the quality of the aliphatic carboxylic acids in the soil organic matter. The spectrum of aliphatic acids extracted from a number of buried Ah horizons indeed suggests either well drained or poorly drained conditions during soil formation regardless of the mode of deposition of materials before or after the soil-forming interval. The climate required for development of the well drained paleosols was inferred to be similar to the climate under which surficial Black Chernozemic Ah horizons were formed.


A segmented body-plan has developed at least twice during metazoan evolution: in the lineage including annelids and arthropods, where the segment is the unit of body structure, and in the ancestors of vertebrates, where a primary segmentation of the middle, mesodermal cell layer of the embryo imposes a spatially periodic character upon derivatives of other layers. The mechanism controlling the development of these periodic patterns has the property that the number of the serially homologous structures formed within each species is largely independent of the linear dimension, or scale, at which pattern formation occurs in individual cases. In this they contrast with other patterns of dispersed, homologous structures occurring in animal epidermis and dermis. The performance of various classes of model for the control of number in vertebrate somite formation are compared, in the light of experimentally and naturally observable properties of this aspect of pattern.


2021 ◽  
Vol 118 (40) ◽  
pp. e2110670118
Author(s):  
Anyuan Li ◽  
Norikazu Matsuoka ◽  
Fujun Niu ◽  
Jing Chen ◽  
Zhenpeng Ge ◽  
...  

Patterned ground, defined by the segregation of stones in soil according to size, is one of the most strikingly self-organized characteristics of polar and high-alpine landscapes. The presence of such patterns on Mars has been proposed as evidence for the past presence of surface liquid water. Despite their ubiquity, the dearth of quantitative field data on the patterns and their slow dynamics have hindered fundamental understanding of the pattern formation mechanisms. Here, we use laboratory experiments to show that stone transport is strongly dependent on local stone concentration and the height of ice needles, leading effectively to pattern formation driven by needle ice activity. Through numerical simulations, theory, and experiments, we show that the nonlinear amplification of long wavelength instabilities leads to self-similar dynamics that resemble phase separation patterns in binary alloys, characterized by scaling laws and spatial structure formation. Our results illustrate insights to be gained into patterns in landscapes by viewing the pattern formation through the lens of phase separation. Moreover, they may help interpret spatial structures that arise on diverse planetary landscapes, including ground patterns recently examined using the rover Curiosity on Mars.


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