Vincent Caron, Brice Deschamps, Alexandre ROBERT-DUARTE, J. Bailleul
{"title":"生物结核的新定量描述指标(形状和大型钻孔):小安的列斯群岛和新西兰的实例","authors":"Vincent Caron, Brice Deschamps, Alexandre ROBERT-DUARTE, J. Bailleul","doi":"10.2110/palo.2023.002","DOIUrl":null,"url":null,"abstract":"Encrusting (Ei), Macroboring (Mi), and Dissymmetry (Di) indices are proposed as quantitative descriptors of biogenic nodules. (Ei) measures the amount of encrustation, (Mi) the contribution of boring traces affecting the internal structure of nodules, and (Di) the regularity of the biogenic accretion around the nucleus. The latter has been used to construct a classification scheme of possible shapes for encrustations. Raw data to calculate the indices were obtained from numerical treatments of digitized photographs of nodule cross-sections. The morphometric (Di) and taphonomic (Ei and Mi) indices have been calculated for carbonate nodules from subtidal temperate and tropical settings in New Zealand (Flat Point Beach) and in the Caribbean (St. Bartholomew Island), respectively. Results for nucleated rhodoliths collected from shallow high-energy settings in these two climatic settings show that their morphometric and taphonomic characters are not species-specific (Lithoporella/Mastophora rhodoliths from St. Barth, and Lithothamnion-Sporolithon rhodoliths from New Zealand), but depend instead on hydrodynamic conditions and on the original shape of nuclei. Acervulinid macroids sampled in deeper waters (28 m) off St. Barth are nucleus-free and have a Macroboring index (Mi) significantly higher than that of rhodoliths from shallower environments, due to discontinuous influence of waves and currents, and low sedimentation rates. The quantitative descriptors proposed here might: (1) complement the characterization of biogenic nodules in specific depositional environments; (2) aid in hydrodynamic and paleoenvironmental reconstructions of biogenic nodule-bearing deposits; and (3) constitute valuable tools in future comparative studies.","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"65 5","pages":""},"PeriodicalIF":1.5000,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"NEW QUANTITATIVE DESCRIPTORS (SHAPE AND MACROBORING) OF BIOGENIC NODULES: EXAMPLES FROM THE LESSER ANTILLES AND NEW ZEALAND\",\"authors\":\"Vincent Caron, Brice Deschamps, Alexandre ROBERT-DUARTE, J. Bailleul\",\"doi\":\"10.2110/palo.2023.002\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Encrusting (Ei), Macroboring (Mi), and Dissymmetry (Di) indices are proposed as quantitative descriptors of biogenic nodules. (Ei) measures the amount of encrustation, (Mi) the contribution of boring traces affecting the internal structure of nodules, and (Di) the regularity of the biogenic accretion around the nucleus. The latter has been used to construct a classification scheme of possible shapes for encrustations. Raw data to calculate the indices were obtained from numerical treatments of digitized photographs of nodule cross-sections. The morphometric (Di) and taphonomic (Ei and Mi) indices have been calculated for carbonate nodules from subtidal temperate and tropical settings in New Zealand (Flat Point Beach) and in the Caribbean (St. Bartholomew Island), respectively. Results for nucleated rhodoliths collected from shallow high-energy settings in these two climatic settings show that their morphometric and taphonomic characters are not species-specific (Lithoporella/Mastophora rhodoliths from St. Barth, and Lithothamnion-Sporolithon rhodoliths from New Zealand), but depend instead on hydrodynamic conditions and on the original shape of nuclei. Acervulinid macroids sampled in deeper waters (28 m) off St. Barth are nucleus-free and have a Macroboring index (Mi) significantly higher than that of rhodoliths from shallower environments, due to discontinuous influence of waves and currents, and low sedimentation rates. 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NEW QUANTITATIVE DESCRIPTORS (SHAPE AND MACROBORING) OF BIOGENIC NODULES: EXAMPLES FROM THE LESSER ANTILLES AND NEW ZEALAND
Encrusting (Ei), Macroboring (Mi), and Dissymmetry (Di) indices are proposed as quantitative descriptors of biogenic nodules. (Ei) measures the amount of encrustation, (Mi) the contribution of boring traces affecting the internal structure of nodules, and (Di) the regularity of the biogenic accretion around the nucleus. The latter has been used to construct a classification scheme of possible shapes for encrustations. Raw data to calculate the indices were obtained from numerical treatments of digitized photographs of nodule cross-sections. The morphometric (Di) and taphonomic (Ei and Mi) indices have been calculated for carbonate nodules from subtidal temperate and tropical settings in New Zealand (Flat Point Beach) and in the Caribbean (St. Bartholomew Island), respectively. Results for nucleated rhodoliths collected from shallow high-energy settings in these two climatic settings show that their morphometric and taphonomic characters are not species-specific (Lithoporella/Mastophora rhodoliths from St. Barth, and Lithothamnion-Sporolithon rhodoliths from New Zealand), but depend instead on hydrodynamic conditions and on the original shape of nuclei. Acervulinid macroids sampled in deeper waters (28 m) off St. Barth are nucleus-free and have a Macroboring index (Mi) significantly higher than that of rhodoliths from shallower environments, due to discontinuous influence of waves and currents, and low sedimentation rates. The quantitative descriptors proposed here might: (1) complement the characterization of biogenic nodules in specific depositional environments; (2) aid in hydrodynamic and paleoenvironmental reconstructions of biogenic nodule-bearing deposits; and (3) constitute valuable tools in future comparative studies.
期刊介绍:
PALAIOS is a monthly journal, founded in 1986, dedicated to emphasizing the impact of life on Earth''s history as recorded in the paleontological and sedimentological records. PALAIOS disseminates information to an international spectrum of geologists and biologists interested in a broad range of topics, including, but not limited to, biogeochemistry, ichnology, paleoclimatology, paleoecology, paleoceanography, sedimentology, stratigraphy, geomicrobiology, paleobiogeochemistry, and astrobiology.
PALAIOS publishes original papers that emphasize using paleontology to answer important geological and biological questions that further our understanding of Earth history. Accordingly, manuscripts whose subject matter and conclusions have broader geologic implications are much more likely to be selected for publication. Given that the purpose of PALAIOS is to generate enthusiasm for paleontology among a broad spectrum of readers, the editors request the following: titles that generate immediate interest; abstracts that emphasize important conclusions; illustrations of professional caliber used in place of words; and lively, yet scholarly, text.