Chondrites is a trace fossilichnogenus, preserved as small branching burrows of the same diameter that superficially resemble the roots of a plant. The origin of these structures is currently unknown. Chondrites is found in marine sediments from the Cambrian period of the Paleozoic onwards. It is especially common in sediments that were deposited in reduced-oxygen environments.[1]
There are four recognized Chondrites ichnospecies, however, aberrant forms of unknown taxonomic affinity have been discovered.[2] The fossils are made of infilled dendritic rootlike burrows. The branching angles are 30° to 40°, while a shaft diameter varies between 0.1 mm and 10 mm, remaining constant within a single system.[1]Chondrites is classified as a fodinichnion.[3]
Occurrenceedit
First appearing during the Cambrian, Chondrites is still produced today. It is one of the most common ichnotaxa throughout the fossil record and is widely distributed in all types of marine sedimentary rocks, including sandstone, shale, limestone and marl that formed in environments ranging from subtidal shelves to the abyssal zone.[1][4] The maker of the traces has been able to tolerate highly variable redox conditions. For example, Chondrites is abundant almost to the exclusion of other ichnogenera in Posidonia Shale, formed from laminated, black, carbonaceous clay, deposited in an anoxic, reducing environment. In the oxic, extensively bioturbated units of Austin Chalk, the fossil is very common as well.
Interpretationedit
Though the characteristic burrows are still produced today (in deep-sea deposits), no organism has ever been observed inside them. Several theories exist regarding the origin of these structures. While some authors hypothesize Chondrites to be the product of an infaunal abyssal nematode, others propose it to be formed by a chemosymbiotic organism, pumping methane and hydrogen sulfide from the sediments.[5][6] Another study suggests it to be a fecal storage structure.[7]
The ichnogenus is found both in anaerobic, organic-rich sediments and in oxic layers, where it is almost invariably the last in the bioturbation sequence, i.e., it was placed deep within the sediments, away from oxidizing surficial and interstitial water. These suggest the trace-maker's ability to tolerate oxygen deprivation very well. Therefore, Chondrites can be used as an indicator of anoxia in sediments.[1]
Referencesedit
^ abcdBromley, R. G.; A. A. Ekdale (May 1984). "Chondrites: A Trace Fossil Indicator of Anoxia in Sediments". Science. 224 (4651): 872–874. doi:10.1126/science.224.4651.872. PMID 17743196.
^Swinbanks, David D.; Yoshihisa Shirayama (October 1984). "Burrow stratigraphy in relation to manganese diagenesis in modern deep-sea carbonates". Deep-Sea Research Part A: Oceanographic Research Papers. 31 (10): 1197–1223. doi:10.1016/0198-0149(84)90058-x.
^Encinas, Alfonso; Luis A. Buatois; Kenneth L. Finger (2008). "Paleoecological and paleoenvironmental implications of a high-density Chondrites association in slope deposits of the Neogene Santo Domingo Formation, Valdivia, south-central Chile". Ameghiniana. 45 (1): 225–231.
^Kotake, Nobuhiro (1991). "Packing process for the filling material in Chondrites". Ichnos: An International Journal for Plant and Animal Traces. 1 (4): 277–285. doi:10.1080/10420949109386362.
April 12, 2024
chondrites, genus, stony, meteorite, chondrite, chondrites, trace, fossil, ichnogenus, preserved, small, branching, burrows, same, diameter, that, superficially, resemble, roots, plant, origin, these, structures, currently, unknown, chondrites, found, marine, . For stony meteorite see Chondrite Chondrites is a trace fossil ichnogenus preserved as small branching burrows of the same diameter that superficially resemble the roots of a plant The origin of these structures is currently unknown Chondrites is found in marine sediments from the Cambrian period of the Paleozoic onwards It is especially common in sediments that were deposited in reduced oxygen environments 1 ChondritesTemporal range Cambrian to Recent PreꞒ Ꞓ O S D C P T J K Pg NIllustration of Chondrites bollensis A sample of Chondrites from the Middle Silurian Trace fossil classificationIchnogenus ChondritesSternberg 1833 Contents 1 Morphology 2 Occurrence 3 Interpretation 4 ReferencesMorphology editThere are four recognized Chondrites ichnospecies however aberrant forms of unknown taxonomic affinity have been discovered 2 The fossils are made of infilled dendritic rootlike burrows The branching angles are 30 to 40 while a shaft diameter varies between 0 1 mm and 10 mm remaining constant within a single system 1 Chondrites is classified as a fodinichnion 3 Occurrence editFirst appearing during the Cambrian Chondrites is still produced today It is one of the most common ichnotaxa throughout the fossil record and is widely distributed in all types of marine sedimentary rocks including sandstone shale limestone and marl that formed in environments ranging from subtidal shelves to the abyssal zone 1 4 The maker of the traces has been able to tolerate highly variable redox conditions For example Chondrites is abundant almost to the exclusion of other ichnogenera in Posidonia Shale formed from laminated black carbonaceous clay deposited in an anoxic reducing environment In the oxic extensively bioturbated units of Austin Chalk the fossil is very common as well Interpretation editThough the characteristic burrows are still produced today in deep sea deposits no organism has ever been observed inside them Several theories exist regarding the origin of these structures While some authors hypothesize Chondrites to be the product of an infaunal abyssal nematode others propose it to be formed by a chemosymbiotic organism pumping methane and hydrogen sulfide from the sediments 5 6 Another study suggests it to be a fecal storage structure 7 The ichnogenus is found both in anaerobic organic rich sediments and in oxic layers where it is almost invariably the last in the bioturbation sequence i e it was placed deep within the sediments away from oxidizing surficial and interstitial water These suggest the trace maker s ability to tolerate oxygen deprivation very well Therefore Chondrites can be used as an indicator of anoxia in sediments 1 References edit a b c d Bromley R G A A Ekdale May 1984 Chondrites A Trace Fossil Indicator of Anoxia in Sediments Science 224 4651 872 874 doi 10 1126 science 224 4651 872 PMID 17743196 Uchman Alfred Andreas Wetzel February 1999 An aberrant helicoidal trace fossil Chondrites Sternberg Palaeogeography Palaeoclimatology Palaeoecology 146 1 4 165 169 doi 10 1016 S0031 0182 98 00148 5 Hasiotis Stephen 2011 Chondrites von Strenberg 1833 University of Kansas Archived from the original on August 26 2012 Retrieved April 14 2013 Gluszek Arkadiusz 1998 Trace fossils from Late Carboniferous storm deposits Upper Silesia Coal Basin Poland Acta Palaeontologica Polonica 43 3 517 546 Swinbanks David D Yoshihisa Shirayama October 1984 Burrow stratigraphy in relation to manganese diagenesis in modern deep sea carbonates Deep Sea Research Part A Oceanographic Research Papers 31 10 1197 1223 doi 10 1016 0198 0149 84 90058 x Encinas Alfonso Luis A Buatois Kenneth L Finger 2008 Paleoecological and paleoenvironmental implications of a high density Chondrites association in slope deposits of the Neogene Santo Domingo Formation Valdivia south central Chile Ameghiniana 45 1 225 231 Kotake Nobuhiro 1991 Packing process for the filling material in Chondrites Ichnos An International Journal for Plant and Animal Traces 1 4 277 285 doi 10 1080 10420949109386362 Retrieved from https en wikipedia org w index php title Chondrites genus amp oldid 1159154297, wikipedia, wiki, book, books, library,
