Tsuyoshi Komiya

The University of Tokyo | Todai · College of Art and Science & Graduate School of Arts and Sciences

While it is widely accepted that early animals originated and primarily evolved during the Neoproterozoic to Cambrian period, there remains ongoing debate over how fluctuations in marine-atmospheric oxygen levels influenced their evolution and diversification. To investigate this, we analyzed pristane/phytane ratios—a redoxproxy based on organic ge...

Carbonate, the major carbon reservoir on Earth’s surface, can enter into the mantle by subduction. However, evidence for recycled surficial carbonates in the deep mantle is still scarce. Ocean island basalts from Cook-Austral islands and St. Helena Island, widely called HIMU basalts because of their high μ = ²³⁸U/²⁰⁴Pb sources, are thought to be fe...

The Nuvvuagittuq supracrustal belt (NSB) comprises one of the oldest supracrustal rocks; thus its geologic information can constrain the evolution of the early Earth. The supracrustal rocks are mostly composed of unique mafic rocks (Ujaraaluk Unit (UU)), which are highly depleted in Ca because they contain cummingtonite instead of hornblende. They...

Stable carbon isotope records in metasedimentary rocks showed that life has existed in the early Archean. Therefore, it may become next subjects of interest what kind of ecosystem existed and whether life existed prior to Archean. However, they are still ambiguous because little information other than isotope records is available from the early Arc...

Lamproites are rare mantle-derived peralkaline ultrapotassic rocks, and they are commonly geographically associated with the ultramafic lamprophyres and kimberlites. Their unique geochemistry and mineralogy make determining their mantle source and origin important because of the significance for inferring specific geodynamic processes. In this stud...

Raman and Fourier-transform infrared (FTIR) microspectroscopic analyses were performed to examine the chemical signatures and their spatial distribution of organic-walled microfossils together with organic matter (OM) in a black chert nodule from the Ediacaran (635–551 Ma) Doushantuo Formation in China. Raman spectral parameters (I-1350/1600 values...

The Kuanchuanpu biota (ca. 535 Ma) from the basal Cambrian in South China yields various phosphatized, three-dimensionally preserved microscopic fossils, such as animal embryos, cyanobacteria, and algae. This provides an exceptional window for investigating the rapid divergent evolution of animal phyla in the early Cambrian ocean. However, the foss...

Noble gases are chemically inert and, as such, act as unique tracers of physical processes over geological timescales. The isotopic composition of atmospheric xenon, the heaviest stable noble gas, evolved following mass-dependent fractionation throughout the Hadean and Archaean aeons. This evolution appears to have ceased between 2.5 and 2.1 Ga, ar...

Although fossil evidence suggest that various animal groups were able to move actively through their environment in the early stages of their evolution, virtually no direct information is available on the nature of their muscle systems. The origin of jellyfish swimming, for example, is of great concern to biologists. Exceptionally preserved muscles...

The diversity of small shelly fossils (SSFs) demonstrates that multicellular organisms underwent large‐scale radiation at the beginning of the Cambrian, which is highlighted by the coexistence of various metazoans and the occurrence of their embryo fossils. However, little is known about early Cambrian eukaryotic multicellular algae, the primary pr...

This paper presents first U–Pb detrital zircon ages, major and trace element geochemical data and whole-rock Nd and Hf-in-zircon isotope data from sandstones of the Char and Zharma zones of eastern Kazakhstan. Petrographically the sandstones represent greywackes. The U–Pb ages of detrital zircons show unimodal distributions peaked at 345–340 and 33...

The Eoarchean Nulliak supracrustal rocks in the Saglek Block of northeastern Labrador, Canada, contain some of the world’s oldest carbonate rocks. This work attempted to reveal the origin of the carbonate rocks and estimate the surface environmental conditions of the early Earth based on their occurrence and geochemistry. They occur together with m...

Compositional variability found in modern mid-ocean ridge basalt (MORB) and ocean island basalt (OIB) reflects differentiation processes associated with material recycling in the mantle-crust system. To investigate the timing at which this recycling system was established and how it transformed into the present-day system, we present geochemical an...

The tetraradial or pentaradial fossil embryos and related hatched individuals from the early Cambrian Kuanchuanpu Formation are of great interest for understanding the early evolution of medusozoans. The phylogenetic and evolutionary significance of their external and internal characters (e.g. manubrium, tentacles, septa and claustra) is still cont...

Moulting behaviour has a long history, hitherto, can be dated back to 535 Ma.

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Представлены результаты геологических, геохимических и изотопно-геохронологических исследований субвулканических риолитов Западного Горного Алтая и Рудного Алтая, принадлежащих двум крупным герцинским вулканическим системам, Алтае-Минусинской и Алтае-Салаирской. Результаты изотопного U–Pb-датирования цирконов показали две группы возрастов: ~410–405...

The Earth is the only planet where liquid water and life have existed through geologic time. Therefore, it is important to investigate the surface environments of the early Earth to understand its early life. However, little is known about the environments of the early Earth because of a lack of geologic evidence. Recently, > 3.95 Ga supracrustal r...

The paper reports the results of geological, geochemical, and isotope–geochronological studies of subvolcanic rhyolites of NW Gorny Altai and Rudny Altai, which belong to the large Hercynian volcanic systems: Altai-Minusa and Altai–Salair, respectively. U–Pb zircon dating revealed two age groups: ~410–405 and 390–381 Ma. The isotope–geochemical cha...

With millions of extant species, ecdysozoans (Scalidophora, Nematoida and Panarthropoda) constitute a major portion of present-day biodiversity. All ecdysozoans secrete an exoskeletal cuticle which must be moulted periodically and replaced by a larger one. Although moulting (ecdysis) has been recognized in early Palaeozoic panarthropods such as tri...

The article presents new geological, geochronological, mineralogical, geochemical, and isotopic data on the Early Cretaceous granitic rocks of the southern part of the Zhuravlevka Terrane (Sikhote-Alin). It is shown that four intrusive complexes containing significant amounts of granitic rocks were formed almost simultaneously in this area in the E...

Conventional and synchrotron radiation‐based (SR) Fourier transform infrared microspectroscopies (micro‐FTIR) were applied to four types of ~ 810 Ma organic‐walled microfossils together with diffuse organic matter (OM) and one irregularly shaped structure from the Fifteenmile Group, in Yukon, Canada, for their chemical characterization. The microfo...

The Ediacaran to Cambrian periods are characterized by the diversification and extinction of metazoans, carbon-cycle perturbation, and ocean oxygenation. Ocean nutrient cycles play a major role in the primary production and productivity-driven shallow water anoxia that was responsible for mass extinction in some Phanerozoic intervals. However, the...

The Earth is a unique planet, on which plate tectonics has operated to form highly evolved and diversified surface environments throughout geologic time. The occurrence of 4.03 Ga orthogneiss in the Acasta Gneiss Complex suggests that plate tectonics goes back to the Eoarchean, but it is still debated when plate tectonics began because of a lack of...

Fluid inclusions in hydrothermal quartz in the 2.4 Ga Ongeluk Formation, South Africa, are expected to partially retain a component of the ancient seawater. To constrain the origin of the fluid and the quartz precipitation age, we conducted Ar-Ar dating for the quartz via a stepwise crushing method. The obtained argon isotopes show two or three end...

The metamorphic P–T conditions and processes of the mid-Archean Barberton Greenstone Belt (BGB), South Africa were examined with petrological and thermodynamic data from metamorphosed banded iron formation (BIF) and garnet amphibolite in the Inyoni shear zone (ISZ). Equilibrium mineral assemblages in these two rocks range from Grt + Cpx + Gru + Mag...

There is a wide range of controversial tectonic concepts for the final development of the Paleo-Asian Ocean (PAO) in the western Central Asian Orogenic Belt (CAOB), largely due to scarcity of geochronological and geochemical data. Our paper presents first results of U-Pb zircon dating and detailed geochemical studies (major and trace elements, Sr,...

Abstract It was previously revealed that the total CO2 concentration in seawater decreased during the Late Archean. In this paper, to assess the secular change of total CO2 concentration in seawater, we focused on the Paleoproterozoic era when the Earth experienced its first recorded global glaciation. The 2.4 Ga Ongeluk Formation outcrops in the K...

The vestiges of life in Eoarchean rocks have the potential to elucidate the origin of life. However, gathering evidence from many terrains is not always possible1,2,3, and biogenic graphite has thus far been found only in the 3.7–3.8 Ga (gigayears ago) Isua supracrustal belt4,5,6,7. Here we present the total organic carbon contents and carbon isoto...

We describe here Sinaster petalon gen. et sp. nov., a new embryonic form from the c. 535 million-yearold Kuanchuanpu Formation of South China (Ningqiang, Shaanxi Province). The excellent three-dimensional, phosphatic preservation of these microfossils allowed us to use x-ray microtomographic techniques to make accurate reconstructions of their inte...

We determined highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, and Re) concentrations and ¹⁸⁷Os/¹⁸⁸Os ratios for ultramafic rocks distributed over the Eoarchean gneiss complex of the Saglek-Hebron area in northern Labrador, Canada in order to constrain to what extent variations in HSE abundances are recorded in Early Archean mantle that have we...

The early Cambrian Carinachitidae, a family in the subclass Conulata, are intriguing and important small shelly fossils. Their gently tapering, tube-shaped skeletons consist of convex faces separated from each other by broad, deep corner sulci, and they exhibit triradial, pentaradial, or predominantly tetraradial symmetry. However, the morphology o...

Abundant microstructures have been discovered in small skeletal fossils (SSFs) and embryo-like fossils collected from the Lower Cambrian Kuanchuanpu Formation (ca. 535 Ma) in Xixiang County, Shaanxi Province, China. These involve two co-occurring structures: (1) long, unbranched cylindrical filaments, which are comparable to phosphatic casts of mic...

The Ediacaran–Cambrian transition is characterized by numerous events such as the emergence of large multi-cellular metazoans and surface environmental disturbances. Based on geological evidence, it has been proposed that this transition coincided with the increase in the atmospheric oxygen level that was key to the evolution of life. Even though a...

Banded Iron Formations (BIFs) are chemical sediments, ubiquitously distributed in the Precambrian supracrustal belts; thus their trace element compositions are helpful for deciphering geochemical evolution on the earth through time. However, it is necessary to elucidate factors controlling the whole-rock compositions in order to decode the ancient...

The earliest fossil record of animal biomineralization occurs in the latest Ediacaran Period ( c . 550 Ma). Cloudina and Sinotubulites are two important tubular taxa among these earliest skeletal fossils. The evolutionary fate of Cloudina -type fossils across the Ediacaran–Cambrian transition, however, remains poorly understood. Here we report a mu...

Synchrotron radiation-based Fourier transform infrared microspectroscopy (SR micro-FTIR) was applied to ∼830 Ma prokaryotic fossils in a doubly polished thin section in order to examine the micrometer-scaled spatial distributions of organic components in the microfossils. Mapping analysis allowed us to locate aliphatic C-H bonds (∼2925 cm⁻¹ band an...

The Ongeluk Formation mainly consists of submarine volcanics (pillow lavas and sheet flows) composed of basaltic andesites that is between underlying and overlying glaciogenic deposits (i.e., the Makganyene diamictite and a dropstone layer at the base of the Hotazel Formation, respectively). The stratigraphic position of the Ongeluk Formation indic...

Molecular phylogenetic analysis reveals that the splitting of the phylum Cnidaria into Anthozoa and Medusozoa probably took place in deep time as early as Cryogenian–Ediacaran (720–541 Ma), a long period with low dissolved oxygen concentration in the ocean. However, the pelagic life-style of medusae and the skeleton construction of anthozoans are e...

Ediacaran vendobionts are worldwide and diverse, and most of them, particularly frondlike forms, have long remained problematic in affinity and feeding behavior. Here we report five microscopic specimens of vendobionts from the early Cambrian Kuanchuanpu Formation in south China (535 Ma). The exceptional Orsten-type preservation reveals isomeres ex...

The Archean continental crusts account for ca. 20% of the present volume, but the thermal history of the Earths' mantle suggests much more continental crusts were formed in the early Archean. Because the Archean continental crust underwent severe metamorphism, it is important to avoid influence by the later thermal events. We carried out a comprehe...

The Acasta Gneiss Complex, located in the western part of the Slave Province, Canada, is widely recognized as the oldest Eoarchean terrane. In addition to felsic gneisses with the ages of 3.6–4.0 Ga, minor mafic rocks occur as rounded to elliptical enclaves and inclusions within the felsic gneisses. Despite serving as potential sources of geochemic...

We present a new approach for recognizing the origin of accreted basaltic rocks based on ocean plate stratigraphy (OPS), and on the petrology and geochemistry of basalts from mid-oceanic ridges (MORB) and oceanic islands (OIB) using examples from four accretionary complexes (AC) in SW Japan: Akiyoshi, Mino–Tamba, Chichibu and Shimanto. The key to t...

A new form of dendroid multicellular thallophyte is documented in the Ediacaran Doushantuo phosphorite at Weng’an, Guizhou Province, southern China. The dendroid thallophytes have variable forms, possibly owing to heteromorphic variation. Many lateral branches extend from the upper portions of the main axes; the lateral branches bear terminal veget...

The early Cambrian pentamerous microfossil Olivooides/Punctatus in South China, which is characterized by a diagnostic stellate tubular apex, has been well-known for its almost complete development sequence that can be confidently traced from embryos and hatched juveniles, to conical adults. However, its zoological affinity remains highly controver...

Sponges are widely viewed as the most primitive metazoans. Sponge gemmule-like structures have been recovered from the lower part of the Doushantuo Formation in the Yangtze Gorges area (South China), that were deposited between 635 and 580 Ma. Gemmosclere-like structures are embedded in the outer coat of the sponge structures. Electron probe microa...

Cap Carbonates overlie the Marinoan Snowball Earth-related glacial diamictite, and possibly record the drastic surface environmental change and biological evolution after the Snowball Earth. We conducted on-land drilling from the Liantuo Formation, through the Nantuo, to the lower Doushantuo Formation in the Three Gorges area of South China to coll...

The Neoproterozoic Era records several important events in Earth history. The associations between BIF deposition, Snowball Earth events and the redox state of seawater are the key to explain the re-appearance of banded iron formations (BIF) during the Neoproterozoic. Unraveling ancient iron cycles provides important information about the linkage b...

The evolution of paleoecosystems was often accompanied by the expansion of ecological niches; organismal habitats extended from the sediment surface to the water column, and then to the interior part of the sediment. A major step in ecosystem innovation was recorded in the macrobiota of the upper Doushantuo Formation during the middle-late Ediacara...

The earth is a unique planet, which has been highly evolved, diversified and complicated through geologic time, and underwent many key events, including giant impact, magma ocean, core formation, large-scale mantle differentiation and late heavy bombardment, especially in the dawn. But, our knowledge of early earth is limited due to the lack of the...

The Siberian Platform is the largest structure of Northeast Asia, which records practically its entire geological history since the Early Archean. The basee ment of the platform crops out in the Aldan Shield in the southeast, Anabar Shield, Olenek Uplift in the north, and as small inliers along its southwestern periphery (Kan, Sharyzhalgai, Irkutny...

The Barberton Greenstone Belt (BGB), South Africa, consists of volcano-sedimentary and sedimentary successions deposited between 3.5 and 3.2 Ga, which are subdivided into three Groups: the Onverwacht, Fig Tree, and Moodies. After deposition, the Barberton Greenstone Belt underwent relatively low-grade tectonothermal events, enabling estimation of s...

The evolution of paleoecosystems was often accompanied by the expansion of ecological niches; organismal habitats extended from the sediment surface to the water column, and then to the interior part of the sediment. A major step in ecosystem innovation was recorded in the macrobiota of the upper Doushantuo Formation during the middle-late Ediacara...

To improve estimates of the extent of ocean oxygenation during the late Ediacaran Period, we measured the U and Mo isotope compositions of euxinic (anoxic and sulfidic) organic-rich mudrocks (ORM) of Member IV, upper Doushantuo Formation, South China. The average δ238U of most samples is 0.24 ± 0.16 ‰ (2SD; relative to standard CRM145), which is sl...

Living medusozoans and their Middle Cambrian ancestors are characterized fundamentally by four-fold symmetry. The symmetric pattern of their earlier antecedents during the Ediacaran-Cambrian transition, traditionally expected to be tetramerous, need to be reconsidered in the light of Cambrian pentamerous fossil medusozoans. Here we present a microa...

Granitoids are widespread in Precambrian terranes as well as the Phanerozoic orogenic belts, but they have garnered little attention in paleomagnetic studies, because granitoids often contain abundant coarse-grained, magnetically unstable oxides. In this study, the first example of tiny, needle-shaped, exsolved oxides in plagioclase in a Paleoarche...

Extant cubozoans are active swimmers and voracious predators characterized by a square shape, four bundles of interradial tentacles and complex eyes in the perradii. A few probable cubozoan fossils have been described from the famous Mazon Creek biota (Pennsylvanian) and the Middle Cambrian Marjum Formation of Utah but earlier possible representati...

Important ecological changes of the Earth (oxidization of the atmosphere and the ocean) increase in nutrient supply due to the break-up of the super continent (Rodinia) and the appearance of multi-cellular organisms (macroscopic algae and metazoan) took place in the Ediacaran period, priming the Cambrian explosion. The strong perturbations in carbo...

Phosphatized microfossils from ca. 580Ma from the Doushantuo Formation in the Weng'an region of South China were analyzed by Fourier transform infrared (FTIR) microspectroscopy for their chemical characterization. Two morpho-types of phosphatized embryo-like fossils (Megasphaera and Megaclonophycus) were analyzed, together with algal fossils. Trans...

The Neoproterozoic and Cambrian were two of the most dramatic periods in the history of the Earth, because large multi-cellular animals first appeared then in the so-called “Cambrian Explosion”. To better understand this event, many paleontological and geochemical studies now focus on rocks in South China, because of the fossiliferous succession an...

A remarkable increase of the animal genera and a subsequent mass extinction in the late Early Cambrian are well known as the “Cambrian explosion” and the “Botomian–Toyonian crisis.” A composite global curve of the carbon isotope ratios for inorganic carbon (δ¹³Ccarb) shows multiple fluctuations during the evolution events, and it indicates signific...

Environmental investigation of the Early Cambrian is assessed through molecular fossils based from three core samples drilled in the Three Gorges area, South China. The core samples record environmental information dating from the earliest part of the Early Cambrian to nearly the end of the Early Cambrian, making this investigation unique from prev...

The bivalved bradoriid arthropod Kunmingella douvillei (Mansuy, 1912) is the most common species in the Lower Cambrian Chengjiang Lagerstatte. Its soft anatomy has been reported based on well-preserved specimens. However, as with other Cambrian arthropods, its reproductive behavior is poorly documented. Rare specimens of K. douvillei preserved with...

The appearance of multicellular animals and subsequent radiation during the Ediacaran/Cambrian transition may have significantly changed the oceanic ecosystem. Nitrogen cycling is essential for primary productivity and thus its connection to animal evolution is important for understanding the co-evolution of the Earth's environment and life. Here,...

The Ediacaran–Cambrian was one of the most important periods for the evolution of life. Recent studies have provided detailed chemostratigraphies that decipher the linkages between ambient surface environmental changes and biological evolution. The occurrence of skeletal fossils in Ediacaran rocks suggests that the possible onset of Ca-biomineraliz...

The Ediacaran and Cambrian periods were one of the most important periods for the evolution of life. The biodiversity drastically expanded in the period. However, the origins are still ambiguous because surface environmental changes through the time have not been well understood yet. We conducted in-situ analyses of the phosphorus contents of carbo...

Geochemical compositions are reported for Late Miocene to Pliocene granitoids from the Taitao Peninsula near the Chile ridge subduction zone. Major element compositions of Taitao granitoids show a resemblance with those of TTG suites. However, trace element compositions are characterized by low Sr (50-300 ppm), moderately high Y (10-45 ppm) and Yb...

Extant cubozoans are voracious predators characterized by their square shape, four evenly spaced outstretched tentacles and well-developed eyes. A few cubozoan fossils are known from the Middle Cambrian Marjum Formation of Utah and the well-known Carboniferous Mazon Creek Formation of Illinois. Undisputed cubozoan fossils were previously unknown fr...

Drawings and reinterpretation of virtual sections of an Olivooides-like embryo (GMPKU3089) [13]. A–D, respectively redrawings of fig. 3f, 3j,3k, 3l, respectively in [13]. (TIF)

Micro-CT movie of succesive transverse sections of ELISN31-5 from the Kuanchuanopu Formation, South China. (MP4)

Micro-CT movie of external profile of ELISN108-343. (MP4)

Micro-CT movie of external profile of ELISN66-14. (MPG)

Micro-CT movie of transverse sections of ELISN96-103. (MP4)

ELISN31-5, succesive lateral sections of ELISN31-5. (MP4)

Micro-CT movie of external profile of ELISN66-15. (MP4)

Micro-CT movie of transverse sections of ELISN108-343. (MP4)

Micro-CT movie of lateral sections of ELISN 108-343. (MP4)