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Tracer (Sr and 18O) studies on 170 carbonate rocks indicate that diagenetic transformation of the metastable into a stable carbonate assemblage involves a partially closed wet chemical system. If the assumptions about present-day counterparts of Mesozoic facies are correct, the following tracer redistribution is indicated: (1) calcite is relatively stable and the decrease in Sr is 5 and the 18O negative shift is 0-2.5; (2) aragonite and Mg-calcites ar reprecipitated with varying efficiency as autochthonous calcite, which results in 10 Sr decrease and 18O negative shift of 1-5. Strontium content of dolomites decreases with geologic age, because of reduction in available lattice positions due to the Fe substitution.

The Tertiary carbonate rocks of the Kirkuk oil field in Iraq have been subdivided into 18 major lithologic facies. Their spatial relationships suggest that carbonate deposition proceeded in alternating carbonate ramp and carbonate rimmed shelf settings. Geochemically, these 18 facies can be grouped into three populations: namely, the nearshore (mud flat and bioherm), foreslope, and basinal populations. The nearshore population consists of mudstone, wackestone, packstone, and grainstone with bioclasts of miliolids, peneroplids, rotalids, red algae, corals, Numulites, Lepidocyclina, and crinoids. The basinal population encompasses mudstone and wackestone with Globigerina, radiolarians, and tintinids. The foreslope population consists of packstone and grainstone with a mixtu e of Nummulites, Lepidocyclina, and traces of corals and red algae. The nearshore and foreslope groups are characterized by severe recrystallization and contain abundant cements. The porosity is of primary (intergranular and intraskeletal) and secondary (dissolution and fracture) types and is associated mainly with the bioherm and foreslope facies. The nearshore population is characterized by low sodium and strontium contents and light ^dgr18O and ^dgr13C, whereas the basinal one has the opposite attributes. The foreslope group represents a mixture of these two end members, with nearshore components being dominant. Comparison of the approximate composition of diagenetic solutions responsible for deposition and/or mineralogic stabilization of carbonate constituents with present-day waters of various geologic environments led to the conclusion that the nearshore population was stabilized in a near-surface, meteoric, well-oxygenated aquifer. In contrast, the basinal population was deposited and stabilized in waters of marine parentage.

Carbonate rocks with geological attributes of marine sediments are a minor component of the Archean greenstone belts. Despite their relative scarcity, these rocks are important because they record chemical and isotopic properties of coeval oceans. The greenstones containing such carbonates appear to cluster at approximately 2.8 +/- 0.2 and approximately 3.5 +/- 0.1 Ga ago. The samples for the younger group are from the Abitibi, Yellowknife, Wabigoon (Steep Rock Lake), Michipicoten and Uchi greenstone belts of Canada and the "Upper Greenstones" of Zimbabwe. The older group includes the Swaziland Supergroup of South Africa, Warrawoona Group of Australia and the Sargur marbles of India. Mineralogically, the carbonates of the younger greenstones are mostly limestones and of the older ones, ferroan dolomites (ankerites); the latter with some affinities to hydrothermal carbonates. In mineralized areas with iron ores, the carbonate minerals are siderite +/- ankerite, irrespective of the age of the greenstones. Iron-poor dolomites represent a later phase of carbonate generation, related to post-depositional tectonic faulting. The original mineralogy of limestone sequences appears to have been an Sr-rich aragonite. The Archean carbonates yield near-mantle Sr isotopic values, with (87Sr/86Sr)o of 0.7025 +/- 0.0015 and 0.7031 +/- 0.0008 for younger and older greenstones, respectively. The best preserved samples give delta 13C of +1.5 +/- 1.5% PDB, comparable to their Phanerozoic counterparts. In contrast, the best estimate for delta 18O is -7% PDB. Archean limestones, compared to Phanerozoic examples, are enriched in 16O as well as in Mn2+ and Fe2+, and these differences are not a consequence of post-depositional alteration phenomena. The mineralogical and chemical attributes of Archean carbonates (hence sea water) are consistent with the proposition that the composition of the coeval oceans may have been buffered by a pervasive interaction with the "mantle", that is, with the oceanic crust and the coeval ubiquitous volcanosedimentary piles derived from mantle sources.

Cretaceous rudists, with thick, multilayered, bimineralic (aragonite and low-Mg calcite) shells, have been studied for the effects of meteoric diagenesis on their textural and chemical attributes. The original fine, compact, prismatic or cellular-prismatic microstructures of low-Mg calcitic layers have been preserved frequently, despite the vagaries of their subsequent diagenetic histories. These layers usually suffered only partial recrystallization, which caused fusion of crystal units, rounding of prism comers, and partial cementation confined to intercrystalline and intraparticle pore spaces. In contrast, the originally aragonitic parts of the shell usually suffered either complete dissolution or, at best, retained some vestiges of their crossed-lamellar or complex crossed-lamella , microstructures. Synsedimentary submarine diagenetic events, such as borings by endolithic fauna, internal micritic and/or peloidal sedimentation, and submarine aragonite and/or high-Mg calcite cements within the primary inter- and intraparticle pore spaces, were coeval with rudist accretion. The subsequent meteoric cementation has been characterized by the formation of bladed and equant ferroan calcites which occluded the residual primary and secondary porosities. Diagenetic stabilization of aragonite to diagnetic low-Mg calcite and low-Mg calcite to diagenetic low-Mg calcite is believed to have been a two-stage process. Initially, Sr and Na have been partially depleted during an early meteoric diagenetic phase (calcitization of metastable phases), with expulsion of Sr at a slower rate than that of Na. This stage is followed by incorporation of more Mn, Fe, and Mg due to precipitation of late ferroan calcite. Stabilization of aragonite causes more pronounced trace-element repartitioning than the stabilization of low-Mg calcite. However, the degree of repartitioning depends not only on mineralogy, but also on the structural buildup of a given shell layer, suggesting that factors such as water/rock ratio (surface kinetics) are of considerable sig ificance for the process of diagenetic stabilization. Rudist skeletal components with preserved original mineralogy and texture have trace-element chemical signatures analogous to Holocene marine bivalves. This similarity argues for comparable chemical composition of the Cretaceous and Holocene seawater, as well as for similar modes of incorporation of trace elements into mollusc shells.

This study examines the oxygen and carbon isotopic distribution in the brachiopods, crinoids, rugose corals, and matrix/cement from the Mississippian Burlington Limestone (Iowa and Missouri) and the Silurian Read Bay Formation (Arctic Canada). The isotopic data can be reconciled with textural and trace element observations only if the 18O content of ancient oceans differed from that of the present oceans. This postulated secular variation in the 18O content of seawater requires a separate evaluation of the Mississippian and Silurian carbonate components. Examination of the 18O content of the least-altered low-Mg calcite fossil components of the two formations suggests that the 18O of Mississippian seawater was, on average, about 1.5 lighter, and that of Silurian seawater was about 5.5 lighter than the 18O of present day ocean water. The average diagenetic shift in 18O for the Read Bay Formation, which stabilized in a partly closed diagenetic phreatic meteoric system, is about - 1 for the original low-Mg calcite and about -2 for the original high-Mg calcite and aragonite components. Conversely, for the Burlington Limestone, which stabilized in an open diagenetic phreatic meteoric system, the average diagenetic shift in 18O is about -3 for the original low-Mg calcite and about -4 f r the original high-Mg calcite components. The 13C values of the originally low-Mg calcite (or high-Mg calcite with less than 7 mole % MgCO3) brachiopods and rugose corals, the originally high-Mg calcite crinoids, and the originally aragonite lime mud of the Burlington Limestone and Read Bay Formation are bimodally distributed. This bimodal 13C distribution is independent of geologic age, inferred original mineralogy of the component, degree of diagenetic alteration, and the type of diagenetic meteoric system, with components from both the Read Bay Formation and Burlington Limestone contributing to both 13C groups. The mode of the light -13C group is +0.25% and for the heavy -13C group it is +3.25% (PDB).Both 13C groups also show a decrease in 13C of about 1% with increasing diagenetic alteration (stabilization).

From the planetary point of view, the Earth can be imagined as a system comprised of intertwined natural populations propagated through time via recycling. This recycling, or “birth/death” process, imposes age patterns on natural populations of the solid earth, hydrosphere, atmosphere and living entities. Mathematically, the concept is analogous to that of population dynamics in living systems. The populations of the Earth system form a hierarchical structure. The hierarchy of crustal tectonic realms contains populations of

Coated grains, which may have skeletal cores, are non-skeletal carbonate and non-carbonate grains formed in marine as well as non-marine environments. These grains are classified according to their structure and environmental parameters (Peryt, this vol.). Peloids are micritic grains without recognizable structures and are represented by individual grains and aggregates. Ooids, oncoids, rhodoids, and vadoids are coated grains with distinct structural features.

The Triassic of the Western Carpathians consists of "hypersaline" sequence in the north, grading southwards into dolomite and then limestone. This zonal arrangement was due to the development of algal reefs (banks) in the south, with subsequent "hypersaline" lagoonal evolution in the back-reef (bank) area. It is proposed that the dolomites within the lagoonal sequence originated by a very early diagenetic replacement of an aragonite mud, with clay minerals serving as charged net membranes or seeds for penetrating interstitial brines with high Mg/Ca ratios. It is also proposed that these brines were squeezed out from the lagoonal sequence into the porous algal reefs (banks) during later stages of diagenesis, causing dolomitization of the lagoonal side of the reefs (banks).

Sedimentary carbonate rocks of the Western Carpathians have been analysed for major constituents (CaO, MgO, I.R. = Insoluble Residue) and minor and trace elements (Sr, Ba, Mn, Ti). The distribution of Ba, Ti and Mn is controlled generally by the clay fraction of the I.R., or constituents associated with it. Sr is associated with the carbonate fraction. The distribution of Mn/Ti and possibly also Mg/Ca ratios seems to be influenced by climatic factors. The distribution of Sr in pure limestones is of a bimodal (or polymodal) type. Two possible alternatives explaining this feature could be a bimodal nature of diagenetic solutions or bimodality of Sr distribution in the original sediment (aragonite vs. calcite), which is preserved in spite of the diagenetic repartition. The data are not sufficient to decide this question, but the latter alternative is favoured by the authors.

The distribution of Sr in Mesozoic carbonate rocks of the Central Western Carpathians is facially controlled. This facies control is demonstrated on 75 facies types and more than 1,200 single analyses. The distribution of Sr in limestones is bimodal, with high Sr concentrations in hypersaline, dark coloured and deep sea rock types and low Sr concentrations in littoral, neritic and shallow bathyal limestones of organogenic and organodetrital types. The data, although not quite conclusive, indicate that this bimodality is inherited from original sediments. The early diagenetic dolomites contain higher Sr concentrations than the late diagenetic ones. This might be related to a partition of Sr between aragonite vs. dolomite and calcite vs. dolomite for the two dolomitic facies types.

THE question of the contraction, stability or expansion of the Earth during geological time is one of the basic problems of the geosciences.

The hypersaline facies of the lower Paleozoic carbonate sequence of Arctic Canada contain ≳230 ppm of soluble Na, whereas their open-marine counterparts are characterized by concentrations below this value. This chemical difference, imposed by sedimentary and (or) diagenetic environments, is preserved in spite of the order of magnitude postdepositional redistribution of sodium.

Hydrogen isotope geolocation of insects is based on the assumption that the chitin in the wings of adult migratory insects preserves the hydrogen isotope composition (δ2H) of the larval stages without influence of adult diet. Here, we test this assumption by conducting laboratory feeding experiments for monarch butterflies (Danaus plexippus) including: (1) a starvation treatment where adults were not fed and (2) an enriched treatment where adults were fed a diet isotopically enriched in deuterium (~ +78‰) compared to the larval diet. The δ2H values of adult wings were measured at different time steps along the 24-day experiment. We also investigated intra-wing differences in δ2H values caused by wing pigmentation, absence of wing scales, and presence of major wing veins. We conclude that, although the magnitude of the changes in δ2H values are small (~6‰), wing δ2H values vary based on adult diet and insect age, particularly early after eclosion (i.e., 1-4 days). We found that wing shade, wing pigmentation, and the presence of wing scales do not alter wing δ2H values. However, wing samples containing veins had systematically higher δ2H values (~9‰), suggesting that adult diet influences the hemolymph that circulates in the wing veins. We hypothesise that there is a stronger influence of adult diet on the isotope signal of wings during early adult life relative to later life because of increased metabolic and physiologic activity in young insect wings. We argue that the influence of the isotopic contribution of adult diet is generally small and is likely minimal if the wings are carefully sampled to avoid veins. However, we also demonstrated that wings are not inert tissues, and that adult feeding contributes to some of the intra-population δ2H variance. We conclude that d2H geolocation using insect wings remains valid, but that adult feeding, butterfly age and wing vein sampling generate an inherent uncertainty limiting the precision of geolocation., CB and GT acknowledge funding from the SSHRC CRSH New Frontiers in Research Fund 2018 (NFRFE-2018-00738). MR acknowledges funding from the Ontario Graduate Scholarship 2021–2022. GT acknowledges funding from the grant PID2020-117739GA-I00 from MCIN/AEI/10.13039/501100011033 and the grant LINKA20399 from the CSIC iLink program. EL acknowledges funding from the G.G. Hatch Award of the Ján Veizer Stable Isotope Laboratory Scholarship, University of Ottawa, 2022, the TD Green Bursaries, 2021 and the O’Connor Associates Environmental Scholarship, 2021., 1. Introduction 2. Materials and methods 2.1. Feeding experiment 2.1.1. Larval stage 2.1.2. Adult stage 2.2. Sample preparation 2.3. Stable isotope analysis 2.4. Statistical analysis 2.4.1. Multivariate linear regression 2.4.2. Tukey HSD test 2.4.3. Paired t-tests 3. Results 3.1. Trends in wing δ2H based on adult diet and insect age 3.2. Intra-wing differences in δ2H values 4. Discussion 4.1. Identifying non-significant controls on δ2H values in butterfly wings 4.2. Identifying significant controls on δ2H values in butterfly wings 4.3. Isotope element cycling and isotope-based geographic assignments for migratory insects 4.4. Limitations and future studies 4.5. Summary Data availability statement Author contributions Funding Acknowledgments Conflict of interest Publisher’s note Supplementary material References