8a, Table 2). Reviews aren't verified, but Google checks for and Two anomalously-large-sized grains were found in lherzolite BFA16 (250m-sized grain; Befang Group I) and in lherzolite H54 (149m-sized grain; Wum Group I). 9) and trace element pattern has well defined positive Eu and Sr anomalies (Electronic Supplementary Material 6). The chapters that address evolutionary ecology, such as expression of variation, evolution of sex, evolution of life histories and sex ratios, and sexual selection, make effective use of selected contemporary biological examples to illustrate the concepts being presented. The sequence of events, comprising melting followed by melt metasomatism, was proposed for nearby Lake Nyos lherzolites by Liu et al. This concise and clear introduction to evolutionary biology introduces what is essential and exciting in the subject. Introduction to Physical Anthropology 2010-2012. Because of this, the sections show local embrittlement, which was unavoidable during their preparation. The book goes on to investigate the study of conservative systems through the time evolution operator and Ehrenfest s theorem. 4f). Thus, the Befang xenoliths represent a narrower part of the mantle profile than those from Wum (Fig. Stearns, Stephen C. and Rolf Hoekstra. 8a). WebEvolution An Introduction. Home; Evolution 101. Secondary lherzolites metasomatized by melts of similar characteristics occur in the Ronda Massif in Spain (Marchesi et al., 2013). 5). The temperatures recorded in Group I xenoliths (910973C) cover around 5km of the depth profile (Fig. ISSN 0018-067X (print), https://doi.org/10.1046/j.1365-2540.2000.0827b.x. The amphibole in H46 and H71 is enriched in Ti relative to that in H69 (TiO2=2.52.7 vs. 0.6wt.%) and depleted in Cr (Cr2O3=1.0 vs. 1.7wt.%, see Electronic Supplementary Material 1). Therefore, we suggest that both ortho- and clinopyroxene in the lherzolites of Group I crystallized and/or recrystallized during reactive percolation of melt which was similar to that from which websterites of Group A originated. Trace element and REE contents were normalized to Primitive Mantle (PM) using values of McDonough & Sun (1995). In one of the sections (HX1) the Na content in orthopyroxene was below the detection limit of the microprobe, and we used a Na content equal to 0. We are grateful to Dr. Ralf Tappert and an anonymous Reviewer for their reviews, which helped us to improve the final version of the text, and we appreciate editorial handling by Tod Waight. (2021), which shows that most (>85%) of the Oku Volcanic Group lavas, which erupted during last 12Ma, come from asthenospheric sources and are not contaminated by lithospheric mantle. Crystal-preferred orientation studies of both suites (this study and Tedonkenfack et al., 2021) shows that lherzolites of Group I consist of an olivine framework having consistent fabric, in which differently oriented grains of spinel and clinopyroxene occur. This study originated thanks to the project of Polish National Centre of Research (NCN) 2017/27/B/ST10/00365 to JP. & Schilling, J.-G. (, Goussi Ngalamo, J. F., Bisso, D., Abdelsalam, M. G., Atekwana, E. A., Katumwehe, A. The Author(s) 2023. This indicates that (1) they crystallized after olivine and (2) their primary CPO was not overprinted by strong plastic deformation. Toteu et al. The results are reported in Table 2 and the details of calculations are summarized in Electronic Supplementary Material 8. (e) Lherzolite H69. Lherzolites are porphyroclastic (Fig. The volume of the CVL lavas is small and they are mostly alkaline (Fitton, 1980), varying in composition from basanite to hypersthene-normative basalt (Njome & de Wit, 2014). The two-pyroxene geothermometer of Brey & Khler (1990) is based on exchange of Mg, Fe, Ca and Na between coexisting ortho- and clinopyroxene. Phase map. The diversity of the living world is staggering. (, Aulbach, S., Gerdes, A. The minerals of Group Ia lherzolites H41, H55 and HX2 show small, gradually varying differences (Table 2, Figs. Evolutionists no longer are concerned with obtaining evidence to support the fact of evolution but rather are concerned with what sorts of knowledge can be obtained from different sources of evidence. Crystal-preferred orientation (CPO) was studied by the EBSD technique in 10 rocks, and 87Sr/86Sr compositions in clinopyroxene were analyzed in situ by LA-ICP-MS in all studied samples and in amphibole in one sample. The 87Sr/86Sr ratio in clinopyroxene from H13 is 0.702120.00018 (1, n=8), while that from H53 is 0.702060.00020 (1, n=5; Fig. (2020), who obtained a Lu-Hf isochron at ~2.0Ga. The Sr content of clinopyroxene (295g/g) suggests involvement of silicate melts in which incompatible elements are strongly enriched (the ratios of Ti/Eu=3956 and LaN/YbN=0.38 exclude carbonatitic metasomatism, Coltorti et al., 1999). (2021) to represent the protolith of Group I, whereas we here recognize the more depleted Group III lherzolites as the protolith. 7) and contain aluminous spinel (Cr# 0.080.10; Fig. For full access to this pdf, sign in to an existing account, or purchase an annual subscription. This website is designed to hold most of the materials you need for the practical exercises you will do during the course. Oxford University Press, Oxford. WebEvolution is descent with modification and this takes place because of differential survival and reproduction of individuals. Clinopyroxene in these lherzolites is less LREE-depleted compared with that of Group I or is mildly LREE-enriched (Fig. That is, apart from possible complications arising from subsolidus trace element redistribution, the premise of full equilibrium with a melt is not fulfilled for sample H65. etina (cs) Deutsch (de) English (en) Human evolution an introduction to man's adaptations by Bernard Grant Campbell. and JavaScript. Other living things make up a crucial component of an organisms environment. WebThe introduction to a book about evolution can serve many pur- poses as for example to disabuse the notion that evolution has di- Introduction 5 rectionality or purpose, which is a common misconception that can lead to heated debates where none should exist. The insignificant effect of recent Oku volcanism on the underlying mantle lithosphere is also indicated by the study of Asaah et al. 6, 7, 8,). The succeeding chapters on systematics and historical processes in evolution are very clear and build nicely on concepts presented earlier. Even if the lamellae spacing is greater than the size of ablation crater, their oblique dip relative to the section surface (depending on how sections were cut) results in co-ablation of host and lamellae. Within continents, geological knowledge about the lithology and the evolution of lithospheric mantle is accumulated by bringing together fragmentary information yielded by studies of xenoliths brought to the surface, typically by alkaline volcanic rocks, and of tectonically exhumed mantle fragments embedded in crustal orogenic sequences (e.g. (f) Websterite H39. The minerals are grouped using an approach similar to that applied in prior papers (Matusiak-Maek et al., 2014; Tedonkenfack et al., 2021). The olivine framework is locally discontinuous in lherzolites containing less than 55 vol.% of this mineral (H41, H42, H54, H55; cf. Group III lherzolites may represent the sub-Moho layer which was not included in the evolution of deeper-seated parts of lithospheric mantle. Summary. Two websterites have been described by Temdjim (2012) from the Lake Nyos xenolith suite. In this paper we present a model for the origin of DMM-like mantle occurring in subcontinental setting. This book introduces what is essential and exciting in evolutionary biology. Despite the presence of abundant olivine (NY-03: 23 vol.%, NY-04: 31 vol.%), NY-03 is similar, both in terms of major and trace element compositions of minerals, to websterites of Group A from Wum. Very similar are lherzolites H41, H55, HX2, HX1 and H47 (olivine Fo 88.890.1, NiO 0.340.43wt.%, <220 to 760g/g Ca, orthopyroxene 0.171.19 atoms Al pfu, clinopyroxene 0.270.30 atom Al pfu, spinel Cr# 0.080.14; Figs. PM-normalized (McDonough & Sun, 1995) REE patterns of clinopyroxene from the Wum xenoliths shown according to grouping (see text for details); also shown is amphibole pattern for sample H69. A., Bouyo, M. H., van Schmus, W. R., Jelsma, H., Moloto-A-Kenguemba, G. R., da Silva Finho, A. F., Lerouge, C. & Doucoure, M. (, Van Achterberg, E., Ryan, C. G., Jackson, S. E. & Griffin, W. L. (, Waters, C. L., Sims, W. W. K., Perfit, M. R., Blichert-Toft, J. By: Stephen Stearns (Author), Rolf Hoekstra (Author) 381 pages, 150 illus. (, Coltorti, M., Bonadiman, C., Hinton, R. W., Siena, F. & Upton, B. G. J. 978-0521812689. Although it is also texturally late, the composition of pyroxenes in this rock is different compared with other lherzolites. It contains significant amounts of pargasitic amphibole (3.9 vol.%). Automatic indexing was performed using AZTec software (version 3.5) from Oxford Instruments, with a step size of 20 or 35m. Because the two-pyroxene geothermometer reproduces equilibration temperatures within 30C (Brey & Khler, 1990), we believe that these results indicate equilibrium between ortho- and clinopyroxene. The lithospheric mantle as sampled by peridotite xenoliths in some continental settings resembles the source of mid-ocean ridge basalts (MORB). Evolution simply means change over time, just as Jean-Baptiste de Lamarck predicted. (2019). Updates? Published by Oxford University Press. It coexists with Al-poor ortho- and clinopyroxene and spinel with Cr#=0.18 (Figs. The REE patterns of clinopyroxene are spoon shaped (Fig. 4b) to equigranular (Fig. Reviews This book is a carefully crafted, valuable, and fresh new resource for An example is shown in Electronic Supplementary Material 3. Heredity The clinopyroxene REE pattern is depleted in HREE-MREE relative to those of Group A websterites, and mimics them in the LREE except that it has a well-defined positive Eu anomaly (Fig. Division of Environmental and Evolutionary Biology, Sir Harold Mitchell Building, University of St Andrews, St Andrews, Fife, KY16 9TH, UK, You can also search for this author in evolution, theory in biology postulating that the various types of plants, animals, and other living things on Earth have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations. The theory of evolution is one of the fundamental keystones of modern biological theory. The CAOB originated by the collision of the Congo Craton with the Sahara Craton at the time of Gondwana assembly (Neoproterozoic Panafrican orogeny; Abdelsalam et al., 2002). Michigan: University of Michigan. The Group II lherzolites supposedly occur close to lithosphere-asthenosphere boundary and record interaction with lavas of the Cameroon Volcanic Line, whereas Group III lherzolites occur in the shallow part of the mantle profile and represent the protolith from which the Group I lherzolites were formed. Cambridge University Press. (2013), see text for detailed explanation. Their pyroxenes are Al-poor (orthopyroxene 0.15, clinopyroxene 0.23 atoms of Al pfu; Fig. 9), and the trace element patterns are characterized by well-defined negative Nb-Ta and Ti anomalies and positive U and Pb anomalies (Electronic Supplementary Material 6). This variation is analogous to that occurring in the Lherz lherzolites close to their contact with harzburgitic protolith (Le Roux et al., 2007, 2008). The trace element pattern has positive Sr anomaly (Electronic Supplementary Material 6). Grains with a surface smaller than 10 pixels were removed to avoid bias caused by potential indexing error. On the other hand, the seismic tomographic study of Reusch et al. Uploaded by (2020);, Tedonkenfack et al. & Gervilla, F. (, Bouyo, M. H., Zhao, Y., Penaye, J., Zhang, S. H. & Njel, U. O. 11) suggest that the lherzolites of Groups II and III occur at mantle levels different from lherzolites of Group I and Ia, and therefore probably evolved independently. 4), but no sulfide is present, suggesting that the parental melt did not reach sulfide saturation, in contrast to Group A websterites (Electronic Supplementary Material 9). Zhu et al. Analytical data underlying this paper are available in the paper and in its online supplementary material. It seems to have no effect on the composition of pyroxenes, therefore the temperatures were calculated as in the amphibole-free rocks. In order to constrain the identity of the melt from which the Group A websterites accumulated, the REE patterns of hypothetical melts from which the clinopyroxene crystallized were calculated using measured REE contents in clinopyroxene and diopside-melt partition coefficients of Yao et al. This enables calculating metasomatizing melt composition from mineral composition, as is conventionally done in mantle xenolith studies (e.g. Group II are lherzolites with LREE-enriched clinopyroxene, which shows the same deformation history as olivine and orthopyroxene. Question marks in the deeper part of the lithosphere indicate uncertainty regarding the age of the protolith prior to ca. ), the intergrowths (usually lamellar) in phases I are denoted as II, and the minerals occurring in fine-grained interstitial aggregates, as small individual interstitial grains or as margins on primary grains are denoted as III (Fig. Lin et al., 2022). & O'Reilly, S. Y. WebAn Introduction to Behavioral Ecology, 3rd ed. Niu, 1997) and its source is characterized by a mild depletion in incompatible elements (Salters & Stracke, 2004; Workman & Hart, 2005). Porphyroclasts of orthopyroxene and foliation defined by streaks of spinel and grain size variation. This is a brief introduction to evolutionary biology. The Sahara craton was remobilized and the term Sahara metacraton (Abdelsalam et al., 2002; Sobh et al., 2020) is commonly used. WebBiological Evolution An Introduction Biological evolution, the theory of natural selection and of common descent, is a triumph both of human reasoning and scientic undertaking. One approximation of the LAB depth is the intersection of the mantle adiabat (1300C potential temperature) with the steady-state geotherm, here taken to be the 60mW/m2 geotherm of Hasterok & Chapman, which crosses the adiabat at a depth of 90km (Fig. Lava compositions vary from basanite to trachyte and rhyolite (Asaah et al., 2015). (2016); Morales & Tommasi (2011); Puziewicz et al. At the steady-state thermal conditions recorded by the xenoliths, a monosulfide is expect to be stable (Naldrett et al., 1967; Naldrett & Kullerud, 1967; Kullerud et al., 1969), which decomposes into a low-temperature assemblage (Craig & Kullerud, 1969; Craig, 1973; Lorand, 1989; Makovicky & Karup-Mller, 1995; Alard et al., 2000; Lorand & Grgoire, 2006). Lherzolite H69 contains more amphibole. Their similar ages may reflect a common origin either via in-situ formation during the Eburnean subduction and collision at the northern edge of the Congo craton (e.g. The depth to the Moho discontinuity and that to LAB constrained by geophysical studies (Goussi Ngalamo et al., 2017, 2018; see text for details). (2021) comes almost entirely from the mantle section affected by MORB-like melt infiltration, and the xenoliths of Group II correspond to the Group Ia defined in this study for Wum xenolith suite. Lecture Notes in Earth Sciences. Forsterite content in olivine (Fo) is calculated as atomic 100*Mg/(Mg+Fe+Mn) per formula unit. (2013). Most of the xenoliths from Wum and Befang show consistent temperatures of pyroxene equilibration varying between 900 and 1000C. Jur. The temperatures of equilibration of pyroxene margins are higher than those recorded in grain centers and in REE exchange (Electronic Supplementary Material 8). Websterite H65 contains olivine streaks in addition to pyroxenes and spinel. This, together with the high 87Sr/86Sr ratio of 0.7028, suggests that this rock is transitional between Group I and II lherzolites. 11). Group A websterites likely formed as cumulates from that melt. With each new & Hirschmann, M. M. (, Druelle, B., Ngounouno, I. if the environment is the theatre, then evolution is the play. Biological evolution is a process of descent with modification. Specific aspects of evolution are discussed in the articles coloration and mimicry. Two of these correspond to the groups defined in the Befang xenolith suite on the basis of REE-patterns in clinopyroxene (Group I LREE depleted, Group II LREE enriched; Tedonkenfack et al., 2021). This concept was first proposed by Lenoir et al. Pp. 6, 7, 8, 9, 10). Textbook. (, Kaczmarek, M.-A., Bodinier, J.-L., Bosch, D., Tommasi, A., Dautria, J.-M. & Kechid, S. A. Ortho- and clinopyroxene are aluminous (ca. 4a) or serial-mosaic (Fig. Because the major element composition of ortho- and clinopyroxene is not equilibrated, temperature calculation by the method of Brey & Khler (1990) yields results varying between 925 and 1052C. Clinopyroxene is chemically similar in terms of REE, trace elements and 87Sr/86Sr ratio to that occurring in the websterites of Group A. Oku, Babanki, Nyos and Nkambe); Mt. WebOrganelles such as mitochondria and chloroplasts serve as good intracellular examples. Semi-quantitative phase diagram showing melting relations of lherzolite KLB-1 (based on diagram of Jennings & Holland, 2015), which is similar to the lherzolites of Group I in terms of mineral compositions (cf. This resulted in ordering of CPO of olivine and pyroxenes in the matrix and low internal deformation of the clinopyroxene porphyroclast (Fig. In this rock the porphyroclasts of orthopyroxene are smaller than in the other websterites, and are associated with spinel grains of similar size. 13). Hauri, 1997; Bodinier et al., 2004). Print. The lithospheric mantle underlying oceans is residual after decompression melting of asthenosphere upwelled beneath ocean rifts (e.g. 0521812682. There are two midterms and a paper. Surface wave tomography: imaging of the lithosphereasthenosphere boundary beneath central and southern Africa? 6a) and from <220 to 560g/g Ca. 2000. Alternatively, reactive percolation of melt chemically similar to MORB can modify subcontinental lithospheric mantle such that it resembles its oceanic counterpart. The xenoliths from Wum are from 5 to 12cm across in the longest dimension, rounded to subangular. On a supervisory level, leadership is required to complement organiza-tional systems The olivine websterite H60 is different from the websterites of Group A. Sulfides occur in 8 of 14 samples of lherzolites and in 4 of 5 samples of websterites in Wum (Electronic Supplementary Material 9). The CVL is located on the metamorphic-igneous basement of the Central African Orogenic Belt (CAOB; Fig. 8, Table 2). Since the Adamawa-Yade terrain is located to the SSE of the Oku Volcanic Group, this may indicate that the Paleoproterozoic (Eburnean) mantle lithosphere continues to the NW under the Neoproterozoic (Cryogenian Ediacaran) crust formed during the Panafrican orogeny (Fig. Goussi Ngalamo et al. In both the Wum and the Befang suites, sulfides occur as subordinate phases enclosed in ortho- or clinopyroxene, rarely in olivine. 11), as independently constrained from seismic observations (Goussi Ngalamo et al., 2018, see Geological Context). White denotes Cenozoic sedimentary rocks. By analogy with lherzolite H71 (discussed below), we suggest that amphibole crystallized later than the minerals of the host (see Origin of amphibole in the Oku lithospheric mantle). In both samples, the grains of amphibole do not display internal deformation. Subsequently, a separate event affected the Oku mantle lithosphere, locally adding small amounts of amphibole. Chemical characteristics of minerals coupled with the crystal-preferred orientation data suggests that Group I lherzolites originated in the spinel stability field by reactive intergranular percolation of an incompatible element-depleted MORB-like melt. This is supported by olivine CPO with girdles on (100) and (001) axes and a strong concentration on (010) axes perpendicular to the foliation plane. The coexisting spinel has high Cr# (0.280.29). On the other hand, the ~2.02.25Ga age does not fit the Neoproterozoic age of the crystalline basement of the Northern Domain, which underlies the OVG (see Crust and lithospheric mantle underlying CVL). The volume of orthopyroxene may be overestimated in websterites when present as 1015mm porphyroclasts, because the standard 28 x 48mm sections that we use are too small to be representative for these coarse-grained samples. PM-normalized (McDonough & Sun, 1995). An introduction to evolution: what is evolution and how does it work? Care has been taken to express ideas in simple language, examples and summaries attempt to make reading accessible. In contrast, the scarce lherzolites of Group III are more refractory: they contain 7278 vol.% olivine, Al-poor pyroxenes, and spinel with Cr# 0.18. The analytical setup for olivine included Ti, Al and Cr. & Liu, Y. Today, were continuing our commitment to give players more choice and value by introducing Xbox Game Pass Core, launching on September 14.Game Pass Core is the After macroscopic examination and exclusion of weathered specimens, we selected 19 samples for detailed study. 9). Sample runs were bracketed by measurements of NIST 612 glass, which was used for sensitivity calibration (reference values of Jochum et al., 2011, were applied). The major element compositions of minerals from this lherzolite are similar to those of H69 lherzolite in this study, except amphibole, which contains slightly more titanium (1.2wt.% of TiO2) and no potassium. human evolution, the process by which human beings developed on Earth from now-extinct primates. Lherzolite H69 contains significant amounts of amphibole (3.9 vol.%), occurring as interstitial grains or aggregates around spinel, which are texturally later than the olivine-pyroxene fabric (Fig. (2000) in their study of mantle xenoliths occurring in the French Massif Central. 4e). WebHis books include "Evolutionary Medicine" (Sinauer, 2015) with Ruslan Medzhitov, "Evolution, an introduction" (Oxford, 2000, 2nd Ed 2005) with Rolf Hoekstra, "Watching, from the Edge of Extinction" (Yale, 1999) with his wife Beverly Peterson Stearns, "The Evolution of Life Histories" (Oxford, 1992), and two edited volumes, "Evolution in health and disease" In most lherzolites, orthopyroxene CPO shows (001) axes forming a point concentration at low angle to olivine (100) axes and to X (Fig. (2019). 1 for location of sites). These observations suggest that it crystallized without strain, and after orthopyroxene. (2021), Fo, forsterite content; a pfu, atoms per formula unit; nc, not calculated, m, measured and normalized to in-house reference MIR-A (Rankenburg, 2002)Cr#=atomic Cr/(Cr+Al). The sparse websterites of Group C precipitated from ascending alkaline lavas, but little metasomatic modification of mantle peridotites occurred, with the possible exception of the of Group II lherzolites, which are suggested to derive from near the LAB on account of their higher equilibrium temperatures. (2008) and Zaffarana et al. WebEvolution 101. Pintr et al. The 87Sr/86Sr ratios in clinopyroxene from three studied rocks are identical within uncertainty (H39 and H500.7019, H430.7020; Fig. Characterization of the sub-continental lithopsheric mantle beneath the Cameroon volcanic line inferred from alkaline basalts hosted peridotite xenoliths from Barombi Mbo and Nyos Lakes, Three major types of subcontinental lithospheric mantle beneath the Variscan orogen in Europe, Institut fr Mineralogie. Evolution guides how our bodies respond to various treatments, how pathogens will respond to treatments, and how pathogens responses will change over time. Interstitial location of smaller grains of ortho- and clinopyroxene relative to olivine framework. A detailed discussion of the life and thought of Charles Darwin is found in the article Darwin, Charles. Natural selection occurs because individuals having more-useful traits, such as more-acute vision or swifter legs, survive better and produce more progeny than individuals with less-favourable traits. These characteristics suggest that the melt source once contained plagioclase and that the residuum after melting contained garnet, thus the melt source was deeper-seated than that from which Group A websterites formed. The latter is an aborted rift which originated during the late Cretaceous opening of the southern Atlantic (e.g. (2020) suggested they dated melt depletion in lherzolite xenoliths from Lake Nyos at ~2.0Ga. 12). 280K higher relative to the surrounding mantle. Moreover, in sample H64 clinopyroxene axes display only a weak point concentration on [010] at 45 to Z, and this clinopyroxene is undeformed and occurs in the interstices. For amphibole, we used the IMA-recommended classification (Hawthorne et al., 2012), with structural formulae calculated by the spreadsheet of Li et al. Optical image, PPL; (c) Lherzolite H64. 9). The analysis of clinopyroxene concentrates from xenolith C271D (Lee et al., 1996) yielded an 87Sr/86Sr ratio 0.70307410, also broadly similar to H69 (0.7027 in clinopyroxene and 0.7031 in amphibole), and we assume that both rocks were chemically re-equilibrated during the amphibole-forming event. CITATIONS READS. (2017) suggests a model depletion age of ca. The steady thermal state of mantle lithosphere at the time of xenolith entrainment allows the independently constrained regional geotherm to collocate the xenoliths in the lithosphere column without a prior knowledge of their pressures of equilibration. PubMedGoogle Scholar, Meagher, T. Evolution An Introduction. The strength of the CPO was estimated using the J-index (Bunge, 1982). It provides a readable account of selected topics, in both contemporary evolutionary ecology as well as a broad overview of long-term evolutionary history. Natural selection was the fundamental concept in his explanation. WebThis concise and clear introduction to evolutionary biology introduces what is essential and exciting in the subject. Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. 6a, 7, 8). Tedonkenfack et al., 2021). To describe rock textures, we use the terminology of Mercier & Nicolas (1975); in some instances, it is coupled with textural terms used in metamorphic petrology to describe rock fabric. The Ca content in olivine (590790ppm) is relatively high, and the Cr# of spinel (0.14) is also higher than that of the majority of Groups I and Ia lherzolites (Fig. Edition. We include into the A websterites also the layered rock H50, because its minerals are chemically identical to those occurring in other rocks of this Group (Table 2, Figs. Sulfides occur in 7 of 9 Group I xenoliths and in 3 of 5 samples from Group II peridotites from Befang, whereas in websterite BFA13 and harzburgite BFA24 they are absent (Electronic Supplementary Material 9). Tchouankoue et al., 2021; Stern, 2023) or as complementary crust and lithospheric mantle of a Paleoproterozoic microcontinent (Nkoumbou et al., 2014). WebEvolution 101. This coincides with our observation that no record of reactive percolation of CVL lavas occurs in the xenoliths from Befang (Tedonkenfack et al., 2021; 16 xenoliths studied in detail) and Wum (this study; 19 xenoliths studied in detail). on August 13, 2020. 2.6Ga using 187Os/188Os-Al2O3 relationships. An introductory section provides a background on evolution, genetics, and taxonomy. It is the extremely complex process by which living organisms change across time as traits are passed from one generation to the next. 1125C, significantly higher than the temperature of equilibration between discrete grains (ca. Xenolith suites from Wum (this study) and Befang (Tedonkenfack et al., 2021) are dominated by the lherzolites of Group I (Tables 2, 3). The area of plagioclase lherzolite is marked grey. It reacts with it, and this is the reactive melt percolation, which enables the solid minerals of the framework to change their composition. For developers, there is a C++ library and a command line tool for use in scripts. The fluid-metasomatized amphibole-bearing lherzolite H69 and two lherzolites constituting group III, which originated by metasomatism by alkaline melts similar to those of the CVL, depart from the melting-refertilization trend (Fig. Measurements with a mean angular deviation (MAD) greater than 1.3 were removed, and grains were then calculated by imposing an orientation difference smaller than 10 for any two neighboring measurements belonging to the same grain. By analogy with the Lherz massif, we suggest that this lherzolite represents a cryptic metasomatism front preceding the but not affected by the melting and melt percolation which shaped Group I lherzolites. These lherzolites have similar Al content in orthopyroxene (0.160.19 atoms pfu, Fig. However, the REE contents of hypothetical melts calculated from clinopyroxene are much richer in LREE than the lavas. 10). If this feature is robust, it suggests that the parental melt left a garnet-free (therefore probably shallow spinel-facies) source, which otherwise would have more strongly retained HREE than MREE, imparting a negative slope in the Sm-Lu pattern. Xenolith H50 has the composition of olivine websterite (Fig. They used Lu-Hf isochron and Os aluminochron ages as well as Re-depletion ages to argue that melt metasomatism occurred right after melt extraction. These data show that a significant part of the mantle lithosphere beneath Oku consists of secondary lherzolites (Group I) which compositionally resemble the DMM sensuWorkman & Hart (2005).

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