Diagenetic Research Articles

Stable isotopic (δ13C and δ18O) signatures of biogenic calcretes marking discontinuity surfaces: a case study from Upper Cretaceous carbonates of central Dalmatia and eastern Istria, Croatia

Biogenic calcretes associated with a regional Cretaceous to Paleogene subaerial unconformity and an intraformational composite (polygenic) surface in Upper Cretaceous intra-platform peritidal successions in central Dalmatia and eastern Istria, Croatia (Adriatic-Dinaridic Carbonate Platform), were analyzed for their δ13C and δ18O signatures in order to provide insight into the conditions of subaerial exposure and calcrete development. The distinctly negative δ13C signatures of biogenic calcretes marking the regional subaerial unconformity differ considerably from the δ13C values of the host marine limestones. This indicates carbon isotope exchange of primary marine CaCO3 with CO2 released by root and rhizomicrobial respiration and subsequent precipitation of pedogenic calcrete. The range of δ13C (from −13.1 to −8.2 ‰ Vienna PeeDee Belemnite standard, VPDB) and δ18O (from −10.1 to −6.1 ‰ VPDB) values of calcretes are similar to those reported from calcretes elsewhere, and the δ13C values of biogenic calcretes with typical Microcodium aggregates (−13.1 to −12.3 ‰ VPDB) at the Sibenik locality are very close to, or at the lower limit of, values for soil carbonates formed in isotopic equilibrium with soil CO2. These values are expected for authigenic pedogenic carbonates formed under the influence of C3 plant communities, without influence from heavier carbon from pre-existing carbonate and lack of input of atmospheric CO2. Such low δ13C values support the interpretation of Microcodium aggregates as being precipitated under a direct biological control within the soil, although the relationship between formation mechanisms and stable isotope signatures of Microcodium needs further investigation. The δ13C values (−4.4 to −3.6 ‰ VPDB) of rhizogenic calcretes formed inside firmground Thalassinoides burrows of the composite surface at the Sibenik locality are more negative than the δ13C values of the host marine limestones, which confirms that the composite surface went through a phase of meteoric pedo(dia)genesis. However, the overall δ13C values of calcretes are less negative than expected, which might reflect contamination from associated primary marine carbonate. This study represents the first detailed stable isotope investigation of calcretes from carbonate successions of the External Dinarides, and the results may be applied to discontinuities present in other shallow-water carbonate rock successions.

INSIGHTS INTO THE DISTRIBUTION OF SHALLOW-MARINE TO ESTUARINE EARLY MIOCENE OYSTERS FROM SOUTHWESTERN PATAGONIA: SEDIMENTOLOGIC AND STABLE ISOTOPE CONSTRAINTS

Fil: Cuitino, Jose Ignacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geologicas; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires; Argentina

Diagenesis of Clastic Reservoirs: Advances and Prospects

Diagenesis of Clastic Reservoirs: Advances and Prospects

Tafonomía del Sitio de Nidificación de Neosaurópodos de Sanagasta (la Rioja, Argentina): Ejemplo de Preservación Excepcional en un Paleoambiente Hidrotermal del Cretácico

Fil: Fiorelli, Lucas Ernesto. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Regional de Investigaciones Cientificas y Transferencia Tecnologica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Cientificas y Transferencia Tecnologica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Cientificas y Transferencia Tecnologica de la Rioja. - Secretaria de Industria y Mineria. Servicio Geologico Minero Argentino. Centro Regional de Investigaciones Cientificas y Transferencia Tecnologica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Cientificas y Transferencia Tecnologica de La Rioja; Argentina

Research Status and Advances in the Diagenetic Facies of Clastic Reservoirs

Research Status and Advances in the Diagenetic Facies of Clastic Reservoirs

MINERALOGY AND GEOCHEMISTRY OF THE Co-RICH FERROMANGANESE CRUSTS FROM THE SOUTH WEST INDIAN RIDGE

Eight samples of Co-rich ferromanganese crusts collected from the south west Indian Ridge have been analyzed for their mineralogy and geochemistry by using XRD and XRF methods.Based on the data,the genetic classification and the source of materials are further explored.The mineralogy of the crust suggests that Manganese minerals and Iron minerals are the main components of the crusts.Vernadite is the dominant component of manganese oxide with Todorokite the minor.The most abundant phase of the ferric minerals is X-ray amorphous FeOOH with Goethite identified by a weak X-ray peak.The concentration of Mn,Fe,Co,Cu,and Ni in the crusts ranges between the Pacific Ocean crusts and the Atlantic Ocean crusts or the Indian Ocean crusts,in an average value of 18.96%,19.71%,0.53%,0.099%and 0.47%respectively.The Co-rich ferromanganese crusts are of hydrogenetic origin deduced from mineral composition,element groups and element ratios.The early diagenesis has slight impact on the crusts while the local hydrothermal effect has not been identified.

DUOSTOMINIDAE (FORAMINIFEREA, ROBERTINIDA) FROM THE UPPER TRIASSIC BEDS OF THE SLOVENIAN BASIN (SOUTHERN ALPS, SLOVENIA)

Twelve species of genera Diplotremina Kristan-Tollmann, 1960, Duostomina Kristan-Tollmann, 1960, and Variostoma Kristan-Tollmann, 1960 have been described from the Norian and Rhaetian strata of the Slovenian Basin (eastern Southern Alps). A lamellar wall structure has been confirmed for Duostomina and observed for the first time in Variostoma. The multi-layered nature of the lamellae of Diplotremina and Duostomina may be a result of a diagenetic alteration of the single-layered lamellae. The position of Variostoma in the family Duostominidae remains doubtful due to the alveolar nature of its wall.

GEOPHYSICAL RESPONSE OF THE LIUHUA CARBONATE PLATFORM IN NORTHERN SOUTH CHINA SEA

The complexity of carbonate deposition and diagenesis leads to the carbonate reservoir heterogeneity.The analysis of the intersections of well logs in the area of the Liuhua oil field on Dongsha massif suggest that velocity,density and seismic acoustic impedance are the most relevant physical parameters of porosity.Based on the quantitative analysis of reservoir physical properties from 3d seismic and logging data,we summarized in this paper the heterogeneous characteristics of the reef carbonate platform,and described its physical properties,by using the techniques of seismic inversion and attributes analysis.The results show that the seismic reflection,acoustic impedance inversion,seismic amplitude attributes,and coherence can be used in description of carbonate reservoir characteristics.Finally,we analyzed the genesis of the heterogeneity of reservoir of the Lliuhua oil field.It is concluded that the karst and sinkhole caused by acid gas are one of the main reasons for the heterogeneity of a reservoir.

Advances in the Role of Iron in Marine Sediments during Early Diagenesis

Advances in the Role of Iron in Marine Sediments during Early Diagenesis

Relative Contributions of Various Early Diagenetic Pathways to Mineralization of Organic Matter in Marine Sediments: An Overview

Relative Contributions of Various Early Diagenetic Pathways to Mineralization of Organic Matter in Marine Sediments: An Overview

An Isotopic (Sr, Nd and Pb) Tracer Study on the Xiaoxinancha Gold‐rich Copper Deposit in Yanbian, China: Implication for the Geodynamic Model of Diagenesis and Metallogenesis

Abstract:An isotopic study was systemically carried out on the granitic complex, diorite‐porphyrite, ores and ore minerals of the 103 Ma Xiaoxinancha gold‐rich copper deposit in Jilin province to determine the geodynamic model of diagenesis and metallogenesis. Results show that the initial Nd and Sr isotopic compositions of the granitic complex are in the range of 0.70425–0.70505 for (87Sr/86Sr)i, 0.51243–0.51264 for INd, and –1.31 to + 2.64 for εNd(t); those of the diorite‐porphyrite are in the range from 0.70438–0.70448 for (87Sr/86Sr)i, 0.51259–0.51261 for INd, and + 1.56 to + 2.09 for εNd(t). For ores and sulfides, the (87Sr/86Sr)i, INd, and εNd(t) values are in the range from 0.70440–0.70805, 0.51259–0.51279 and +1.72 to +5.56, respectively. The Pb isotopic ratios of the granitic complex range from 18.2992–18.6636 for 206Pb/204Pb, from 15.5343–15.5660 for 207Pb/204Pb, and from 38.1640–38.5657 for 208Pb/204pb For diorite‐porphyrite, the isotopic ratios of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204b are 18.3919, 15.5794 and 38.3566, respectively, whereas those of the ores and ore sulfides vary from 18.2275–18.3770 for 206Pb/204Pb, from 15.5555–15.5934 for 207Pb/204Pb and from 38.1318–38.3131 for 208Pb/204Pb. The results indicate that the mineralization was correlated to the formation and evolution of the granitic complex and the diorite‐porphyrite. Combining with the reported data in petrologic characteristics, elemental geochemistry and chronology, conclusions can be drawn that the geodynamic settings of diagenesis and metallogenesis of this deposit were consistent with the subduction of the Izanagi oceanic plate during the Early Cretaceous. The diorite‐porphyrite was formed by the emplacement of the adakitic magma triggered by partial melting of the enriched mantle, which originated from the derivative continental lithospheric mantle metasomatized by dehydration fluids from the subducting oceanic crust. The granitic complex was produced by fractional crystallization of the mixture between the adakitic magma and the high‐K calc‐alkaline acidic magma, which were generated by the remelting of the lower crust in the course of intraplate upwelling of the adakitic magma. The ore‐bearing fluid reservoir convened in a late stage of the evolution of the mixed magma chamber.

Karst bauxites in the Campania Apennines (southern Italy): a new approach

In this study new data on two bauxite districts in the Campania region (southern Italy) are reported: the Matese Mts. and the Caserta province, exploited in the first part of the XX century. The nature and distribution of diagenetic and detrital mineral phases were investigated by means of transmitted-light and scanning electron (SEM) microscopy, X-ray powder diffraction (XRPD) and energy dispersive spectroscopic microanalysis (EDS), whole-rock geochemical analyses (ICP-OES and ICP-MS), complemented by preliminary QEMSCAN ® investigation. The textures of the bauxite ore range between oolitic and oolitic-conglomeratic and arenitic. Boehmite is the most abundant phase, while other Al-bearing phases (gibbsite and diaspore) are very subordinate. The Fe-minerals hematite, goethite and lepidocrocite occur, and Ti-minerals anatase and rutile are ubiquitous. Among clay minerals, kaolinite is prevailing at the Regia Piana (Matese Mts.) and illite-montmorillonite in the Caserta province. Most recorded trace minerals are quartz, calcite, zircon and monazite. Small clusters of not previously detected qandilite [(Mg, Fe 2+ ) 2 (Ti, Fe 3+ , Al) O 4 ], and of hercynite-type spinels also occur. By means of QEMSCAN ® it has been possible to better recognize some diagenetic textures (e.g. mainly matrix- or ooids-supported bauxite, the clay/Al-hydroxides distribution etc.) and to detect other detrital minerals (feldspar, muscovite, olivine, titanite and possibly a serpentine/talc-like phase). A similar detrital mineral association has been found also in the Aptian “Orbitoline ” marls, which are marine sediments supposed to be the non-weathered equivalent of bauxites. Very detailed data about major, minor and trace element (comprising “bauxitophile ” and REEs) concentrations and some significant geochemical ratios are reported for the bauxite samples, and a new interpretation on the possible source of the parent material has been proposed. The detrital heavy mineral association may suggest not only a windblown volcanic source material (Dinarides explosive volcanism?), as hypothesized in literature, but also a partial origin from an exposed terrain. The exact nature and paleogeographic position of this source could not be determined by chemical analyses of major and trace elements (including REE), Eu/Eu* and TiO 2 /Al 2 O 3 ratios and Ni-Cr contents. However, due to the isolated position of the Appennine carbonate platform during the Cretaceous, the paleogeographic model precludes any possible fluviomarine transport for the source material (windblown?) of the bauxites.

CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF UPPER CALLOVIAN-LOWER BERRIASIAN SUCCESSIONS FROM THE SOUTHERN ALPS, NORTH ITALY

Calcareous nannofossil biostratigraphy was investigated in uppermost Callovian-lower Berriasian sections from Southern Alps, previously detected through magnetostratigraphy, in order to achieve an integrated stratigraphic framework valid at low latitudes. Nannofossil investigations were carried out on smear slides and ultra-thin sections, revealing generally scarce to common abundances and poor-moderate preservation of nannofloras. An exhaustive taxonomic revision was performed to unambiguously separate forms which are transitional between two species and better delineate rapidly evolving groups. Four new species have been described: Zeugrhabdotus fluxus , Nannoconus puer , Nannoconus erbae , Hexalithus geometricus . Particular attention was paid to taxonomical aspects of primitive nannoconids, appearing and evolving across the early-late Tithonian transition and the Tithonian/Berriasian boundary intervals; the revision was also verified at DSDP Site 534A from Atlantic Ocean. Fourty-eight nannofossil bioevents were detected and the results help to increase potential stratigraphic resolution in this interval. Thirty-seven nannofossil bioevents in the upper Kimmeridgian-lower Berriasian interval have been directly correlated to magnetostratigraphy (CM22-CM17) revealing a systematically older stratigraphic occurrence of these taxa than previously reported. A revised and partly new Tethyan calcareous nannofossil zonation scheme is here proposed for the uppermost Callovian-lower Berriasian interval. It consists of seven bio-zones and eight subzones based on thirty-one bioevents, thirteen of them related to dissolution resistant taxa assuring highest reproducibility even in sections with high diagenetic overprint. The proposed biostratigraphic scheme gives higher resolution than previous zonations, especially for the Callovian-Kimmeridgian interval, where no biozonation was available for the Tethyan Realm.

Distribution and Characteristics of n-fatty Acid amides in Late-Quaternary Sediments from Northwestern China and their Paleoclimatic Significance

A series of analogs of n-fatty acid amide(n-FAA)have been identified in different late Quaternary sedimentary strata from northwest China by using the gas chromatography-mass spectrometry(GC-MS).Based on the carbon distribution as well as the characteristics of n-FAA and previous studies,we suggest that the n-FAA originates from biogenic sources rather than petrolic residues,or any other potential contaminant.By comparing the distribution of n-FAA in different paleo-lakes and loess strata,we propose that Ejina basin is one of the main source areas of Luochuan loess deposits.Alternatively,the relationship of the material source between the Qaidam Basin and Luochuan Loess deposit is low.The ratios of unsaturated to saturated n-FAA(UFAA)show trends comparable to that of the magnetic susceptibility and grain size variation within the loess,especially the lowest values associated with warm/humid episodes.This phenomenon indicates that the distribution of the n-FAA is influenced by early diagenetic processes,which are controlled by paleoclimatic variations.Our results highlight the variation within n-FAA,which is naturally formed in the physiology of different organisms.n-FAA can also record the paleoclimatic variation,similar to lipids,which originate from the constitutional unit of a cell membrane.

The effect of tissue structure and soil chemistry on trace element uptake in fossils

Abstract Trace element profiles for common divalent cations (Sr, Zn, Ba), rare-earth elements (REE), Y, U, and Th were measured in fossil bones and teeth from the c. 25 ka Merrell locality, Montana, USA, by using laser-ablation ICP-MS. Multiple traverses in teeth were transformed into 2-D trace element maps for visualizing structural influences on trace element uptake. Trace element compositions of different soils from the fossil site were also analyzed by solution ICP-MS, employing progressive leaches that included distilled H2O, 0.1 M acetic acid, and microwave digestion in concentrated HCl–HNO3. In teeth, trace element uptake in enamel is 2–4 orders of magnitude slower than in dentine, forming an effective trace element barrier. Uptake in dentine parallel to the dentine–enamel interface is enhanced by at least 2 orders of magnitude compared to transverse, causing trace element “plumes” down the tooth core. In bone, U, Ba and Sr are nearly homogeneous, implying diffusivities ∼5 orders of magnitude faster than in enamel and virtually complete equilibration with host soils. In contrast all REE show strong depletions inward, with stepwise linear segments in log-normal or inverse complementary error function plots; these data require a multi-medium diffusion model, with about 2 orders of magnitude difference in slowest vs. fastest diffusivities. Differences in REE diffusivities in bone (slow) vs. dentine (fast) reflect different partition coefficients (Kd’s). Although acid leaches and bulk digestion of soils yield comparable fossil–soil Kd’s among different elements, natural solutions are expected to be neutral to slightly basic. Distilled H2O leachates instead reveal radically different Kd’s in bone for REE than for U–Sr–Ba, suggest orders of magnitude lower effective diffusivities for REE, and readily explain steep vs. flat profiles for REE vs. U–Sr–Ba, respectively. Differences among REE Kd’s and diffusivities may explain inward changes in Ce anomalies. Acid washes and bulk soil compositions yield misleading Kd’s for many trace elements, especially the REE, and H2O-leaches are preferred. Patterns of trace element distributions indicate diagenetic alteration at all scales, including enamel, and challenge the use of trace elements in paleodietary studies.

Changjiang Delta Sedimentation in Response to Catchment Discharge Changes: Progress and Problems

The influence of catchment changes on river deltas is an issue of global importance.As far as the Changjiang River is concerned,the fluvial sediment discharge has been decreasing since the early 1980s in response to catchment human activities,which results in significant sedimentological and geomorphological changes over the deltaic areas.In the present contribution,some research topics are proposed on the basis of a review of the progress made in recent years.In terms of geomorphology,bathymetric changes and coastal accretion/erosion patterns indicate that the sediment discharge is now below the critical quantity for the maintenance of the delta,i.e.,the delta has reached an eoroding stage.Analysis carried out in the present study demonstrates that the critical value on the basis of chart comparison and localized deposition rate measurements is actually underestimated.For the entire subaqueous delta,accurate calculations for the critical value will depend upon a sound understanding of the sediment retention of the deltaic system.Moreover,it would be appropriate to consider two critical discharges,one for the maintenance of the delta volume,and the other for the maintenance of the surface area of the delta on land.In sedimentology,sediment cores collected from the depocentre of the subaqueous delta show a trend of decrease in accretion rate over the last 30 years,representing the effect of catchment sediment discharge changes.In the future,analysis of the sediment samples from the entire sub-aqueous delta will be beneficial to an improved understanding of the deltaic response to the cathcment changes.At the same time,such a data set will be useful for the study of the sediment retention index and the material cycling patterns(e.g.carbon cycling) over the estuarine waters.Furthermore,in order to improve the interpretation of the deltaic sedimentary record,e.g.,to identify climate and environmental changes using the record,the various parameters derived from analyses of the cores should be standardized by evaluating the temporal changes caused by early diagenesis and decay,and by determining the rate of deltaic shoreline changes which control the relative position of the record within the deltaic sedimentary system.

Stable Carbon Isotopic Response of the Benthic Foraminifera from IODP 311 to the Marine Methane Hydrate Geo-system

A preliminary research of the benthic Foraminifera from Integrated Ocean Drilling Program(IODP) Expedition 311 has been carried out for the purpose of better understanding their stable carbon isotopic response to the marine gas hydrate geo-system.SEM photographs and stable oxygen isotopes of the species Uvigerina peregrina and Bulimina mexicana indicated that diagenesis and authigenic carbonate precipitation had little effect on Foraminifera.Uvigerina peregrina and Bulimina mexicana collected from the sediments in seepage Site U1328 and in adjacent non-seepage Site U1327 exhibited a distinct negative δ13C excursion with values of U.peregrina-0.67‰～-2.75‰ PDB,B.mexicana-0.51‰～-1.52‰ PDB in Site U1327 and U.peregrina-0.72‰～-2.71‰ PDB,B.mexicana-0.58‰～-1.45‰ PDB in Site U1328 respectively.The formation of distinct stable carbon isotopic excursions of benthic Foraminifera could be most likely interpreted by the involvement of both anaerobic oxidation of methane(AOM) and food sources in sediments.The distinct negative carbon isotopic excursion of benthic Foraminifera thus could be believed as one of indicators to recognize the marine gas hydrate geo-system.

MAASTRICHTIAN TO EOCENE CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY FROM THE TABIAGO SECTION, BRIANZA AREA, NORTHERN ITALY

Calcareous nannofossil biostratigraphic investigations have been carried out on samples collected from the Tabiago section, Brianza, northern Italy. This section records early Maastrichtian (CC23b nannofossil zone) to early Eocene (NP10 nannofossil zone) calcareous nannofossil assemblages. The Cretaceous-Tertiary transition is characterized by major changes in sedimentation rates and two likely stratigraphic gaps. The Cretaceous Brenno Formation was deposited with a high sedimentation rate (~20 m/m.y.), whilst the Tabiago Formation of Paleogene age records a drastic decrease (~10 m/m.y.). The absence of the CC26 zonal marker Micula prinsii may indicate a stratigraphic hiatus or an extremely condensed level in the latest Maastrichtian. However, only two samples have been collected and analyzed in this interval due to low exposure of the outcrop, and the absence of M. prinsii could be the result of diagenetic overprint or insufficient sampling. A stratigraphic hiatus or a very condensed interval corresponds to the upper part of NP1 nannofossil zone and PƒN foraminiferal Zone and P1a Subzone in the early Paleocene. The poor exposure of the outcrop prevents to precisely locate the zonal boundaries between NP4 and NP5 and between NP9 and NP10 and impedes the documentation of possible further stratigraphic gaps or condensed intervals.

Specific features in the composition, structure, and properties of volcaniclastic rocks

The paper discusses patterns in the formation of composition, structure, and properties (physical and physical-mechanical) of volcaniclastic rocks, which are rocks of specific origin occupying an intermediate position between magmatic and sedimentary rocks. A database of volcaniclastic rocks, which contains geological, petrographic, and petrophysical information, has been created and analyzed. It has been shown that volcaniclastic rocks are a group that is extremely variable in its composition and properties, with rock properties varying within a wide range. It has been found that the conditions of volcaniclastic rock formation and subsequent lithification are the principal geological factors that determine their properties. There are two different origins of the properties of these rocks: (1) a long-term process of loose pyroclastic sediment lithification and (2) immediate origination of solid rock because of the welding or baking of a sedimentary material. The following series of volcaniclastic rocks, organized by the degree of declining their physical and mechanical parameters, has been reconstructed: clastic lavas → lava clastic rocks → ignimbrites → tuffs → hyaloclastites → agglutinates.

INVESTIGATION OF DATOLITE (CaB[SiO4/(OH)]) FROM BASALTS IN THE NORTHERN APENNINES OPHIOLITES (ITALY): GENETIC IMPLICATIONS

Datolite, ideally CaB[(OH/SiO4)], from hydrothermal veins crosscutting pillow basalt in 10 different localities of the Northern Apennine ophiolites was investigated with regard to mineral chemistry and fluid inclusion microthermometry. Bulk analyses of datolite crystals show REE contents below chondritic, except for La and Ce. With respect to host rock, datolite is occasionally enriched in La, Rb, Cs, Be, and shows relatively high contents of chalcophile elements (Cu, Zn, Pb, Ni) when occurring in contact with sulfide- mineralized basalt. Volatiles escaped during the decomposition in the temperature range 600 and 700 C. The main component is water. The temperature maximum of water release is different and frequently with a shoulder or a second maximum. Together with water, sulfur species as H2S and SO2 and traces of boron species escaped. The CO2 release by the decomposition especially of datolite from Castellaro and Cinghi has a maximum in the range of 500–580 C and is different from the decomposition of calcite. Together with CO2 a boron species escaped. Chlorine does not detect. Two-phase (L+V) fluid inclusions texturally identifiable as primary and secondary were observed, yielding average homogenization-temperatures of 236 and 173 C, respectively. Fluid inclusion cooling data yield calculated salinity in the range of 10–16wt% NaCl equivalents, thus relatively higher compared with seawater. The results are compatible with those reported for fluids formed under diagenetic conditions, but differ from those observed in seafloor hydrothermal systems and/or emanating from magmas. Distribution of trace elements between datolite and host basalt indicates enrichment with respect to the host rock limited to a few elements such as La, Rb, Cs, Be, Ni, Cu, Zn and Pb. The lithophile elements can be hosted in the datolite lattice, whereas the chalcophile metals and Ni are probably carried in sub-microscopic inclusions.