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The 17.44 Ma Walgidee Hills lamproite in the West Kimberley province of Western Australia is the type locality for several K-, Ba- and Ti-rich minerals characteristic of lamproites and, at 490 ha, the largest known lamproite. The Walgidee Hills pipe comprises a thin sequence of tuffs and breccia formed by explosive eruptions that excavated a large shallow crater that was infilled by lamproite magma which cooled and crystallised in situ. The lamproite is zoned in grain size, mineralogy, and mineral and rock composition from porphyritic olivine lamproite at the margin through medium-grained lamproite comprised of olivine (altered), titanian phlogopite, diopside, leucite (altered) and titanian potassic richterite to coarse gained lamproite rich in potassic richterite, priderite, jeppeite, perovskite, apatite, wadeite and noonkanbahite at the centre of the body. Compositional zoning is evident across the lamproite in phlogopite (to lower Mg and Al, higher Fe), potassic richterite (to higher Fe and Na, lower Ti), priderite (to lower Cr) and perovskite (to lower Cr and Fe, higher Na, Sr, Y, Nb, U, REE). The Walgidee Hills lamproite is ultrapotassic and ranges from olivine lamproite (up to ~21 wt % MgO, ~800 μg/g Ni, ~4 wt % K2O) to sanidine/leucite-rich lamproite (~7 wt % MgO, ≤100 μg/g Ni, ~8 wt % K2O) at the centre of the pipe. The lamproite has low Al2O3, total Fe, Na2O and CaO (except for intensely carbonate-veined rocks at the centre) and is highly enriched in TiO2 (3–6.5 wt %), Ba, Rb, Sr, Zr and LREE (LaN = 150–520 x primitive mantle). A transect and geochemical contours show MgO, Ni and Cr contents decrease and P, K, Ti, Fe, Rb, Sr, Y, Zr, Nb, REE, Hf, Pb, Th and U abundances increase inwards to the most evolved rocks at the centre of the pipe, consistent with fractionation by inwards in situ crystallisation. The parent magma is estimated from the composition of the porphyritic olivine lamproite at the margins of the pipe to have ~16 ± 1 wt % MgO, ~600 μg/g Ni, ~6 wt % K2O with La/Yb ~ 150. Modelling suggests that the most MgO-rich lamproites result from entrainment of ~15–20 wt % mantle olivine in the parent magma. Cooling of the magma resulted in fractional crystallisation of olivine and in situ crystallisation with the evolved coarse-grained lamproites at the centre of the pipe crystallised from residual magma enriched in the more incompatible elements. Mantle xenocrysts include abundant Cr–Al spinel, chrome diopside, chrome pyrope, and rare diamond. Thermobarometry on the Cr diopside xenocrysts defines a cold paleogeotherm of ~38 mW/m2 and a thick lithosphere (~235 km) extending from the Kimberley craton. Many of the Cr diopsides from the deeper lithospheric mantle are enriched in K, Ba and LREE and these, and the Ti-rich spinel xenocrysts, are inferred to be derived from metasomatised mantle peridotite. The enriched trace element and Sr–Nd–Pb isotopic signatures of the Walgidee Hills lamproite suggest derivation from or extensive incorporation of ancient formerly depleted lithospheric mantle that has undergone metasomatism and long term (≥2 Ga) geochemical enrichment including by melts from Paleoproterozoic subducted crust. [ABSTRACT FROM AUTHOR]

The paper presents detailed petrographic research using optical microscopy on lamproite rocks around the village of Mrzen, North Macedonia. Detailed microscopic examinations of 5 specimens show that the rocks have typical porphyritic structures and in some places they also show sub-rounded textures with cavities filled with secondary calcite. Phenocrystals that have idiomorphic forms are represented by olivine, clinopyroxene, orthopyroxene, plagioclase, and magnetite. In some places there are changes - alterations in phenocrystals that are represented by iddingsite, smectite-chlorite-goethite), clay and/or zeolites, and calcite. Microscopic examination shows that they are lamproites. [ABSTRACT FROM AUTHOR]

Origin of abundant alkaline and related lamproite massifs and dykes in Aldan shield have no explanation and the geochemistry of rocks and their xenocrysts is used for the explanation. Bulk-rock geochemistry, mineral chemistry data of the Kayla lamproites of Russia and mineral chemical data (trace and rare elements) of the mantle xenocrysts found in these lamproites was studied using ICP MS and electron microprobe analyses (EPMA). The trace element spectrum of Kayla tuffs and breccias show the similarity with the olivine lamproites and belong to the orogenic type according to Th–U–Nb systematics. Primitive mantle normalized trace element (TRE) spider diagrams show right-leaning patterns with the peaks in large ion lithophile elements Sr, Pb, U, and troughs in Ta, Nb suggesting melting of original peridotites mixed with the ancient EMI (according to Nd, Sr isotopes) source probably belonging to eclogites or lower crust. The age of the emplacement is 132–134 Ma, similar to the Chompolo lamprophyres and many other alkaline Aldan complexes. Thermo-barometric estimation from Cr-diopsides and chromites xenocrysts suggest the origin from the spinel-garnet transition in the lithospheric mantle region. The P–T estimates derived from low-Cr-clinopyroxene xenocrysts, and related to lamproites show a high heat flow of 90 mW/m2 due to interaction with the plume-related magma. The Cr-diopsides and chromites give 45 mW/m2 geotherm similar to regional heat flow. The chondrite normalized rare earth element (REE) pattern for chrome-diopsides is steeper, compared to the low-chrome varieties. Primitive mantle normalized spidergram of Cr-diopsides displays peaks for Sr, U, and Th, and deep troughs of Nd, Nb, Ta. REE. The trace element spider diagrams of both types of xenocrysts show that they were equilibrated with the lamproitic melts and reconstructed parental melts of low-Cr-clinopyroxene coincides with the lamproite spectrums. [ABSTRACT FROM AUTHOR]

Kareevlei is the first diamond mine to be hosted in a K-richterite- and leucite-bearing Kaapvaal lamproite (formerly termed Group II kimberlite). To constrain the petrogenesis and lithospheric setting of the Kareevlei Kaapvaal lamproites, we present petrography, groundmass mineral compositions, bulk-rock major and trace element concentrations and Sr Nd isotopes for 13 coherent-textured samples, along with garnet indicator mineral compositions and Ni-in-garnet thermobarometry. Two distinct mineralogical varieties of Kaapvaal lamproites are identified: (1) phlogopite-diopside olivine lamproites and (2) leucite-richterite olivine lamproites. Phlogopite macrocryst and microcryst laths have two distinct core populations, interpreted as xenocrysts from phlogopite peridotites and MARIDs, whereas rims represent crystallisation from the magma. The leucite-richterite lamproites are characterised by higher bulk-rock SiO 2 , Al 2 O 3, and Na 2 O, and lower MgO contents compared to the phlogopite-diopside lamproites. The two mineralogical varieties have distinct incompatible trace element concentrations, with the leucite-richterite samples having lower concentrations of light REEs (LREE: La = 656–828; Ce = 518–597; Nd = 234–261 times chondrite) compared to the phlogopite-diopside samples (La = 1125–1391; Ce = 817–1029; Nd = 333–415 times chondrite). Additionally, these two groups exhibit clear separation in trace element ratios, with higher La/Sm and Gd/Yb in the phlogopite-diopside lamproites, which is interpreted to represent formation by lower degrees of partial melting relative to the leucite-richterite lamproites. However, both lamproite varieties have similar 87Sr/86Sr i and 143Nd/144Nd i ratios, suggesting derivation from an isotopically homogeneous source in the SCLM. The indicator mineral suite at Kareevlei comprises, in decreasing abundances, oxides (predominantly ilmenite and chromite), garnet, corundum, and rare clinopyroxene. Garnets are largely eclogitic (59%) with only smaller proportions of peridotitic G9 (19%) and G10 (8%) garnets observed. Peridotitic garnet thermobarometry indicates a paleogeotherm with an estimated surface heat flux of ∼44.3–44.9 mW/m−2 and an estimated lithospheric thickness of ∼187–195 km, which is within error of the nearby highly diamondiferous Finsch Kaapvaal lamproite (cf. 192 ± 6 km). Single mineral garnet thermobarometry suggests that most peridotitic garnets at Kareevlei were sampled by the lamproite at relatively shallow depths above the diamond stability field. The dominance of eclogitic garnet and the absence of peridotitic garnet that equilibrated within diamond stability suggests that the high-value diamonds extracted from Kareevlei are predominantly eclogitic in origin. • Petrology of richterite- and leucite-bearing Kareevlei diamondiferous lamproites • Mineralogical / bulk-rock geochemistry related to variable degrees of partial melting • Indicator minerals suggest LAB at ±188 km • High-value diamonds likely eclogitic in origin [ABSTRACT FROM AUTHOR]

Sierra Leone contains two Jurassic-aged diamondiferous kimberlite clusters, namely Koidu and Tongo-Tonguma (hereafter referred to as Tongo), consisting of eruptive pipes and NE-SW trending dikes. In this study, a combination of detailed petrography, and phlogopite, spinel, and olivine compositions in hypabyssal samples is presented to classify and constrain the petrogenesis of these kimberlites. Both the Koidu and Tongo rocks are predominantly macrocrystic and highly micaceous with phlogopite abundances, normalised to olivine-free, of 36–65 vol% in the groundmass. These phlogopite contents are comparable to those of some cratonic lamproites and significantly higher than any other kimberlites. Other groundmass minerals include spinel, perovskite, and apatite set in a base of carbonate and serpentine. Phlogopite and spinel have similar compositions in the Koidu and Tongo samples, displaying evolutionary trends consistent with those observed in worldwide kimberlites. Olivine macrocrysts and microcrysts display complex zoning with distinct cores, internal zones, and rims. The core compositions display a range in Mg# (81–95) and are interpreted to be derived from the disaggregation of lithospheric mantle xenoliths and proto-kimberlite related megacrysts. The Tongo olivine rims, interpreted to be primary magmatic crystallisation products, have similar compositions from various locations within the cluster whereas the Koidu samples display a range in rim compositions (Mg# 87–89) from different locations within the cluster. The average Koidu rim compositions display a strong positive correlation with the average core compositions, consistent with the trend formed by kimberlites worldwide and indicative of a strong control by melt-lithosphere interaction on melt compositions. Previously, it has been shown that the Mg# of olivine rim's negatively correlates with the abundance of groundmass phlogopite (± oxide minerals) in kimberlites. However, the Koidu and Tongo kimberlites are exceptionally phlogopite-rich given their olivine Mg#, fall outside of the worldwide kimberlite array and have olivine compositions and phlogopite abundances like some cratonic lamproites. This leads us to suggest that Koidu and Tongo represent a rare style of highly micaceous kimberlite magmatism, not previously reported in other cratonic regions, and are genetically linked to the assimilation of K 2 O-rich, metasomatic mantle lithologies. We further suggest that the K 2 O content, reflected by groundmass phlogopite abundances, of worldwide kimberlite and cratonic lamproite parent magmas ascending to the surface may be related to assimilation of craton-specific styles of metasomatic lithologies in the SCLM. • Unique highly micaceous kimberlites from Sierra Leone. • Olivine compositions constraining melt-SCLM interactions. • Craton-specific melt-SCLM assimilation and K2O enrichment. [ABSTRACT FROM AUTHOR]

This study reports a petrographic and crystal chemical analysis of three types of micas (yangzhumingite, light brown phlogopite and dark brown phlogopite) found in a lamproitic dyke at the Kvaløya Island (North Norway). The study was carried out integrating different analytical techniques: electron microprobe, single crystal X-ray diffraction, inductively coupled plasma mass spectrometry, Mössbauer and micro-Fourier Transform infrared spectroscopy. Kvaløya yangzhumingite (second occurrence in nature) was characterized for the first time in detail via single crystal X-ray diffraction. The different mica types are distinguishable on the basis of the VI Fe and Mg versus Si content. Yangzhumingite composition is intermediate between those of KMg 2.75 (Si 3.5 Al 0.5 )O 10 F 2 and KMg 2.50 Si 4 O 10 F 2 synthetic compounds reported in the literature. Light and possibly dark brown phlogopite is a Mg-rich fluorotetraferriphlogopite, the latter having a greater Fe content. The infrared spectra of yangzhumingite and the light brown phlogopite show the occurrence of OH − absorption bands respectively at: ~ 3586 cm − 1 which correlates well with the measured F content; 3707 cm − 1 and 3686 cm − 1 assigned mainly to 3Mg 2 + –K + –OH − (phlogopitic) environment. Structural analyses, performed only on yangzhumingite and light brown phlogopite show that both samples are 1 M polytypes with the expected space group C 2/ m . Crystal chemical details are compatible with the following major substitution mechanisms: 2 XII K + + VI [] ↔ 2 XII [] + VI R 2 + (where R 2 + = Mg, Fe), OH − ↔ F − for yangzhumingite and 2 VI R 2 + ↔ VI Ti 4 + + VI [] (Ti-vacancy), OH − ↔ F − for light brown phlogopite. All three types of micas formed at relatively constant low pressure, but over a large temperature range in equilibrium with a grain boundary fluid that underwent significant changes in composition during reaction progress. Light brown phlogopite cores and dark brown phlogopite rims formed during crystallization from the lamproitic magma, while yangzhumingite formed as a result of reactions between the already formed phlogopite and the highly reactive fluid that was derived from the volatile-rich lamproite magma. [ABSTRACT FROM AUTHOR]

The extensional Thrace basin (NW Anatolia) contains an association of early Miocene diopside--leucite--phlogopite (Doğanca) and diopside--phlogopite (Korucuköy) lamproites with Oligocene medium-K calc-alkaline andesites (Keşan volcanics), early Miocene shoshonitic rocks (Altınyazı trachyte) and middle Miocene Na-alkaline basalts (Beğendik basalts). The Doğanca lamproite (K2O = 5.1-5.5 wt.%; K/Na = 2.78-2.89; MgO = 11.4-11.8 wt.%) consists of olivine (Fo71-86), diopside (Al2O3 = 1.0--5.0, Na2O = 0.2-0.6), phlogopite (TiO2 = 1.1-9.4, Al2O3 = 11.1-13.9), spinel (Mg# = 22.9-32.6; Cr# = 6483.4), leucite, apatite, zircon, Fe--Ti-oxides and magnetite in a poikilitic sanidine matrix. The potassic volcanic units (lamproites and trachytes) in the region have similarly high Sr and low Nd isotopic compositions (87Sr/86Sr(i) = 0.70835-0.70873 and 143Nd/144Nd(i) = 0.51227-0.51232). The major and trace element compositions and Sr--Nd--Pb isotopic ratios of the shoshonitic, ultrapotassic and lamproitic units closely resemble those of other Mediterranean ultrapotassic lamproites (i.e., orogenic lamproites) from Italia, Serbia, Macedonia and western Anatolia. The Beğendik basalts show intraplate geochemical signatures with an Na-alkaline composition, an absence of Nb negative anomalies on primitive mantle-normalized multi-element diagrams, as well as low Sr (~ 0.70416) and high Nd (0.51293) isotopic ratios; and include olivine (Fo72-84), diopside, spinel, Fe--Ti-oxides and magnetite. The Oligocene Keşan volcanics were emplaced in the earlier stages of extension in Thrace, and represent the typical volcanic products of post-collisional volcanism. The continental crust-like trace element abundances and isotopic compositions of the most primitive early Miocene ultrapotassic rocks (Mg# up to 74) indicate that their mantle sources were intensely contaminated by the continental material. By considering the geodynamic evolution of the region, including oceanic subduction, crustal accretion, crustal subduction and post-collisional extension, it is suggested that the mantle sources of the potassic volcanic units were most likely metasomatized by direct subduction of continental blocks during accretion and assemblage of various Alpine tectono-stratigraphic units. Overall, the magma production occurred in an extensional tectonic setting that controlled the core-complex formation and related basin development, with the middle Miocene Beğendik basalts being derived from asthenospheric sources during the late stages of extension. [ABSTRACT FROM AUTHOR]

Abstract: Petrography, mineral chemistry, and major and trace element data are presented for the newly discovered Mesoproterozoic (1.33–1.43Ga) lamproites from the Ramadugu field (RLF), at the NW margin of the Paleo-Mesoproterozoic Cuddapah basin, in the Eastern Dharwar craton (EDC), southern India. RLF lamproites are emplaced as dykes, have a NW–SE trend and their petrography reveal the effects of low-temperature alteration. However, their textural features, mineralogy and geochemistry are closely similar to other well-characterised lamproites worldwide, including examples from the Eastern Dharwar craton, Leucite Hills, West Kimberley, Smoky Butte and Labrador. The RLF magmas have undergone varying degrees of olivine+clinopyroxene fractionation; yet their compatible and incompatible trace element concentrations are sufficiently high to signal a primitive character. Incompatible element ratios suggest limited contamination by continental crust. Geochemical evidence indicates the derivation of RLF magmas from metasomatised harzburgite within the garnet stability field. Rare earth element inversion modelling further highlights substantial involvement of the sub-continental lithospheric mantle in their genesis. The RLF lamproites are geochemically similar to the well-known extension-related ultrapotassic lavas from eastern Virunga and western Anatolia, and exclude an affinity with orogenic lamproites, such as those from the Mediterranean region. Bulk-rock geochemical models, recently developed to infer diamond potential, reveals that RLF lamproites are non-prospective. Lamproites of the RLF, together with those from the Krishna lamproite field and Cuddapah basin are interpreted as an expression of extensional events in the Eastern Dharwar craton possibly related to the break-up of the supercontinent of Columbia between 1.5 and 1.3Ga. [Copyright &y& Elsevier]

The volcano of Tallante (Pliocene) in the Betic Cordillera (Spain) exhumed a heterogeneous xenolith association, including ultramafic mantle rocks and diverse crustal lithologies. The latter include metagabbroids and felsic rocks characterized by quartz-rich parageneses containing spinel ± garnet ± sillimanite ± feldspars. Pressure–temperature estimates for felsic xenoliths overlap (at 0.7–0.8 GPa) those recorded by the mantle-derived peridotite xenoliths. Therefore, we propose that an intimate association of interlayered crust and mantle lithologies characterizes the crust–mantle boundary in this area. This scenario conforms to evidence provided by the neighbouring massifs of Ronda and Beni Bousera (and by other peri-Mediterranean deep crust/mantle sections) where exhumation of fossil crust–mantle boundary reveals that this boundary is not sharp. The results are discussed on the basis of recent geophysical and petrological studies emphasizing that in non-cratonic regions the crust–mantle boundary is often characterized by a gradational nature showing inter-fingering of heterogeneous lithologies. Silica-rich melts formed within the crustal domains intruded the surrounding mantle and induced metasomatism. The resulting hybrid crust–mantle domains thus provide suitable sources for exotic magma types such as the Mediterranean lamproites. [ABSTRACT FROM AUTHOR]

Abstract: New whole-rock geochemical, quantitative mineralogical and electron-microprobe data are presented from lamproite, olivine minettes and mafic trachyte of the Milk River area, southern Alberta, and latites, trachytes and high-K rhyolite of the Sweet Grass Hills, northern Montana. These rocks comprise dikes, small plugs and a pipe complex associated with mainly syenite and hornblende monzonite plutons that core several buttes in the Sweet Grass Hills and mark the northern extent of the Cenozoic Montana Alkaline Province. Minerals restricted to peralkaline lamproite at the 49th Parallel locality include Ti-rich phlogopite–annite with Fe3+ in tetrahedral coordination, Na-poor sanidine, Ba-rich and Cl-poor fluorapatite, K-rich titano-ferronyböite/ferro-obertiite, LREE-rich strontian fluorapatite (SrO=17.5–25.2wt.%, Ce2O3 =2.9–3.3wt.%), ilmenite, strontian barite, barian celestine, and unidentified Zr–Ti phase (TiO2 =76.7–88.0wt.%, ZrO2 =2.1–7.2wt.%) perhaps replacing primary Zr–Ti silicates. The strontian fluorapatite has the highest SrO content thus far reported in the literature for apatites from lamproites. Olivine minettes and mafic trachyte of the Milk River area contain augite, Al-diopside, Ti-rich magnetite, sanidine with higher Na, hyalophane, Cl-bearing fluorapatite with negligible Ba, ferroan magnesite phenocrysts, and primary calcite, all of which are notably absent in the 49th Parallel lamproite. Mica displays distinct core-to-rim zoning trends in these rocks, characterized by increasing FeOt and TiO2 at decreasing Al2O3 in lamproite and increasing FeOt and TiO2 at increasing Al2O3 in minettes and trachytes. The 49th Parallel lamproite has higher Ti, K, P, Ba, Rb, Sr, Nb, Th, U, Zr, Hf and REE concentrations, higher K/Al, (Ce/Yb)CN, (La/Sm)CN, (Gd/Yb)CN, Rb/Cs, Ce/Pb, Th/Ta, Th/Yb, and lower Ba/La, Ba/Th and Nb/U relative to minettes of the Milk River area. Major-element, least-squares mass balance and trace-element models call for the origin of latites, trachytes and high-K rhyolite in the Sweet Grass Hills complex by two-stage fractional crystallization of primitive olivine minette magmas concurrent with negligible, if any, assimilation of crustal materials. Oscillatory and reverse zoning in phenocrysts and hybrid phenocryst assemblages record recharge of more evolved magma chambers with primitive minette magmas. The calculated evolutionary models are inconsistent with the compositional variations displayed by the olivine minettes and lamproite of the Milk River area. These rocks represent distinct low-degree partial melts of sub-lithospheric mantle enriched in K and volatiles by the recent (<100Ma) plume activity or convective upwelling of the upper mantle above subducted Farallon slab, which underwent variable assimilation of the ancient, LREE-Ba–Sr enriched and HFSE depleted Wyoming–Medicine Hat lithosphere during the post-Laramide extension. The olivine minettes derived from more oxidized, carbonated region of the mantle source, compared to the more reduced source of the 49th Parallel lamproite. The extremely negative εNd values, unradiogenic Pb and moderately radiogenic Sr isotopic compositions, correlated with LREE, Ba enrichment and relative Nb, Ta, Ti and other HFSE depletions of the Cenozoic K-rich rocks of the MAP, may reflect carbonatite metasomatism of the lithospheric mantle associated with the widespread Mesoproterozoic (1.5–1.4Ga) anorogenic magmatism and intracontinental rifting related to mantle upwelling and plume activity beneath a thick Precambrian supercontinent. [Copyright &y& Elsevier]

Abstract: In the Italian peninsula leucite-free and -bearing ultrapotassic rocks occur intimately associated but well separated in time. Silica-saturated ultrapotassic and associated shoshonitic magmas erupted during the Pliocene to Lower Pleistocene. Silica under-saturated leucite-bearing ultrapotassic rocks, mainly leucitites, were emplaced sometime later, during the Middle–Upper Pleistocene. The transition from leucite-free to -bearing rocks is diachronous and in some cases is complicated by the occurrence of crustal-derived magmas coeval with early leucite-free magma. The Monte Cimino–Vico area is a key locality for studying the transition from leucite-free to -bearing ultrapotassic rocks. There a volcanic complex is overlain by some 500ka younger leucite-bearing rocks of Vico stratovolcano. Most of the potassic and ultrapotassic rocks of the Monte Cimino volcanic complex are characterised by high Mg-# (66.4–77.8), and compatible element abundances in spite of their high silica contents (52.9–58.0wt.%). Ultrapotassic leucite-free rocks transitional to lamproites are olivine-bearing orthopyroxene- and plagioclase-free latites and K-rich basaltic trachyandesite and they are confined in the final mafic activity of the Monte Cimino volcanic complex. Two-pyroxene parageneses are observed in the early Monte Cimino volcanic complex giving equilibration temperature as high as 1050°C and suggesting a sub-crustal derivation of their parental magmas. A two-pyroxene high-K calc-alkaline magma is then inferred for the genesis of the early Monte Cimino activity (e.g. dome complex and silicic lava flows and ignimbrites), which was modelled through crystal-fractionation from a high-K basaltic andesitic magma plus mixing with crustal anatectic rhyolitic magma. Final mafic lavas fill the isotopic and chemical gap between shoshonite-like and lamproite-like rocks, and each lava flow could be considered as a mantle-derived term from a heterogeneous sub-continental lithospheric mantle. Final mafic lavas are high-silica and -MgO ultrapotassic rocks due to crystallisation of primitive magmas generated by partial melting of a vein metasomatised network within a lithospheric upper mantle source, at low pressure and high PH2O. The shift to the younger Vico volcano, in which leucite-bearing magmas prevail, is thought to be due to the arrival in the mantle source of newly formed metasomatic agent from the undergoing slab characterised by the increasing of a sedimentary carbonate recycled component. This new component appears in the Middle Pleistocene and it is responsible for the composition of the magmatism of the Roman region. The recycling of carbonate-bearing pelitic sediments within the mantle wedge produces a carbonate-rich metasomatic agent. The latter is responsible for stabilisation of phlogopite-bearing wehrlitic veins within the mantle wedge. Partial melting of this newly formed vein network under high XCO2 generated silica under-saturated, and then leucite-bearing, ultrapotassic primary melts. A further shift is observed among the Vico post-caldera magmas, in which the appearance of a deep asthenospheric component is argued to be channelled late through slab-tears. [Copyright &y& Elsevier]

Abstract: Lamproites are among the most enigmatic mantle generated melts, and are typically abundant in phlogopite. We investigated the major and trace element chemistry of phlogopite crystals from Mediterranean lamproite occurrences in Spain, Serbia and Turkey. The most primitive lamproite samples were selected in order to evaluate the generation of the different phlogopite populations in their distinct mantle setting(s). Phlogopite hosted in Mediterranean lamproites can be grouped into different compositional arrays on the basis of their major element chemistry using Al2O3, FeOT and TiO2 concentrations. Contents of Cr, F and presumably Ti allow discrimination of the macrocrysts into phlogopite phenocrysts, which are liquidus and near-liquidus phases, and mantle xenocrysts. Further distinction among different populations of mantle-derived phlogopite can be achieved, considering trace element and isotopic ratios. The latter also distinguish between crustal and asthenospheric imprints on the source of the lamproitic parental melt. [Copyright &y& Elsevier]

Occurrence of two lamproitic dykes intruding the basement granite near Khadka village at the northern margin of the Indravati Basin, Bastar craton is reported. Combined field, microscopy, XRD, EPMA and whole-rock geochemical investigations reveal that these lamproites were subjected to high degree of hydrothermal alteration as well as possible metamorphism. However, relicts of their original textures are well-preserved thereby providing important clues as to the nature of the protolith. Quartz, carbonate, chlorite and phlogopite constitute the bulk mineralogy whereas spinel, apatite and iron oxides are the accessory phases. Chemical composition of the groundmass spinels are strikingly similar to those from the lamproites. The Khadka lamproite dykes display high abundances of compatible elements such as Ni (238-396 ppm), Cr (484-892 ppm), and V (160-200 ppm) as well as high-field strength elements such as Zr (719-2057 ppm) and Nb (92-126 ppm) that resemble those in lamproites. Khadka lamproites also have high whole-rock REE abundances (ΣREE up to 1260 ppm) and display fractionated chondrite-normalized REE patterns (La/Yb= 113-237) which together with their average compatible and incompatible trace elemental ratios (e.g. Nb/Zr, Nb/La, Ba/Rb) are strikingly similar to those of the Mesoproterozoic Krishna lamproites of the Eastern Dharwar craton. Available field evidences suggest the Khadka lamproites to be of at least Palaeoproterzoic age (1.88 Ga) which makes them some of the oldest such rocks as yet documented from the Indian shield. [ABSTRACT FROM AUTHOR]

Abstract: Petrology and geochemistry of eleven Mesoproterozoic lamproites from the Krishna valley, Eastern Dharwar craton, are presented. The Krishna lamproites show wide variation in their petrography and modal mineralogy and constitute excellent examples of rare phenomenon of heteromorphism. Ti-phlogopite, clinopyroxene, richterite, Fe-rich sanidine, sphene, F-rich apatite, ilmenite, and rutile are the major minerals present in varying proportions. Their mineral compositions overlap with those present in world-wide Phanerozoic lamproites and casts doubt on recent suggestions regarding the absence of archetypal lamproites and kimberlites from the Indian cratons. Incompatible trace element ratios (i) rule out the Krishna lamproites to be products of direct plume- (asthenospheric) derived mantle as well as subduction-related components and (ii) demonstrate their derivation from sources similar to those of the co-spatial Cuddapah basin lamproites and Wajrakarur- and Narayanpet-kimberlites from the Eastern Dharwar craton. The source enrichment of the Krishna lamproites is related to the period of global-scale mantle upwelling at ∼1.9Ga that included the emplacement of Large igneous provinces of similar age and magmatism in the Dharwar and Bastar cratons (India), the Superior Craton (Canada) and the Kaapvaal craton (southern Africa). We find that the observed petrological and geochemical characteristics of the Krishna lamproites can be best explained by the vein-plus-wall-rock model involving phlogopite+amphibole+rutile+clinopyroxene+apatite+titanite occuring as metasomatic veins in a depleted lithospheric mantle, within the garnet stability field. Our study illustrates the significant role of the lithospheric thickness and its attendant metasomatism in influencing petrogenesis of the co-spatial Mesoproterozoic lamproites and kimberlites from the Eastern Dharwar craton. [Copyright &y& Elsevier]

Abstract: This paper studies the petrology of K-alkaline lamproite-carbonatite complexes, which are widespread in Siberia. They are exemplified by the Murun and Bilibino massifs in West and Central Aldan. In these massifs, the entire range of differentiates was first found, from K-ultrabasic-alkalic rocks through basic and intermediate ones to alkali granites and unique residual calc-silicate rocks (benstonite Ba-Sr carbonatites and charoite rocks). Also, intrusive equivalents of lamproites occur in these massifs, and the Murun massif was probably formed from highly differentiated lamproite magmas. In many K-alkaline complexes, silicate and silicate-carbonate magma layering takes place. Stages of magmatism are described for both massifs. Binary and ternary petrochemical diagrams exhibit the same compositional trend from early to late rocks. In this paper, lamproites are considered from the chemical point of view; their diagnostic properties are described in terms of chemical and mineral composition. From geological, petrological, and geochemical data, formational analysis of alkaline complexes was performed, four formational types of world lamproites were first identified, and diamond content criteria were developed for them. The carbonatite problem was studied from the petrological point of view, and four formational types of carbonatites were identified using geological, geochemical, and genetic criteria. It has been suggested that for dividing carbonatite complexes into four formational types the following criteria be used: the alkalinity type (Na or K) of alkalic rocks in the complex and the time when the carbonatite liquid separates from silicate melts in different stages of primary magma differentiation. These linked parameters influence the ore content type of carbonatite complexes. A formation model for K-alkaline carbonatite complexes is given, and the Tomtor alkaline carbonatite massif with tuffaceous rare-metal ores is described to prove that they have ore reserves. The geochemistry of C, O, Sr, and Nd isotopes shows that K-alkaline complexes, depending on their geotectonic setting, can originate from three types of mantle sources: depleted mantle, enriched mantle 1 (EM1), and enriched mantle 2 (EM2). It is concluded that ore-bearing ultrabasic-alkaline complexes of lamproites and carbonatites can melt out of different types of mantle, whose composition only slightly influences their ore content. Apparently, the main factors are the low degree of selective mantle melting (less than 1%) and plumes supplying fluid and alkaline components, which stimulate this melting. Later on, the processes important for the accumulation of ore and trace elements are long-term magma differentiation and its layering during crystallization. [Copyright &y& Elsevier]

Abstract: An integrated study of the petrology and Re–Os geochemistry of a suite of peridotite xenoliths, some carrying abundant diamonds, from the richly diamondiferous Argyle AK1 lamproite pipe provides definitive evidence for a depleted lithospheric root of Neoarchean age (TRD eruption ∼2.2–3.1Ga) beneath the Proterozoic Halls Creek Orogen at the margin of the Kimberley Craton, Western Australia. The microdiamonds from the peridotitic xenoliths are similar in their properties to the minor population of small, commercial sized, peridotitic diamonds from Argyle, both formed in the Archean from isotopically mantle-like carbon. The major element bulk chemistry and mineral chemistry of the Argyle peridotites are slightly less depleted than Archean cratonic peridotites as a whole but similar to those reported from Neoarchean–Paleoproterozoic cratonic provinces. The Argyle peridotite xenoliths were derived from within the diamond stability field (1050–1300°C and 4.9–5.9GPa) near the base of the lithosphere (typically 160–200km depth) with a geothermal gradient of 41.5mW/m2. This thick diamondiferous lithosphere, estimated at up to 225km thick from present day seismic S-wave tomography, appears to have persisted since the time of eruption of the Argyle lamproite (∼1180Ma). The existence of late Archean age lithosphere beneath the Argyle diamond pipe, in a region where no crustal rocks of Archean age are known, suggests a decoupling of the crust and mantle in the region of the Halls Creek Orogen, perhaps as a consequence of Paleoproterozoic (∼1.85Ga) reworking and/or subduction at the margin of the Kimberley Craton. The confirmation of an Archean lithospheric root beneath the Argyle pipe at the margin of the Kimberley Craton seemingly conforms with “Clifford''s Rule”, regarding the restriction of economic diamond deposits to those underlain by Archean cratons. However, Argyle owes its rich diamond grades not to its Neoarchean mantle roots but to the presence of richly diamondiferous eclogitic material accreted to the craton root during the Proterozoic. [Copyright &y& Elsevier]

Kaapvaal lamproites, also known as orangeites, are H 2 O-rich, diamondiferous, highly micaceous, ultrapotassic rocks. Olivines in kimberlites have been shown to be extremely useful in tracking melt evolution, highlighting the importance of the chemical effects of SCLM assimilation on asthenosphere-derived melts. Kaapvaal lamproites are derived from melting metasomatised SCLM and may be expected to form an endmember to the asthenosphere melt-SCLM trend defined by kimberlites. In this contribution, we use olivine composition in Kaapvaal lamproites to further understand melt evolution in the SCLM and assess the similarity between Kaapvaal lamproite, other diamondiferous lamproites, and kimberlite petrogenesis in cratonic regions. We present olivine composition for representative on- and off-craton Kaapvaal lamproites from Finsch and Melton Wold, respectively. Olivines from these Kaapvaal lamproites are characterized by distinct core and rim zones, regardless of the size of individual grains. Polycrystalline grains are abundant at Finsch but relatively rare at Melton Wold. The olivine cores from both occurrences are predominantly Mg-rich (Fo >89) whereas Fe-rich cores (Fo <89) are rare. Mg-rich cores are interpreted to be derived from the disaggregation of mantle peridotites, including sheared peridotites, whereas Fe-rich cores are derived from olivines of the Cr-poor megacryst suite. The average Fo and NiO concentrations of the Melton Wold cores are lower than Finsch cores, likely related to less refractory off-craton mantle. The olivine rims at Finsch and Melton Wold are characterized by reverse zoning with ranges of Fo 89-92 and Fo 90-91 , respectively. The rims are interpreted to represent crystallisation related to a complex interplay between increasing oxidation, assimilation of orthopyroxene, and increasing alkali content of the melt during evolution. The average core and rim compositions of Finsch and Melton Wold, in conjunction with data from diamondiferous lamproites of other cratonic regions, define a broad positive correlation. Kaapvaal lamproites have Mg-rich core and rim compositions, similar to that of Lac de Gras kimberlites, and interpreted to reflect sampling and equilibration of low volume Kaapvaal lamproite melt with refractory mantle. In contrast to Lac de Gras kimberlites, Kaapvaal lamproites have high abundances of groundmass phlogopite that reflect metasomatic material in the SCLM source, likely present as veins within refractory peridotite. This suggests that increasing proportions of melt-metasomatised SCLM interactions are not always linked with increasing Fe content of melts. We show that the petrogenesis of Kaapvaal lamproites is similar to that of kimberlites and lamproites from other cratonic regions, however, the high abundance of phlogopite and Fo-rich olivine rims suggest a distinct metasomatic lithology in the source and that olivine composition ; i.e., a proxy for melt composition, may be strongly controlled by melt volume during melt-SCLM interactions. • Orangeites have olivine zoning similar to kimberlites. • In contrast to Kimberley kimberlites, olivine rims are Mg-rich. • In contrast to Kimberley kimberlites, Fe-rich cores are rare. • Olivine average core-rim compositions in addition to high phlogopite groundmass abundance suggests refractory yet metasomatised source. • Olivine in orangeites suggests similar petrogenesis to diamondiferous lamproites and kimberlites worldwide. [ABSTRACT FROM AUTHOR]

Abstract: In the Mediterranean area, lamproitic provinces in Spain, Italy, Serbia and Macedonia have uniform geological, geochemical and petrographic characteristics. Mediterranean lamproites are SiO2-rich lamproites, characterized by relatively low CaO, Al2O3 and Na2O, and high K2O/Al2O3 and Mg-number. They are enriched in LILE relative to HFSE and in Pb, and show depletion in Ti, Nb and Ta. Mediterranean lamproites show huge regional variation of Sr, Nd and 207Pb/204Pb isotopic values, with 87Sr/86Sr range of 0.707–0.722, εNd range from −13 to −3, and 207Pb/204Pb range of 15.62–15.79. Lamproitic rocks are derived from melts with three components involved in their origin, characterized by contrasting geochemical features which appear in 206Pb/204Pb, 87Sr/86Sr and 143Nd/144Nd space: (i) a mantle source contaminated by crustal material, giving rise to crust-like trace element patterns and radiogenic isotope systematics, (ii) an extremely depleted mantle characterized by very low whole-rock CaO and Al2O3, high-Fo olivine and Cr-rich spinel, which isotopically resembles European peridotitic massifs and lithospheric mantle; (iii) a component originating from the convecting mantle, characterized by unradiogenic 87Sr/86Sr and radiogenic 143Nd/144Nd and 206Pb/204Pb. These components demand multistage preconditioning of the lamproite-mantle source, involving an episode of extreme depletion, followed by involvement of terrigenous sediments, and finally interaction with melts originating from the convecting mantle, some of which are probably carbonatitic. We use our data on Mediterranean lamproites to characterize the mantle composition under the whole Alpine-Himalaya belt. Lamproites are an integral part of postcollisional volcanism, and are the most extreme melting products from a mantle which is ubiquitously crustally metasomatized. Enriched isotope signatures in Himalayan volcanics can also be explained by the involvement of subducted sediments instead of by proterozoic mantle lithosphere. [Copyright &y& Elsevier]

A phase of Mesozoic extension associated with the termination of continental collision at the southern margin of the Aldan Shield produced ultrabasic lamproites in a discontinuous belt 500 km long and ∼150 km wide. The lamproites, locally poorly diamondiferous, were emplaced as dykes, sills and pipes. All Aldan lamproites have primitive chemical characteristics (e.g. MgO up to 22·7 wt %) and are ultrapotassic (K2O up to 8·3 wt %) and peralkaline with K2O + Na2O/Al2O3 in the range 0·6–1·16. A distinctive feature of these rocks is their low TiO2 content (0·5–1·4 wt %). Aldan lamproites are moderately light rare earth element (LREE) enriched with (La/Yb)N ranging from 10 to 47. Heavy rare earth element (HREE) abundances are lower than for all other lamproites by up to a factor of five. Therefore, the combined major and trace element characteristics of the Aldan samples are not typical of other lamproite occurrences. Large ion lithophile element concentrations are high (100–800 × Primitive Mantle) but the high field strength elements (HFSE; Nb, Ta, Ti) plus Th and U display unusually low concentrations for rocks of this type. The style of trace element enrichment recorded by the Aldan Shield lamproites is comparable with that of subduction-related magmatism. The Aldan lamproites have among the most extreme initial isotopic ratios yet recorded from mantle-derived magmas; ɛNdi = −10·3 to −22·3, 87Sr/86Sri = 0·7055–0·7079, ɛHfi = −7·6 to −29·4 and 206Pb/204Pbi = 16·6–17·4. When interpreted in terms of multi-stage Pb isotope evolution, the Pb isotope data require fractionation from a Bulk Earth reservoir at 3·0 Ga and subsequent evolution with second-stage μ values between 6·4 and 8·0. The inferred Archaean age of the lamproite source is consistent with Nd and Hf model ages, which range from 1·5 to 3·0 Ga. Aldan lamproites have ΔɛHf values that range from +3 to −7. Trace element and Sr–Nd–Pb–Hf isotopic ratios show coherent variations that suggest that Archaean source enrichment produced the negative ΔɛHf as a result of metasomatism by slab-derived hydrous melts that left rutile–garnet-bearing residua. We conclude that relatively large degrees of partial melting produced the lamproites (>5%), which explains the preservation of the isotope–trace element correlations and the low REE contents. Although high-quality trace element data (e.g. HFSE) are not available for most lamproites, it appears that many of their source regions contain a component of recycled oceanic crust, possibly including subducted sediment. The sources of the Aldan and many other lamproites are distinct from ocean island basalt mantle sources. This suggests that the long-term storage of trace element enriched lamproite sources occurred in the sub-continental lithospheric mantle and not at depth within the convecting asthenosphere. [ABSTRACT FROM AUTHOR]

The Serbian province of Tertiary ultrapotassic volcanism is related to a post-collisional tectonic regime that followed the closure of the Tethyan Vardar Ocean by Late Cretaceous subduction beneath the southern European continental margin. Rocks of this province form two ultrapotassic groups; one with affinities to lamproites, which is concentrated mostly in the central parts of the Vardar ophiolitic suture zone, and the other with affinities to kamafugites, which crops out in volcanoes restricted to the western part of Serbia. The lamproitic group is characterized by a wide range of 87Sr/86Sri (0·70735–0·71299) and 143Nd/144Ndi (0·51251–0·51216), whereas the kamafugitic group is isotopically more homogeneous with a limited range of 87Sr/86Sri (0·70599–0·70674) and 143Nd/144Ndi (0·51263–0·51256). The Pb isotope compositions of both groups are very similar (206Pb/204Pb 18·58–18·83, 207Pb/204Pb 15·62–15·70 and 208Pb/204Pb 38·74–38·99), falling within the pelagic sediment field and resembling Mesozoic flysch sediments from the Vardar suture zone. The Sr and Nd isotopic signatures of the primitive lamproitic rocks correlate with rare earth element fractionation and enrichment of most high field strength elements (HFSE), and can be explained by melting of a heterogeneous mantle source consisting of metasomatic veins with phlogopite, clinopyroxene and F-apatite that are out of isotopic equilibrium with the peridotite wall-rock. Decompression melting, with varying contributions from depleted peridotite and ultramafic veins to the final melt, accounts for consistent HFSE enrichment and isotopic variations in the lamproitic group. Conversely, the most primitive kamafugitic rocks show relatively uniform Sr and Nd isotopic compositions and trace element patterns, and small but regular variations of HFSE, indicating variable degrees of partial melting of a relatively homogeneously metasomatized mantle source. Geochemical modelling supports a role for phlogopite, apatite and Ti-oxide in the source of the kamafugitic rocks. The presence of two contrasting ultrapotassic suites in a restricted geographical area is attributable to the complex geodynamic situation involving recent collision of a number of microcontinents with contrasting histories and metasomatic imprints in their mantle lithosphere. The geochemistry of the Serbian ultrapotassic rocks suggests that the enrichment events that modified the source of both lamproitic and kamafugitic groups were related to Mesozoic subduction events. The postcollisional environment of the northern Balkan region with many extensional episodes is consistent at regional and local levels with the occurrence of ultrapotassic rocks, providing a straightforward relationship between geodynamics and volcanism. [ABSTRACT FROM AUTHOR]

In the East European Alpine belt, leucite-sanidine-phlogopite-olivine-bearing volcanic rocks of Late Cenozoic age occur at eight localities within the Vardar suture zone and at one locality in the Southern Carpathian fold-and-thrust belt. Most of these volcanics are characterized by high Mg# (66.6–78.6), high abundances of Ni (117–373 ppm) and Cr (144–445 ppm) as well as high primary K2O contents (5.63–7.01 %) and K2O/Na2O values (1.93–4.91). Rocks with more differentiated compositions are rare. A lamproite affinity of these rocks is apparent from their relatively low contents of Al2O3 (9.9–14.3 wt%) and CaO (6.2–8.3 wt%) in combination with high abundances of Rb (85–967 ppm), Ba (1,027–4,189 ppm), Th (18.9–76.5 ppm), Pb (19–54 ppm), Sr (774–1,712 ppm) and F (0.16–0.52 wt%), and the general lack of plagioclase. Although eruption of the magmas took place in post-collisional extensional settings, significant depletions of Nb and Ta relative to Th and La, low TiO2 contents (0.92–2.17 %), low ratios of Rb/Cs, K/Rb and Ce/Pb as well as high ratios of Ba/La and Ba/Th suggest close genetic relationships to subduction zone processes. Whereas Sr and Nd isotope ratios show relatively large variations (87Sr/86Sr = 0.7078–0.7105, 143Nd/144Nd = 0.51242–0.51215), Pb isotope ratios display a very restricted range with 206Pb/204Pb = 18.68–18.88 and variable but generally high Δ7/4 (11–18) and Δ8/4 (65–95) values. The observed petrographic, geochemical and isotopic characteristics are best explained by a genetic model involving preferential melting of phlogopite-rich veins in an originally depleted lithospheric mantle source, whereby the metasomatic enrichment of the mantle source is tentatively related to the addition of components from subducted sediments during consumption of Tethyan oceanic lithosphere. [ABSTRACT FROM AUTHOR]

Kokchetav ‘lamproite’ occurs in the east end of Kokchetav massif and consists of phenocryst (mainly clinopyroxene) and matrix (mainly feldspar). The compositions of clinopyroxene, magnetite and biotite phenocryst were determined using wavelength dispersive spectrometry on a JEOL Super-probe 8900 electron microprobe for the purpose of revealing the process of magma evolution. Analyses revealed a core–rim variation, which is consistent with three stages of magmatic evolution: Mg-rich clinopyroxene cores (diopside) and biotite cores (phlogopite) crystallized in a deep magma chamber (stage I); Fe-rich clinopyroxene rim (salite) and biotite rim crystallized at low pressure in a shallow magma chamber (stage II); Magnetite phenocryst core also crystallized in a shallow magma chamber, and co-exists with Fe-rich clinopyroxene rim and biotite rim. The magnetite rims probably formed during magma eruption at the same time when groundmass crystallized (stage III). The calculated temperatures for ilmenite–magnetite pair range from 679 to 887°C, log fO2 values range from −11.1 to −14.9 log units. These values represent the latest conditions of magma as ilmenite exsolution in magnetite probably occurred during magma eruption from the shallow chamber to surface. [Copyright &y& Elsevier]

Diamondiferous rock types worldwide are broadly divided into kimberlite and lamproite, the latter of which have unique characteristics in different regions and include carbonate-rich varieties (formerly orangeites/Group II kimberlites). Diamondiferous rocks in West Africa are typically micaceous and share petrographic, mineralogical, and geochemical characteristics with both kimberlites and lamproites. To further constrain the classification and petrogenesis of diamondiferous rocks worldwide and their variability between different cratonic regions, in this study we combine detailed petrographic observations with olivine, phlogopite, and spinel chemistry for hypabyssal samples from the Jurassic Tongo dike (Sierra Leone) and the Neoproterozoic Weasua cluster (Liberia). The Tongo dike contains macrocrysts of olivine and phlogopite in a groundmass of olivine, abundant phlogopite, spinel, perovskite, and apatite with a base of calcite, dolomite, and lesser serpentine. The phlogopite is characterised by concurrent FeO and Al 2 O 3 enrichment, which is typical of kimberlites and unlike lamproites. These features and the kimberlite-like spinel compositions allow us to classify the Tongo samples as micaceous kimberlites. The Weasua rocks comprise macrocrysts of olivine in a groundmass of olivine, phlogopite, diopside (zoned towards aegirine-rich rims), spinel, perovskite, and apatite with a base of serpentine and less common calcite. The composition of Weasua phlogopite trends to significant FeO enrichment and Al 2 O 3 depletion, i.e. towards tetraferriphlogopite. The enrichment in mica, phlogopite chemistry and presence of magmatic diopside indicates that these rocks are olivine lamproites. The populations of olivine macrocrysts and microcrysts at Tongo and Weasua are similar and characterised by distinct core and rim zones. Two distinct olivine core populations are observed. 1) forsterite-rich (Fo > 90) olivine interpreted to reflect xenocrysts from typical mantle peridotites. Al-in-olivine thermometry suggests that these cores have P-T equilibration within diamond stability at Weasua and Tongo. 2) Al-, Ca- and Na- rich cores with P-T formation conditions extending beyond the mantle adiabat. These cores are interpreted to reflect metasomatic and thermal perturbation linked with the infiltration of kimberlite/lamproite melts in the deep lithosphere shortly before entrainment in the ascending magma. The olivine rims at Tongo and Weasua show limited variations in Fo contents at similar values of 88.9 ± 0.8 for Tongo and 89.6 ± 1.2 for Weasua, as well as similar minor and trace element concentrations. Thus, whereas the Tongo and Weasua rock types are classified as kimberlite and olivine lamproite, respectively, the olivine chemistry suggests a similar petrogenetic evolution. • Here we classify unusual transitional kimberlite-lamproites from West Africa. • Tongo rocks are micaceous transitional kimberlites. • Weasua rocks are diopside-bearing olivine lamproites. • West African diamondiferous rocks defy clear classification. • Olivine chemistry indicates similar petrogenesis both localities. [ABSTRACT FROM AUTHOR]

The article presents a research conducted to explore the occurrence of Lamproite and other related rocks in Yangtze Craton in China. It states that researcher G.L. Liu and colleagues have given the details of petrology and mineralogy of Lamproite rocks found in Dahongshan area in China and mentions the efforts done by Geological Bureau of Guangxi in locating and collecting diamonds from Quaternary sedimentary rocks found in Yangtze.