Cognate Mafic Enclaves Formed by Cumulated Mush Convection in a Granitic Magma Chamber:Evidence from Mineral Chemistry of the Triassic Zhashui Pluton,Qinling Orogen

Mafic enclaves in granites are generally considered to represent coeval mafic melts that derived from metasomatized mantle,which can provide valuable information about crust-mantle interaction.Exploring the genetic links between the mafic enclaves and their host monzogranite from the Triassic Zhashui Pluton,Qinling orogenic belt.The enclaves(220±4.6 Ma)and the monzogranite(220±2.8 Ma)display identical zircon U-Pb ages,and they also share similar trace element and zircon Lu-Hf isotopes,indicating a cognate source.The monzogranite displays zirconεHf(t)values of−0.99 to+1.98,while the mafic enclaves show similar values of−0.45 to+3.26;however,differences in mineral chemistry reveal different crystallization conditions.The amphibole from the mafic enclaves has higher temperature and pressure(757℃;2.65 kbar)compared to those of the host monzogranite(733℃;1.96 kbar),suggesting that mafic minerals in the enclaves crystallized at an early stage.Moreover,apatite in the mafic enclaves displays slightly higher volatile contents(0.72 wt%)than those of the monzogranite(0.66 wt%),indicating a volatile-rich condition.These results suggest that the mafic enclaves represent early hydrous mafic cumulates in the granitic chamber,and subsequent magma convection would have led to the formation of the mafic enclaves.

Magma Mixing Genesis of the Mafic Enclaves and Related Granitoids in the Kan Granite-Gneiss Complex of Central Côte d’Ivoire: Evidence from Geology, Petrology and Geochemistry

The mafic enclaves from Paleoproterozoic domain are considered to be the results of large-scale crust-mantle interaction and magma mixing. In this paper, petrography, mineralogy and geochemistry were jointly used to determine the origin of the mafic enclaves and their relationship with the host granitoids of the Kan granite-gneiss complex. This study also provides new information on crust-mantle interactions. The mafic enclaves of the Kan vary in shape and size and have intermediate chemical compositions. The diagrams used show a number of similarities in the major elements (and often in the trace elements) between the mafic enclaves and the host granitoids. Geochemical show that the Kan rock are metaluminous, enriched in silica, medium to high-K calc-alkaline I-type granite. The similarities reflect a mixing of basic and acid magma. Mafic enclaves have a typical magmatic structure, which is characterized by magma mixing. The genesis of these rocks is associated with the context of subduction. They result from the mixing of a mafic magma originating from the mantle and linked to subduction, and a granitic magma (type I granite) that arises from the partial melting of the crust.

Origin of Felsic Microgranitoid Enclaves in Granite in Zhangjiakou District,China:Implication for Process and Lifespan of Granitic Magma Chambers

Sparse felsic microgranitoid enclaves(FMEs)in the Shangshuiquan granite of the Zhangjiakou district,the north margin of the North China Craton,are fine-grained,dark-colored and exhibit subangular to subspherical shapes.They share similar mineral assemblages,chemical compositions,and zircon Hf isotope compositions to the host granite.New zircon U-Pb geochronology reveals that the FMEs crystallized at 156-153 Ma,while the Shangshuiquan granite formed at ca.146 Ma.The FEMs are,therefore,10 to 7 Ma older than the host granite.Combined with petrological evidence,we suggest that the FMEs are fragments of rapidly crystalized magmas,which were captured by the younger Shangshuiquan magma.Magmas of the FMEs and Shangshuiquan granite originated from the same reservoir.The Shangshuiquan granite is the result of small batches of magma being built up incrementally,and the FMEs belong to the earlier batches of magma.The lifespan of the Shangshuiquan magma reservoir exceeds 10 Ma.FMEs derived from cogenetic fragments have the potential to offer critical information about the formation process and timescale of granitic plutons.

Types of Enclaves and Their Features and Origins in Intermediate-Acid Intrusive Rocks from the Tongling District, Anhui Province, China

Abstract: Enclaves in intermediate-acid plutons from Tongling can be divided into three types: xenoliths, relics and magmatogenic enclaves. The magmatogenic enclaves consist of cumulates, micrograined dioritite mixtite and dioritic chilled border enclaves. Petrologically, relics with eyed and meta-poikilitic texture are characterized by high content of biotite (>80%) and low content of cordierite and grossular. The cumulates with accumulate texture consist of a great amount of pyroxene, hornblende and minor spinel and phlogopite. The micrograined dioritic mixtite is composed of more hornblendes and feldspar and less needle apatites and an ellipsoid basic core included in plagioclase. The chilled border enclaves have the same mineral association, but more dark minerals than the host rocks consisting of plagioclase, quartz, alkaline feldspar, hornblende and biotite. Geochemically, the relics exhibit high REE content (455.8×10?6) and high ratio of LREE/HREE, more obvious Eu negative anomaly and are rich in Cr and Ni, poor in Ba, Nb and Sr. All kinds of magmatogenic enclaves have the same REE pattern without Eu anomaly, and the total REE is 74.9×10?6 for spinel pyroxene cumulate, 179.7×10?6 for hornblende cumulate, 226.9 × 10?6 for hornblende cumulate crystal, 289.9×10?6 for micrograined dioritic mixtite and 131.2×10?6 for chilled border enclaves. Calculation with the thermometer and barometer for minerals shows that the temperature and pressure of formation are 1126 °C and 8.44 kbar (7.15–9.04 kbar) for the spinel pyroxene cumulate, 1065 °C-1029 °C and 8.23 kbar (7.13–9.50 kbar) for the hornblende pyroxene cumulate, 959 °C and 3.40 kbar (2.86–4.09 kbar) for the micrograined dioritic mixtite enclaves, and 951 °C and 0.59 kbar for the dioritic chilled border enclaves, respectively. Thus, the following conclusions can be drawn. Relic enclaves were derived from the crustal partial melting and all cumulate enclaves originated from deep magma chambers near the Moho in the lower crust, which are cumulate fragments formed by fractional crystallization of basic magma; mixtite came from shallow magma chambers in the middle-upper crust, formed by the mixture of mantle-derived magma and acid magma derived from the crustal partial melting; and the chilled border enclaves came from the border fragments of early intrusive bodies.

Geochronology of the Gabbro-mafic Microgranular Enclaves-granite Associations in the Gejiu District, Yunnan Province and Their Geodynamic Significance

Many igneous rocks distribute in Gejiu tin polymetallic ore-field at Yunnan province, rocks including basalt, gabbro, mafic microgranular enclaves, granites （porphyritic granite and equigranular granite） and akaline rocks. The ages of the granites and akaline rocks which are considered to have genetic connecting with the mineralization have been comfirmed, but the gabbro- mafic microgranular enclaves-granite assemblage＇s ages are still unknown. By means of LA-ICP-MS zircon U-Pb dating, the data of Shenxianshui equigranular granite, the mafic microgranular enclave in Jiasha area, the host rock of the mafic microgranular enclaves and the Jiasha gabbro are around ~80 Ma. Besides the above mentioned data, a group of new ages at ~30 Ma were discovered in this study, which is from gabbro and mafic microgranular enclaves. Based on the previous data and the new data gained this time, we suggest the major geochronology framework of the magmatism and mineralization events in Gejiu area is ~80 Ma, which is consistent with the Late Cretaceous magmatism and mineralization events in the whole southeast Yunnan and west Guangxi area and they were suggested to belong to the same geotectonic setting in late Yenshannian. And the new ages of the ~30 Ma obtained in this study is considered to represent a responding to the complicate tectonic evolution history of the Tibetan orogenic events in Cenozoic.

Enrichment of Mantle-derived Fluids in the Formation Process of Granitoids: Evidence from the Himalayan Granitoids around Kunjirap in the Western Qinghai-Tibet Plateau

Taking the Himalayan granitoids around Kunjirap in the western Qinghai-Tibetplateau as an example, the authors present in this paper the characteristics of the granitoids richin mantle-derived fluid components and discuss their rock-forming mechanism. The research resultsindicate that the rock assemblage of the studied granitoids involves diopside syenite-diopsidegranite-biotite (monzonitic) granite, consisting mainly of K-feldspar, oligoclase, quartz,iron-phlogolite, diopside and edenite. The rocks are rich in mantle-derived fluid components ofvolatiles including F, alkali metal elements such as K, Na, Rb, Sr and Ha, and radiogenicheat-producing elements such as U and Th. They were generated by the influx of mantle-derived fluidsinto the lower crest to give rise to partial melting during the lithosphere thinning in theQinghai-Tibet plateau.

Petrological and Mineralogical Study of Enclaves in Plutons in the Typical Mining Districts of Tongling, Anhui and Its Bearing on the Process of Magmatism Metallogeny

Two types of enclaves occur in magmatic plutons in Tongling, Anhui. Enclaves of the first type are residuals of metamorphic rocks of high amphibolite facies, and those of the other type are magmatic rocks ranging from monzonitic to dioritic in composition. A combined petrological and mineralogical study has been carried out on the two types of enclaves in order to estimate their forming conditions and analyze their relations to their hosts, so as to have an insight into the material sources of magmatic rocks and associated mineral deposits and give a clue to better understanding the mechanism of magmatism metallogeny. This leads us to propose a new metallogenic model for strata bound skarn type ore deposits associated with a syntectic type of magmatic rocks. The new model can be simply summarized as partial melting of old metamorphic basement rocks at depth and accumulating, differentiating and positioning of magmas to form deep level and shallow level magma chambers, followed by mixing of different magmas associated with their crypto explosion, migration of gas bearing ore fluids and precipitation of metals in fluids within the magmas.

Gold Content of Mantle-Derived Rocks from Eastern China and Its Implications

We have analyzed the gold content of 65 samples of mantle-derived xenoliths and their host rocks from eastern China, which is found to be inhomogeneous, falling in the ranges of 1.0×109-8.2×109 (averaging 3.8 ×10-9) and 0.2×10-9-5.3×10-9 (averaging 2.7×10-9) in the mantle-derived xenoliths and the host basalts respectively. Except the samples from Wanquan County of Hebei Province and Anding County of Hainan Province, the gold content is the highest on the margins of the North China platform and decreases spatially towards the north and south, and temporally the samples of the Tertiary have a higher gold content than those of the Quaternary. The gold content of the mantle-derived xenoliths and the host Paleozoic kimberlites is 3.8×10-9-180×109and 0.1×10-9-38.0×10-9 respectively, which are higher than that in the mantle-derived xenoliths in basalt and the host Cenozoic basalts. The mantle-derived xenoliths have a higher gold content than the host rocks, but their relativity is not very clear, suggesting that the genetic relationship between them is complex. Our data indicate that the average gold content of the lithospheric mantle in eastern China is approximately equal to or approaching 3.8×10-9, which is lower than the average abundance of the upper mantle (5.0×10-9), higher than the average abundance of the continental crust (3.0×10-9) and only slightly higher than the average abundance of the lower continental crust (3.4×10-9). Except the samples from Hainan Province, the mantle-derived xenoliths in basalts with a high gold content are distributed on the two margins of the North China platform, corresponding to the gold deposits-concentrated districts in northwest Hebei Province and Shandong Province, showing the control by the old continental lithospheric mantle and the lower continental crust on the margins of the North China platform. The gold content of the mantle-derived xenoliths from Hainan Province ranges from 7.1×10-9 to 15×10-9, suggesting that some blocks of the lithospheric mantle in Hainan Province may be derived from the ancient gold-rich lithospheric mantle of western Australia and that Hainan Province may possibly be an important gold deposits-concentrated district. Some mantle-derived xenoliths in kimberlite of Shandong Province have an excessively high gold content amounting to 180×10-9, which provides new evidence for the possibility of 'finding gold deposits near kimberlite pipes or alkali-basalt volcanic vents'. Thererfore, the gold content of the mantle-derived xenoliths may be an indicator to the distribution of gold deposits-concentrated districts.

LA-ICP-MS Zircon U-Pb Dating of the Huangyangshan Pluton and Its Enclaves from Kalamaili Area Eastern Junggar,and Geological Implications

LA-ICP-MS zircon U-Pb dating has revealed that the Huangyangshan pluton in Eastern Junggar was formed at 311±12 Ma,and that microgranular enclaves were formed at 300±6 Ma;both ages are very consistent within errors.It is the first time that the microgranular enclaves age in Kalamaili area was determined.Petrochemistry and geochemistry research shows the characteristics of host rock as follows:

Discovery of Enclaves from Cenozoic PuluVolcanic Rocks in West Kunlun Mountains and ItsGeological Implications

In this paper, we present the occurrence and mineral components of the enclaves firstly discovered in the Cenozoic Pulu volcanic rocks in west Kunlun Mountains, and propose that the enclave is accumulated by fractional crystallization within high-level magma chamber. In addition, the chemical compositions of its primary magma are calculated. The calculated compositions are similar to those of the Kangxiwa volcanic rocks that belong to the same volcanic belt in the Pulu volcanic region, suggesting their origin from the same source region. However, the temperatures and oxygen fugacity of magmas at high-level magma chamber decreased along with fractional crystallization.

Destruction of the Northern Margin of the North China Craton in Mid-Late Triassic: Evidence from Asthenosphere-derived Mafic Enclaves in the Jiefangyingzi Granitic Pluton from the Chifeng Area, Southern Inner Mongolia

The petrology, geochronology and geochemistry of the mafic enclaves in the Mid-Late Triassic Jiefangyingzi pluton from Chifeng area, southern Inner Mongolia, in China are studied to reveal their petrogenetic relationship with the host pluton. Furthermore, the coeval magmatic assemblage and its petrogenesis on the northern margin of the North China craton(NCC) are studied synthetically to elucidate their tectonic setting and the implications for the destruction of the NCC. Zircon U-Pb dating reveals that the mafic enclaves formed at 230.4 ± 2.2 Ma, which is similar to the age of the host pluton. The most basic mafic enclaves belong to weak alkaline rocks, and they display rare earth element(REE) and trace element normalized patterns and trace element compositions similar to those of ocean island basalt(OIB). In addition, they have positive εNd(t) values(+3.84 to +4.94) similar to those of the Cenozoic basalts on the northern margin of the NCC. All of these geochemical characteristics suggest that the basic mafic rocks originated from the asthenosphere. Petrological and geochemical studies suggest that the Jiefangyingzi pluton and the intermediate mafic enclaves were formed by the mixing of the asthenosphere-derived and crust-derived magmas in different degrees. The Mid-Late Triassic magmatic rocks on the northern margin of the NCC could be classified into three assemblages according to their geochemical compositions: alkaline series, weak alkaline–sub-alkaline series and sub-alkaline series rocks. Petrogenetic analyses suggest that the upwelling of the asthenosphere played an important role in the formation of these Mid-Late Triassic magmatic rocks. Basing on an analysis of regional geological data, we suggest that the northern margin of the NCC underwent destruction due to the upwelling of the asthenosphere during the Mid-Late Triassic, which was induced by the delamination of the root of the collisional orogeny between Sino-Korean and Siberian paleoplates in Late Permian.

A Study on the Ore-forming Effect of Mantle-derived Fluid

Based on summarizing of the effect of mantle-derived fluid on the formation of ores, especially on gold ore, and with the latest investigations, such as the formation of ore from the action of shallow-deep fluid, the transportation effect of the thermal energy by mantle-derived fluid, this paper mainly aims at the effect of mantle-derived fluid on the generation of hydrocarbons. With the proof from geochemistry and fluid inclusion, it was suggested that the mantle-derived fluid not only supplied source materials for hydrocarbons, but also supplied essential energy and matter necessary for the generation of hydrocarbons. The mantle-derived fluid had a good effect, but at the same time it had an adverse effect under specific conditions, on the formation of reservoirs. This paper also discusses the future direction and significance of studying mantle-derived fluid.

The Principles for Discrimination of the Source Composition of Mantle-Derived Igneous Rocks and the Nature of the Mantle Source Region of the Emeishan Basalts

This paper discusses the discrimination principles. deduction and methods for probing into the source composition of mantle-derived magma. The magmatophile (incompatible) source elements are not all optimal tracers for mantle source composition. The ratios of two strong magmatophile elements (D<1) or the ratios of two trace elements with the same D value are not controlled by the formation mode and evolution degree of a magma, but maintain the characteristics of their composition in mantle source region prior to the magma formation. The ratios are related to different mantle-crust structures and dynamics. The mantle source composition of the Emeishan Basalt series is similar to that of the South Atlantic Rio Grande Rise-Walvis Ridge Basalts and Brazil continental-margin basalts. This may indicate that these basalt series might have similar source regions and tectonic environments.

The Discovery and Study of Mantle-Derived Dunite Inclusions in Hornblende-Diorite in the Handan-Xingtai Area,Hebei

Phlogopiie-and diopside-bearing dunite occurs as rounded inclusions in hornblende-diorite. Thepetrofabrics, mineral composition and abundances of the trace elements in the dunite indicate that the inclu-sions were derived from the upper mantle and are the residues of high-degree partial melting of mantlepeirdotite. The study of trace elements in the inclusions and their host rocks shows that the magma was origi-nated from the mantle which was enriched in incompatible elements by mantle metasomatism prior to the par-tial melting.

GEOCHEMISTRY AND TECTONIC ENVIRONMENT AND RESERVOIR FORMATION OF MANTLE-DERIVED NATURAL GAS IN THE SONGLIAO BASIN, NORTHEASTERN CHINA

During several decades of exploration, a number of mantle-derived natural gas pools have been discovered in the vicinities of deep faults in the Songliao Basin, northeastern China. The natural gas in these pools has a δ13C1 value of ?16.50/00 to ?24.20/00, a reversed arrangement in the amount of carbon isotopes in methane and its endogamous products (namely, δ13C1 >δ13C2 >δ13C3 >δ13C4), a 3He/4He value of 1.97 to 2.34×10-6,and an Ar/36Ar value of 1063 to 1949. This indicates a mantle 40 source for the natural gas. The trace elements Cd, In, Te and Re, never found in organic-sourced hydrocarbons, are highly enriched in certain crude oils from the Basin; respectively, concentrations of these elements were found to be 751, 28, 16 and 323 times the average crustal values in China, and this also supports a mantle-derived natural gas origin. The characteristics of mantled-derived magmatic rocks, hydrothermal fluids and gaseous fractions distributed in and near the deep Songliao Basin faults indicate that rifting tectonics is providing the mechanisms for this outgassing of the mantle. Deep extensional (normal) faults provide pathways for upward movement of these materials, and in the Songliao Basin, these deep rift fault zones are associated with reservoir occurrence and cap rock seals, forming good sites for accumulation of mantle-derived natural gas. Furthermore, a layer of low velocity, low density and high conductivity in the deep crust has been identified as a potential reservoir for mantle-derived natural gas.

Petrogenesis of the ükapili Granitoid and its Mafic Enclaves in Elmal Area (Nigde, Central Anatolia, Turkey)

The Late Cretaceous Uckapth Granitoid including mafic microgranular enclaves intruded into metapelitic and metabasic rocks, and overlain unconformably by Neogene ignimbrites in the Ni^de area of Turkey. It is mostly granite and minor granodiorite in composition, whereas its enclaves are dominantly gabbro with a few diorites in composition. The Uckapdl Granitoid is composed mainly of quartz, K-feldspar, plagioclase, biotite, muscovite and minor amphibole while its enclaves contain mostly plagioclase, amphibole, minor pyroxene and biotite. The Uckapth Granitoid has calcalkaline and peraluminous （AJCNK= 1.0-1.3） geochemical characteristics. It is characterized by high LILE/HFSE and LREE/HREE ratios （（La/Lu）N 3-33）, and has negative Ba, Ta, Nb and Eu anomalies, resembling those of comsion granitoids. The {）fkaplh Granitoid has relatively high STSr/S6Sr0） ratios （0.711189--0.716061） and low eNd（t） values （-5.13 to -7.13）, confirming crustal melting. In contrast, the enclaves are tholeiitic and metaluminous, and slightly enriched in LILEs （K, Rb） and Th, and have negative Ta, Nb and Ti anomalies; propose that they were derived from a subduction-modified mantle source. Based on mineral and whole rock chemistry data, the Uckapth granitoid is H-（hybrid） type, post-collision granitoid developed by mixing/mingllng processes between crustal melts and mantle-derived mafic magmas.

Petrological Significance of Zoned Plagioclase in Eldjurti Granite and Mafic Microgranular Enclaves, North Caucasus, Russia

Plagioclase phenocrysts from mafic enclaves and plagioclase from its host granite possess a pat-tem of complex zonation. A plagioclase phenocryst can generally be divided into three parts : an oscillatory, locally patchy zoned core (An47-19), a ring with dusty, more calcic plagioclase (An64-20) and a normally zoned rim composed of sodic plagioclase (An22-3. 3). Majordiscontinuities in zoning coincide with resorption suffeces that are overgrown by the more calcic plagioclase. The cores of large plagioclase phenocrysts from mafic enclaves and host granite show similar zoning patterns and similar compositions, indicating their crystallization under the same conditions . Steep normal zoning of the rims of plagioclases both from host granite and mafic enclaves illustrates a drastic decrease in An content which is considered to have resulted from the continuous differentiation of hybrid magma and efficient heat loss because of the upward emplacement of the residual magma. Wide rims of plagioclases from the host granite against thc discrete rims of plagioclases from mafic enclaves indicate that differentiation and cooling lasted much longer in the host granite than in the mafic enclaves.

Geological Implications for the Deep-Derived Mafic Enclaves from Cenozoic Shoshonitic Rocks in Jianchuan-Dali Area, West Yunnan

There exist intermediate to intermediate-acid shoshonitic rocks dated at 26.3- 36.7Ma in the Early Tertiary extensional basins along the NE flank of the Dali-Jianchuan section of the Honghe-Ailaoshan left-lateral strike-slip ductile shear zone, where some high- and medium-high grade metamorphosed mafic enclaves have been found. According to the P-T conditions and mineral assemblage characteristics, the enclaves are grouped into three types: type-Ⅰ, garnet diopsidite, formed at lower crust or in the transitional section between the mantle and the crust with the metamorphic condition P=(10.47-11.51)×108 Pa and T=771-932℃; type-Ⅱ, garnet- and diopside-bearing amphibolite, formed at the depth of middle to lower crust with the metamorphic condition: P=(6-10) ×108 Pa and T=780-830℃; type-Ⅲ, metamorphosed gabbro, formed at relatively higher levels than the above 2 types with lower metamorphic condition. Type-Ⅰand type-Ⅱenclaves had experienced a decompressional retrograde metamorphism caused by tectonic elevation associated with the metasomatism of SiO 2, Na 2O-rich fluid phase with the new equilibrated temperature at T=761-778℃. Geochemical evidence indicates that both deep-derived mafic enclaves and host rocks have similar EM Ⅱ properties, which are related to the involvement of subducted materials. The sustaining subduction, compression and strike-slip ductile shearing between the India plate and the Yangtze craton are the main constraints on the subcontinental mantle properties, interaction between crust and mantle, and the formation and evolution of alkali-rich magma.

Deep-derived enclaves (belonging to middle-lower crust metamorphic rocks) in the Liuhe-Xiangduo area, eastern Tibet: Evidence from petrogeochemistry

Petrological and geochemical studies of deep-derived enclaves from the Liuhe-Xiangduo area, eastern Tibet, showed that the enclaves involve five types of rocks, i.e., garnet diopsidite, garnet amphibolite, garnet hornblendite, amphibolite and hornblendite, whose main mineral assemblages are Grt+Di+Hbl, Grt+Pl+Hbl+Di, Grt+Hbl+Pl, Pl+Hbl, and Hbl+Bt, respectively. The enclaves exhibit typical crystalloblastic texture, and growth zones are well developed in garnet (Grt) in the enclaves. In view of major element geochemistry, the deep|derived enclaves are characterized by high MgO and FeO+*, ranging from {12.00%} to {12.30%} and {8.15%} to {10.94%}, respectively. The protolith restoration of metamorphic rocks revealed that the enclaves belong to ortho-metamorphic rocks. The REE abundances vary over a wide range, and ∑REE ranges from {53.39} to {129.04} μg/g. The REE patterns slightly incline toward the HREE side with weak LREE enrichment. The contents of Rb, Sr, and Ba range from {8.34} to 101μg/g, 165 to 1485 μg/g, and 105 to 721 μg/g, respectively. The primitive mantle-normalized spider diagrams of trace elements show obvious negative Nb, Ta, Zr and Hf anomalies. Sr-Nd isotopic compositions of the enclaves indicated that the potential source of deep-derived enclaves is similar to the depleted|mantle, and their {({}+{87}Sr/+{86}Sr)-i} ratios vary from {0.706314} to {0.707198}, {({}+{147}Nd/+{144}Nd)-i} ratios from {0.512947} to {0.513046}, and {ε-{Nd}(T)} values from {+7.0} to {+9.0}, respectively. The potential source of the enclaves is obviously different from the EM2-type mantle from which high-K igneous rocks stemmed (the host rocks), i.e., there is no direct genetic relationship between the enclaves and the host rocks. Deep-derived enclaves in the host rocks belong to mafic xenoliths, and those in the Liuhe-Xiangduo area, eastern Tibet, are some middle-lower crust ortho-metamorphic rocks which were accidentally captured at 20-50 km level by rapidly entrained high-temperature high-K magma, whose source is considered to be located at 50-km depth or so.

Recognizing Brazilian Cerrado Enclaves by Modeling Geoenvironmental Parameters

This work focused on the prediction modeling of Cerrado occurrences in the Atlantic Rainforest predominance in the S&#227;o Paulo Metropolitan Region (SPMR), the fourth largest urban area, in the city of Guarulhos, southeastern Brazil. The methodology was based on the selection of records of occurrence of Cerrado in georeferenced databases, thematic maps of geoenvironmental layers, and modeling of the distribution of species through the MaxEnt tool. Besides that, field research confirmed the presence or not of the species in the areas with a high probability of occurrence of Cerrado (≥0.7). As a result, the model observed a great capacity for the prediction of the occurrence of Cerrado in Ecotonal and anthropic regions (AUC = 0.82), revealing important hotspots such as relics from the past or Cerrado enclaves of high biodiversity. The work also points priority areas for the conservation and preservation of this increasingly endangered biome.