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Apatite is an excellent tracer of petrogenetic processes as it can incorporate a large range of elements that are sensitive to melt evolution (LREE-MREE, Sr, Pb, Mn, halogens, Nd isotopes). Recent advances in the understanding of trace element concentrations and isotope ratios in apatite provide a novel tool to investigate magmatic petrogenesis and sediment provenance. Recent experimental work has better characterized trace element partition coefficients for apatite, which are sensitive to changes in magma composition (e.g., SiO2 and the aluminum saturation index value). The chemistry of apatites from granitoids has been suggested to reflect the composition of the host magma and yield information about petrogenetic processes that are invisible at the whole-rock scale (mixing, in situ crystal fractionation, metasomatism). Nd isotopes in apatite can now be analyzed by LA-MC-ICP-MS to constrain mantle and crustal contributions to the source(s) of the studied magma. These recent advances highlight exciting new horizons to understand igneous processes using accessory minerals. In this contribution, we use a compilation of recent data to show that apatite in the matrix and as inclusions within zircon and titanite is useful for providing insights into the nature and petrogenesis of the parental magma. Trace element modeling from in situ analyses of apatite and titanite can reliably estimate the original magma composition, using appropriate partition coefficients and careful imaging. This provides a new way to look at magmatic petrogenesis that have been overprinted by metamorphic processes. It also provides the rationale for new investigations of sedimentary provenance using detrital accessory minerals, and could provide a powerful new window into early Earth processes if applied to Archean or Hadean samples.

The Shimensi deposit (South China) is a newly discovered W-Cu-Mo polymetallic deposit with a reserve of 0.76 million tones WO3, one of the largest tungsten deposits in the world. We report elemental and Sr-Nd isotopic data for scheelites from the giant deposit, to determine the source region and genesis of the deposit. Scheelite is the most important ore mineral in the Shimensi deposit. Trace elements (including REEs) and Nd-Sr isotopic compositions of scheelites were used to constrain the origin of the mineralizing fluids and metals. Our data reveal that the REEs of scheelite are mainly controlled by the substitution mechanism 3Ca2+ = 2REE3++ ∎Ca, where ∎Ca is a Ca-site vacancy. Scheelites from the Shimensi deposit show negative Eu anomalies in some samples, but positive Eu anomalies in others in the chondrite-normalized REE patterns. The variation of Eu anomalies recorded the ore-forming processes. Considering the close spatial and temporal relationship between the mineralization and porphyritic granite, we think the negative Eu anomalies were inherited from the porphyritic granite and the positive ones from destruction of plagioclase of country rock during fluid-rock interaction. The variation of cathodeluminescence (CL) color of a single scheelite from red to blue and to yellow was likely associated with the increase of REE contents. The scheelites hosted in the Mesozoic porphyritic granite with negative Eu anomalies formed in a primitive ore-forming fluid, whereas the scheelites hosted in Neoproterozoic granite with positive Eu anomalies precipitated in an evolved ore-forming fluid. The high Nb, Ta, LREE contents, and LREE-enriched REE patterns of scheelites from the Shimensi deposit reveal a close relationship with magmatic hydrothermal fluids. The scheelites from the Shimensi deposit are characterized by low εNd(t) values (-6.1 ∼ -8.1) and unusually high and varied initial 87Sr/86Sr ratios (0.7230∼0.7657). The εNd(t) values of scheelites are consistent with those of the Mesozoic porphyritic granite, but the Sr isotopic ratios are significantly higher than those of the granites, and importantly, beyond the Sr isotopic range of normal granites. This suggests that the ore-forming fluids and metals cannot be attributed to the Mesozoic porphyritic granites alone, the local Neoproterozoic Shuangqiaoshan Group schists/gneisses with high Rb/Sr ratios and thus radiogenic Sr isotopic compositions should have contributed to the ore-forming fluids and metals, particularly, in a later stage of ore-forming process, by intense fluid-rock interaction. This is different from a commonly accepted model that the ore-forming fluids and metals were exsolved exclusively from the granite plutons.

The Jurassic Linglong granites, intrusive into the North China Craton (NCC) in eastern China, provide a critical record of the first major episode of lithospheric-scale extension and magmatism in NE China during Mesozoic time. Our U–Pb zircon dating reveals that the Linglong granites were emplaced during 161–158 Ma, shortly after the inception of a shallow subduction of the Palaeo-Pacific plate beneath East Asia during Middle Jurassic time. These granites have high alkali contents (K2O + Na2O = 8–9 wt%), low MgO and Mg no. values and variable Cr–Ni abundances. Their relatively high Ba and Sr concentrations, relatively low heavy rare Earth element (HREE) and strongly fractionated REE patterns characterize them as high Ba–Sr granites. The negative whole-rock εNd(t) values ranging from −22.4 to −10.9 and wide-ranging zircon εHf(t) values of −39.1 to −1.5 suggest that magmas of the Linglong granites were produced by partial melting of a garnet-amphibolite-bearing lower crust of the Jiaobei Terrane and by re-melting of the Triassic ultrahigh-pressure (UHP) metamorphic rocks and alkaline suites of the Sulu Terrane. The occurrence in the granitic rocks of inherited zircons of the Neoarchaean, Palaeoproterozoic, Neoproterozoic, Palaeozoic and Triassic ages suggests that magmas of the Linglong granites interacted with the ancient crust in these terranes during their ascent. Asthenospheric upwelling, induced by the steepening and rapid rollback of the Palaeo-Pacific slab during Late Jurassic time, provided the heat source for the inferred lower crustal melting. Trench migration and thermal weakening of the crust caused extensional deformation and thinning in the eastern part of the NCC.

Middle-Late Jurassic Cimmerian events in Turkey have been actively discussed in the past three decades, but proposed tectonic models associated with magmatism, metamorphism, and stratigraphic features remain controversial. To address this issue, Upper Jurassic mafic lavas are investigated at three locations (Alucra, Gümüşhane, and Olur) in the eastern Sakarya Zone, northeastern Turkey. These lavas are submarine and form planar flows parallel with the bedding plane in the Upper Jurassic carbonate sequence near the base or just below in the clastic sedimentary rocks. The basaltic lavas show calc-alkaline features and possess Nb-Ta values and Nb/U, Nb/La, and Ce/Pb ratios that are greater than those of island arc basalts. Multielement patterns are almost hump shaped, similar to ocean island basalts, which experience Pb depletion and weak negative Nb-Ta, Zr-Hf, and Ti anomalies. The low initial (87Sr/86Sr) ratios (0.70372–0.70554), positive initial εNd values (+2.7 to +4.4), and initial Pb isotope ratios that plot between mid-ocean-ridge and ocean island basalts are consistent with a melt derived from subcontinental lithospheric mantle, metasomatized by earlier fluids from subducted sediments and plume materials from the asthenosphere. Moderate Dy/Yb ratios with an average value of 1.8 imply partial melting in the spinel-garnet transition zone at depths of ∼70–100 km. Slab breakoff is suggested as a geodynamic mechanism that accounts for these geochemical signatures. This inference is also favored by stratigraphic and sedimentologic evidence from the Upper Jurassic–Lower Cretaceous sedimentary rocks, which is consistent with short-lived vertical (epirogenic) movements in the region. Lower-Middle Jurassic sequences are transgressive, suggesting that subduction-related extension opened a backarc basin (Neotethys) in the south of the Sakarya Zone. Upper Jurassic–Lower Cretaceous carbonates point tectonically to tranquility during carbonate deposition in the Neotethys Ocean, which seems to have been achieved by complete closure of the Paleotethys in the north. About 15–20 m.yr. later (Kimmeridgian), after first carbonate deposition, intraplate-type mafic lavas ascended up to the shelf surface of the Neotethys. This was followed by formation of disconformity surfaces and then accumulation of coarse clastic sediments. All this points to a short-lived epirogenic movement that we ascribe to the breakoff of the southward-subducting Paleotethyan oceanic lithosphere in the Late Jurassic.

The East Asian winter monsoon (EAWM) has a profound effect on the winter climate in East Asia. The modern EAWM variability is tightly linked to the high-latitude Northern Hemisphere climate change through the Siberian High and can also be regulated by the low-latitude El Niño-Southern Oscillation through oceanic or atmospheric teleconnections. However, the Quaternary EAWM evolution has long been only attributed to the high-latitude climate change, resulting in the uncertainty in interpreting the out-of-phased EAWM variation recording in the East Asian continent and marginal seas. Here we presented a sediment record at Integrated Ocean Drilling Program Site U1427 in the southern Japan Sea to reconstruct the EAWM evolution since the last glacial maximum. By combining our record with previous reconstructions and simulations, we found the synchronous relationship between winter monsoon in northern and southern regions of East Asia from ∼24 to 8 ka, but anti-correlated relationship since ∼8 ka. We proposed the winter insolation and Atlantic meridional overturning circulation were the main drivers from last glacial to early Holocene, and then ENSO became a dominant factor in controlling the regional heterogeneity of EAWM evolution in the middle and late Holocene. This research explains much of the controversy in the Quaternary EAWM records and highlights the low-high latitude interaction in East Asian winter climate change.

Eocene–Oligocene magmatic rocks are well exposed in the region south of Birjand, eastern Iran. The ages, geochemistry and petrogenesis of these rocks are important to understand eastern Iran’s magmatic and geodynamic history during the Cenozoic. Detailed field investigations show that numerous intrusive, intermediate to felsic units are intruded into a thick sequence of Eocene–Oligocene lava flows and their accompanying pyroclastic rocks. The volcanic rocks are mainly basaltic andesitic to rhyolitic, whereas intrusive rocks are characterized by dioritic to granitic composition. Previously compiled U–Pb geochronological data indicate that Eocene–Oligocene magmatism in eastern Iran formed continuously from ∼46 Ma to ∼25 Ma. Our new zircon U–Pb data reveal crystallization ages of 43.6 ± 0.4 Ma to 39.5 ± 0.6 Ma, consistent with the upper end of this age range. Geochemically, the igneous rocks have high-K calc-alkaline to shoshonitic signatures. Rare-earth and trace element patterns show enrichment in LREEs, K, Rb, Cs, Pb, Th and U and depletion in HFSEs such as Nb, Zr and Ti, typical of a subduction-related environment. 87Sr/86Sr(i) and ϵNd(i) values range from 0.7051 to 0.7064 and −0.1 to +0.2, respectively. We postulate that the Cretaceous northeastward subduction of the Neo-Tethyan oceanic lithosphere underneath the Iranian Plateau caused sub-continental lithospheric mantle (SCLM) metasomatism by slab-derived fluid components. Subsequently, slab roll-back of the Neo-Tethyan oceanic lithosphere associated with asthenospheric upwelling led to lithospheric thinning and melting of the metasomatized SCLM. The resulting parental magmas probably interacted with upper continental crust during magma ascent to form Eocene–Oligocene magmatism in eastern Iran.

Sediments within accretionary complexes, preserving key information on crust growth history of Central Asian Orogenic Belt, did not get enough attention previously. Here, we conduct comprehensive geochemical study on the turbidites from the North Tianshan Accretionary Complex (NTAC) in the Chinese West Tianshan orogen, which is a good example of sediments derived from juvenile materials. The turbidites, composed of sandstone, siltstone, and argillaceous siliceous rocks, are mainly Carboniferous. All the investigated samples have relatively low Chemical Index of Alteration values (35–63) and Plagioclase Index of Alteration values (34–68), indicating relatively weak weathering before erosion and deposition. The sandstone and siltstone, and slate samples display high Index of Compositional Variability values of 0.89–1.50 and 0.89–0.93, suggesting a relatively immature source. The sandstones and siltstones were mainly derived from intermediate igneous rocks, and the slates from felsic igneous rocks, formed in oceanic/continental arc settings. The investigated samples roughly display high positive εNd(t) values (mainly at +5.5 to +7.9, except one spot at +0.8), with corresponding Nd model ages at 672 Ma–522 Ma (except one at ∼1.1 Ga). Combined with the previous studies, we suggest that the turbidites in the NTAC were mainly derived from intermediate to felsic igneous rocks with juvenile arc signature, and thus the northern Chinese West Tianshan is a typical site with significant Phanerozoic crust growth.

Modern fluvial sediments provide important information about source-to-sink process and regional tectono-magmatic events in the source area, but many factors, e.g., chemical weathering, sedimentary cycles and source-rock types, can interfere with the establishment of the source-sink system. The Lalin River (LR) and the Jilin Songhua River (JSR) are two important tributaries of the Songhua River in the Songnen Plain in NE China. They have similar flow direction, topography and identical climate backgrounds, but have notably different parent-rock types in the headwater, which provides an opportunity to explore the influencing factors of river sediment composition. To this end, the point bar sediments in the two rivers were sampled for an analysis of geochemistry (including element and Sr-Nd isotopic ratios), heavy mineral and detrital zircon U-Pb dating. The results are indicative of the fact that the two rivers have the similar geochemical composition (e.g., elements and Sr isotopes) as well as chemical weathering (CIA = 51.41–57.60, CIW = 59.68–66.11, PIA = 51.95–60.23, WIP = 56.00–65.47, Rb/Sr = 0.38–0.42) and recycling (SiO2/Al2O3 = 5.79 and 5.03, ICV = 1.0 and 1.2, CIA/WIP = 0.81–1.03) characteristics, showing a major control of climate on the low-level weathering and recycling of the river sediments. However, there are significant differences in the detrital zircon U-Pb age (a significant Mesozoic age peak for the LR but an additional Precambrian peak for the JSR), Nd isotope ratio (−6.2812–8.5830 and −8.1149–10.2411 for the LR and the JSR, respectively) and to a certain extent heavy mineral composition (e.g., for the < 63 μm fraction, a dominance of hornblende and magnetite in the LR, but haematite-limonite in the JSR) in the two river sediments, indicating that source rocks largely control the composition of the river sediments. Some of the major tectono-magmatic events (e.g., crustal growth and cratonisation of the North China Craton, closure of the Paleo-Asian Ocean, subduction and rollback of the Paleo-Pacific plate) occurring in the eastern Songnen Plain are well documented in the JSR sediments but not in the LR, the difference of which is largely regulated by the source rocks in the source area.

Most continental flood basalt (CFB) provinces of the world contain silicic (granitic and rhyolitic) rocks, which are of significant petrogenetic interest. These rocks can form by advanced fractional crystallization of basaltic magmas, crustal assimilation with fractional crystallization, partial melting of hydrothermally altered basaltic lava flows or intrusions, anatexis of old basement crust, or hybridization between basaltic and crustal melts. In the Deccan Traps CFB province of India, the Barda and Alech Hills, dominated by granophyre and rhyolite, respectively, form the largest silicic complexes. We present petrographic, mineral chemical, and whole-rock geochemical (major and trace element and Sr–Nd isotopic) data on rocks of both complexes, along with 40Ar–39Ar ages of 69.5–68.5 Ma on three Barda granophyres. Whereas silicic magmatism in the Deccan Traps typically postdates flood basalt eruptions, the Barda granophyre intrusions (and the Deccan basalt flows they intrude) significantly pre-date (by 3–4 My) the intense 66–65 Ma flood basalt phase forming the bulk of the province. A tholeiitic dyke cutting the Barda granophyres contains quartzite xenoliths, the first being reported from Saurashtra and probably representing Precambrian basement crust. However, geochemical–isotopic data show little involvement of ancient basement crust in the genesis of the Barda–Alech silicic rocks. We conclude that these rocks formed by advanced (70–75 %), nearly-closed system fractional crystallization of basaltic magmas in crustal magma chambers. The sheer size of each complex (tens of kilometres in diameter) indicates a very large mafic magma chamber, and a wide, pronounced, circular-shaped gravity high and magnetic anomaly mapped over these complexes is arguably the geophysical signature of this solidified magma chamber. The Barda and Alech complexes are important for understanding CFB-associated silicic magmatism, and anorogenic, intraplate silicic magmatism in general.

The Neoproterozoic (840 Ma) Sin Quyen deposit in northwestern Vietnam contains replacement Cu-LREE-Au orebodies in Proterozoic metasedimentary rocks. In this deposit, LREE-bearing minerals include allanite-(Ce), monazite-(Ce), chevkinite-(Ce), and fluorapatite. Fluorapatite from orebodies has undergone variable degrees of metasomatic alteration. Samarium-neodymium isotopic analyses were conducted on altered fluorapatite, and also on allanite-(Ce) and monazite-(Ce), to investigate whether such metasomatism can affect the Sm-Nd isotope system. Allanite-(Ce) and monazite-(Ce) have 147Sm/144Nd ratios ranging from 0.0359 to 0.0549, and 143Nd/144Nd ratios from 0.51147 to 0.51172. Their initial 143Nd/144Nd values at the time of mineralization range from 0.51126 to 0.51148, but mostly cluster between 0.51135 and 0.51145. Thus, the primary ore-forming fluids were relatively homogeneous in their Sm-Nd isotopic compositions. In the 147Sm/144Nd vs. 143Nd/144Nd diagram, the compositions of allanite-(Ce) and monazite-(Ce) generally plot along a Sm-Nd isochron of 840 Ma, implying that the Sm-Nd isotopic systems of these minerals were either closed or only slightly modified. In contrast, altered fluorapatite crystals have 147Sm/144Nd ratios varying from 0.0667 to 0.1348, and 143Nd/144Nd ratios from 0.51160 to 0.51199. The calculated initial 143Nd/144Nd ratios range widely from 0.51114 to 0.51141, with most values lower than those of the allanite-(Ce) and monazite-(Ce). In the 147Sm/144Nd vs. 143Nd/144Nd diagram, their compositions mostly plot below the 840-Ma Sm-Nd isochron. Petrographic observations and trace elemental analyses show that metasomatic modification of fluorapatite grains led to increases of their Sm/Nd ratios. The unaltered domains in the grains have Sm/Nd ratios varying from 0.114 to 0.200, with an average value of 0.161; whereas the altered domains have Sm/Nd ratios varying from 0.111 to 0.254, with an average value of 0.183. The increased Sm/Nd ratios can cause the calculated initial 143Nd/144Nd ratios to be lower than actual initial isotopic ratios, and can also result in compositional deviations from the reference Sm-Nd isochron. This study demonstrates that the traditionally assumed inert Sm-Nd isotopic system can be metasomatically disturbed due to changes in the Sm/Nd ratio. Therefore, care must be taken when interpreting the Sm-Nd isotopic data from apatite/apatite-rich rocks that have undergone metasomatic alteration.