Light δD apatites reveal deep origin water in North China Craton intracontinental granites and basalts

Domain: earth_science
Published: 2024-10-09
Editorial outcome: minor_revision

Abstract
Water is essential to the formation of intracontinental granites, but its origin remains elusive. Here we address this scientific problem by analyzing D/H isotopes of apatites, hydrous minerals in Jurassic and Early Cretaceous granites and basalts from eastern North China Craton, where water was previously interpreted as derived from subducting slab. Results reveal extremely low δD values in pristine Early Cretaceous granitic (−203‰ to −127‰) and basaltic (−197‰ to −107‰) apatites, contrasting with relatively high δD values (−137‰ to −47‰) in Jurassic granites. Given the depth-dependent D/H isotopic fractionation during slab dehydration and high-water contents in coeval primitive mafic magmas, the Early Cretaceous magma water is attributed to the stagnant slab within the mantle transition zone. Secular change in the depth of water aligns with steepening of subducting Paleo-Pacific plate from Jurassic to Early Cretaceous, demonstrating the potential of apatite H isotopes in tracing water origin in granites and basalts.

Introduction
Water is essential for partial melting of the continental crust (CC) to produce granites1,2. There are two dominant mechanisms for water supply in this process: decomposition of hydrous minerals in the CC and external water fluxing into melting system3. Recent studies suggest water-fluxed crustal melting is the primary drive to produce granites in the sub-arc region, in which water primarily originates from the dehydration of subducting slabs2. However, a significant volume of granites, formed through water-fluxed crustal melting also occurs within the interior of continent, well beyond the scope of an arc system4,5. A typical example is the North China Craton (NCC) which hosts a large volume of Late Mesozoic granites that formed far distance (>1000 km) from the Paleo-Pacific plate margin (Fig. 1)4–6. More interestingly, these intracontinental granites, particularly the Early Cretaceous ones, contain abnormally higher water contents in zircon than typical continental arc magmas7. However, the water origin of these intracontinental granites remains poorly constrained.

Hydrogen isotopes are useful to constrain origin of water. Continental arc granites typically exhibit relatively enriched deuterium (D), with primary δD values (~−80‰ to ~−30‰; Supplementary Data 3) greater than that of depleted mantle (δD=−80±10‰; parts per thousand relative to the Standard Mean Ocean Water, SMOW)8 and comparable to metasomatized enriched mantle (−94‰ to −30‰)9. This is due to the release of high δD water by dehydration from subducting slab at sub-arc depth (<~200 km) to overlying mantle wedge and crust. Complementally, the dehydrated slab has low δD9–12 and accordingly water from this source is isotopically light. Apatite usually crystallizes early in deep-emplacement granitic magmas13–16 and tends to be trapped as inclusion in other igneous minerals (e.g., feldspar, amphibole, biotite, zircon, etc.)16–19. It can thus record the original volatile compositions of the magma13–19.

Here, the in situ hydrogen and oxygen isotope compositions, along with water content, of apatites in Jurassic and Early Cretaceous granites and basalts from the NCC (Fig. 1) were simultaneously measured by secondary ion mass spectrometry (SIMS). The H isotope compositions of biotites and amphiboles in some granites were also determined by TC/EA technique and SIMS, respectively. Major and minor element concentrations (F, Cl, Na, Mn, etc.), and Nd isotope compositions were analyzed by electron probe microanalysis (EPMA) and laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS), respectively, to identify the influence of magma sources and post-crystallization processes. The results show significant variability in δD from −203‰ to −47‰ and contrasting δD values in Jurassic and Early Cretaceous, which are attributable to slab dehydration at different depths. In conjugation with geological records and geophysical investigation, the extremely light δD values suggest a deep origin of water from the previously dehydrated slab, probably stored in the mantle transition zone. This study introduces the use of apatite H isotope analysis as a method to investigate the origin of water in magmatic systems.

Results
Intracontinental granites and basalts formed during the destruction of the NCC
The NCC is bordered by the Central Asia Orogen to the north, while the Dabie-Sulu Orogen separates it from the Yangtze Craton in southeastern China (Fig. 1a). The eastern NCC consists of Archean to Paleoproterozoic basement rocks overlain by unmetamorphosed Mesoproterozoic to Paleozoic sediments. During the Late Mesozoic, the NCC lost much of its lithospheric root20,21, nowadays known as cratonic destruction4. The destruction of the NCC is evidenced by widespread basalts and extensive granitic magmatism over an intracontinental area of ~70,000 km2 (refs. 4,7). Two major sub-provinces of Jurassic (200‒145 Ma) and Early Cretaceous (145‒110 Ma) granites have been identified4, with the latter accounting for ~75% of the entire Jurassic-Cretaceous province. These Early Cretaceous granitic magmatisms are attributed to lithospheric thinning and crustal extension in the eastern NCC4. About 20,000 km2 of intrusive rocks are distributed in Liaodong Peninsula, along with minor volcanic rocks (Fig. 1b). The apatite phenocrysts, apatite inclusions in zircons (AIZ), and hydrous minerals (i.e., biotite and amphibole) were selected from nine I- and A-type granites of eight well-characterized plutons from this region (Jurassic, 155‒178 Ma; Early Cretaceous, 119‒129 Ma) (Fig. 1b; Supplementary Table 1). Early Cretaceous granites have been subject to more pronounced weathering than those of Jurassic (Supplementary Fig. 1). Additionally, apatite grains from two Early Cretaceous (~120‒124 Ma) fresh basalts of Yixian formation in the adjacent area (Chaoyang and Sihetun) were analyzed (Fig. 1a). The Sihetun basalt (12.1 wt% MgO) that collected from the lower unit is more primary than upper-unit Chaoyang basalt (1.3 wt% MgO), both of which originated from the sub-continental lithospheric mantle (SCLM)22.

Compositions of apatite phenocrysts, inclusions, and hydrous minerals
Most apatite phenocrysts separated from granites and basalts are 100 μm to 200 μm in length with homogeneous or oscillatory zoning in the cathodoluminescence (CL) images (Supplementary Fig. 2). The AIZs that are sufficiently large for micro-probe analysis are only found in Early Cretaceous granites (Supplementary Fig. 2). All apatite grains in granites and basalts from the NCC are fluorapatite (Supplementary Fig. 3a) and have similar variation of volatiles (F, Cl, H2O) (Supplementary Fig. 3). Water contents calculated from oxide contents based on chemical formula of apatite match with those measured by SIMS (0.03‒0.55 wt%) (Supplementary Fig. 3b). The AIZs and apatite phenocrysts from the same samples have indistinguishable F and Cl contents (Fig. 2a). The Early Cretaceous apatites are also characterized by elevated εNd(t) (−14.9 to −8.2) compared to Jurassic grains (εNd(t) −43.6 to −21.3) (Supplementary Data 5).

The Jurassic granitic apatite phenocrysts have a δD range of −137‰ to −47‰ with a median of −107‰ (Fig. 2b, c). In contrast, the apatite phenocrysts in Early Cretaceous granites have δD ranging from −203‰ to −127‰ with a median of −160‰ (Fig. 2b, c), which are similar to those contemporaneous basalts (δD=−197‰ to −107‰, median −158‰) but significantly lower than those of Jurassic granites (Fig. 2b, c). The ΔD (ΔD = δD A − δD B) for all apatites is as large as 150‰, well beyond the range of the external precisions of SIMS analyses (<37‰, 2SD). The δD values of Jurassic biotite and hornblende range from −54‰ to −107‰, comparable to those of apatites (Fig. 2c). Early Cretaceous hydrous minerals show δD values of −117‰ to −147‰, higher than those of co-existing apatites (Fig. 2c). δD values for Jurassic granitic apatites and hydrous minerals from the NCC overlap with those of typical island arc granites and SCLM peridotites (δD from ~−120 to ~−70‰) (Fig. 2c). The low δD of apatite in Early Cretaceous granites and basalts are similar to those of melt inclusions in olivines of picrite and komatiite (Fig. 2c), which are supposed to represent the hydrogen isotope compositions of dehydrated slab or the mantle transition zone (MTZ)11,12 (Fig. 2c).

The δ18O values of apatite grains from Early Cretaceous granites (3.7–9.1‰) are slightly lower than those of Jurassic granites (4.7–9.9‰) (Supplementary Data 1), with the external precision better than 1‰ (2SD). Jurassic hydrous minerals analyzed by TC/EA technique have δ18O values of 4.3±0.6‰ to 6.1±0.6‰. Two Early Cretaceous biotite samples have low δ18O values of −0.4±0.6‰ and 1.6±0.6‰, while one biotite sample have δ18O of 5.7±0.6‰ (Supplementary Fig. 4). The low δ18O values of Early Cretaceous biotites, together with their comparatively higher δD relative to co-existing apatite, indicates the incorporation of meteoric water in biotites and hornblende during weathering processes for their layered structure and well-developed cleavages.

Resistance of apatite to water-rock interaction
The fresh basalts, characterized by their rapid solidification and absence of hydrothermal signature, exhibit low δD values that cannot be attributed to water-rock interactions (Fig. 2c). But the hydrogen isotope composition in granites could be altered by hydrothermal fluids. Previous studies have documented markedly reduced δD values (<−230‰ or even <−300‰), often attributable to the involvement of low-δD glacial meltwaters in Antarctica or during syn-Snowball Earth23,24. The paleolatitude of the NCC at Late Mesozoic is 40°–60°N and the average δD for meteoric water at this time in North China is approximately −120‰ (ref. 25). The hydrogen isotopic fractionation between mineral and aqueous fluids, ΔDmineral-water, can theoretically reach as low as −100‰10. If this extreme fractionation applies to apatite-water system, the exceptionally low δD value (as low as −203‰) in Early Cretaceous granitic apatite (Fig. 2b) could potentially result from interactions with Mesozoic meteoric water.

To assess the viability of this hypothesis, we performed water-rock interaction simulations to emulate such scenarios (Supplementary Fig. 5). The results indicate that, assuming an initial δD of −130‰ for the granite, a water-to-rock ratio (W/R) exceeding 1 wt% is necessary to produce a decrease in δD to values below −150‰ (Supplementary Fig. 5). A lower δD in apatite (or a higher initial δD for granite) requires higher W/R ratios (Supplementary Fig. 5). A W/R ratio of 1 wt% signifies a water-rich environment compared to the typical water content of apatite in Early Cretaceous (~0.04 wt% to ~0.4 wt%). Such conditions would increase water content in both apatite and whole rock26. However, all the studied Early Cretaceous apatites exhibit low δD values, irrespective of their water contents or F/H2O (Fig. 3a; Supplementary Fig. 6a), indicating that water-rock interactions are unlikely predominant mechanism responsible for the low δD characteristics in Early Cretaceous apatites.

Furthermore, it is important to emphasize that although the lack of H isotope fractionation coefficient between apatite and water currently hinders us to quantitatively evaluate the influence of hydrothermal fluids on δD of apatites, it is difficult obtain a ΔDapatite-water as low as −100‰. Such extreme fractionations have only been reported in epidote (400°C)27 and smectite (25°C)28. For most mineral-water systems, ΔD is larger than −60‰ (refs. 10, 27). Achieving low δD values in Early Cretaceous apatites through water-rock interactions is thus challenging. Moreover, apatite is readily to be altered within days to several tens of days in aqueous fluids at temperature >100°C29,30, a process that can profoundly change the texture, element concentrations, and Nd isotope composition in apatites16,31,32. Specifically, altered apatites are characterized by jagged zones of varying brightness in CL images, high F/Cl ratios, reduced εNd(t) values and Na2O content16,31,32. The absence of expected correlations between F/Cl ratios and δD, the negative correlation between Na2O contents and δD in apatites, and coupled apatite εNd(t) with zircon εHf(t) (Fig. 3b, c; Supplementary Fig. 6b) hence preclude hydrothermal alteration of the studied apatites.

Kinetic fractionation arising from H and D diffusion during water-rock interactions could result in lighter H isotope composition in minerals, generating an extremely low δD rim33. If it occurs at temperatures below 100°C, an apatite grain of 200 μm would preserve a measurable diffusion profile of H isotopes over a timescale of 1–10 Ma (Supplementary Fig. 7). Because H diffuses faster than D, kinetic fractionation is expected to lead to substantially lower δD values at the rim compared to the core (ΔDrim-core <−300‰) (Supplementary Fig. 7). However, such expected core-rim δD profiles are not observed in individual apatite grains (Fig. 3d).

Hydrogen isotope fractionation in magmatic processes
Experiments suggest that the diffusion rates of F, Cl, and OH in apatite are relatively rapid in magma chambers34, with H-D exchange occurring even more quickly35. This would typically result in a homogeneous distribution of volatiles and hydrogen isotopes within granitic apatites. However, natural samples often deviate from these experimentally defined trends. The halogen and water content of individual apatite grains from granite exhibit a compositional gradient of volatile contents and δD from core to rim, indicative of volatile content variation during magmatic processes13,17. The chemical isolation is a possible mechanism to keep apatite being pristine34,35. In this study, we observed uniform volatile contents and H isotope compositions in intra- and inter-apatite grains within the same granite sample, suggesting equilibration of the volatiles between apatites and granitic melts.

Furthermore, the hydrogen isotopic fractionation between minerals and melts is temperature independent and rather small, with δD variation generally less than 15‰ (refs. 8, 26, 36). This is corroborated by the overlapping δD values between Jurassic apatite and unweathered biotite and hornblende (Fig. 2c). Consequently, magma differentiation processes were not responsible for the large difference in δD (ΔD > 150‰) between Jurassic and Early Cretaceous apatites from the NCC.

In contrast, degassing of magma chamber has been proved to have a substantial influence on hydrogen isotope composition of melt, especially in open systems37. D tends to fractionate into water (ΔDwater-melt > 0), resulting in a D-depleted residual melt after magma degassing37,38. Changes in element content of melts due to magma degassing, similar to water-rock interactions, are characterized by decreasing Na2O, and increasing F/Cl and F/H2O ratio39–41. As a result, Na2O and F/Cl (or F/H2O) ratio would positively and negatively correlate with δD, respectively. The data, however, do not reflect these expected trends (Fig. 3a, b; Supplementary Fig. 5).

The AIZs provide more insights into the preservation of original concentration of volatiles that were incorporated at the time of entrapment19,42,43. For example, apatite grains in the matrix contain lower Cl and H2O contents and higher F content in porphyry deposits and plutonic complex than AIZs (Fig. 2a), because Cl and H2O were discharged from matrix apatite during magma degassing whereas AIZs remain intact44,45. Virtually identical volatile contents in apatite inclusions in zircon and in apatite phenocrysts underscore that the magma degassing has not significantly influenced the volatile contents in apatite phenocrysts (Fig. 2a). Early crystallization of apatites and great emplacement depth of granites may be favorable for the preservation of original volatile contents and H isotope compositions in apatite phenocrysts13–16. Another contributing factor may be that the apatite phenocrysts are also enclosed in other rock-forming minerals such as feldspar and amphibole, preventing them from subsequent modifications16–18. Moreover, the other components involved in Jurassic and Early Cretaceous apatites are characterized by different δD but similar mantle-like δ18O (4.7–5.9‰) of apatite (Fig. 4). Due to very limited D/H fractionation during magmatic differentiation and melting8,36, the similarity of apatite δD in Early Cretaceous granites and contemporaneous basalts further argues for the ingress of external water in granite source, probably from mantle-derived hydrous fluids/melts (Fig. 2c). Specifically, the mantle component involved in the Jurassic granites is more enriched in D (Metasomatized mantle I, δD > ~−80‰) than in Early Cretaceous granites (Metasomatized mantle II, δD < ~−200‰) (Fig. 4). Hydrogen isotope composition of the former is consistent with that of SCLM, while that of the latter is close to the dehydrated slab and MTZ values (Fig. 2c). The two metasomatized mantle components also have higher zircon water contents than the CC component (Supplementary Fig. 8c)7, which is in accordance with the occurrence of Late Mesozoic hydrous basalts (aver. 3.4 wt% H2O) in the NCC22,50–52.

In addition to two metasomatized mantle components, low-δ18O (<4.7‰) apatites in Early Cretaceous granites may suggest the involvement of minor amount of altered oceanic crust (AOC) in the source of granites53,54. What is more, the presence of apatite with intermediate δD (ca. −130‰) but mantle-like δ18O in Early Cretaceous granites also suggests the involvement of isotopically heavy AOC or metasomatic mantle I in their sources (Fig. 4).

Extremely D-depleted and hydrous MTZ beneath the NCC
The heterogeneous Late Mesozoic mantle beneath the NCC was attributable to the dehydration of slab at variable depths, given the pressure-dependent D/H fractionation during slab dehydration10. The average δD of the subducting oceanic plate and the depleted mantle are estimated to be −50±20‰ and −80±10‰8,10, respectively. During subduction, dehydration of the slab at sub-arc depths liberates D-enriched water, which has δD of about −30‰ given for the ΔDwater-mineral =~20‰ (ref. 10). This process leaves behind a D-depleted dehydrated slab, which may go beyond the zone of magma generation beneath the volcanic arc. Fluids released by an already dehydrated slab at a greater depth are expected to have isotopically lighter hydrogen10,12,57. The dehydrated slab in the MTZ is predicted to have even lower δD than −230‰10.

Basaltic lavas generated from a source containing dehydrated, recycled oceanic crust usually show arc-like δD values9. Extremely low primitive δD (<−200‰) are only found in melt inclusions of olivines in picrites and komatiites from Lesser Antilles volcanic arc and stable cratons (Fig. 2c)12,58, which may have been sourced from a greater depth, i.e., dehydrated slab and the MTZ. One possible mechanism for the scarcity of low-δD lavas is the rehydration of dehydrated slab surface by fluids from dehydrating isotopically heavy serpentine in cooler, deeper parts of the slab in the depth of >~200 km (ref. 9). Alternatively, upwelling fluids released from dehydrated slab are inevitably contaminated by relatively high-δD water in depleted mantle or metasomatized mantle. The extremely low δD in Early Cretaceous granites and basalts indicate the presence of dehydrated, isotopically light slab beneath the NCC. Although primitive δD of oceanic arc magma from Grenada, Lesser Antilles, can be lower than −140‰ (down to −202‰)12, due to the long distance (>1000 km) of the study area from island arc in Early Cretaceous4–6 and the absence of low-δD rocks in Japan arc59,60, the water in the NCC magmas is most likely to come from the MTZ.

Whether the deep mantle can accommodate a large amount of water is a matter of hot debate. Thermodynamic modeling showed that majority of water of subducting slab is lost by sub-arc dehydration61. As a result, dehydrated slab going further down become essentially dry and carry only small amount of water62. However, the MTZ and the lower part of the upper mantle beneath the NCC have the highest electrical conductivity in the world63, consistent with an exceptionally hydrated mantle in this region22,50–52. Such a peculiar scenario is probably related to the continuous release of water from the stagnant slab within the MTZ to overlying upper mantle50,64. A hydrous MTZ is further suggested by experiments that show major constituent phases of the MTZ can accommodate much higher water than shallow mantle minerals65, and by hydrous ringwoodite found in deep-originated diamonds66. A similar scenario can be envisaged for the eastern NCC during the late Mesozoic, as a big mantle wedge structure may have initiated as early as in the Early Cretaceous67–71.

Water from Paleo-Pacific slab dehydrated at different depths
The recently reconstructed Paleo-Pacific subduction history4,67–69,71 provides a plausible tectonic framework that helps us understand the different apatite δD values in Jurassic and Early Cretaceous granites. It has been suggested that progressive shallowing of the subducting Paleo-Pacific Plate in the Middle-Late Jurassic was followed by subsequent slab rollback in Early Cretaceous4,6,67,69. Relatively flat subduction of the Paleo-Pacific Plate beneath the NCC in Jurassic expelled the asthenospheric mantle between the lithosphere and subducting slab. The cooling effect caused by the cold slab beneath the lithospheric mantle limited the dehydration of the subducted slab at sub-arc and underneath the lithosphere (Fig. 5a)4. As a result, a metasomatized mantle with arc-like δD was generated, and only a small amount of water with intermediate δD fluxed into the crust (Fig. 5a). This explains the relatively small volume of Jurassic granites and their arc-like δD values (Fig. 2c). Although water that existed in the mantle prior to subduction could potentially have H isotope compositions (δD −94‰ to −30‰)9 similar to those of arc magmas, its low water content (<1 wt% in basalts)9 makes it unlikely to be dominant in the water that fluxed into the crust from the mantle.

In Early Cretaceous, Liaodong Peninsula was located farther from the trench due to trench retreat4,5,67,69. Meanwhile, the Paleo-Pacific Plate started to rollback widening the asthenospheric window beneath the NCC (Fig. 5b). Subducting slab became stagnated within the MTZ, which released a large amount of extremely D-depleted water into and metasomatized overlying SCLM. Water fluxing triggered the melting of the SCLM generating the Early Cretaceous basalts22. Underplating of hydrous mafic magmas at the crust-mantle boundary introduced a large amount of water into the lower crust, producing voluminous granites with an extremely low δD (Fig. 5b).

While this study favors that the extremely low δD values of apatites in Early Cretaceous granites of the NCC ultimately reflect a deep mantle origin of water, alternatives such as water-rock interaction and magmatic degassing cannot be fully ruled out at this stage. The role of these processes in D/H isotopic fractionation deserves further investigation. Following research strategies are desirable. (1) Comparing δD values of hydrothermally altered apatites against those of pristine magmatic apatites in granites is necessary to elucidate the influence of hydrothermal alteration on δD. (2) If the interpretation presented in this study is valid, Late Mesozoic granites and basalts further west from the trench should have similar low hydrogen isotopic compositions. Consequently, hydrogen isotopic analyses on a much broader selection of Late Mesozoic granites and mantle-derived rocks from diverse geological settings will help build a comprehensive perspective on δD as a geochemical tracer. (3) Examining the hydrogen isotopic composition of hydrous minerals (such as hornblende) in Cenozoic primitive mantle xenoliths and their host lavas, with a particular focus on those influenced by the subducted Pacific slab, could provide insights to the fluid processes in the big mantle wedge underneath east Asia. Some mantle components with extremely low δD are expected from this region.

Methods
SIMS analysis of Apatite H, O isotope composition and water contents
Apatite and zircon grains with apatite inclusion were embedded in random orientations to Sn-Bi alloy mounts for SIMS analysis, following the method of Zhang et al.72. All separated apatite phenocrysts and apatite inclusions in zircon were documented with CL images to reveal their internal textures and choose appropriate areas (free of inclusions, fractures, and surface contaminations) for SIMS analysis. Analyses were performed using a CAMECA IMS 1280-HR at the Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS). The vacuum of the analysis chamber remained at ~1.7×10−9 mbar. A primary Cs+ beam current of about 4.0 nA was used. A uniform flat-bottom sputter crater was ensured by using a 15 μm raster73. The water background can be reduced to <10 ppm or even to 1.2 ppm74,75.

The 16O, 16O1H, 18O, 17O1H, 16OD signals were simultaneously counted in a single acquisition which was divided into 3 sequences. The value of mass resolving power (MRP) used to separate 16OD from 17O1H was set at 15,000. The measuring of 17O1H was to check whether 16OD was measured correctly or 17O1H and 16OD are completely separated. Each measurement consisted of 16 cycles, with a total analysis time of approximately 12 min, including pre-analysis sputtering and peak centering73.

The water content of apatite was determined from the measured 16O1H/16O ratio, and a calibration curve ([H2O] = 121.78×[16O1H/16O]; R2=0.9991) was constructed by the analyses of previously characterized two apatite standards, Kovdor apatite (H2O=0.98 wt%) and Durango apatite (H2O=0.0478 wt%)73,76. The two relative standard errors (2RSE) is ~4% that include internal precision of single analysis and uncertainties in linear regression. Measured 16OD/16O and 18O/16O values were normalized to the Vienna Standard Mean Ocean Water composition (SMOW, 16OD/16O=155.76×10-6, 18O/16O=2.0052×10-3). Corrections for instrumental mass fractionation (IMF) on hydrogen and oxygen isotopic compositions of apatite were performed using the Durango apatite standard (δD=−86±4‰, δ18O=9.8±0.3‰)76 and monitored by analyzing Qinghu apatite with recommended δ18O of 5.6±0.2‰77. We measured the H isotope composition of Qinghu apatite using TC/EA technique, and its δD value is −110±3‰ (Supplementary Data 2). The internal precision of δD for single analysis of SIMS ranges from 5‰ to 34‰ (2SE). High water content apatite usually shows better precision. The external precisions (i.e., reproducibility) of δD for Durango apatites are 21‰ (2SD, n=16) and 37‰ (2SD, n=18) in two alloy mounts. Both the internal and external precisions of δ18O are <1‰ (2SE or 2SD). δD and δ18O of Qinghu apatite that calculated from total 19 analysis spots across two alloy mounts are −114±32‰ (2SD) and 5.7±1.3 (2SD), in agreement with recommended values.

EPMA analysis of apatite element concentrations
In situ major element analyses were obtained using a CAMECA SXFive field emission Electron Probe Microanalyzer (EPMA) at GIGCAS. The mounts were coated with carbon before analysis. Concentrations were quantified using the PAP (Pouchou and Pichoir) matrix correction procedure78. Point analysis of Si, Mg, Fe, Mn, Ca, Na, P, S, F, and Cl of separated apatite phenocrysts were acquired using an electron beam of 15 kV accelerating voltage, 20 nA beam current, and 20 μm beam size. Si, Ca, P, F and Cl of apatite inclusions in zircon were acquired using an electron beam of low energy (15 kV accelerating voltage, 5 nA beam current) with a beam size of 5 μm. The detailed configurations of instrument and analytical procedures were described in He et al.79. Stoichiometry calculation for H2O in apatite is based on F and Cl contents from EPMA analysis, according to the structural formula of apatite80, i.e., 26 oxygen for the OH-poor apatite in this study (mole fraction of OH < 0.5). Calculated water contents match well with SIMS-measured water contents except for the high water contents (>~0.4 wt%) which maybe affected by analysis error that propagated from major elements (e.g., Ca, P, F) and simplificational algorithm in stoichiometry calculation80.

LA-MC-ICP-MS analysis of apatite Nd isotope
In situ Nd isotope compositions of apatites were obtained by a Neptune Plus multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) equipped with a NWR 193 nm ArF Excimer laser-ablation system at the Guangzhou Tuoyan Analytical Technology Co., Ltd., Guangzhou, China. The spot size is 70 μm dependent on Nd signal intensity. Other parameters are the same as analyses of trace elements. Eight Faraday cups receive 142Nd, 143Nd, 144Nd, 145Nd, 146Nd, 147Sm, 148Nd and 149Sm at the same time. The mass discrimination factor for 143Nd/144Nd was determined using 146Nd/144Nd (0.7219) with the exponential law. The 149Sm signal was used to correct the remaining 144Sm interference on 144Nd, using the 144Sm/149Sm ratio of 0.22332. The mass fractionation of 144Sm/149Sm was calibrated by the 147Sm/149Sm ratio of 1.08680 and exponential law. Data reduction was conducted using “Iso–Compass” software81. Two natural apatite megacrysts, Durango and MAD, were used as the unknown samples to verify the accuracy of the calibration method for Nd isotope analysis of apatites. The 147Sm/144Nd and 143Nd/144Nd obtained for Durango and MAD standards were 0.0902±0.0055 (2SD) and 0.512401±0.000077 (2SD); 0.0867±0.0066 (2SD) and 0.511235±0.000053 (2SD), respectively, consistent with their reference values82.

Bulk analysis of H, O isotope, and water content of biotite, hornblende and Qinghu apatite
Samples were weighed into silver capsules, degassed for 1 h at 100°C, then crushed and loaded into a zero-blank autosampler. The hydrogen isotopic composition was measured using a MAT 253 Stable Isotope Ratio Mass Spectrometer coupled to a Thermo Scientific TC/EA High Temperature Conversion Elemental Analyzer, with a precision for δD of 3‰ (2SD).

Oxygen isotope analysis were conducted at the Queen’s Facility for Isotope Research, Queen’s University, Canada. Samples were acidified prior to oxygen extraction to remove carbonates using 20% HCl at room temperature until no reaction was observed. Samples were rinsed 3x using 18.2 MW deionized water and dried in an oven overnight at 100°C. Oxygen was extracted from ca. 5 mg of treated silicate sample at 550–600°C according to the conventional BrF5 procedure of Clayton and Mayeda83. Samples and standard reference materials (NBS 28 and an in-house basalt) were loaded into Ni bombs with excess BrF5 and heated overnight. The liberated oxygen was converted to CO2 via sublimation of a carbon rod (EMS, CVP grade) and analyzed using the multiport of a dual inlet system on a Thermo-Finnigan Delta Plus XP Isotope Ratio Mass Spectrometer (IRMS). Sample gas was measured against a reference gas calibrated using a suite of international standards (NBS 18, NBS 19, NBS 20, and NBS 23) for 8 cycles, at 2500 mV intensity, in CO2 gas configuration using Isodat 3.0. A 17O correction using the SSH algorithm was applied84 to the measured values. The precision for δ18O is 0.6‰ (2SD).

SIMS analysis of hornblende H isotope composition
The hornblende grains were also embedded in Sn-Bi alloy mounts. The in-situ hydrogen isotope analysis of hornblende was conducted by using the CAMECA IMS 1280-HR at GIGCAS. A Cs+ primary beam of 1.4–2.4 nA with an impact energy of 10 keV was used to sputter secondary ions from the samples. A normal-incidence electron gun (diameter ~100 μm; 0.3–0.8 μA current flow from the sample holder) was used to compensate for the charge. Negative secondary ions were extracted and accelerated through a 10 kV with a 400 μm contrast aperture. The size of the analytical area was 30×30 μm (15 μm spot size + 15 μm rastering). The energy slit was closed to a bandwidth of 50 eV width and shifted 5 eV below the maximum transmission. A 122 μm entrance slit, 608 μm exit slit, and 100× transfer optical magnification were used to guide the secondary ions. A peak jump model sequentially measures the mass of H, D, and 28Si, and 10 cycles were collected, making a single analysis last 11 minutes. The Faraday cup with a 1012 Ω resistor (mono-collector system) was used to detect H and 28Si, while the electron multiplier (EM) (mono-collector system) was used to detect D. Before each analysis session, the Faraday cup and the electron multiplier high voltage were calibrated to ensure their consistent yielding. The waiting time and counting time for H, D, and 28Si in each mass scan cycle are 6, 1.2 and 2 s and 10, 15 and 2 s, respectively. Peak centering was performed before each analysis by centering the peak of 1H, which was also used as the internal reference signal. The pre-sputtering process lasted for 180 s with a 25×25 μm raster area, which was larger than the analysis area, to minimize the water background signal. Appropriate pre-sputtering in an ultra-high vacuum can attain the limit of detection of less than 1 ppm. Instrument mass fractionation (IMF) for H isotopes are corrected by standard hornblende samples, Kipawa (δD=−88‰)85. Other additional hornblende standards, Bamble (δD=−61‰) and Seljas (δD=−64‰)85, were repeatedly analyzed during data acquisition for quality control. Internal precision is better than 15‰ (2SE). The external precision of δD for Kipawa is 15‰ (2SD, n=13). The δD values obtained for Bamble and Seljas are −78±13‰ (2SD, n=12) and −75±15‰ (2SD, n=12), which are consistent with recommended values within the error.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "The authors newly analyzed the volatile, H-O isotopic data for the hydrous phenocrysts, and also Nd\nisotope and trace elements of the apatite. The authors also stressed many of my previous comments,\nand revised the manuscript much. They did a lot of efforts to improve the quality of the manuscript.\nHowever, after reading the revised version, I feel that there are still some essential points are confused,\nwhich are needed to improve further more.\nThe main concerns for the revised manuscript include:\n1) The samples, methods and data quality are not shown clearly. Basalts are also analyzed and discussed.\nHowever, I believe for any readers, it could not be known what kinds of agencies from the basalts were\nanalyzed, if only the main text were read. Similarly, the uncertainty of the water content and deltaD for\napatites and hydrous phenocrysts should be put in the main text, not totally hidden in the methods or\nsupplementary materials. About the uncertainty of deltaD, the authors mentioned +-38‰ for monitoring\nstandard. However, the error bar in the figures are much smaller than this. This discrepancy should be\nexplained, or the data should be examined carefully.\n2) As my previous comments, the hydrous minerals in late Cretaceous granites are rather critical to judge\nthe reliability of their low deltaD. Although these data have been added, they are not described clearly\nto support the conclusions. The authors just simply say the biotite and holbendite in these rocks are\n“weathered”. No any data or petrological image to support this inference. Note that this is rather critical,\nbecause the measured deltaD of main hydrous minerals in late Cretaceous granites are much higher than\nthat of apatite, otherwise the Jurassic and late Cretaceous granite would have no clear differences in\ndeltaD, if the large uncertainty was considered.\n3) The oxygen isotopic data of hydrous phenocrysts in late Cretaceous granite has clearly shown that the\nmeteorite water-granite interaction was heavy. How this interaction affects the isotope of apatite should\nbe discussed in a quantitative way. How long time is needed to modify the oxygen isotopes? During this\nperiod, how the water content and hydrogen isotopic composition of the apatite were changed? The\ndiagram of H2O vs. deltaD will be helpful, I see no such figure in main text.\n4）standards. Why in this version, the deltaD of Qinghu apatite standard is so different from the\nprevious one? If I understand right, the value of this standard should be independent to the update of\ndeltaD for Durango standard, and should come from an analysis method other than SIMS. This issue\nshould be explained well. By the way, the uncertainty of deltaD, delta18O of the typical analysis should\nbe clearly demonstrated. I can’t find it in both main text and methods.\n5) the profile of the big story. The Fig. 4 in this revised manuscript, the mixing among MTZ mantle with\nextremely low deltaD, and continental crust, and altered oceanic crust was suggested to explain the\nspreading of deltaD and delta18O. These mixing should be source mixing, right? Then how the\nendmember of MTZ mantle with a little mixing of continental crust to for GRANITE? The author did not\ngive a satisfied explanation to this issue.\n124-128 All the deltaD data should be mentioned together with analysis uncertainty. So do the oxygen\ndata.", "reviewer_2": "The study is done and the paper is well written and well illustrated, it interprets low-dD values of Early\nCretaceous apatites within granites on N China Craton as a result of deep mantle processes of slab\ndegassing. I have read the reviews and the answers to reviewers and these are reasonable. The main\nconcern is the veracity of apatite to hold to their dD content, and second is the uncertain isotopic\nfractionation between apatite and water. The devil is in the detail (still unknown to full extent, including\nanalytical matrix correction, reconstruction of water) and authors moved good way to address these\nquestions. However, as an informed reader, I remain somewhat skeptical on the ladder of measurements\nand models proposed in which one conclusion is based on a each subsequent one. I still think the paper\ncan be published and be judged as its implications can be tested.\nThe absolute values that these authors obtained are not as extreme as they claim, especially that all OH-\nbearing materials have 80‰ fractionations (Sheppard and Gilg,1996; Hudak et al. 2022 GCA). The -300‰\nvalues have been measured in Cretaceous (!) glasses from Antarctica (Nelson, Cottle et al. 2022, Nat\nComm, attributed to local glaciation) and -240‰ is the second lowest word's value in 2.4 Ga syn-\nSnowball earth rocks (Bindeman et al. 2014, Geosphere). Furthermore, the thermal separation of\nhydrogen in nature is huge, 43 permil per 100°C (Bindeman, Lundstrom 2013, EPSL) and thus one can\nobtain very low-dD values at the hot end (in cooling intrusion) if there is a reasonable transport\nmechanism via the hydrothermal system. I do not anticipate that this later process is predominant deep\ndown the earth but they may operate near hydrothermal systems around the intrusions where gradients\ncan be maintained on reasonable timescales. Finally, the “reservoir effects” needs to be considered as\nthe preduminant one. Imagine a cooling subsolidus granitic intrusion with 1vol% pore space dominated\nby water. Most water is already in hydrous minerals but temperatures are low and fractionations are\nhigh, and diffusion of D/H is still going on. The origin of this 1vol% of fluid can be magmatic or\nmeteoric, as you write is low enough, -140‰. If it fills the pores, it can dominate D/H budget, this is why\nmany protonic rocks were considered problematic by Hugh Taylor in 1970's. The latter is perhaps a\nmechanism that authors should address in a subsection of the paper or supplementary.\nAttributing very low-dD values for the mantle is the possibility, but note that kaersutites and\nphlogopites that are coming from the mantle, and also D/H in nominally anhydrous minerals are not\nextreme at (-110‰ at the most), so we don’t have direct evidence that such extreme dD exist in the\nmantle. So please indicate how did you obtain Metasomatized mantle II in Fig. 4.\nIt would perhaps be better for the authors to water down their conclusion section and say “…after\nconsidering the above possibilities, deep mantle origin can stand as an interpretation to be tested\nfurther by xyz. “ So offer some other ways to test your interesting hypothesis."}, "author_response": "Revision notes\nWe are grateful for the time and effort you have dedicated to reviewing our manuscript.\nYour constructive feedback has provided valuable insights that have enabled us to enhance the\nclarity, comprehensiveness, and scientific robustness of our work. Below, we address each of\nthe comments raised in detail, outlining the changes and additions we have made to the\nmanuscript in response to your suggestions.\nReviewer #1 (Remarks to the Author):\nThe authors newly analyzed the volatile, H-O isotopic data for the hydrous phenocrysts, and\nalso Nd isotope and trace elements of the apatite. The authors also stressed many of my previous\ncomments, and revised the manuscript much. They did a lot of efforts to improve the quality of\nthe manuscript. However, after reading the revised version, I feel that there are still some\nessential points are confused, which are needed to improve further more.\nResponse: Thank you very much for your recognition of our efforts to address your\nprevious comments and for your thoughtful review and continued feedback. We have carefully\nconsidered each of your suggestions and have made corresponding revisions to the manuscript.\nBelow are our responses to your main concerns.\nThe main concerns for the revised manuscript include:\n1) The samples, methods and data quality are not shown clearly. Basalts are also analyzed and\ndiscussed. However, I believe for any readers, it could not be known what kinds of agencies\nfrom the basalts were analyzed, if only the main text were read. Similarly, the uncertainty of\nthe water content and δD for apatites and hydrous phenocrysts should be put in the main text,\nnot totally hidden in the methods or supplementary materials. About the uncertainty of δD, the\nauthors mentioned ±38‰ for monitoring standard. However, the error bar in the figures are\nmuch smaller than this. This discrepancy should be explained, or the data should be examined\ncarefully.\nResponse: We apologize for the confusion caused by the ambiguity in presenting the\nsamples, methods, and data quality. We have undertaken the following revisions in our\nmanuscript:\n(1) Clarity on Samples. In the revised manuscript, we have expanded the description of\nmajor characteristics of mineralogy and chemistry of basalts and explicitly stated that our\nanalyses focused on apatite grains separated from basalts (Abstract and Subsection\n“Intracontinental granites and basalts formed during destruction of NCC”) to ensure that\nreaders can clearly understand the specific types and agencies of basalt samples we investigated.\n(2) Presentation of uncertainty. We have thoroughly reviewed the uncertainties (internal\nand external precisions) associated with water content, δD, and δ18O, and have now explicitly\ndelineated uncertainties in the main text (Subsection “Compositions of apatite phenocrysts,\ninclusions, and hydrous minerals”) and Methods to improve transparency and reproducibility.\n(3) Discrepancy between the uncertainty and the error bars of δD in the figures. In\nSIMS analysis, the reported precisions encompass both internal and external precisions. The\nerror bars in our figures depict internal precisions (two standard errors, 2SE), obtained from\nsingle SIMS analysis with 16 analysis cycles, which are widely utilized as uncertainties in\nSIMS analysis. The internal precisions are correlated with the water contents in apatites. High\nwater content leads to better internal precision due to enhanced ionization yields of H and D.\nFor example, apatites with 0.02 wt% and 0.4 wt% water contents have internal precisions of\napproximately 20‰ and 6‰ (2SE), respectively. The external precisions (reproducibility) of\nδD values during SIMS analysis, denoted by two standard deviations (2SD) of Durango apatite\nstandards, are 21‰ (16 spots) and 37‰ (18 spots) across two alloy mounts. The δD uncertainty\nof ±32‰ for monitoring standard, Qinghu apatite, previously mentioned in our Response to\nthe Reviewers, represents 2SD calculated from 19 analysis spots across two alloy mounts,\nwhich can also be considered external precision. Both internal and external precisions are\nfundamental for evaluating data and are typically reported in the literature. It is important to\nnote that internal precisions are often worse than external precisions in SIMS stable isotope\nanalysis (Kita et al., 2009). Even so, the external precisions documented in our study are\nsufficiently precise to distinguish between H isotope compositions of Jurassic and Early\nCretaceous apatites (∆D > 150‰). In the revised manuscript, Methods and\nJurassic-Cretaceous\nSupplementary Dataset, we have provided accurate error estimations and explanations.\n2) As my previous comments, the hydrous minerals in late Cretaceous granites are rather critical\nto judge the reliability of their low δD. Although these data have been added, they are not\ndescribed clearly to support the conclusions. The authors just simply say the biotite and\nhornblende in these rocks are “weathered”. No any data or petrological image to support this\ninference. Note that this is rather critical, because the measured δD of main hydrous minerals\nin late Cretaceous granites are much higher than that of apatite, otherwise the Jurassic and late\nCretaceous granite would have no clear differences in δD, if the large uncertainty was\nconsidered.\nResponse: A typo in the comment. It is Early Cretaceous (not late Cretaceous). The\nweathered state of hydrous mineral in granite is visually evident under natural light. Fresh\nbiotite and hornblende are characteristically dark-colored, typical in Jurassic granites. While in\nthe Early Cretaceous granites they are bronze-brown, a clear sign of weathering. Regrettably,\nthe exhaustion of Early Cretaceous rock samples precludes us from capturing additional\nphotographic evidence. However, photomicrographs of thin sections (Fig. S1 in Supplementary\ninformation) vividly illustrate the contrast between mineralogy of two-stage granites. In\nJurassic granites, biotite grains exhibit clear and well-defined boundaries and cleavages, and\nthe feldspars appear clean and unaltered (Fig. S1 in Supplementary information). In contrast,\nin Early Cretaceous granites, the boundaries of biotite grains are less distinct and blurred, and\nthe surfaces of feldspar are turbid (Fig. S1 in Supplementary information), indicating a more\nadvanced stage of weathering. In addition, if the low δ18O values in Early Cretaceous biotite\nsamples indicate intensive hydrothermal alteration, one would expect to see similar low δ18O\nin apatite, rather than magmatic O isotope composition observed in apatite (Fig. 4 in revised\nmanuscript). It can be more plausibly explained that inherent crystal structure and well-\ndeveloped cleavage in biotite and hornblende exacerbate their more severe weathering than\napatite. We have added the figures and discussions into the revised manuscript and\nsupplementary information.\n3) The oxygen isotopic data of hydrous phenocrysts in late Cretaceous granite has clearly shown\nthat the meteoric water-granite interaction was heavy. How this interaction affects the isotope\nof apatite should be discussed in a quantitative way. How long time is needed to modify the\noxygen isotopes? During this period, how the water content and hydrogen isotopic composition\nof the apatite were changed? The diagram of H O vs. δD will be helpful, I see no such figure\n2\nin main text.\nResponse: We fully acknowledge the critical role of quantitatively analyzing the effect of\nmeteoric water-granite interaction on the isotope of apatite, particularly focusing on the\nassociated time-dependent changes in water content and hydrogen isotopic composition.\nTo address this aspect, we first modeled the changes of δ18O in apatite due to oxygen\ndiffusion at temperature between 100℃ to 500℃ over time scales of 1 Ma and 10 Ma (Fig.\nR1). The diffusion rate of 18O in apatite for our calculation was extrapolated from hydrothermal\nexperiments performed at temperature ranging from 500℃ to 800℃ (Farver and Giletti, 1989).\nOur results demonstrate that δ18O in apatite starts to change at ~300℃ and becomes complete\nmodified at temperature > ~500℃, regardless of time scale (Fig. R1). The kinetic fractionation,\ncaused by oxygen diffusion, would theoretically produce zones of extremely light oxygen\nisotopes within apatite at temperature between 300℃ and 500℃ (Fig.R1), analogous to the\nkinetic fractionation pattern of H isotopes (Fig. S7 in Supplementary information). Such a\ndistribution pattern of δ18O in apatite is not observed in our study.\nFigure R1. Oxygen isotope fractionation modeling based on 16O-18O differential diffusion.\nIt is assumed that a semi-infinite apatite grain (thickness, 2L) with a homogeneous initial\nconcentration, C , in contact with an infinite well-mixed external reservoir of concentration, C ,\n0 1\nthe diffusion profile along the direction perpendicular to the surface is determined by the\nanalytical solution: 𝐶(𝑥,𝑡) = 1− 4 ∑∞ (−1)𝑛 𝑒𝑥𝑝( −𝐷(2𝑛+1)2𝜋2𝑡 )𝑐𝑜𝑠( (2𝑛+1)𝜋𝑥 ) (Ingrin,\n𝐶1−𝐶0 𝜋 𝑛=0 2𝑛+1 4𝐿2 2𝐿\n2006), where D is diffusion coefficient for 16O or 18O. The temperature dependent diffusion\ncoefficient for 18O is given by Farver and Giletti (1989) as: 𝐷 = 9×10−9𝑒𝑥𝑝(− 205 ) [𝑚2/𝑠].\n𝑅𝑇\nThe diffusion rate of 16O is estimated as the square root of atomic mass ratio (√18/16) times\nthe diffusion rate of 18O (Roskosz et al., 2018). Initial δ18O values of apatite and meteoric water\nare assumed to be +10‰ and -16‰, respectively.\nA more efficient way to change the composition of apatite is dissolution and precipitation\nof apatite in hydrothermal fluids (i.e., metasomatization). We are sorry that we are currently\nunable to quantitatively model such a process. Nevertheless, experimental studies have revealed\nthat apatite can be altered within days to several tens of days in acidic fluids at the temperature\ngreater than 100℃ (Chappell et al., 2023; Gysi and Harlov, 2021). In natural environments, this\nprocess may proceed at a slower pace due to different fluid composition, yet it is likely to be\nconsiderably faster than diffusion that occurred on the time scale of million years.\nHydrothermal altered apatite is typically characterized by changes in texture, H, O, Nd isotopes,\nand element concentrations (Bouzari et al., 2016; Chappell et al., 2023; Gysi and Harlov, 2021;\nHarlov, 2015; Long et al., 2023). However, these features are not supported by our data.\nIndeed, as you pointed out, hydrothermal alteration can lead to an increase in the water\ncontent of apatite. Given that water (hydroxyl, OH, in apatite) in apatite competes with F and\nCl (Ca (PO ) (OH,F,Cl)) for lattice position, F/H O ratio serves as a sensitive indicator of water\n5 4 3 2\ncontent changes in apatite. Based on this rationale, we had previously presented a figure in\nSupplementary information depicting δD plotted against the F/H O ratio, which did not reveal\n2\ndiscernible correlation (Fig. S6a in Supplementary information). Following your suggestions,\nwe have devised a new diagram (Fig. 3a in revised manuscript) that plots δD against water\ncontent. This diagram also fails to reveal any relationship between the two variables.\nThese considerations have been thoroughly integrated into the revised manuscript\n(Subsection: Resistance of apatite to water-rock interaction) and Supplementary information.\n4) standards. Why in this version, the δD of Qinghu apatite standard is so different from the\nprevious one? If I understand right, the value of this standard should be independent to the\nupdate of δD for Durango standard, and should come from an analysis method other than SIMS.\nThis issue should be explained well. By the way, the uncertainty of δD, δ18O of the typical\nanalysis should be clearly demonstrated. I can’t find it in both main text and methods.\nResponse: We apologize for the confusion regarding the δD of the Qinghu apatite standard.\nThe δD values of Qinghu apatite in the previous version were independently analyzed several\ntimes by SIMS and calibrated by Durango apatite with the recommended value of -120‰\n(Greenwood et al., 2008), resulting in an average of approximately -150‰ for Qinghu apatite.\nSubsequently, following your suggestion, we employed the TC/EA technique to determine the\nH isotope compositions of hydrous minerals in granites, and simultaneously measured the δD\nvalues of Qinghu apatite. This method yielded a δD of approximately -110±3‰. The\ncorresponding data has been provided in the supplementary dataset.\n5) the profile of the big story. The Fig. 4 in this revised manuscript, the mixing among MTZ\nmantle with extremely low δD, and continental crust, and altered oceanic crust was suggested\nto explain the spreading of δD and δ18O. These mixing should be source mixing, right? Then\nhow the endmember of MTZ mantle with a little mixing of continental crust to for GRANITE?\nThe author did not give a satisfied explanation to this issue.\nResponse: Thank you for highlighting this issue. Indeed, we interpret the variations of δD\nand δ18O as a consequence of source mixing. Recent studies have proposed that the late\nMesozoic granites in North China Craton were mainly generated by water-fluxed crustal\nmelting (Xue et al., 2023; Yang et al., 2022). This process involves mantle-derived water-rich\nmelts/fluids fluxed into the lower continental crust (probably through magmatic underplating),\ncausing crustal melting and generation of granites (Brown, 2013; Collins et al., 2016; Collins\net al., 2020; Weinberg and Hasalová, 2015). The water in granites mainly comes from mantle\nsources rather than the continental crust, based on the following lines of evidence:\n(1) The water content of zircon in Jurassic granites of the NCC is comparable to that of\ntypical continental arc granites (Yang et al., 2022), where the water mainly originate from the\nunderlying metasomatized mantle wedge. More importantly, the zircon in Early Cretaceous\ngranites contain much more abundant water than Jurassic granites (Yang et al., 2022).\nConsidering the scarcity of hydrous minerals in the lower crust of North China (Zhai et al.,\n2001; Zheng et al., 2004), it is challenging for dehydration melting to form such water-\nrich granites only through breakdown of hydrous minerals in continental curst (Yang et al., 2022).\n(2) Increasing water content is also accompanied by the cooperative change of zircon Hf-\nO isotopes, indicating a mantle origin of water in granites (Yang et al., 2022). The average water\ncontent in Early Cretaceous basalts is 3.4 wt%, which is comparable to arc magmas (Xia et al.,\n2013) and sufficient to supply a considerable volume of water to continental crust. It is\nimportant to emphasize that apatites from contemporaneous basalts show similar extremely low\nδD to the Early Cretaceous granites, indicating the potential linkage between basalt and granitic\nmagmas.\n(3) Both chemical composition and thermodynamic simulation corroborate the hypothesis\nthat water from metasomatized lithospheric mantle and subsequent hydration of the lower\ncontinental crust triggered widespread Early Cretaceous magmatism in the NCC (Xue et al.,\n2023). Furthermore, our recent studies on Late Mesozoic granites in the NCC reveal a positive\ncorrelation between magma water content and oxygen fugacity (unpublished data), echoing the\nformation pathways of arc magmas.\nThe above discussion has been incorporated in the subsection “Variable mantle contribution\nto two suites of granites from the NCC” in the revised manuscript.\n6) 124-128 All the δD data should be mentioned together with analysis uncertainty. So do the\noxygen data.\nResponse: According to your suggestion, we have reorganized this section, presenting H\nisotope and oxygen isotope data separately, including errors for accuracy.\nReviewer #2 (Remarks to the Author):\n1) The study is done and the paper is well written and well illustrated, it interprets low-δD\nvalues of Early Cretaceous apatites within granites on North China Craton as a result of deep\nmantle processes of slab degassing. I have read the reviews and the answers to reviewers and\nthese are reasonable. The main concern is the veracity of apatite to hold to their δD content,\nand second is the uncertain isotopic fractionation between apatite and water. The devil is in the\ndetail (still unknown to full extent, including analytical matrix correction, reconstruction of\nwater) and authors moved good way to address these questions. However, as an informed reader,\nI remain somewhat skeptical on the ladder of measurements and models proposed in which one\nconclusion is based on a each subsequent one. I still think the paper can be published and be\njudged as its implications can be tested.\nResponse: We deeply appreciate your thorough evaluation of our manuscript and the\nrecognition of the efforts we have made to address the complexities inherent in our study. We\nare pleased that you agree that the paper can be published and judged based on its implications,\nwhich can be tested further. We understand and respect your skepticism regarding the\nmeasurements and models leading to our conclusions. We admit that this is a complex issue\nthat requires further investigation and therefore have modified our conclusions in the revised\nmanuscript. And leave it open.\n2) The absolute values that these authors obtained are not as extreme as they claim, especially\nthat all OH-bearing materials have 80‰ fractionations (Sheppard and Gilg,1996; Hudak et al.\n(Nelson, Cottle et al. 2022, Nat Comm, attributed to local glaciation) and -240‰ is the second\nlowest word's value in 2.4 Ga syn-Snowball earth rocks (Bindeman et al. 2014, Geosphere).\nFurthermore, the thermal separation of hydrogen in nature is huge, 43 permil per 100°C\n(Bindeman, Lundstrom 2013, EPSL) and thus one can obtain very low-δD values at the hot end\n(in cooling intrusion) if there is a reasonable transport mechanism via the hydrothermal system.\nI do not anticipate that this later process is predominant deep down the earth but they may\noperate near hydrothermal systems around the intrusions where gradients can be maintained on\nreasonable timescales. Finally, the “reservoir effects” needs to be considered as the predominant\none. Imagine a cooling subsolidus granitic intrusion with 1vol% pore space dominated by water.\nMost water is already in hydrous minerals but temperatures are low and fractionations are\nhigh, and diffusion of D/H is still going on. The origin of this 1vol% of fluid can be magmatic or\nmeteoric, as you write is low enough, -140‰. If it fills the pores, it can dominate D/H budget,\nthis is why many plutonic rocks were considered problematic by Hugh Taylor in 1970's. The\nlatter is perhaps a mechanism that authors should address in a subsection of the paper or\nsupplementary.\nResponse: We have revised the manuscript to explicitly compare our findings with previous\nreports of much lower δD values in Cretaceous glasses from Antarctica (Nelson et al., 2022)\nand 2.4 Ga rocks (Bindeman et al., 2014). While we emphasize that the low δD values of apatite\ngrains from in our study are more likely reflect their source isotope compositions, distinct from\nthose influenced by glacial meltwater.\nThe seminal work by Bindeman et al. (2013) on stable isotope fractionation of silicate rocks\ndue to thermal diffusion offers a critical perspective for interpretating stable isotope\ncompositions. This research elucidates that thermal diffusion can drive large fractionation of\nthe stable isotopes, with lighter isotopes becoming enriched at high-temperature ends\n(Bindeman et al., 2013). This insight is highly pertinent in silicate rocks with high water content\nand hydrothermal systems linked to intrusions, because the fluids can efficiently facilitate\nisotope exchange and transport, such as up to 43‰ per 100℃ for H isotopes (Bindeman et al.,\n2013). Although the Early Cretaceous granites in our study are relatively water-rich and have\nhigher temperature than that of Jurassic granties, which could thoretically favor light H isotope\nenrichment by thermal diffusion, this process occurred at the temperature > 400℃ also result\nin O isotope fractionation, albeit less intensely at 2‰ per 100℃ (Bindeman et al., 2013). The\nO isotope composition of our apatite sample in the Early Cretaceous granite, however, remains\ncomparable to that of the Jurassic counterparts, showing no significant decline (Fig. 4 in revised\nmanuscript).\nThe “reservoir effect” offers an alterantive explanation for the low δD values in granites,\nhypothesizing that these values arise from water-rock interactions that take place under low\nwater/rock ratios (W/R) conditions (Taylor, 1977). We conducted simulations to emulate such\nscenarios (Fig. S5 in Supplementary information). Our results indicate that, assuming an initial\nδD of -130‰ for the granite, a W/R ratio exceeding 1 wt% (~3 vol% in volume unit) is\nnecessary to cause a decrease in δD to values below -150‰ (Fig. S5 in Supplementary\ninformation). To achieve even lower δD of < -180‰, a W/R ratio > 4 wt% (~12 vol%) is needed\n(Fig. S5 in Supplementary information). If the initial δD values of granites is assumed to be -\n50‰, the W/R ratio of 5 wt% (15 vol%) is required to produce < -150‰ δD values. A W/R\nratio of 1 wt% is still significantly higher than water content of apatite (~0.04 wt% to ~0.4 wt%),\nwhich would lead to an increase in the water content of apatite, as well as in whole rock (Taylor,\n1977). However, our observations reveal that all Early Cretaceous apatites show low δD,\nirrespective of their water contents (Fig. 3a in revised manuscript), indicating that water-rock\ninteraction may not be responsible for the low δD characteristics in Early Cretaceous apatites.\nIn addition, the lack of isotopic fractionation coefficients between apatite and water impedes\ndefinitive conclusions regarding the potential for extreme H isotope fractionation. While we\ncannot categorically exclude fractionation to -100‰ or -80‰, such scenarios are highly\nimprobable based the available data for other minerals. Existing data indicates that ∆D for\nepidolite and water reachs -100‰ at ~400℃ and to ∆Dfor clay and water can fractionate to -\n100‰ at 25℃; for other minerals, ∆D generally remain above -60‰. Although inequilibrium\nfractionation can reach very extreme levels, it is typically confined to the rim of minerals in\nshort periods. On geological timescales, such transient conditions are unlikely to persist. We\nhave discussed the possibility of diffusion-induced kinetic fractionation of H isotopes and find\nthat such a fractionation pattern could be recorded in apatite even on a time scale of 10 Ma.\nThis fractionation results in a great heterogeneity in the H isotope composition of apatite (∆D<-\n300), which is not found in our apatite. Furthermore, if water-rock interactions were a\nsignificant factor, they would be expected to induce changes in the texture of apatite, as well as\nNa O and volatile concentrations, alongside shifts in Nd isotope composition. However, these\n2\nalterations have not been detected in our study, reinforcing the negligible “reservoir effect” on\napatite δD. Given that apatites in basalts have comparable low δD isotopic signatures, we are\nmore inclined to propose that H isotopes in granites are plausibly inherited from a deep mantle\nsource, rather than originating from water-rock interactions.\nWe have added these discussions to the subsection “Resistance of apatite to water-rock\ninteraction”.\n3) Attributing very low-δD values for the mantle is the possibility, but note that kaersutites and\nphlogopites that are coming from the mantle, and also D/H in nominally anhydrous minerals\nare not extreme at (-110‰ at the most), so we don’t have direct evidence that such extreme δD\nexist in the mantle. So please indicate how did you obtain Metasomatized mantle II in Fig. 4.\nResponse: Indeed, your observation regarding the scarcity of mantle rocks exhibiting\nextremely low δD values is accurate. This rarity is likely due to the dilution of D-depleted\nwaters released from the mantle transition zone (MTZ), as they mix with higher δD waters,\nthereby obscuring the original isotopic signatures.\nTwo mechanisms have been posited to explain this isotopic blurring. Dixon et al. (2017)\nproposed a dehydration-rehydration sequence within subducting slab. Here, D-depleted,\ndehydrated oceanic crust undergoes rehydration by fluids derived from dehydration of\nsubcrustal isotopically heavier serpentinized mantle in cooler, deeper parts of the slab\n(Dixon et al., 2017). An alternative mechanism involves the rehydration of MTZ-derived materials at\nshallow depth by relatively D-enriched water released below the arcs, leading to an elevation\nin δD values. The occurrence of basalts with such anomalously low δD values in the North\nChina Craton can be attributed to prolonged subduction of paleo-Pacific plates beginning ~180\nMa. During this process, the MTZ or the stagnant slabs in MTZ would have released substantial\nquantities of low δD water into the upper mantle. It is noteworthy that the lithospheric mantle\nwas notably water-rich (> 1000 ppm H O) in the Early Cretaceous.\ninclusions in olivines from cratonic komatiites (Sobolev et al., 2019) or arc picrites (minimum\nδD of -202‰) (Bouvier et al., 2010). These melt inclusions are believed to originate from MTZ\nor dehydrated slabs. The data set designated as “Metasomatized mantle II” (Fig. 4 in revised\nmanuscript) is a rough estimation of MTZ that derived from those above δD measurements.\nThe δD values of uncontaminated melt inclusions is from -181‰ to -289‰ (Sobolev et al.,\n2019). Taken into consideration that our lowest δD value is ~-200‰, we set an end member of\n“Metasomatized mantle I” (MTZ) of δD in the range of -200‰ to -289‰. We have explained\nthis in the caption of Fig. 4 in revised manuscript.\nIn addition, we indicate in the last section, that future study of H isotopes can be carried\nout on mantle xenoliths and their host basalts from east China, which may provide more\nconstraints on the extremely low δD reservoirs.\n4) It would perhaps be better for the authors to water down their conclusion section and say\n“…after considering the above possibilities, deep mantle origin can stand as an interpretation\nto be tested further by xyz.” So offer some other ways to test your interesting hypothesis.\nResponse: We fully agree that framing our conclusions in a more exploratory manner will\nenhance the scientific discourse surrounding our findings. We have incorporated the following\nwords in the last paragraph of the revised manuscript (Lines: 379-394):\nWhile this study favors that the extremely low δD values of apatites in Early Cretaceous\ngranites of the NCC ultimately reflect a deep mantle origin of water, alternatives such as water-\nrock interaction and magmatic degassing cannot be fully ruled out at this stage. The role of\nthese processes in D/H isotopic fractionation deserves further investigation. Following\nresearch strategies are desirable. (1) Comparing δD values of hydrothermally altered apatites\nagainst those of pristine magmatic apatites in granites is necessary to elucidate the influence\nof hydrothermal alteration on δD. (2) If the interpretation presented in this study is valid,\nMesozoic granites and basalts further west from the trench should have similar low hydrogen\nisotopic compositions. Consequently, hydrogen isotopic analyses on a much broader selection\nof Late Mesozoic granites and mantle-derived rocks from diverse geological settings will help\nbuild a comprehensive perspective on δD as a geochemical tracer. (3) Examining the hydrogen\nisotopic composition of Cenozoic primitive mantle xenoliths and their host lavas, with a\nparticular focus on those influenced by the subducted Pacific slab, could provide insights to the\nfluid processes in the big mantle wedge underneath east Asia. Some mantle components with\nextremely low δD are expected from this region.\nReferences\nBindeman, I.N., Lundstrom, C.C., Bopp, C., Huang, F., 2013. Stable isotope fractionation by\nthermal diffusion through partially molten wet and dry silicate rocks. Earth Planet. Sci.\nLett. 365, 51-62.\nBindeman, I.N., Serebryakov, N.S., Schmitt, A.K., Vazquez, J.A., Guan, Y., Azimov, P.Y.,\nAstafiev, B.Y., Palandri, J., Dobrzhinetskaya, L., 2014. Field and microanalytical\nisotopic investigation of ultradepleted in 18O Paleoproterozoic “Slushball Earth” rocks\nfrom Karelia, Russia. Geosphere 10, 308-339.\nBouvier, A.S., Métrich, N., Deloule, E., 2010. Light elements, volatiles, and stable isotopes in\nbasaltic melt inclusions from Grenada, Lesser Antilles: Inferences for magma genesis.\nGeochem. Geophys. Geosyst. 11.\nBouzari, F., Hart, C.J.R., Bissig, T., Barker, S., 2016. Hydrothermal Alteration Revealed by\nApatite Luminescence and Chemistry: A Potential Indicator Mineral for Exploring\nCovered Porphyry Copper Deposits. Econ. Geol. 111, 1397-1410.\nBrown, M., 2013. Granite: From genesis to emplacement. Geol. Soc. Am. Bull. 125, 1079-1113.\nChappell, J.C., Gysi, A.P., Monecke, T., Chang, Z., 2023. Experimental study of apatite-fluid\ninteraction and partitioning of rare earth elements at 150 and 250 °C. Am. Mineral. 108,\n1409-1420.\nCollins, W.J., Huang, H.Q., Jiang, X.Y., 2016. Water-fluxed crustal melting produces\nCordilleran batholiths. Geology 44, 143-146.\nCollins, W.J., Murphy, J.B., Johnson, T.E., Huang, H.Q., 2020. Critical role of water in the\nformation of continental crust. Nat. Geosci. 13, 331-338.\nDixon, J.E., Bindeman, I.N., Kingsley, R.H., Simons, K.K., Le Roux, P.J., Hajewski, T.R.,\nSwart, P., Langmuir, C.H., Ryan, J.G., Walowski, K.J., Wada, I., Wallace, P.J., 2017.\nLight Stable Isotopic Compositions of Enriched Mantle Sources: Resolving the\nDehydration Paradox. Geochem. Geophys. Geosyst. 18, 3801-3839.\nFarver, J.R., Giletti, B.J., 1989. Oxygen and strontium diffusion kinetics in apatite and potential\napplications to thermal history determinations. Geochim. Cosmochim. Acta 53, 1621-\n1631.\nGreenwood, J.P., Itoh, S., Sakamoto, N., Vicenzi, E.P., Yurimoto, H., 2008. Hydrogen isotope\nevidence for loss of water from Mars through time. Geophys. Res. Lett. 35.\nGysi, A.P., Harlov, D., 2021. Hydrothermal solubility of TbPO , HoPO , TmPO , and LuPO\n4 4 4 4\nxenotime endmembers at pH of 2 and temperatures between 100 and 250 °C. Chem.\nGeol. 567.\nHarlov, D.E., 2015. Apatite: A Fingerprint for Metasomatic Processes. Elements 11, 171-176.\nIngrin, J., 2006. Diffusion of Hydrogen in Minerals. Rev. Mineral. Geochem. 62, 291-320.\nKita, N.T., Ushikubo, T., Fu, B., Valley, J.W., 2009. High precision SIMS oxygen isotope\nanalysis and the effect of sample topography. Chem. Geol. 264, 43-57.\nLong, X.-Y., Tang, J., Xu, W.-L., Sun, C.-Y., Luan, J.-P., Xiong, S., Zhang, X.-M., 2023. Trace\nelement and Nd isotope analyses of apatite in granitoids and metamorphosed granitoids\nfrom the eastern Central Asian Orogenic Belt: Implications for petrogenesis and post-\nmagmatic alteration. Geoscience Frontiers 14.\nNelson, D.A., Cottle, J.M., Bindeman, I.N., Camacho, A., 2022. Ultra-depleted hydrogen\nisotopes in hydrated glass record Late Cretaceous glaciation in Antarctica. Nat\nCommun 13, 5209.\nRoskosz, M., Deloule, E., Ingrin, J., Depecker, C., Laporte, D., Merkel, S., Remusat, L., Leroux,\nH., 2018. Kinetic D/H fractionation during hydration and dehydration of silicate glasses,\nmelts and nominally anhydrous minerals. Geochim. Cosmochim. Acta 233, 14-32.\nSobolev, A.V., Asafov, E.V., Gurenko, A.A., Arndt, N.T., Batanova, V.G., Portnyagin, M.V.,\nGarbe-Schönberg, D., Wilson, A.H., Byerly, G.R., 2019. Deep hydrous mantle\nreservoir provides evidence for crustal recycling before 3.3 billion years ago. Nature\n571, 555-559.\nTaylor, H.P., 1977. Water/rock interactions and the origin of H O in granitic batholiths. J. Geol.\nWeinberg, R.F., Hasalová, P., 2015. Water-fluxed melting of the continental crust: A review.\nLithos 212-215, 158-188.\nXia, Q.K., Liu, J., Liu, S.C., Kovacs, I., Feng, M., Dang, L., 2013. High water content in\nMesozoic primitive basalts of the North China Craton and implications on the\ndestruction of cratonic mantle lithosphere. Earth Planet. Sci. Lett. 361, 85-97.\nXue, S., Zhang, W., Ling, M.-X., Sun, W., Ding, X., 2023. Large-Scale Cretaceous Adakitic\nMagmatism Induced by Water-Fluxed Melting of Continental Crust during the North\nChina Craton Destruction. J. Petrol. 64.\nYang, C.M., Xu, Y.G., Xia, X.P., Yang, J.H., Sun, J.F., Zhang, W.F., Yang, Q., Yang, Y.N., 2022.\nHigh Water Contents in Zircons Suggest Water-Fluxed Crustal Melting During\nCratonic Destruction. Geophys. Res. Lett. 49.\nZhai, M.G., Guo, J.H., Liu, W.J., 2001. An exposed cross-section of early Precambrian\ncontinental lower crust in North China craton. Phys. Chem. Earth Pt. A 26, 781-792.\nZheng, J.P., Griffin, W.L., O’Reilly, S.Y., Lu, F.X., Yu, C.M., Zhang, M., Li, H.M., 2004. U–Pb\nand Hf-isotope analysis of zircons in mafic xenoliths from Fuxian kimberlites:\nevolution of the lower crust beneath the North China craton. Contrib. Mineral. Petrol.\n148, 79-103."}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have clarified my questions, and revised the manuscript well. I have no additional\ncomments.\nLine 67 to 71:\nMajor and minor element, and Nd isotopes were analyzed by EPMA and LA-ICP-MS, respectively, to …….\nNote that Nd isotope could not be analyzed by EPMA or LA-ICP-MS.", "reviewer_2": "I have examined the new MS and have these minor editorial comments\nChange to: scientific problem\n53 …(δD = -80 ± 10‰; parts per thousand relative to the Standard Mean\nI thought that “mantle” values have always been -40 to -80‰ historically, but now using ref 9 is\nsomewhat revised upward. Please check, it is not -80±10‰\n135 …d18O od Cretaceous granites (3.7–9.1‰) , this is large range requiring explanation of why is it. Do\nd18O correlate to dD?\n390 (3) Examining the\n391 hydrogen isotopic composition of Cenozoic primitive mantle xenoliths and their host\n392 lavas, with a particular focus on those influenced by the subducted Pacific slab…\nThis would only work if suitable large hydrous minerals (such as amphiboles) are found in these\nxenoliths. May be mention this since mantle xenoliths are typically anhydrous."}, "author_response": "Reviewer #1 (Remarks to the Author):\nThe authors have clarified my questions, and revised the manuscript well. I have no additional\ncomments.\nLine 67 to 71:\nMajor and minor element, and Nd isotopes were analyzed by EPMA and LA-ICP-MS,\nrespectively, to …….\nNote that Nd isotope could not be analyzed by EPMA or LA-ICP-MS.\nResponse: Thank you. We have changed “LA-ICP-MS” to “LA-MC-ICP-MS”.\nReviewer #2 (Remarks to the Author):\nI have examined the new MS and have these minor editorial comments\n(1) 22 Here we address this long-lasting issue..\nChange to: scientific problem\nResponse: revised.\n(2) 53 …(δD = -80 ± 10‰; parts per thousand relative to the Standard Mean\nI thought that “mantle” values have always been -40 to -80‰ historically, but now using ref 9\nis somewhat revised upward. Please check, it is not -80±10‰\nResponse: Thank you. The δD value of -80 ± 10‰ is referred to the values of the depleted\nmantle, which has not been revised in ref. 9 (Dixon et al., 2017). As you pointed out that,\nhistorically “mantle” values, including depleted mantle and enriched mantle, are estimated\nbetween -40‰ to -80‰. Dixon et al. (2017) measured δD value of enriched mid-ocean ridge\nbasalts and showed that the δD value of metasomatized enriched mantle ranges from -30‰ to\n-94‰. In particular, the δD value of Pacific mantle fall between -57‰ to -94‰. Given that we\ncannot definitively determine whether the mantle that has not been metasomatized by Pacific\nplate derived fluids is depleted or enriched, it is thus necessary to consider the role of a general\n“mantle” with δD value of -30‰ to -94‰ (Dixon et al., 2017) in the formation of Jurassic\ngranites for their comparable H isotope compositions. The low water content (< 1wt% in basalts)\n(Dixon et al., 2017) makes it unlikely to be dominant in the water that fluxed into the crust from\nthe mantle. We have added these considerations into the revised manuscript (Line 54-55, 322-\n326).\n(3) 135 …δ18O of Cretaceous granites (3.7–9.1‰), this is large range requiring explanation of\nwhy is it. Do δ18O correlate to δD?\nResponse: The low-δ18O (3.7‰) apatites in Early Cretaceous granites are attributed to the\ninvolvement of altered oceanic crust in the source of granites, which has been proposed in\nprevious studies (Wei et al., 2002; Yang et al., 2017). The high-δ18O endmember may contain\nmore continental crust materials (Fig. 4 in the revised manuscript). There is no clear correlation\nbetween δ18O and δD in Early Cretaceous granitic apatites, but we do observe the negative\ncorrelation in Jurassic granitic apatites.\n(4) 390 (3) Examining the\n391 hydrogen isotopic composition of Cenozoic primitive mantle xenoliths and their host\n392 lavas, with a particular focus on those influenced by the subducted Pacific slab…\nThis would only work if suitable large hydrous minerals (such as amphiboles) are found in these\nxenoliths. May be mention this since mantle xenoliths are typically anhydrous.\nResponse: Thank you. We have revised this sentence to “(3) Examining the hydrogen isotopic\ncomposition of hydrous minerals (such as hornblende) in Cenozoic primitive mantle xenoliths\nand their host lavas…” in the revised manuscript (Line 347).\nReferences\nDixon, J.E., Bindeman, I.N., Kingsley, R.H., Simons, K.K., Le Roux, P.J., Hajewski, T.R.,\nSwart, P., Langmuir, C.H., Ryan, J.G., Walowski, K.J., Wada, I., Wallace, P.J., 2017.\nLight Stable Isotopic Compositions of Enriched Mantle Sources: Resolving the\nDehydration Paradox. Geochem. Geophys. Geosyst. 18, 3801-3839.\nWei, C.S., Zheng, Y.F., Zhao, Z.F., Valley, J.W., 2002. Oxygen and neodymium isotope\nevidence for recycling of juvenile crust in northeast China. Geology 30, 375-378.\nYang, W.-B., Niu, H.-C., Hollings, P., Zurevinski, S.E., Li, N.-B., 2017. The Role of Recycled\nOceanic Crust in the Generation of Alkaline A-Type Granites. J. Geophys. Res. Solid\nEarth 122, 9775-9783."}]

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