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Rubiaceae is the fourth largest and a taxonomically complex family of angiosperms . Many species in this family harbor low reproductive isolation and frequently exhibit inconsistent phenotypic characteristics. Therefore, taxonomic classification and their phylogenetic relationships in the Rubiaceae family is challenging, especially in the genus Leptodermis. Considering the low taxonomic confusion and wide distribution, Leptodermis oblonga is selected as a representative Leptodermis for genome sequencing. The assemblies resulted in 497 Mbp nuclear and 155,100 bp chloroplast genomes , respectively. Using the nuclear genome as a reference, SNPs were called from 37 Leptodermis species or varieties. The phylogenetic tree based on SNPs exhibited high resolution for species delimitation of the complex and well-resolved phylogenetic relationships in the genus. Moreover, 28,987 genes were predicted in the nuclear genome and used for comparative genomics study. As the first chromosomal-level genome of the subfamily Rubioideae in Rubiaceae, it will provide fruitfully evolutionary understanding in the family.

Leptodermis scabrida complex is one of the important components of genus Leptodermis, which is mainly distributed in the Himalaya Mountains. It includes species of L. gracilis, L. hirsutiflora, L. hirsutiflora var. ciliata, L. kumaonensis, L. pilosa var. acanthoclada and L. scabrida. However, species boundaries and relationships within this complex are unclear based on current morphological and molecular evidence. We sequenced 13 complete chloroplast (cp) genomes representing seven taxa of the complex and two non-Leptodermis scabrida complex taxa. After de novo assembly and annotation, we performed comparative genomic analysis. All cp genomes showed highly conserved structures, and the genome sizes ranged from 154,369 bp to 154,885 bp and possessed the same GC content (37.5%). A total of 113 unique genes were identified in each cp sample, including 79 protein coding genes, 30 tRNAs, and four rRNAs. Repeat sequences and SSRs were detected, showing great similarity among all taxa in this complex. Six highly variable regions, including trnS-trnG, rps2-rpoC2, ndhF, rpl32-ccsA, ccsA-ndhD, and ndhA, were screened as potential molecular markers for phylogenetic reconstruction. Based on a total of 27 complete cp genome sequences, the consistent and robust phylogenetic relationships were firstly constructed and the same species within L. scabrida complex clustered into a group. The divergence time of Leptodermis from ancestral taxa occurred at the middle Eocene, which might be due to geological and climatic changes. The 13 complete cp genome sequences reported will provide new clues for phylogeny elucidation, species identification and evolutionary history speculation of Leptodermis, as well as in Rubiaceae.

Isotopes (Rb Sr, C, O, S, and Pb) were investigated from the Zhenzigou Pb Zn deposit in the Qingchengzi mineral field (QMF) of the North China Craton as an aid to determine the genesis of stratiform Pb Zn deposits in the Liao-Ji Rift. A step-dissolution Rb Sr age of 1798 ± 8 Ma with 206Pb/204Pb ratios of 17.7477–17.8527 were obtained from sphalerite. Sulfur isotopic ratios for pyrite (5–14.4‰), sphalerite (2.4–8.6‰), and galena (− 0.3–8.6‰) from Zhenzigou have a narrower range than those from the host Paleoproterozoic Dashiqiao Formation, and granite in the area. Calcite and limestone from ore and wallrocks at the deposit have similar C and O isotope compositions, with δ13CPDB ranging from − 6.0 to − 2.3‰ and δ18OSMOW from 9.8 to 13.7‰, which are similar to those of carbonatite and the mantle. Comprehensive analysis of the Pb isotopic composition of the sulfide from the Zhenzigou deposit and Pb Zn deposits in adjacent area show that the Pb originated from the upper crust and mixed with Pb from the mantle. Sulfur isotopes from Zhenzigou deposit indicate that the mineralization has a volcanic eruption source. The δ13CPDB and δ18OSMOW values indicate that the CO2 originated from a mixed mantle, marine carbonate and organic source. Combined with the study of regional metallogenic background, this paper proposes that deposition of stratiform Pb Zn mineralization in the QMF began ca. 2052 Ma during development of the Liaoji Rift. The mineralization extended to ca. 1798 Ma prior to deformation associated with the Lvliang Movement, which dismembered the stratiform Pb Zn mineralization. The veined mineralization in the region cross-cuts the stratiform deposits and represents remobilized and redeposited deposits associated with the emplacement of Triassic plutons such as the Xinling and Shuangdinggou granites.

During geological investigations conducted over the past several years, the authors found a group of A-type granites in the middle segment of the Bangonghu–Nujiang suture on the Tibetan plateau. These granitic plutons occur as stocks with exposed areas of less than 1 km 2 and lithologically include biotite granite and granodiorite porphyry, which had intruded into Cretaceous sedimentary rocks. Petrogeochemically, the A-type granites contain high SiO 2 levels varying from 68.62%–75.36 wt.%. Moreover, they contain relatively high Fe 2 O 3 T (0.86–5.39 wt.%) and low Al 2 O 3 (12.76–15.54 wt.%) levels and are weak peraluminous to metaluminous. A trace element N-MORB-normalized spider diagram showed apparent enrichment of the large ion lithophile elements (LILE) Rb, Th, U, K, and Pb with marked depletions of Ba and Sr. The high field strength elements (HFSE) Nb, Ta and Ti were sharply depleted, with relative enrichment of Zr and Hf. These signatures are characteristic of A-type granite. The granite samples had high rare earth element (REE) contents with ∑ REE = 122.37–291.19 ppm. Light REE were rich relative to heavy REE with LREE/HREE = 4.89–9.58. And negative Eu anomalies were sharp with δEu varying from 0.14–0.5 and a mean value of 0.34. Their chondrite-normalized rare earth element distribution patterns appear as gently right-dipping V-types. Zircon U–Pb LAICPMS dating for three granitic plutons yielded weighted mean ages of 109.6 ± 1.4 Ma (MSWD = 3.7), 112.3 ± 0.51 Ma (MSWD = 0.21) and 113.73 ± 0.5 Ma (MSWD = 0.21), indicating that they formed in the late stage of the early Cretaceous epoch. The Nd, Sr and Pb isotopic results showed that the granites were rich in radiogenic isotopes. The 87 Sr/ 86 Sr and I Sr ratios varied from 0.719842–0.786395 and 0.706900–0.710378, respectively. The 143 Nd/ 144 Nd ratios were from 0.512123–0.512392, with relatively large negative e Nd values (− 3.37 to − 10.34). The 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb ratios ranged from 18.703–19.070, 15.680–15.732 and 39.121–39.576, respectively, exhibiting isotopic signatures typical of crustal sources. All of the data demonstrated unanimously that these granites were derived from partial melting of arc basaltic rocks underplated in the lower crust during oceanic crust subduction. The high-temperature heat source for melting of anhydrous basaltic rocks of the lower crust was from upwelling asthenosphere through slab windows formed as a result of slab break-off during post-collisional extension of the orogenic zone.