Spatial and temporal influence of Pacific subduction on South China: geochemical migration of Cretaceous mafic–intermediate rocks

2020 ◽  
Vol 177 (5) ◽  
pp. 1013-1024
Author(s):  
Chengshi Gan ◽  
Yuejun Wang ◽  
Tiffany L. Barry ◽  
Yuzhi Zhang ◽  
Xin Qian
Keyword(s):  
South China ◽  
Igneous Rocks ◽  
Geochemical Data ◽  
Content Type ◽  
The Pacific ◽  
Group A ◽  
Temporal Influence ◽  
Pacific Slab ◽  
Supplementary Material ◽  
Group B

The Cretaceous igneous rocks in the South China Block (SCB) were associated with the slab subduction and roll-back of the Pacific Plate. Thus, they provide excellent opportunities to examine the spatial–temporal geochemical migration of magmatism in the retreating subduction margins. The Cretaceous mafic–intermediate igneous rocks from the southeastern SCB were aged between 142 and 71 Ma, and can geochemically be subdivided into three groups: Group A (126–129 Ma and 83–93 Ma), Group B (126–142 Ma and 71–108 Ma) and Group C (116–142 Ma and 70–110 Ma). Group A and B were mainly distributed in the SCB interior and derived from asthenosphere and asthenosphere–lithosphere interaction sources, respectively. Group C occurred to the east of the Ganjiang Fault and originated from slab–lithosphere interaction. From the coastal provinces to the interior, these mafic–intermediate igneous rocks show increasing incompatible element ratios and Nd isotopic compositions, reflective of a westerly decreasing involvement of slab-derived components. They show two similar age-pulses at c. 125 Ma and c. 90 Ma as well as the Cretaceous A-type granites, indicating two episodes of subduction retreat of the Pacific slab during the Cretaceous. This spatial–temporal pattern of the Cretaceous mafic–intermediate igneous rocks suggests that the Cretaceous slab metasomatism of Pacific subduction retreat was limited to the east of the Ganjiang Fault.Supplementary material: Tables of geochemical data and additional figures are available at https://doi.org/10.6084/m9.figshare.c.4938576

Olivine chemistry of the Quaternary Datong basalts of the Trans-North China Orogen: Insights into mantle source lithology and redox–hydration state

2020 ◽  
pp. SP510-2020-142
Author(s):  
Lubing Hong ◽  
Zhang Yinhui ◽  
Le Zhang ◽  
Yi-Gang Xu ◽  
Zhe Liu ◽  
...  
Keyword(s):  
Oceanic Crust ◽  
Mantle Source ◽  
Partition Coefficients ◽  
North China ◽  
Mantle Wedge ◽  
Content Type ◽  
The Pacific ◽  
Hydration State ◽  
Pacific Slab ◽  
Supplementary Material

AbstractCenozoic intraplate basalts are widespread above the Big Mantle Wedge (BMW) and its front in East Asia. While the mantle source lithology and redox-hydration state have been demonstrated to be crucial in generation of the basalts above the BMW, their nature and role on the basalts above the front of the BMW is poorly constrained. To address this, we report olivine compositions of the Quaternary Datong basalts. The Datong basalts exhibit OIB-like trace-element compositions and depleted Sr-Nd isotopes with slightly enriched signatures (EMI) for tholeiitic basalts. Olivines of the Datong basalts show high Ni and Fe/Mn, and low Ca, Mn, and Mn/Zn values, pointing to a pyroxenite source. Applying V and Ca partition coefficients between olivine and whole-rock, respectively, the Datong basalts lie −0.44 to 0.64 log units above the fayalite-magnetite-quartz buffer for fO2, and contain 2.1-3.4 wt.% H2O but highly variable H2O/Ce values (265-1498). Both fO2 and H2O/Ce in the basalts vary with whole-rock and olivine compositions, indicating the source was the main control, thus, a heterogeneous redox-hydration state in the source: the EMI component being relatively reduced but extremely wet, and recycled oceanic crust being relatively oxidized but dry. The extremely wet EMI component was likely derived from the mantle transition zone. In the light of our findings, we propose a model in which mantle upwelling carried the recycled oceanic crust and EMI component from the MTZ to shallow mantle, due to the Pacific slab stagnating in the MTZ, to form pyroxenite, which subsequently melted to generate the Datong basalts.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5227668

K-bentonites in Ordovician–Silurian transition from South China: implications for tectonic evolution in the northern margin of Gondwana

2020 ◽  
Vol 177 (6) ◽  
pp. 1245-1260 ◽  
Author(s):  
Wei Liu ◽  
Yuan Liu ◽  
Zuoxun Zeng ◽  
Baozhong Yang ◽  
Lianhong Peng ◽  
...  
Keyword(s):  
South China ◽  
Tectonic Evolution ◽  
Hunan Province ◽  
Geochemical Data ◽  
Foreland Basins ◽  
Volcanic Event ◽  
Content Type ◽  
Northern Margin ◽  
Collision Type ◽  
Supplementary Material

Numerous K-bentonites from the Ordovician–Silurian (O–S) transition in South China record important information about the geodynamics of volcanic activity in the northern margin of Gondwana. A series of K-bentonite beds have been identified in the Zhoujiaxi Group (Early Silurian) in foreland basins from central Hunan Province, China. They are dominantly composed of illite with minor kaolinite. Volcanogenic minerals include quartz, feldspar, biotite, and lesser apatite and zircon. U–Pb zircon ages from three beds, 442.8 ± 1.8, 442.2 ± 1.9 and 441.6 ± 2.0 Ma are compatible with the age of the O–S global boundary. Geochemical results indicate calc-alkaline felsic magmas derived from continental crust and erupted in a subduction-related collisional environment. Isopach schemes and grain size reveal that the volcanic ashes were sourced from a volcanic event likely with a volcanic explosivity index of 8, and transported 300–1000 km away from the palaeo SSE. The volcanism was associated with northwestern subduction of the Zhenghe-Dapu Ocean beneath the southeastern South China Block (SCB) on the northern margin of Gondwana. The Zhenghe-Dapu fault might be a suture zone, implying the consumption of the Zhenghe-Dapu Ocean during collision between the Nanhai terrane and the SCB. This study supports that the Wuyi-Yunkai Orogenic Belt is a collision-type orogen rather than an intraplate belt.Supplementary material: Plots and geochemical data are available at https://doi.org/10.6084/m9.figshare.c.5027096

Beta—tricalcium phosphate as a substitute for autograft in interbody fusion cages in the canine lumbar spine

2002 ◽  
Vol 97 (3) ◽  
pp. 350-354 ◽  
Author(s):  
Takashiro Ohyama ◽  
Yoshichika Kubo ◽  
Hiroo Iwata ◽  
Waro Taki
Keyword(s):  
Lumbar Spine ◽  
Tricalcium Phosphate ◽  
Interbody Fusion ◽  
Donor Site ◽  
Posterolateral Approach ◽  
Content Type ◽  
Spine Model ◽  
Group A ◽  
Group B ◽  
Fine Print

Object. An interbody fusion cage has been introduced for cervical anterior interbody fusion. Autogenetic bone is packed into the cage to increase the rate of union between adjacent vertebral bodies. Thus, donor site—related complications can still occur. In this study a synthetic ceramic, β—tricalcium phosphate (TCP), was examined as a substitute for autograft bone in a canine lumbar spine model. Methods. In 12 dogs L-1 to L-4 vertebrae were exposed via a posterolateral approach, and discectomy and placement of interbody fusion cages were performed at two intervertebral disc spaces. One cage was filled with autograft (Group A) and the other with TCP (Group B). The lumbar spine was excised at 16 weeks postsurgery, and biomechanical, microradiographic, and histological examinations were performed. Both the microradiographic and histological examinations revealed that fusion occurred in five (41.7%) of 12 operations performed in Group A and in six (50%) of 12 operations performed in Group B. The mean percentage of trabecular bone area in the cages was 54.6% in Group A and 53.8% in Group B. There were no significant intergroup differences in functional unit stiffness. Conclusions. Good histological and biomechanical results were obtained for TCP-filled interbody fusion cages. The results were comparable with those obtained using autograft-filled cages, suggesting that there is no need to harvest iliac bone or to use allo- or xenografts to increase the interlocking strength between the cage and vertebral bone to achieve anterior cervical interbody fusion.

Prevention of postoperative posterior tethering of spinal cord after resection of ependymoma

2003 ◽  
Vol 99 (2) ◽  
pp. 181-187 ◽  
Author(s):  
Takeo Goto ◽  
Kenji Ohata ◽  
Toshihiro Takami ◽  
Misao Nishikawa ◽  
Akimasa Nishio ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Neurological Deterioration ◽  
Fisher Exact Test ◽  
Content Type ◽  
Exact Test ◽  
Spinal Ependymoma ◽  
Group A ◽  
Delayed Neurological Deterioration ◽  
Group B ◽  
Fine Print

Object. The authors evaluated an alternative method to avoid postoperative posterior tethering of the spinal cord following resection of spinal ependymomas. Methods. Twenty-five patients with spinal ependymoma underwent surgery between 1978 and 2002. There were 16 male and nine female patients whose ages at the time of surgery ranged from 14 to 64 years (mean 41.8 years). The follow-up period ranged from 6 to 279 months (mean 112.4 months). In the initial 17 patients (Group A), the procedure to prevent arachnoidal adhesion consisted of the layer-to-layer closure of three meninges and laminoplasty. In the subsequently treated eight patients (Group B), the authors performed an alternative technique that included pial suturing, dural closure with Gore-Tex membrane—assisted patch grafting, and expansive laminoplasty. In Group A, postoperative adhesion was radiologically detected in eight cases (47%), and delayed neurological deterioration secondary to posterior tethering of the cord was found in five cases. In Group B, there was no evidence of adhesive posterior tethering or delayed neurological deterioration. A significant intergroup statistical difference was demonstrated for radiologically documented posterior tethering (p < 0.05, Fisher exact test). Moreover, patients with radiologically demonstrated posterior tethering suffered a significant delayed neurological functional deterioration (p < 0.01, Fisher exact test). Conclusions. This new technique for closure of the surgical wound is effective in preventing of postoperative posterior spinal cord tethering after excision of spinal ependymoma.

A positron emission tomography study of cerebrovascular reserve before and after shunt surgery in patients with idiopathic chronic hydrocephalus

1999 ◽  
Vol 91 (4) ◽  
pp. 605-609 ◽  
Author(s):  
Petra M. Klinge ◽  
Georg Berding ◽  
Thomas Brinker ◽  
Wolfram H. Knapp ◽  
Madjid Samii
Keyword(s):  
Positron Emission Tomography ◽  
Emission Tomography ◽  
Chronic Hydrocephalus ◽  
Content Type ◽  
Cerebrovascular Reserve ◽  
Shunt Placement ◽  
Positron Emission ◽  
Group A ◽  
Group B ◽  
Fine Print

Object. In this study the authors use positron emission tomography (PET) to investigate cerebral blood flow (CBF) and cerebrovascular reserve (CVR) in chronic hydrocephalus.Methods. Ten patients whose mean age was 67 ± 10 years (mean ± standard deviation [SD]) were compared with 10 healthy volunteers who were 25 ± 3 years of age. Global CBF and CVR were determined using 15O—H2O and PET prior to shunt placement and 7 days and 7 months thereafter. The CVR was measured using 1 g acetazolamide. Neurological status was assessed based on a score assigned according to the methods of Stein and Langfitt.Seven months after shunt placement, five patients showed clinical improvement (Group A) and five did not (Group B). The average global CBF before shunt deployment was significantly reduced in comparison with the control group (40 ± 8 compared with 61 ± 7 ml/100 ml/minute; mean ± SD, p < 0.01). In Group A the CBF values were significantly lower than in Group B (36 ± 7 compared with 44 ± 8 ml/100 ml/minute; p < 0.05). The CVR before surgery, however, was not significantly different between groups (Group A = 43 ± 21%, Group B = 37 ± 29%). After shunt placement, there was an increase in the CVR in Group A to 52 ± 37% after 7 days and to 68 ± 47% after 7 months (p < 0.05), whereas in Group B the CVR decreased to 14 ± 18% (p < 0.05) after 7 days and returned to the preoperative level (39 ± 6%) 7 months after shunt placement.Conclusions. The preliminary results indicate that a reduced baseline CBF before surgery does not indicate a poor prognosis. Baseline CBF before shunt placement and preoperative CVR are not predictive of clinical outcome. A decrease in the CVR early after shunt placement, however, is related to poor late clinical outcome, whereas early improvement in the CVR after shunt placement indicates a good prognosis.

scholarly journals Temporal Variability of Coastal Planctomycetes Clades at Kabeltonne Station, North Sea

2011 ◽  
Vol 77 (14) ◽  
pp. 5009-5017 ◽  
Author(s):  
Ilaria Pizzetti ◽  
Bernhard M. Fuchs ◽  
Gunnar Gerdts ◽  
Antje Wichels ◽  
Karen H. Wiltshire ◽  
...  
Keyword(s):  
16S Rrna ◽  
North Sea ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Content Type ◽  
Group A ◽  
Related Group ◽  
Group B ◽  
Card Fish ◽  
Group D

ABSTRACTMembers of the bacterial phylumPlanctomycetesare reported in marine water samples worldwide, but quantitative information is scarce. Here we investigated the phylogenetic diversity, abundance, and distribution ofPlanctomycetesin surface waters off the German North Sea island Helgoland during different seasons by 16S rRNA gene analysis and catalyzed reporter deposition fluorescencein situhybridization (CARD-FISH). GenerallyPlanctomycetesare more abundant in samples collected in summer and autumn than in samples collected in winter and spring. Statistical analysis revealed thatPlanctomycetesabundance was correlated to theCentralesdiatom bloom in spring 2007. The analysis of size-fractionated seawater samples and of macroaggregates showed that ∼90% of thePlanctomycetesreside in the >3-μm size fraction. Comparative sequence analysis of 184 almost full-length 16S rRNA genes revealed three dominant clades. The clades, namedPlanctomyces-related group A, unculturedPlanctomycetesgroup B, andPirellula-related group D, were monitored by CARD-FISH using newly developed oligonucleotide probes. All three clades showed recurrent abundance patterns during two annual sampling campaigns. UnculturedPlanctomycetesgroup B was most abundant in autumn samples, whilePlanctomyces-related group A was present in high numbers only during late autumn and winter. The levels ofPirellula-related group D were more constant throughout the year, with elevated counts in summer. Our analyses suggest that the seasonal succession of thePlanctomycetesis correlated with algal blooms. We hypothesize that the niche partitioning of the different clades might be caused by their algal substrates.

Suboccipital and cervical chordomas: the value of aggressive treatment at first presentation of the disease

2002 ◽  
Vol 97 (5) ◽  
pp. 1070-1077 ◽  
Author(s):  
Alexandre Carpentier ◽  
Marc Polivka ◽  
Alexandre Blanquet ◽  
Guillaume Lot ◽  
Bernard George
Keyword(s):  
Clinical Symptoms ◽  
Rank Test ◽  
Aggressive Treatment ◽  
Actuarial Survival ◽  
High Tendency ◽  
Content Type ◽  
Log Rank Test ◽  
Group A ◽  
Group B ◽  
Fine Print

Object. Chordoma is a locally invasive tumor with a high tendency for recurrence for which radical resection is generally recommended. To assess the benefits of aggressive treatment of chordomas, the authors compared results in patients treated aggressively at the first presentation of this disease with results in patients who were similarly treated, but after recurrence. Methods. Among 36 patients with cervical chordomas who were treated at the authors' institution, 22 underwent primary aggressive treatment (Group A) and 14 were treated secondarily after tumor recurrence (Group B). Two cases were excluded from Group A because of unrelated early deaths and three from Group B because of insufficient pre- or postoperative data. Most tumors were located at the suboccipital level and only eight cases at a level below C-2. Radiotherapy and proton therapy were similarly conducted in both groups of patients. The actuarial survival rates were 80 and 65% at 5 and 10 years, respectively, in Group A patients and 50 and 0% at 5 and 10 years, respectively, in Group B patients (p = 0.049, log-rank test). The actuarial recurrence-free rates were 70 and 35% at 5 and 10 years, respectively, in Group A and 0% at 3 years in Group B (p < 0.0001, log-rank test). The numbers of recurrences per year were 0.15 in Group A and 0.62 in Group B (p > 0.05). All other parameters that were analyzed (patient age, delay before diagnosis, clinical symptoms, chondroid type of lesion, and histological features) did not prove to influence prognosis in a statistically significant manner. Conclusions. Aggressive therapy, combining as radical a resection as possible with radiotherapy, seems to improve the prognoses of suboccipital and cervical chordomas when applied at the patient's first presentation with the disease.

scholarly journals Interspecies Communication among Commensal and Pathogenic Streptococci

mBio ◽  
2013 ◽  
Vol 4 (4) ◽  
Author(s):  
Laura C. Cook ◽  
Breah LaSarre ◽  
Michael J. Federle
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Human Pathogens ◽  
Streptococcus Dysgalactiae ◽  
Interspecies Communication ◽  
Content Type ◽  
Streptococcal Species ◽  
Group A ◽  
Group B ◽  
Regulated Gene Expression

ABSTRACTQuorum sensing (QS) regulates diverse and coordinated behaviors in bacteria, including the production of virulence factors, biofilm formation, sporulation, and competence development. It is now established that some streptococci utilize Rgg-type proteins in concert with short hydrophobic peptides (SHPs) to mediate QS, and sequence analysis reveals that several streptococcal species contain highly homologous Rgg/SHP pairs. In group A streptococcus (GAS), two SHPs (SHP2 and SHP3 [SHP2/3]) were previously identified to be important in GAS biofilm formation. SHP2/3 are detected by two antagonistic regulators, Rgg2 and Rgg3, which control expression of theshpgenes. In group B streptococcus (GBS), RovS is a known virulence gene regulator and ortholog of Rgg2, whereas no apparent Rgg3 homolog exists. Adjacent torovSis a gene (shp1520) encoding a peptide nearly identical to SHP2. Using isogenic mutant strains and transcriptional reporters, we confirmed that RovS/SHP1520 comprise a QS circuit in GBS. More important, we performed experiments demonstrating that production and secretion of SHP1520 by GBS can modulate Rgg2/3-regulated gene expression in GAS intrans; likewise, SHP2/3 production by GAS can stimulate RovS-mediated gene regulation in GBS. An isolate ofStreptococcus dysgalactiaesubsp.equisimilisalso produced a secreted factor capable of simulating the QS circuits of both GAS and GBS, and sequencing confirms the presence of an orthologous Rgg2/SHP2 pair in this species as well. To our knowledge, this is the first documented case of bidirectional signaling between streptococcal species in coculture and suggests a role for orthologous Rgg/SHP systems in interspecies communication between important human pathogens.IMPORTANCEPathogenic streptococci, such as group A (GAS) and group B (GBS) streptococcus, are able to persist in the human body without causing disease but become pathogenic under certain conditions that are not fully characterized. Environmental cues and interspecies signaling between members of the human flora likely play an important role in the transition to a disease state. Since quorum-sensing (QS) peptides have been consistently shown to regulate virulence factor production in pathogenic species, the ability of bacteria to signal via these peptides may prove to be an important link between the carrier and pathogenic states. Here we provide evidence of a bidirectional QS system between GAS, GBS, andStreptococcus dysgalactiaesubsp.equisimilis, demonstrating the possibility of evolved communication systems between human pathogens.

Tethered cord syndrome of delayed onset following repair of myelomeningocele

1988 ◽  
Vol 69 (3) ◽  
pp. 393-398 ◽  
Author(s):  
Norihiko Tamaki ◽  
Kunio Shirataki ◽  
Noriaki Kojima ◽  
Yoshiteru Shouse ◽  
Satoshi Matsumoto
Keyword(s):  
Preoperative Evaluation ◽  
Tethered Cord ◽  
Tethered Cord Syndrome ◽  
Clear Understanding ◽  
Mr Images ◽  
Content Type ◽  
Delayed Onset ◽  
Group A ◽  
Group B ◽  
Fine Print

✓ Nine (15%) of 60 patients with repaired myelomeningocele exhibited late deterioration of neurological function with a tethered cord syndrome. Dense adhesions at the lowest laminae and at the site of previous repair were the most common findings at surgery. Postoperatively, 71% of the patients improved. Magnetic resonance (MR) imaging was performed in 29 of the 60 patients. Eight of these 29 patients exhibited a tethered cord syndrome. The MR images in all patients showed a low-lying conus fixed at the site of previous repair, irrespective of the presence or absence of a tethered cord syndrome. The MR images were classified into two groups depending upon the site of adhesions: Group A had potential sites of tethering at the ventral aspect of the last laminae and at the site of previous repair, and Group B showed the adhesion point only at the site of previous repair. Most patients with a tethered cord syndrome were found to be in Group A; conversely, most patients without the syndrome were in Group B. An enlarged low conus was seen in symptomatic patients more commonly than in those without this syndrome. It is concluded that the presence of adhesions specifically at the last laminae as well as a widened low-lying conus may be the cause of tethered cord syndrome in patients with repaired myelomeningoceles. A clear understanding of the tethering process and preoperative evaluation of potential sites of tethering, based on the MR findings, are very important for planning surgery. The release of adhesions at the lowest laminae by laminectomy appeared essential for improvement.

scholarly journals Diversity and Evolution of the Tn5801-tet(M)-Like Integrative and Conjugative Elements among Enterococcus, Streptococcus, and Staphylococcus

2016 ◽  
Vol 60 (3) ◽  
pp. 1736-1746 ◽  
Author(s):  
Ricardo León-Sampedro ◽  
Carla Novais ◽  
Luísa Peixe ◽  
Fernando Baquero ◽  
Teresa M. Coque
Keyword(s):  
Integration Site ◽  
Hot Spot ◽  
Gc Content ◽  
Content Type ◽  
Integrative And Conjugative Elements ◽  
Group A ◽  
Group B ◽  
Site Identification ◽  
Different Origins ◽  
Bacterial Groups

This work describes the diversity and evolution of Tn5801among enterococci, staphylococci, and streptococci based on analysis of the 5,073 genomes of these bacterial groups available in gene databases. We also examined 610 isolates ofEnterococcus(from 10 countries, 1987 to 2010) for the presence of this and other known CTn-tet(M) elements due to the scarcity of data about Tn5801among enterococci. Genome location (by ICeu-I–pulsed-field gel electrophoresis [PFGE] hybridization/integration site identification), conjugation and fitness (by standard methods), Tn5801characterization (by long-PCR mapping/sequencing), and clonality (by PFGE/multilocus sequence typing [MLST]) were studied. Twenty-three Tn5801variants (17 unpublished) clustered in two groups, designated “A” (25 kb;n= 14; predominant inStaphylococcus aureus) and “B” (20 kb;n= 9; predominant inStreptococcus agalactiae). The percent GC content of the common backbone suggests a streptococcal origin of Tn5801group B, with further acquisition of a 5-kb fragment that resulted in group A. Deep sequence analysis allowed identification of variants associated with clonal lineages ofS. aureus(clonal complex 8 [CC8], sequence type 239 [ST239]),S. agalactiae(CC17),Enterococcus faecium(ST17/ST18), orEnterococcus faecalis(ST8), local variants, or variants located in different species and geographical areas. All Tn5801elements were chromosomally located upstream of theguaAgene, which serves as an integration hot spot. Transferability was demonstrated only for Tn5801type B amongE. faecalisclonal backgrounds, which eventually harbored another Tn5801copy. The study documents early acquisition of Tn5801byEnterococcus,Staphylococcus, andStreptococcus. Clonal waves of these pathogens seem to have contributed to the geographical spread and local evolution of the transposon. Horizontal transfer, also demonstrated, could explain the variability observed, with the isolates often containing sequences of different origins.

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