156 research outputs found
Chronology and geochemical composition of cassiterite and zircon from the Maodeng Sn-Cu deposit, Northeastern China: Implications for magmatic-hydrothermal evolution and ore-forming process
Primary tin deposits usually contain little or no copper due to the distinct geochemistry of Sn and Cu. However, examples of copper-rich tin deposits in many tin provinces around the world are also well known. The genesis of copper-rich tin deposits remains controversial. The Maodeng Sn-Cu polymetallic, a typical Cu-rich Sn deposit in the southern Great Xing'an Range (SGXR) Northeast China, offers an excellent opportunity to reveal the genesis of coupled copper-tin deposits. The ore mineralization is associated with the granite porphyry, complement phase of the Alubaogeshan complex, which emplaced into the volcanic rocks of the Lower Permian Dashizhai Formation. Herein, we report new zircon and cassiterite U-Pb ages and their trace elements compositions, with the aim of constraining the metallogenic chronology framework, and clarifying the indicative effects of the ore-forming fluids on mineralization in different ore-forming stages, and thus establishing the genetic model for the Sn-Cu deposit. LA-ICP-MS U-Pb dating of zircon from the granite porphyry yields a weighted mean U-Pb age of 134.6 ± 0.4 Ma, which consistent to the zircon U-Pb age (ca. 138 Ma) of porphyry monzogranite (main phase of the Alubaogeshan complex) and cassiterite U-Pb ages (137–140 Ma), suggesting an Early Cretaceous Sn-Cu mineralization under the Paleo-Pacific plate slab roll-back setting. Granite porphyry displays more evolved characterisrics, with higher SiO2 contents (71.5 ∼ 77.4 wt%), Rb/Sr ratios (3.39 ∼ 10.33) and lower Nb/Ta ratios (10.86 ∼ 13.06) compared to those of porphyry monzogranite (SiO2 contents of 70.4 ∼ 72.1 wt%; Rb/Sr and Nb/Ta ratios of 1.03 ∼ 1.72 and 13.34 ∼ 15.83, respectively). This is further supported by the trace elements contents of zircons from granite porphyry and porphyry monzogranite, because the former has a stronger Eu anomaly, higher Hf concentrations, lower Zr/Hf and Th/U ratios than the latter. Our new data, integrated with previously published geochemical data, suggest that the granites associated with Cu-rich Sn deposits are characterized by higher oxygen fugacity, lower differential degree and aluminum saturation index (ASI) than those of Sn-W deposits. This could also use to address the Sn-Cu deposits usually have relatively small Sn mineralization potential. The trace elements of the cassiterites are characterized by high Fe (up to 3358 ppm), Ti (up to 1894 ppm) and abnormal high In (∼2500 ppm) concentrations, but low Nb, Ta contents. From early to late stage, the W and U contents and Nb/Ta and Zr/Hf ratios are increased, reveal that the ore-forming process experienced the cooling, increasing volatile contents and fluid-rock reaction. Finally, a new metallogenic model was established, which highlight oxidized Cu-rich fluids exsolved from the upwelling mantle magma would add to the reduced, Sn-rich magma chambers. This contribution indicate that, the Cu and Sn metals come from the mantle magma and crustal granitic magma, respectively, and that Cu-rich Sn deposits are more likely a product of spatial coupling
The Size-Mass Relation of Post-Starburst Galaxies in the Local Universe
We present a study of the size--mass relation for local post-starburst (PSB)
galaxies at selected from the Sloan Digital Sky Survey Data
Release 8. We find that PSB galaxies with stellar mass () at
have their galaxy size smaller than or
comparable with those of quiescent galaxies (QGs). After controlling redshift
and stellar mass, the sizes of PSBs are smaller on average than
those of QGs, such differences become larger and significant towards the
low- end, especially at where PSBs can be on average smaller than QGs.
In comparison with predictions of possible PSB evolutionary pathways from
cosmological simulations, we suggest that a fast quenching of star formation
following a short-lived starburst event (might be induced by major merger)
should be the dominated pathway of our PSB sample. Furthermore, by
cross-matching with group catalogs, we confirm that local PSBs at
are more clustered than more massive ones. PSBs
resided in groups are found to be slightly larger in galaxy size and more
disk-like compared to field PSBs, which is qualitatively consistent with and
thus hints the environment-driven fast quenching pathway for group PSBs. Taken
together, our results support multiple evolutionary pathways for local PSB
galaxies: while massive PSBs are thought of as products of fast quenching
following a major merger-induced starburst, environment-induced fast quenching
should play a role in the evolution of less massive PSBs, especially at
.Comment: 16 pages, 7 figures; accepted for publication in Ap
Robust Adaptive Dynamic Surface Control for a Class of Nonlinear Dynamical Systems with Unknown Hysteresis
The output tracking problem for a class of uncertain strict-feedback nonlinear systems with unknown Duhem hysteresis input is investigated. In order to handle the undesirable effects caused by
unknown hysteresis, the properties in respect to Duhem model are used to decompose it as a nonlinear smooth term and a nonlinear bounded “disturbance-like” term, which makes it possible to deal with the unknown hysteresis without constructing inverse in the controller design. By combining robust control and dynamic surface control technique, an adaptive controller is proposed in this paper to avoid “the explosion complexity” in the standard backstepping design procedure. The negative effects caused by the unknown hysteresis can be mitigated effectively, and the semiglobal uniform
ultimate boundedness of all the signals in the closed-loop system is obtained. The effectiveness of the proposed scheme is validated through a simulation example
The ISM scaling relations using inner HI and an application of estimating dust mass
We select a disk-like galaxy sample with observations of the ,
and dust from Herschel Reference Survey (HRS), and derive inner HI masses
within the optical radius. We find that the inner gas-to-dust ratio is almost
independent of gas-phase metallicity, and confirm that the inner gas mass
(+) shows tighter relationship with dust mass and monochromatic 500
luminosity than the integral gas mass. It supports that dust is more
closely associated with co-spatial cold gas than the overall cold gas. Based on
the newly calibrated relationship between inner gas mass and dust mass, we
predict dust masses for disk-dominated galaxies from the xCOLD GASS sample. The
predicted dust masses show scaling relations consistent with fiducial ones in
the literature, supporting their robustness. Additionally, we find that at a
given dust mass and star formation rate (SFR), the galactic WISE W3
luminosities show significant dependence on the [NII] luminosity and the
stellar mass surface density. Such dependence highlights the caveat of using
the W3 luminosity as integral SFR indicator, and is consistent with findings of
studies which target star-forming regions in more nearby galaxies and
accurately derive dust masses based on mapping-mode spectroscopy.Comment: 21 pages, 8 figures, 3 tables. Accepted for Publication in Ap
Learning Domain-Aware Detection Head with Prompt Tuning
Domain adaptive object detection (DAOD) aims to generalize detectors trained
on an annotated source domain to an unlabelled target domain. However, existing
methods focus on reducing the domain bias of the detection backbone by
inferring a discriminative visual encoder, while ignoring the domain bias in
the detection head. Inspired by the high generalization of vision-language
models (VLMs), applying a VLM as the robust detection backbone following a
domain-aware detection head is a reasonable way to learn the discriminative
detector for each domain, rather than reducing the domain bias in traditional
methods. To achieve the above issue, we thus propose a novel DAOD framework
named Domain-Aware detection head with Prompt tuning (DA-Pro), which applies
the learnable domain-adaptive prompt to generate the dynamic detection head for
each domain. Formally, the domain-adaptive prompt consists of the
domain-invariant tokens, domain-specific tokens, and the domain-related textual
description along with the class label. Furthermore, two constraints between
the source and target domains are applied to ensure that the domain-adaptive
prompt can capture the domains-shared and domain-specific knowledge. A prompt
ensemble strategy is also proposed to reduce the effect of prompt disturbance.
Comprehensive experiments over multiple cross-domain adaptation tasks
demonstrate that using the domain-adaptive prompt can produce an effectively
domain-related detection head for boosting domain-adaptive object detection
ChIP-Hub provides an integrative platform for exploring plant regulome
Plant genomes encode a complex and evolutionary diverse regulatory grammar that forms the basis for most life on earth. A wealth of regulome and epigenome data have been generated in various plant species, but no common, standardized resource is available so far for biologists. Here, we present ChIP-Hub, an integrative web-based platform in the ENCODE standards that bundles >10,000 publicly available datasets reanalyzed from >40 plant species, allowing visualization and meta-analysis. We manually curate the datasets through assessing ~540 original publications and comprehensively evaluate their data quality. As a proof of concept, we extensively survey the co-association of different regulators and construct a hierarchical regulatory network under a broad developmental context. Furthermore, we show how our annotation allows to investigate the dynamic activity of tissue-specific regulatory elements (promoters and enhancers) and their underlying sequence grammar. Finally, we analyze the function and conservation of tissue-specific promoters, enhancers and chromatin states using comparative genomics approaches. Taken together, the ChIP-Hub platform and the analysis results provide rich resources for deep exploration of plant ENCODE. ChIP-Hub is available at https://biobigdata.nju.edu.cn/ChIPHub/.Peer Reviewe
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