Decoupling of Lu-Hf and Sm-Nd Isotopic System in Deep-Seated Xenoliths from the Xuzhou-Suzhou Area, China: Differences in Element Mobility during Metamorphism

Meng, Fanhao; Xu, Wen‐Liang; Xu, Qinglin; Guo, Jingliang

doi:10.1007/s12583-019-1255-4

Cited by 6 publications

(1 citation statement)

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“…They document a decoupling of the Lu-Hf and Sm-Nd isotopic systems and the Lu/Hf isochron age of 2 424 Ma is similar to the zircon age peak of the studied xenoliths and the dominant age of NCC basement, indicating an affinity of the igneous protoliths of the xenoliths to the Archean basement of the NCC. Thus, the data gained by Meng F X et al (2019) valuable contribute to a better understanding of the development of the lower crust beneath this part of the NCC.…”

Section: Metamorphism and Orogenic Belts-contributions To This Speciamentioning

confidence: 99%

Preface: Metamorphism and Orogenic Belts—Response from Micro- to Macro-Scale

Schertl

Reinhardt

2019

J. Earth Sci.

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The geological toolbox for the analysis of orogenic processes has seen substantial additions over the recent decades. Major advances have been made in the ability to simulate geological conditions and processes by computer modeling, we have a much improved knowledge of geochemical processes (trace elements and isotopes in particular), and, last but not least, the range and versatility of micro-analytical methods and instrumentation available to us has been expanded dramatically. The latter aspect has had a particular impact on metamorphic petrology as the conventional tools to determine pressure-temperaturetime paths via rock and mineral analysis combined with isotope geochronology have generally gained in precision and accuracy through a much improved resolution. Geochronology has moved from whole-grain analysis to spot analyses on zoned single grains while analyzing trace elements and isotopes at the same time. It is therefore possible to recognize complex multi-stage orogenic events in single samples or single grains. Diffusion profiles in minerals provide us with timescales of metamorphic and magmatic processes. Major and trace elements as well as isotope profiles of mineral grains give us insight into changing ambient conditions during mineral growth. This special issue focuses on pressure-temperature conditions and geochronology of metamorphic rocks, isotope studies of magmatic rocks, partial melting and metasomatic processes, all with a view at tectonic implications and orogeny. Much of the evidence has been gained from small-scale observation and analysis. Diligent field work and detailed microscopic examination remain indispensable, though, as demonstrated clearly by the "expansion" of the P-T space as applicable to crustal metamorphic processes towards extreme pressures and temperatures. As a consequence, much interest has thus focused on UHP and UHT rocks and the orogenic processes that generate them. There is petrological evidence for subduction to, and subsequent exhumation from, depths in excess of 250 km. While this impacts substantially on the large-scale geodynamic models of orogenic processes, the evidence is gathered primarily from small-scale petrological observation. The same applies in principle to UHT granulites. To generate temperatures in the 900 to 1 100 C range within the sillimanite stability field in orogenic heat budget models remains a serious challenge, however. The large overlap of solid-state metamorphism, partial anatexis and magmatic crystallization in P-T space suggests close interrelationships, and the role and contribution of the diverse magmatic activities in forming orogenic belts, from the onset of subduction to late-orogenic delamination or slab-break-off is crucial for our understanding of geodynamics, with focus on geochemistry and geochronology. Aspects of metasomatism in the framework of orogeny are given some special consideration in this issue. The topics include the formation of sagvandite, pyrope quartzite (or whiteschist), jadeitite and rodingite. One of the ke...

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Section: Metamorphism and Orogenic Belts-contributions To This Speciamentioning

confidence: 99%