Comparison of Different‐sized Chromite Mineralizations in the Yarlung‐Zangbo Ophiolite Belt, Southern Tibet
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2017-05-01 |
| Journal | Acta Geologica Sinica - English Edition |
| Authors | Xiangkun Zhu, Yu-Wei She, Yuan He, Jianxiong Ma, Jian Sun |
| Institutions | Chinese Academy of Geological Sciences |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Documentation & Commercial Analysis: MPCVD Diamond for Extreme Environment Geochemical Analysis
Section titled “Technical Documentation & Commercial Analysis: MPCVD Diamond for Extreme Environment Geochemical Analysis”Executive Summary
Section titled “Executive Summary”This research paper, detailing the formation mechanisms of chromitite deposits in the Yarlung-Zangbo Ophiolite Belt, underscores the need for high-stability, chemically inert materials—such as MPCVD Diamond—to characterize trace elements and perform analysis under simulated extreme crustal and mantle conditions.
- Geochemical Relevance: The study establishes clear differences in Chromium number (Cr#) composition (11-82) between large (Luobusha) and small (Dazhuqu/Dongbo) chromite deposits, correlating chemical fingerprinting to specific formation environments (Supra-Subduction Zone vs. Mid-Ocean Ridge).
- High-Purity Material Demand: Accurate measurement of trace elements (Ni, Ga, V, Sc, FeOt) requires analysis tools featuring exceptionally inert windows, sensors, and anvils, a domain where Single Crystal Diamond (SCD) and Boron-Doped Diamond (BDD) excel.
- Extreme Environment Applications: The melt-rock interaction and fractional crystallization processes discussed mirror the high-pressure, high-temperature (HPHT) environments frequently studied using diamond anvils and heating elements, where 6CCVD provides custom, thick diamond substrates (up to 10mm).
- BDD for Sensing: 6CCVD’s Boron-Doped Diamond (BDD) materials offer superior electrochemical stability and sensitivity required for complex chemical analysis of geological samples, particularly the sensing of transition metals like Chromium (Cr).
- Customization and Scale: We provide high-quality Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) plates up to 125mm for large-scale experimental setups, essential for replicating geological processes or integrating into advanced analytical instrumentation.
Technical Specifications
Section titled “Technical Specifications”The following hard data points extracted from the research paper define the material compositions and geological environments studied, highlighting the extreme chemical range SCD and BDD solutions must withstand for effective analysis.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Luobusha Chromite Cr# Range | 71-82 | Cr# | Formed in Cr-rich Boninitic Melt (Supra-Subduction Zone) |
| Dazhuqu Chromite Cr# Range | 16-63 | Cr# | Formed in MORB-affinity Melt (Mid-Ocean Ridge) |
| Dongbo Chromite Low Cr# Range | 11-47 | Cr# | Small-scale mineralization (Mid-Ocean Ridge) |
| Dongbo Chromite High Cr# Range | 70-81 | Cr# | Small-scale mineralization (Mid-Ocean Ridge) |
| Formation Process (Large Bodies) | Continual Replenishment, Fractionation, Accumulation | N/A | Dynamic Conduit environment |
| Key Trace Elements Tracked | MgO, FeOt, Ni, Ga, V, Sc | N/A | Used for chemical comparison against host peridotites |
| Thickness Requirement (Substrates) | Thin Film (0.1µm) to Bulk (500µm+) | µm/mm | Standard range for analytical windows/heat spreaders |
Key Methodologies
Section titled “Key Methodologies”The research relies on advanced materials characterization and geochemical modeling. 6CCVD diamond solutions enable the following critical steps for similar geo-engineering studies:
- Chemical Compositional Analysis: Determination of major element chemistry (e.g., Cr, Al, Fe) to calculate Cr# and compare chromitites from different massifs (Luobusha vs. Dazhuqu/Dongbo).
- Trace Element Analysis: Measurement of MORB-normalized trace element patterns (Ni, Ga, V, Sc) to differentiate melt sources (Cr-rich boninite vs. MORB-affinity melts).
- Petrogenetic Modeling: Comparison of composition trends between chromite, dunite envelopes, and host peridotites to establish whether formation occurred via melt-rock interaction (in-situ crystallization) or fractional crystallization/settling in a dynamic conduit.
- Extreme Environment Simulation: Simulation or analysis of material properties under ultrahigh pressure (UHP) conditions, required for confirming the occurrence of UHP minerals (e.g., diamond and coesite) within chromitites, necessitating highly durable CVD diamond tools.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”6CCVD is positioned as the ideal partner for researchers studying geological materials, extreme environment processes, and high-stability sensing/spectroscopy. Our MPCVD diamond materials meet the stringent requirements for durability, chemical inertness, and precise optical properties necessary to replicate or analyze the processes described in this paper.
Applicable Materials
Section titled “Applicable Materials”| 6CCVD Material | Recommended Grade & Specification | Application Focus in Geo-Engineering |
|---|---|---|
| Boron-Doped Diamond (BDD) | Heavy Doping (< 10 mΩ·cm), Custom Metalization (Ti/Pt/Au) | Electrochemical Sensing: Highly sensitive analysis of transition metals (Cr, Ni, Fe) in acidic or corrosive geological leachates. Used as corrosion-proof electrode material. |
| Optical Grade Single Crystal Diamond (SCD) | High Purity, Thickness 0.1µm - 500µm, Polishing Ra < 1nm | Spectroscopy: Anvil/Window material for high-pressure diamond cells (HPDC) to simulate deep mantle conditions (SSZ/MOR formation) and perform Raman/IR analysis of mineral inclusions. |
| Polycrystalline Diamond (PCD) | High Thermal Conductivity Grade, Wafers up to 125mm | Thermal Management/Structural Support: Heat spreading for high-power lasers used in LIGA or ablation analysis of geological samples; large-area substrates for wear-resistant HPHT tooling. |
| Diamond Substrates | Thick SCD/PCD (up to 10mm) | HPHT Anvils: Ideal material for robust anvils required to achieve the pressures related to UHP mineral occurrence (diamond and coesite) mentioned in the study. |
Customization Potential
Section titled “Customization Potential”The complexity of geochemical research often demands unique material configurations. 6CCVD offers full custom fabrication to meet these needs:
- Custom Dimensions: We supply plates and wafers up to 125mm (PCD) and custom laser-cut shapes for specific HPHT cell geometries.
- Precision Thickness Control: We offer SCD and PCD layers ranging from ultra-thin films (0.1µm) for sensitive detectors to robust substrates (up to 10mm).
- Advanced Metalization: Our in-house cleanroom capability supports custom metal layers (Au, Pt, Pd, Ti, W, Cu) for BDD electrode contacts or specific bonding requirements for analytical equipment integration.
- Ultra-low Roughness Polishing: SCD surfaces are polished to Ra < 1nm, ensuring minimal scattering loss for demanding optical analysis of trace elements.
Engineering Support
Section titled “Engineering Support”6CCVD’s in-house PhD team provides expert consultation on material requirements for extreme environment applications:
- Geochemical Analysis Systems: Assistance with integrating BDD thin films into flow cells and sensing systems for high-resolution analysis of dissolved Chromium (Cr) and other transition metals.
- High-Pressure Physics: Design consultation for sourcing the optimal purity and dimensions of diamond anvils and gaskets used in projects simulating melt-rock interactions and deep mantle recycling processes.
- Material Selection: Guidance on choosing the appropriate diamond type (Type IIa SCD vs. various PCD grades) based on specific mechanical, thermal, or optical transmission requirements for geological sampling and characterization instruments.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Podiform chromitites are characteristically occurred in ophiolites (e.g., Thayer, 1964; Dickey, 1975). However, the metallogenic processes for podiform chromitites are still unclear. Early models involved fractional crystallization and crystal settling from picritic or basaltic melts in magma chambers (Dickey, 1975; Boudier and Coleman, 1981), but it was also proposed that podiform chromitites formed from partial melting and melt extraction in host mantle peridotites (Dick, 1977; Dick and Bullen, 1984). Recent studies by the majority of authors have suggested that melt‐rock interaction at the Moho transition zone may have played a key role in the formation of podiform chromitites (Zhou and Robinson, 1994; Zhou et al., 1996, 2005, 2014; Robinson, 2008; Page and Barnes, 2009; Uysal et al., 2009, 2012; González‐Jiménez et al., 2011, 2015). Based on the occurrence of some ultrahigh pressure minerals (e.g. diamond and coesite) in chromitites, it has been proposed recently that the formation of podiform chromitite is likely related to multiple processes inclusing mantle recycling (Yang et al., 2007; Yamamoto et al., 2013). Although geat progresses have been made towards understanding the genesis of podiform chromitites, some fundamental issues in remain unanswered. For examples, what are the major controls on the size of chromitites? And why some ophiolites contain large podiform chromitite bodies, whereas most ophiolitic massifs are essentially chromitite‐barren? The Yarlung‐Zangbo Ophiolite belt is one of the most famous ophiolite zone in the world. It contains fresh peridotites as well as different‐sided podiform chromitites. The Luobusha ophiolite in the eastern segment of the belt hosts the largest chromite deposit in China. In the central and western segments of belt the Dazhuqu and Dongbo ophiolitic massifs contain some small‐scale chromitite bodies. Such characteristics make the Yarlung‐Zangbo Ophiolites an ideal subject to investigate the major controls on the metallogenesis of podiform chromitites. The Luobusha chromitites are large lens and enclosed in dunite. In contrast, the Dazhuqu and Dongbo chromitites display generally as narrow dykes or irregular seams with dunite envelopes. The closely spatial association of the chromitites and dunite envelopes, together with their textural features, support a petrogenetic model that the chromitites from the Luobusha, Dazhuqu and Dongbo massifs form from reaction of melt with host peridotite. In terms of chemical composition of chromite, there are distinctive differences between those from the Luobusha and the Dazhuqu or the Dongbo. Chromite from the Luobusha chromitites has high Cr # (71-82), whereas Chromite in the Dazhuqu chromitites show relatively low Cr # (16-63), and chromite in the Dongbo chromitites includes low Cr # (11-47) and high Cr # (70-81) types. For the Dongbo and Dazhuqu massifs, linear trends of Cr # with MgO, FeOt, Ni, Ga, V and Sc in chromite from the chromitites and dunites of are similar to those of the host peridotites, suggesting that the melt‐rock reaction may provide major budget of Cr for the chromitites. The similar compositions at a given Cr # in chromite from these rocks also demonstrate that the chromitites may have been formed by in‐situ crystallization of chromite under low melt/rock ratio. In contrast, the Luobusha chromitites have different trends of compositions in chromite from that of the host peridotites, implying that the formation of the chromitite bodies requires a continual replenishment of Cr‐rich melts from deeper mantle. Fractionation and accumulation of chromite from a large volume of Cr‐rich melt may play an important role on the formation of the Luobusha chromitites. MORB‐normalized trace element patterns of chromite from the Luobusha chromitites suggest that it has been formed from Cr‐rich boninitic melt at surpra‐subduction zone (SSZ) setting. However, the Dongbo and Dazhuqu chromitites have formed originally from a MORB‐affinity melt at a mid‐ocean ridge (MOR) environment. In summary, the Luobusha chromitites crystallized from a Cr‐rich melt in a dynamic conduit, where fractional crystallization and crystal settling play a key role in formation of the large chromitites. In contrast, the small‐scale mineralizations of the Dongbo and Dazhuqu chromitite pods are formed from in situ produced melts. Podiform chromitites can be formed in MOR environment, whereas the higher Cr content in boninitic melt and assimilation of subducted slab materials at SSZ setting may benefit the formation of large chromite deposit.