地球物理学报
地毬物理學報
지구물이학보
2010年
1期
111-118
,共8页
橄榄石%相变%成核率参数%深源地震%俯冲带
橄欖石%相變%成覈率參數%深源地震%俯遲帶
감람석%상변%성핵솔삼수%심원지진%부충대
Olivine%Phase transformation%Nucleation parameter%Deep earthquake%Subduction zone
本文研究了橄榄石原位相变实验中加载、加热路径上的相变及其对确定相变动力学参数的影响.利用文献~([1])所给出的退火后先加温后加压,且相对低温条件下实验结果确定出的Ni_2SiO_4橄榄石相变动力学参数,计算了加载、加热路径上所发生的相变对确定成核率、长大率及相变体积分数的影响.结果表明,退火后先加压后加温,且相对高温条件下的实验数据受到加热路径上成核的影响.根据这样的实验数据得到的成核率会明显高于实际温压条件下的成核率.尤其是当多数实验都是高温实验时,根据这些成核率数据所确定的成核率参数会严重偏离其真值,从而严重影响对俯冲带颗粒粒度及俯冲带流变结构的计算.尽管目前有很多关于Mg_2SiO_4橄榄石长大率的实验数据,也有通过对挤碰物理图像的分析对(Mg_(0.89)Fe_(0.11))_2SiO_4橄榄石成核率的估算,但只有文献[2]通过退火后先加压后加温的原位实验得到了Mg_2SiO_4橄榄石的相变成核率,且属于高温实验.根据本文的研究结果,我们认为亟需补充退火后先加温后加压或相对低温的实验数据以得到正确的地幔橄榄石成核率参数.
本文研究瞭橄欖石原位相變實驗中加載、加熱路徑上的相變及其對確定相變動力學參數的影響.利用文獻~([1])所給齣的退火後先加溫後加壓,且相對低溫條件下實驗結果確定齣的Ni_2SiO_4橄欖石相變動力學參數,計算瞭加載、加熱路徑上所髮生的相變對確定成覈率、長大率及相變體積分數的影響.結果錶明,退火後先加壓後加溫,且相對高溫條件下的實驗數據受到加熱路徑上成覈的影響.根據這樣的實驗數據得到的成覈率會明顯高于實際溫壓條件下的成覈率.尤其是噹多數實驗都是高溫實驗時,根據這些成覈率數據所確定的成覈率參數會嚴重偏離其真值,從而嚴重影響對俯遲帶顆粒粒度及俯遲帶流變結構的計算.儘管目前有很多關于Mg_2SiO_4橄欖石長大率的實驗數據,也有通過對擠踫物理圖像的分析對(Mg_(0.89)Fe_(0.11))_2SiO_4橄欖石成覈率的估算,但隻有文獻[2]通過退火後先加壓後加溫的原位實驗得到瞭Mg_2SiO_4橄欖石的相變成覈率,且屬于高溫實驗.根據本文的研究結果,我們認為亟需補充退火後先加溫後加壓或相對低溫的實驗數據以得到正確的地幔橄欖石成覈率參數.
본문연구료감람석원위상변실험중가재、가열로경상적상변급기대학정상변동역학삼수적영향.이용문헌~([1])소급출적퇴화후선가온후가압,차상대저온조건하실험결과학정출적Ni_2SiO_4감람석상변동역학삼수,계산료가재、가열로경상소발생적상변대학정성핵솔、장대솔급상변체적분수적영향.결과표명,퇴화후선가압후가온,차상대고온조건하적실험수거수도가열로경상성핵적영향.근거저양적실험수거득도적성핵솔회명현고우실제온압조건하적성핵솔.우기시당다수실험도시고온실험시,근거저사성핵솔수거소학정적성핵솔삼수회엄중편리기진치,종이엄중영향대부충대과립립도급부충대류변결구적계산.진관목전유흔다관우Mg_2SiO_4감람석장대솔적실험수거,야유통과대제팽물리도상적분석대(Mg_(0.89)Fe_(0.11))_2SiO_4감람석성핵솔적고산,단지유문헌[2]통과퇴화후선가압후가온적원위실험득도료Mg_2SiO_4감람석적상변성핵솔,차속우고온실험.근거본문적연구결과,아문인위극수보충퇴화후선가온후가압혹상대저온적실험수거이득도정학적지만감람석성핵솔삼수.
We investigate the nucleation on heating/loading path and its effects on the olivine phase transformation and the determination of nucleation rate in in-situ experiments, by the numerical simulation based on the kinetic parameters from low temperature experiments of Ni_2SiO_4 olivine phase transformation~([1]). Results show that the high temperature experiments, of which samples are first loaded then heated after annealing, are greatly affected by the nucleation during heating. The predicted nucleation rates based on such experiments are obviously overrated. Especially in the case that most experiments have high target temperatures, the predicted nucleation rates will significantly deviate from their true values, which has influence on the evaluation of the olivine grain size as well as the rheological structures of subduction zones. Although there are many growth data of Mg_2SiO_4 olivine and a rough evaluation on the nucleation rate of (Mg_(0.89) Fe_(0.11))_2 SiO_4 olivine based on the feature of the impingement, only Ref. [2] showed some nucleation rates of Mg_2SiO_4 olivine from high temperature in-situ experiments, in which the samples are finally heated to the target experimental condition. Our present study suggests that the experiments in low target temperature or those reached their experimental condition finally by loading are needed to derive the correct nucleation parameters of mantle olivine.
