CAJ | 학술논문

对华北克拉通重力梯度带东西两侧的河北承德袁家庄和内蒙古四子王旗白脑包出露的晚中生代火山岩进行了地球化学对比研究。全岩主量元素、微量元素和Sr-Nd-Hf同位素数据表明，袁家庄火山岩和白脑包火山岩具有相似的地球化学特征。这些火山岩轻、重稀土强烈分异，富集大离子亲石元素(如Rb，Ba，Th，U，K等)，亏损高场强元素(如Nb，Ta，Zr， Hf，Ti等)；其同位素具有高(87Sr/86Sr)i，低εNd(t)和低εHf(t)的特征，因此认为袁家庄和白脑包火山岩具有相似的源区，即均来源于被交代的古老岩石圈地幔的部分熔融。结合文献资料，作者认为，这些晚中生代火山岩是华北克拉通岩石圈减薄的直接产物，中生代时期华北克拉通岩石圈的减薄不仅仅局限于重力梯度带以东地区，以西的部分地区也有发生。
대화북극랍통중력제도대동서량측적하북승덕원가장화내몽고사자왕기백뇌포출로적만중생대화산암진행료지구화학대비연구。전암주량원소、미량원소화Sr-Nd-Hf동위소수거표명，원가장화산암화백뇌포화산암구유상사적지구화학특정。저사화산암경、중희토강렬분이，부집대리자친석원소(여Rb，Ba，Th，U，K등)，우손고장강원소(여Nb，Ta，Zr， Hf，Ti등)；기동위소구유고(87Sr/86Sr)i，저εNd(t)화저εHf(t)적특정，인차인위원가장화백뇌포화산암구유상사적원구，즉균래원우피교대적고로암석권지만적부분용융。결합문헌자료，작자인위，저사만중생대화산암시화북극랍통암석권감박적직접산물，중생대시기화북극랍통암석권적감박불부부국한우중력제도대이동지구，이서적부분지구야유발생。
The Yuanjiazhuang and Bainaobao volcanic rock suites are of late Mesozoic age located respectively in the east and west of the Daxingˊanling-Taihangshan gravity gradient zone. These volcanic rocks display similar characteristics in incompatible trace elements and radiogenic isotopes. They are highly fractionated in rare earth elements (REE) with a high LREEs/HREEs ratio, enriched in large ion lithophile elements (such as Rb, Ba, Th, U, K), relatively depleted in high field strength elements (HFSE:Nb, Ta, Zr, Hf, Ti), high (87Sr/86Sr)i and lowεNd(t) andεHf(t). All these data suggest that the sources for the two volcanic rock suites are similar and their parental melts must have derived from partial melting of ancient metasomatized mantle lithosphere. Combined with the data in the literature, we propose that the lithospheric thinning beneath the North China Craton happened not only in the east but also to the west of the gradient zone in the late Mesozoic.