����������ϲ����������ʯ�����Ӫ�����ɽ�ҽ��е���ʯ����ѧ�о���������ʯ�����ɽ����Ҫ�������ʴ��氲ɽ�Һʹְ���Ϊ����������������Ӣ���ң��� SiO2 = 53. 8% �� 68. 6wt%�� K2O + Na2O =7. 70% �� 9. 59%��Mg # = 26. 72 �� 33. 89���Ը�����ϡ���ʹ�������ʯԪ�� (LILEs�����b��Ba��Th��U ��)��������ϡ���͸߳�ǿԪ�� (HFSEs���� Nb��Ta��Ti��P ��) Ϊ��������Щ�����븩�����ɽ�����ơ�Ӫ�����ɽ����������Ϊ�������������������ʴ��氲ɽ�ҡ����氲ɽ�Һ�Ӣ���ң����Զ�Ԫ���е͹� (SiO2 = 49. 3% �� 56. 6%)���ͼ� (K2O + Na2O = 4. 57% �� 6. 60%)����þ (Mg # =33. 49 ��59. 51) ����������Ҫ���ڸƼ���ϵ�У���ʾ��ԭʼ�ҽ���Ҫ��Դ�ڵ��; ���Զ�Ԫ�� SiO2 =65. 4% ��74. 9%��K2O + Na2O =3. 23% ��7. 75%����þ (Mg # =21. 76 ��39. 18)��Ӫ�����ɽ��ϡ�������ʽ�������ͣ�������ϡ���ʹ�������ʯԪ�أ�������ϡ���͸߳�ǿԪ�أ��븩�廷����ɽ�����ơ����У�Ӫ���������ҵ���ѧ�������� A �ͻ����ң���ʾ�γ�����չ��������������о��ɹ�����Ϊ��������ϲ����������ɽ�ҵ��γ����̫ƽ������ŷ�Ǵ�½֮�µĸ��������йء���ʯ�����ɽ���γ��ڻ��½��Ե������Ӫ�����ɽ�ҵ��γ�����ʯȦ���������������չ�����йء�

The geochemistry of Early Cretaceous volcanic rocks from Huoshiling and Yingcheng Formations in southern Songliao Basin shows that the volcanic rocks from Huoshiling Formation consist of basaltic andesites��tra- chy- andesites��and minor trachy- dacites��in which SiO 2 contents of 53. 8% ��68. 6%��total alkali (K 2 O + Na 2 O) of 7. 70% ��9. 59% and Mg # of 26. 72 ��33. 89�� with the characteristics of enrichment in light rare elements (L��EEs) and large ion lithophile elements (LILEs; ��b�� Ba�� Th�� U ��etc)�� and depletion in heavy rare elements (H��EEs) and high field strength elements (HFSEs; Nb��Ta��Ti��P��etc)�� The above characteristics are similar to those of the volcanic rocks formed in subduction zone�� Volcanic rocks in Yingcheng Formation mainly compose of rhyolites with minor basaltic trachy- andesites��trachy- andesites and dacites��which are characterized by low silicon (SiO 2 = 49. 3% ��56. 6%)��low alkali (K 2 O + Na 2 O = 4. 57% �� 6. 60%) and high Mg # (Mg # = 33. 49 �� 59. 51)�� The rocks mainly belong to the calc- alkaline series��indicating the mantle materials involved in their primary magma�� Felsic volcanic rocks of Yingcheng Formation are characterized by SiO 2 contents of 65. 4% �� 74. 9%��total alkali content (K 2 O + Na 2 O) of 3. 23% ��7. 75% and Mg # of 21. 76 ��39. 18�� Chondrite- normalized ��EE patterns of vol- canic rocks from Yingcheng Formation are right- inclined in type��enriched in light rare elements (L��EEs) and large ion lithophile elements��and depleted in heavy rare elements (H��EEs) and high field strength elements��sili- mar to the volcanic rocks formed in subduction zone�� The geochemical characters of rhyolites from Yingcheng For- mation are similar to those of the A- type granite��implying an extensional environment for forming�� Combined with the regional geological research��the authors suggest that the Early Cretaceous volcanic rocks in southern Songliao Basin mainly formed under a subduction setting related with the westward- movement of the Paleo- Pacific plate un- derneath the Eurasian Continent�� The volcanic rocks from Huoshiling Formation formed under an active continental margin�� while those from Yingcheng Formation formed under an extensional setting�� related with the delamination of the lithosphere��