广州番禺眉山阶地第四系剖面的年代学框架及构造学意义
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摘要
眉山阶地第四系剖面地处番禺断隆区的边缘,毗邻狮子洋断陷区,是珠江三角洲第一次海侵所到达的区域,附近的断裂包括文冲断裂、化龙—黄阁断裂、新会—市桥断裂等三角洲内典型断裂。发育于网纹红土基座上的堆积阶地,自下而上大致分为杂色砂层、白色砂层、淤泥质层3层,构成一个完整的从动水环境到静水环境的沉积旋回。野外调查及~(14)C测年和光释光(OSL)测年结果表明,眉山第四系剖面年龄约在70～30 ka B.P.之间,相当于深海O同位素4—2阶段。结合前人的研究资料,认为阶地面与沉降区的下旋回原本在同一高度,但自晚更新世以来,在断块差异升降中被错开,垂直距离在20 m以上,直观地指示了断隆区与断陷区的运动特征。
The Meishan Quaternary depositional terrace section is located at the east edge of Panyu uplift block, adjoining the Shizi-yang subsidence block, where the first transgression of the Pearl River Delta could be reached. This area is confined by the Wenchong Fault, Hualong-Huangge Fault and Xinhui-Shiqiao Fault, which are all typical faults in the Pearl River Delta. This terrace is an accumulation terrace developed on reticulated laterite bedrock, and can be roughly divided into three layers of variegated sand layer, white sand layer and silt layer, which constitute a complete depositional cycle from dynamic river environment to hydrostatic one. Detailed field investigation near the Meishan terrace section and indoor tests suggest that: OSL and ~(14)C dating reveal that the age of the Meishan terrace deposits is about 70-30 ka B.P., which is equivalent to MIS4 to MIS2; Combined with previous research, it is shown that the lower cycle of the terrace and subsidence area was originally at the same height. Since the Late Pleistocene, it has been staggered to a vertical distance of more than 20 m in the differential uplift and subsidence of fault blocks, which directly indicates the dynamic characteristics of fault uplift area and fault subsidence area.
The Meishan Quaternary depositional terrace section is located at the east edge of Panyu uplift block, adjoining the Shizi-yang subsidence block, where the first transgression of the Pearl River Delta could be reached. This area is confined by the Wenchong Fault, Hualong-Huangge Fault and Xinhui-Shiqiao Fault, which are all typical faults in the Pearl River Delta. This terrace is an accumulation terrace developed on reticulated laterite bedrock, and can be roughly divided into three layers of variegated sand layer, white sand layer and silt layer, which constitute a complete depositional cycle from dynamic river environment to hydrostatic one. Detailed field investigation near the Meishan terrace section and indoor tests suggest that: OSL and ~(14)C dating reveal that the age of the Meishan terrace deposits is about 70-30 ka B.P., which is equivalent to MIS4 to MIS2; Combined with previous research, it is shown that the lower cycle of the terrace and subsidence area was originally at the same height. Since the Late Pleistocene, it has been staggered to a vertical distance of more than 20 m in the differential uplift and subsidence of fault blocks, which directly indicates the dynamic characteristics of fault uplift area and fault subsidence area.
引文
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王萍,郭良田,董好刚,2011. 珠江三角洲广从断裂东侧“西淋岗断层”成因论证[J]. 岩石学报,27(10):3129-3140.
姚衍桃,詹文欢,刘再峰,等,2008. 珠江三角洲的新构造运动及其与三角洲演化的关系[J]. 华南地震,28(1):29-40.
郑建生,李平日,方国祥,1992. 珠江三角洲北部中更新世白坭组的划分对比[J]. 广东地质, 7(1):60-73.
Fairbanks R G, Mortlock R A, Chiu Tzuchien, et al., 2005. Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/234U/238U and 14C dates on pristine corals [J]. Quaternary Science Reviews, 24(16/17): 1781-1796.
陈国能,格拉佩斯,2009. 花岗岩成因:原地重熔与地壳演化[M]. 武汉:中国地质大学出版社.
冯文立,张平,季文婷,等,2017. 苏北沿海低平原区浅表第四纪地质调查及沉积环境研究:以1∶5万伍佑幅为例[J]. 地质学刊, 41(2):292-296.
黄镇国,李平日,张仲英,等,1982. 珠江三角洲的形成发育演变[M]. 广州:科学普及出版社广州分社.
侯卫生,陈国能,庄文明,等,2011. 西淋岗第四系断层探测及活动性评价[J]. 吉林大学学报(地球科学版),41(3):925-931.
柯维廉,1915. 督办广东治河事宜处报告书[R]. 广州:督办广东治河事宜处.
骆丁,宗开红,苗巧银,2016. 长江镇江段第四纪沉积物重矿物特征及其指示意义[J]. 地质学刊,40(2):243-246.
李甜,燕晓莹,解国爱,等,2017. 南京幕府山地区地质构造特征及断层量化[J]. 地质学刊,41(4):631-636.
苗巧银,陈火根,李向前,等,2016. 江苏镇江东部大路—姚桥断裂新构造运动特征[J]. 地质学刊,40(2):220-227.
宋方敏,汪一鹏,李传友,等,2003. 珠江三角洲部分断裂晚第四纪垂直位移速率[J]. 地震地质,25(2):203-210.
王建华,郑卓,1995. 珠江三角洲白坭组的沉积环境探讨[J]. 中山大学学报(自然科学版),34(2):95-102.
王建华,曹玲珑,王晓静,等,2009. 珠江三角洲万顷沙地区晚第四纪沉积相与古环境演变[J]. 海洋地质与第四纪地质,29(6):35-41.
王萍,郭良田,董好刚,2011. 珠江三角洲广从断裂东侧“西淋岗断层”成因论证[J]. 岩石学报,27(10):3129-3140.
姚衍桃,詹文欢,刘再峰,等,2008. 珠江三角洲的新构造运动及其与三角洲演化的关系[J]. 华南地震,28(1):29-40.
郑建生,李平日,方国祥,1992. 珠江三角洲北部中更新世白坭组的划分对比[J]. 广东地质, 7(1):60-73.
Fairbanks R G, Mortlock R A, Chiu Tzuchien, et al., 2005. Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/234U/238U and 14C dates on pristine corals [J]. Quaternary Science Reviews, 24(16/17): 1781-1796.