【摘要】 班公湖—怒江缝合所代表的中特提斯洋盆的属性及其构造演化过程仍在争论之中.多年来,地质工作者们不断在班公湖—怒江缝合带以南的拉萨地块寻找新的地质证据以求厘清这一关键问题.2016年,地质学家先后在拉萨地块北缘保吉地区新识别出了晚侏罗世碳酸岩地层吐卡日组,这一发现为我们获得古地磁证据提供了新的地层基础.为了进一步明确该地层中载磁矿物的组合类型和特征,本文对采自班戈县保吉地区晚侏罗世吐卡日组灰岩样品进行了饱和等温剩磁曲线获得实验、累计高斯模型线性和梯度曲线分析、三轴等温系统热退磁实验、k-T曲线测试、磁滞回线实验.实验结果表明,保吉地区晚侏罗世吐卡日组灰岩地层中的载磁矿物组合可以分为两类:第一类以高矫顽力的针铁矿、磁赤铁矿`以及赤铁矿为主,含少量低矫顽力矿物;第二类以低矫顽力的磁铁矿以及贫钛的钛磁铁为主,含少量高矫顽力矿物.此外,吐卡日组样品中的磁性矿物颗粒粒径普遍较小,以单畴和假单畴颗粒为主.更多还原

【Abstract】 The properties of the Central Tethys ocean basin represented by the Bangong-Nujiang suture zone are still in dispute. Over the years, geologists have been searching for new geological evidence in the Lhasa terrane south of the Bangong-Nujiang suture zone in an attempt to clarify this key issue. In 2016, geologists successively identified the late Jurassic Carbonate Tukari formation in the Baoji area on the northern margin of the Lhasa terrane. This discovery provided a new stratigraphic foundation for the paleomagnetic evidence. In order to further clarify the types, combinations, and characteristics of the magnetic minerals contained in this stratum, this paper presents a saturated isothermal remanence curve from the late Jurassic Tukari formation limestone samples from the Bangor region to obtain experiments and cumulative Gaussian model linearity and gradients. Curve analysis, three-axis isothermal thermal demagnetization test, k-T curve test, hysteresis loop experiment. The experimental results show that the magnetic mineral components in the limestone strata of the Late Jurassic Tukari formation in the Baoji area can be divided into two categories: The first type is high-coercivity goethite, maghemite, and hematite It is dominated by a small amount of low-coercivity minerals; the second type is dominated by low-coercivity magnetite and titanium-depleted titanium magnets, containing a small amount of high-coercivity minerals. In addition, the particle size of magnetic minerals in the Tukari formation sample is generally small, mainly mono-domain and pseudo-domain particles.更多还原