Tephra layers of the Mýtina Maar, Czech Republic, contain ferrimagnetic Mg–Al-rich titanomagnetite, which is suggested to originate from a fractionated alkaline CO₂-rich lithospheric mantle melt. We investigated the magnetic mineralogy and Curie temperature (T_C) from tephra deposits of two drill cores (< 9 m depth). T_C calculated (208 ± 14 °C) from chemical composition (Fe²⁺_0.8Mg_0.5Fe³⁺_1.1Al_0.3Ti_0.3O₄) is in accordance with T_C retrieved from cooling curves of temperature-dependent magnetic susceptibility measurements (195–232 °C). However, thermomagnetic curves are irreversible either with lower (type I) or higher (type II) T_C in the heating curve. All curves show transition temperatures above ca. 390 °C, indicating maghemitization. We interpret the irreversibility of T_C (∆T_C) in terms of different degrees of cation ordering, overprinted or masked by different degrees of maghemitization, which is a low-temperature phenomenon. Negative ∆T_C indicates that original deposited titanomagnetite has cooled faster and, therefore, has stored a lower degree of cation ordering compared to heating/cooling rate of 11 °C/min in the Kappabridge. Type II with positive ∆T_C indicates higher degree of cation ordering, and, therefore, slower cooling rate. The central part of this deposit shows most severe maghemitization, indicating rather wet emplacement. We, therefore, suggest different eruption styles for deposition of type I pyroclastics with more phreatomagmatic and type II pyroclastics with more phreato-Strombolian eruption styles. Our study is a new approach to discriminate different cooling histories in maar deposits using the Curie temperature of titanomagnetite. We suggest that this method has the potential to discriminate different emplacement modes resulting from different eruption styles.

捷克共和国MýtinaMaar的特非拉层含有富含铁磁的Mg-Al的钛磁铁矿，建议其起源于富分分形的富含CO _2的岩石圈地幔熔体。我们研究了两个钻芯（深度小于9 m）的特非拉沉积的磁性矿物学和居里温度（T _C）。由化学成分（Fe ²⁺ _0.8 Mg _0.5 Fe ³⁺ _1.1 Al _0.3 Ti _0.3 O ₄）计算得出的T _C（208±14°C）符合T _C从与温度相关的磁化率测量值（195–232°C）的冷却曲线中检索。但是，在加热曲线中，较低的（I型）或较高的（II型）T _C都是不可逆的。所有曲线均显示出高于约3℃的转变温度。390°C，指示磁化。我们用不同程度的阳离子有序化，不同的磁化程度覆盖或遮盖的阳离子来解释T _C（∆ T _C）的不可逆性，这是一种低温现象。负∆ T _C表示原始沉积的钛磁铁矿的冷却速度更快，因此与Kappabridge中以11°C / min的加热/冷却速率相比，阳离子有序度较低。ΔT _C为正的II型表示阳离子有序度较高，因此冷却速率较慢。该矿床的中部表现出最严重的磁化作用，表明岩床相当湿润。因此，我们建议使用更多喷发岩浆的I型火山碎屑和具有更多斜方-Strombolian喷发类型的II型火山碎屑沉积方式不同。我们的研究是一种使用钛磁铁矿居里温度来区分玛尔矿床不同冷却历史的新方法。我们建议，这种方法有可能区分由不同喷发方式导致的不同安置模式。