Introduction: Erg Chech 002 belongs to a unique group of achondrites which are characterized by a bulk rock composition that plots in the (trachy-) andesitic field on a Total Alkali vrs. Silica (TAS) diagram [1-3]. Erg Chech 002 was found in 2020 in the Erg Chech region of the Sahara Desert in Algeria (total mass > 40kg) and was proposed to be a likely fragment of a chondritic protoplanet which is over 4.5 billion years old [4-8]. Further known (trachy-) andesites are Almahata Sitta individuals MS-MU 011 / 035 / xxx, NWA 7325 / pairs, NWA 11119 / pairs, NWA 11575, GRA 06128/9 and the most recent find Erg Atouila 001, an albitite [1-8]. Project and results: First results of our studies on Erg Chech 002 have been reported in [8]. From this starting point we decided to extend our investigations to a larger sample set in order to be more representative: our pilot studies characterized Erg Chech 002 as being quite heterogeneous in terms of phase composition / mineralogy and also magnetic signature (susceptibility), the latter mainly reflecting the concentration of Fe-bearing phases. The (surface) morphology and mineralogy of the samples was pre-investigated by digital microscopy followed by detailed and systematic investigations with LASER Raman Spectroscopy (a large number of high resolution mappings) [see 9,10 for details]. Erg Chech 002 is characterized by a low shock degree. Only on a very few spots of fusion crust are present. Minor terrestrial alteration effects can be observed, such as oxidation of iron-sulfides (troilite?)

Introduction We report the first detailed and systematic investigations on the mineral phase composition and distribution of two new meteorite falls from 2020. Both meteorites belong to the class of carbonaceous chondrites and play a prominent role in terms of the Hayabusa 2 (successful sample return from asteroid Ryugu in dec 2020) and Osiris Rex (sample return from asteroid Bennu planned in 2023) missions [1,2]. Both sampled asteroids belong to C type asteroids and are believed to mainly consist of carbon rich material with a similar composition as primitive chondrites. In a parallel study we report pilot results on a third carbonaceous chondrite fall from 2019, the C1 ungrouped type meteorite Flensburg [3]. The Kolang meteorite fireball and fall was reportedly observed in Indonesia on 1st of August 2020 by numerous residents in northwest Sumatra (Central Tapanuli Regency). Four stones have been found with a total mass of 2550 gr. Kolang was classified as a CM 1/2 chondrite and is the first and only witnessed fall known from this meteorite group [4]. The Tarda meteorite fireball and fall occurred in Southern Marocco on 25 of august and was also observed by numerous local inhabitants. Immediate searches by local nomads delivered about 4 kg (total mass) of numerous mainly small and often crusted stones. Tarda was classified as a C 2 ungrouped carbonaceous chondrite [5]. Only four witnessed falls of this type are known, Tagish Lake is the most well known of these (fall 2000, [6]). More details on all these recent meteorite falls are found in [7].

We have developed a database on the magnetic susceptibility (MagSus, and other magnetic parameters) of all so far by us investigated Almahata Sitta individuals and samples. Three sample sets are discriminated, details are found in earlier contributions [1-5]: AS (AHS), MS and MS-MU. Recently, we have extended our database of the MagSus values incorporating now all investigated individuals/samples of the Almahata Sitta fall of 2008, focusing on the above mentioned sample sets.

General: In recent years a large number of new Martian meteorites have been reported [1] which significantly widened our knowledge concerning Martian geology, mineralogy, petrogenesis and formation/chronology. Nevertheless, the hypothesized existence of a strong Martian dipole magnetic field during very early periods of time, < 4 Gyrs, and the basic physical processes behind the strong crustal anomalies of the southern hemisphere are still a mystery. Is it generally accepted that a strong magnetic dipole field represents the most important condition for the formation of a stable atmosphere on a planet over longer period of times, and based on that the existence of liquid water on a planets surface, here Mars. The search for traces of live or prebiotic structures on the Mars surface was without any success so far. Future planed sample return missions are mainly focused in this direction [3]. Presently (5/2018) about 110 Martian meteorites are reported, several more still under investigation (classification process pending), details are found in [1, 2]. In our contribution we will focus on a specific group of Martian meteorites, the nakhlites named after the famous Nakhla fall. In terms of petrogenesis, nakhlites are clinopyroxenites with some content of olivines, for details see [1,2] and are interpreted as shallow mantle rocks, related to chassignites (dunites). In this contribution we will focus on the magnetic and mineralogical signature of the four reported Miller Range nakhlites: MIL03346, MIL 090030, MIL 090032 and MIL 090136. We received 2 samples of each MIL stone, one interior and one exterior (near surface but without FC) chip, all about 0.3 gr in mass. The homogeneity of the magnetic signature was investigated by systematical investigation a 3D array sampled along slices cut across the main mass of MIL 090032, all together 16 sub-samples (27 individual fragments). A large range of (paleo-) magnetic, mineralogical and Raman Spectroscopic parameters have been studied, here we will focus only on selected magnetic parameters and magnetic phase composition (magneto-mineralogy), [MagSus: specific magnetic susceptibility, classification parameter]: Results: 1. Comparison between the 4 MIL stones: MIL 03346 int/ext shows slightly different MagSus values (lower), the MagSus values of other 3 stones lay within a very narrow range (int. 3.73-3.84, ext 3.69-3.80, respect.). 2. MagSus comparison 4 MIL stones int-ext: ext MagSus values are in the range of 0.92-0.98 of the int values, so slightly lower: the effect is due to terrestrial alteration even under Antarctic (cold desert) conditions: the int/ext difference in MagSus of individual meteorites depends significantly on terrestrial age, mineralogy / phase composition, but also on the cover-degree / thickness of the fusion crust. 3. Trends of other magnetic parameters (magnetic remanences such as NRM, several IRM’s) and related parameters will be shown in our poster. 4. The magnetic phases in MIL stones have been investigated within a large temperature range including space conditions (low-T.) in our experiments (Raman data will be reported elsewhere): the dominating phases are (Ti-) bearing magnetite (low Ti content in general), and minor Ilmenite, traces of Fe-sulfides (pyrrhotite?). 5. Comparison with the other nakhlites (10 reported [1]): an update of earlier and existing models concerning burial depth [4-6] will be shown in our poster. 6. MIL sample array (MIL 090032): a very homogenous distribution of MagSus was detected. Acknowledgements: The MIL nakhlite samples have been allocated by K. Righter and his team (LPI/NASA) for our projects which is highly acknowledged.

The fall and discovery of a large number of fragments/individuals of the Almahata Sitta meteorite in the desert of N Sudan has significantly deepened our knowledge concerning the formation, structure and life cycle of asteroids [1,2]. In contrast to earlier findings, Almahata Sitta classified as a polymict ureilite does not only contain small clasts or fragments of different meteorite lithologies but consists of individuals of a growing number of different meteorite types and classes (rubble pile asteroid): various ureilite types and related lithologies (several unknown before) and a growing number of ordinary, carbonaceous and enstatite chondrites. Even unique and new meteorite lithologies such as Trachy-Andesites or an individual with affinity to Rumuruti chondrites have been discovered [2].

Braunschweig meteorite fall It was reported that in the morning of April 23, 2013, a fragmented rock was found by the owner of a private yard in Braunschweig, N Germany, [1]. It could be reconstructed that most probably the fall happened around 2.10am at the same day and was registered in the neighborhood by a loud crash. Additionally, a fireball could be registered in the region around that time. The rock was identified as a meteorite and classified as an L6 ordinary chondrite [1] with a total mass of 1300 gr (see fig.1). Further properties of the new German meteorite have been determined as follows by [1]: shock degree S4, weathering degree W0; main phases found were olivine (with ca. 25mol% fayalite), pyroxene (ferrosilite ca. 21mol%, wollastonite ca. 1.6mol%), kamacite, troilite and feldspar (plagioclase). The magnetic susceptibility value was 4.75 (log spec. 10). First results of a set of investigations have been presented at the 6 German Meteorite Colloquium [2].

Rock magnetic properties of the Nile mud are reported. They indicate that the carrier of magnetization in the Nile mudis predominantly magnetite. Fourty air-dried ceramic samples made of Nile mud were manufactured to ceramics by stepwise heating to 700°C at various field intensities between 0.03 mT and 0.09 mT and with various angles θ between the laboratory field ( F L ) direction and the ceramics. The partial (pTRM) and the total thermoremanent magnetization (TRM) increase linearly as the magnetic field ( F L ) increases. The rate of increase of the pTRM with both F L and temperature T depends on θ , so that it decreases by 25% as θ increases from 0° to 90°. In extreme cases, the effect of the magnetic anisotropy results in overestimating the determined palaeointensity by 33% and underestimating it by 25% from the correct value. The direction of TRM is the same as that of the ambient magnetic field independent of the anisotropy. Applying the laboratory field in the direction of the stable natural remanent magnetization during a Thellier-type experiment results in accurate determination of the palaeointensity.

SIMULATION OF THE NEOFORMATION PROCESSES OF NANO-SIZED FE-Ni AND MAGNETITE PARTICLES IN BROWN COLORED OLIVINES OF SOME MARTIAN METEORITES (SNC). V.H. Hoffmann, T. Mikouchi, T. Kurihara, M. Funaki, M. Torii, 1 Institute for Geosciences and ZAG, University of Tübingen, Sigwartstrasse 10, 72076 Tübingen, and 2 Department of Geoand Environmental Sciences, University of München, Theresienstrasse 41, 80333 München, Germany, 3 Dep. of Earth and Planet. Sci., University of Tokyo, Japan, 4 National Inst. Polar Res., 9-10 Kaga 1 Chome, Itabashi-Ku, Tokyo 173, Japan. 5 Dep. of GeosphereBiosphere System Science, Okayama University of Science, Okayama, Japan.

Mineral magnetic studies were carried out on lacustrine deposits from Pithoragarh palaeolake, Kumaun Lesser Himalaya, India. These deposits have already provided valuable information for the reconstruction of palaeoclimatic changes and tectonic uplift in the Himalayan region. According to radiocarbon chronology, the lake existed from 35 to 10kyr BP. Using magnetic data, radiocarbon ages and lithology, the top of the well-studied 13-m-thick Wadda section can be correlated to the basal part of the 4.7-m-thick Riyasi section. Fuzzy c-means cluster analysis using only magnetic parameters enables a subdivision of the Riyasi section into five magnetic zones based on three clusters. These clusters are related to the relative contribution of the various magnetic constituents, i.e., coarse- (HEM-C) and ultrafine- (HEM-F) grained hematite, both showing relatively soft magnetic behaviour. For the lowermost three zones, existing pollen data from the Wadda section helps to establish the climatic implications of the magnetic clusters and zones. The model is as follows: during humid periods, magnetic mineralogy is mainly controlled by HEM-F formed in situ, whereas during colder and more arid conditions detrital input of HEM-C and also HEM-F from the catchment area predominates. Climatic interpretation for the upper part of the section is attempted on the basis of the magnetic data, but has to be confirmed by further pollen studies.

A total of 170 ceramic specimens from 16 archaeological sites representing 16 well determined ages b from 4000 BC to 150 AD were investigated using the Thellier method. These paleointensities were compared with data from countries near Egypt after reduction to a common latitude to determine a secular variation curve of the geomagnetic field for the time period from 4000 BC to 150 AD. The field intensity increases from about 30 mu T around 3500 BC to a maximum of 70 mu T at about 400 BC when it starts to decrease until 150 AD. The Thellier double heating method was used together with the following additional test measurements: a) during the Thellier experiments the laboratory field F-Lab. pointed in the direction of stable NRM, b) magnetic susceptibility was measured after each double heating step to check for chemical alteration, c) a TRM check was made, by repeating the pTRM induction at a lower temperature, d) recent samples which were fired in a known field were used to test the reliability of our experimental setup and method. Based on rock magnetic measurements magnetite was identified as the predominant carrier of magnetization in the ceramics and bricks.