Masiku ano a Homo sapiens atenga nawo gawo pakusintha kwakukulu kwa chilengedwe, koma ndizovuta kudziwa komwe kudayambika kapena zotsatira zake zoyambirira.Archaeology, geochronology, geomorphology, ndi paleoenvironmental data kuchokera kumpoto kwa dziko la Malawi zikuwonetsa kusintha kwa ubale pakati pa kukhalapo kwa odyetserako ziweto, bungwe la zachilengedwe, ndi kupanga mafani a alluvial mu Late Pleistocene.Pambuyo pazaka za m'ma 1900, zida zowoneka bwino za Mesolithic ndi mafani a alluvial zidapangidwa.Zaka 92,000 zapitazo, mu chilengedwe cha paleo-ecological, panalibe analogi mu mbiri yapitayi ya 500,000.Zomwe akatswiri ofukula zakale apeza komanso kusanthula kwatsatanetsatane kukuwonetsa kuti moto woyambitsidwa ndi anthu umachepetsa ziletso zanyengo zomwe zimayatsa, kusokoneza kapangidwe ka zomera ndi kukokoloka.Izi, kuphatikiza ndi kusintha kwa mvula koyendetsedwa ndi nyengo, pamapeto pake zidapangitsa kusintha kwa chilengedwe kupita kumalo opangirako asanayambe ulimi.
Anthu amakono ndi amphamvu akulimbikitsa kusintha kwa chilengedwe.Kwa zaka masauzande ambiri, asintha chilengedwe mozama komanso mwadala, zomwe zidayambitsa mkangano wokhudza kuti chilengedwe choyamba cholamulidwa ndi anthu chinayambira liti komanso momwe chilengedwe chimakhalira (1).Umboni wochulukirachulukira wamabwinja ndi wamitundu umasonyeza kuti pali chiwerengero chachikulu cha kuyanjana kobwerezabwereza pakati pa foragers ndi chilengedwe chawo, zomwe zimasonyeza kuti makhalidwe amenewa ndi maziko a chisinthiko cha mitundu yathu (2-4).Zofukulidwa pansi ndi deta za majini zimasonyeza kuti Homo sapiens analipo ku Africa pafupifupi zaka 315,000 zapitazo (ka).Deta yofukulidwa m'mabwinja imasonyeza kuti zovuta za makhalidwe omwe akuchitika kudera lonselo zawonjezeka kwambiri m'mbuyomu pafupifupi 300 mpaka 200 ka spans.Mapeto a Pleistocene (Chibanian) (5).Chiyambireni kukhala zamoyo, anthu ayamba kudalira luso lamakono, makonzedwe a nyengo, ndi mgwirizano wovuta wa chikhalidwe cha anthu kuti apite patsogolo.Mikhalidwe imeneyi imatithandiza kupezerapo mwayi pa malo amene kale kunalibe anthu kapena zinthu zoopsa kwambiri, choncho masiku ano anthu ndi nyama zokhazokha zapadziko lonse lapansi (6).Moto unathandiza kwambiri kusintha kumeneku (7).
Zitsanzo zachilengedwe zikuwonetsa kuti kusinthika kwa chakudya chophikidwa kumatha kuyambika zaka zosachepera 2 miliyoni zapitazo, koma sizinali mpaka kumapeto kwa Middle Pleistocene pomwe umboni wazaka zakale wowongolera moto udawonekera (8).Pakatikati pa nyanja yokhala ndi mbiri ya fumbi lochokera kudera lalikulu la Africa ikuwonetsa kuti m'zaka mamiliyoni apitawa, nsonga ya kaboni wa elemental carbon idawonekera pambuyo pa 400 ka, makamaka pakusintha kuchokera ku nyengo yachisanu kupita ku glacial, komanso idachitikanso. Holocene (9).Izi zikuwonetsa kuti pamaso pa 400 ka, moto ku sub-Saharan Africa sanali wamba, ndipo zopereka za anthu zinali zofunika kwambiri mu Holocene (9).Moto ndi chida chomwe abusa a Holocene amagwiritsa ntchito polima ndi kusamalira udzu (10).Komabe, kuzindikira zakumbuyo komanso momwe chilengedwe chimagwiritsidwira ntchito ndi osaka osaka ku Pleistocene koyambirira ndizovuta kwambiri (11).
Moto umatchedwa chida chauinjiniya chogwiritsa ntchito zinthu mu ethnography ndi ofukula zamabwinja, kuphatikiza kukonza zobweza zopezera ndalama kapena kusintha zida.Izi nthawi zambiri zimakhala zokhudzana ndi kukonza kwa anthu ndipo zimafuna chidziwitso chochuluka cha chilengedwe (2, 12, 13).Moto wapamtunda umathandiza alenje kuthamangitsa nyama, kuwononga tizilombo, ndi kuonjezera zokolola za malo okhala (2).Moto pamalopo umalimbikitsa kuphika, kutenthetsa, kuteteza nyama zolusa, komanso mgwirizano wamagulu (14).Komabe, momwe moto wa mlenje umatha kukonzanso zigawo za malo, monga momwe chilengedwe chimakhalira komanso momwe malo akuwonekera, ndizosamvetsetseka (15, 16).
Popanda zidziwitso zakale zamabwinja ndi ma geomorphological komanso zolemba zopitilira zachilengedwe zochokera kumadera angapo, kumvetsetsa zakusintha kwachilengedwe kopangidwa ndi anthu ndikovuta.Zolemba zakale za Lake Deposit kuchokera ku Great Rift Valley ku Southern Africa, kuphatikizidwa ndi zolembedwa zakale zamabwinja m'derali, zimapangitsa kukhala malo ofufuza momwe chilengedwe chimakhudzidwira ndi Pleistocene.Pano, timapereka lipoti la zofukulidwa pansi ndi geomorphology za malo ochuluka a Stone Age kum'mwera chapakati kwa Africa.Kenaka, tinagwirizanitsa ndi paleoenvironmental data yomwe imatenga> 600 ka kuti tidziwe umboni woyambirira wogwirizanitsa khalidwe laumunthu ndi kusintha kwa chilengedwe pazochitika zamoto wopangidwa ndi anthu.
Tidapereka chiletso cha zaka zomwe sitinatchulepo kale za bedi la Chitimwe m'boma la Karonga, lomwe lili kumpoto chakumpoto kwa dziko la Malawi kummwera kwa Rift Valley (Chithunzi 1) (17).Mabedi amenewa amapangidwa ndi wofiira dothi alluvial mafani ndi mitsinje m'dambo, kuphimba za 83 makilomita lalikulu, munali mamiliyoni a zinthu mwala, koma palibe anasunga organic zotsalira, monga mafupa (Supplementary text) (18).Deta yathu yowoneka bwino (OSL) yochokera ku mbiri ya Earth (Chithunzi 2 ndi Matebulo S1 mpaka S3) idasintha zaka za bedi la Chitimwe kukhala Late Pleistocene, ndipo zaka zakale kwambiri zoyambitsa mafani a alluvial ndi kuyikidwa m'manda mwala ndi pafupifupi 92 ka ( 18, 19).The alluvial and river Chitimwe layer chimakwirira nyanja ndi mitsinje ya Pliocene-Pleistocene Chiwondo layer kuchokera ku low-angle unconformity (17).Madipoziti amenewa ali mu fault wedge m'mphepete mwa nyanja.Kapangidwe kawo kakuwonetsa kuyanjana pakati pa kusinthasintha kwa nyanja ndi zolakwika zomwe zimafikira ku Pliocene (17).Ngakhale kuti zochita za tectonic zitha kukhudza mawonekedwe a madera ndi malo otsetsereka a piedmont kwa nthawi yayitali, zolakwika mderali zitha kuchepa kuyambira Middle Pleistocene (20).Pambuyo pa ~ 800 ka ndipo mpaka patangopita 100 ka, hydrology ya Nyanja ya Malawi imayendetsedwa ndi nyengo (21).Chifukwa chake, palibe mwa awa ndikufotokozera kokhako kwa mapangidwe a mafani a alluvial mu Late Pleistocene (22).
(A) Malo a siteshoni yaku Africa yokhudzana ndi mvula yamakono (nyenyezi);buluu ndi wonyowa ndipo wofiira ndi wouma (73);bokosi lomwe lili kumanzere likuwonetsa Nyanja ya Malawi ndi madera ozungulira MAL05-2A ndi MAL05-1B Malo apakati / 1C pakati (kadontho kofiirira), pomwe dera la Karonga limawonekera ngati chithunzi chobiriwira, komanso malo a bedi la Luchamange akuwonekera. ngati bokosi loyera.(B) Kumpoto kwa chigwa cha Malawi, kusonyeza mmene mapiri ali pamwamba pa phiri la MAL05-2A, bedi lotsala la Chitimwe (chigamba cha bulauni) ndi malo okumba a Malawi Early Mesolithic Project (MEMSAP) (dontho lachikasu) );CHA, Chaminade;MGD, mudzi wa Mwanganda;NGA, Ngara;SS, Sadara South;VIN, chithunzi cha library library;WW, Beluga.
Zaka zapakati za OSL (mzere wofiira) ndi zolakwika za 1-σ (25% imvi), zaka zonse za OSL zokhudzana ndi kupezeka kwa zinthu zakale za in situ ku Karonga.Zaka zokhudzana ndi zakale za 125 ka zomwe zikuwonetsa (A) kuchulukitsitsa kwa kernel kwazaka zonse za OSL kuchokera ku dothi la fan, kuwonetsa sedimentary/alluvial fan accumulation (cyan), ndi kumanganso madzi a m'nyanja kutengera kusanthula kwazinthu zazikulu (PCA) m'madzi. zinthu zakale ndi mchere wa authigenic (21) (buluu) kuchokera pakatikati pa MAL05-1B/1C.(B) Kuchokera pachimake MAL05-1B/1C (wakuda, mtengo woyandikira 7000 wokhala ndi nyenyezi) ndi MAL05-2A pachimake (imvi), kuwerengera kwa macromolecular carbon pa gramu yomwe imasinthidwa ndi kuchuluka kwa sedimentation.(C) Margalef species richness index (Dmg) from MAL05-1B/1C core fossil mungu.(D) Peresenti ya mungu wa zinthu zakale zochokera ku Compositae, miombo woodland ndi Olea europaea, ndi (E) Peresenti ya mungu wochokera ku Poaceae ndi Podocarpus.Zonse za mungu zimachokera ku MAL05-1B/1C pachimake.Manambala omwe ali pamwamba amatchula zitsanzo za OSL zomwe zafotokozedwa mu Matebulo S1 mpaka S3.Kusiyana kwa kupezeka kwa data ndi kusamvana ndi chifukwa cha magawo osiyanasiyana a zitsanzo ndi kupezeka kwa zinthu pachimake.Chithunzi S9 chikuwonetsa zolemba ziwiri za macro carbon zosinthidwa kukhala z-scores.
(Chitimwe) Kukhazikika kwa malo pambuyo popanga mafani kumasonyezedwa ndi mapangidwe a nthaka yofiira ndi carbonates yopanga nthaka, yomwe imaphimba matope opangidwa ndi mafani a malo onse ophunzirira (Supplementary text ndi Table S4).Kupangidwa kwa otsatira a Late Pleistocene alluvial ku Lake Malawi Basin sikungochitika ku Karonga kokha.Pafupifupi makilomita 320 kum'mwera chakum'mawa kwa Mozambique, kuya kwa 26Al ndi 10Be kumachepetsa kupanga kwa bedi la Luchamange la dothi lofiira mpaka 119 mpaka 27 ka (23).Kuletsa zaka uku kumagwirizana ndi kalembedwe ka OSL kuchigawo chakumadzulo kwa Nyanja ya Malawi ndipo kukuwonetsa kukulirakulira kwa mafani a alluvial m'chigawo cha Late Pleistocene.Izi zimathandizidwa ndi deta yochokera ku nyanja yapakati pa nyanja, zomwe zimasonyeza kuti kuchuluka kwa matope kumatsagana ndi pafupifupi 240 ka, yomwe ili ndi mtengo wapamwamba kwambiri pa ca.130 ndi 85 ka (mawu owonjezera) (21).
Umboni wakale kwambiri wa kukhazikika kwa anthu mderali ndi wokhudzana ndi matope a Chitimwe omwe adadziwika kuti ~92 ± 7 ka.Chotsatirachi chimachokera ku 605 m3 ya zinyalala zofukulidwa kuchokera ku 14 sub-centimeter control space of archaeological of archaeological and 147 m3 of sediments from 46 of archaeological maenje oyesera, oyendetsedwa molunjika mpaka 20 cm ndi yopingasa mpaka 2 metres (Supplementary text to Figures) Kuphatikiza apo, tidafufuzanso makilomita 147.5, tinakonza maenje 40 oyeserera a geological, ndikusanthula zotsalira zachikhalidwe zopitilira 38,000 kuchokera pa 60 aiwo (Matebulo S5 ndi S6) (18).Kafukufuku wozama komanso zofukulidwa zakalezi zikusonyeza kuti ngakhale kuti anthu akale kuphatikizapo anthu amasiku ano angakhalepo m’derali pafupifupi zaka 92 zapitazo, kudzikundikira kwa matope okhudzana ndi kukwera ndi kukhazikika kwa nyanja ya Malawi sikunasunge umboni wa zinthu zakale zokumbidwa pansi mpaka Kupanga bedi la Chitimwe.
Zomwe akatswiri ofukula zakale apeza zimagwirizana ndi lingaliro lakuti kumapeto kwa Quaternary, kukula kwachitsanzo ndi ntchito za anthu kumpoto kwa Malawi kunalipo zambiri, ndipo miyambo ya chikhalidwe inali ya mitundu ya madera ena a Africa okhudzana ndi anthu oyambirira.Zinthu zambiri zopangidwa ndi miyala ya quartzite kapena quartz, zokhala ndi radial, Levallois, nsanja ndi kuchepetsa mwachisawawa pachimake (Chithunzi S4).Zofukula za morphological diagnostic makamaka zimatengera njira ya Mesolithic Age (MSA)-yamtundu wa Levallois, yomwe yakhala pafupifupi 315 ka ku Africa mpaka pano (24).Bedi lapamwamba kwambiri la Chitimwe linakhalapo mpaka nthawi ya Holocene yoyambirira, yomwe inali ndi zochitika zochepa za Late Stone Age, ndipo zinapezeka kuti zinali zokhudzana ndi alenje a Pleistocene ndi Holocene mu Africa yonse.Mosiyana ndi zimenezi, miyambo ya zida zamwala (monga zida zazikulu zodula) zomwe zimagwirizanitsidwa ndi Early Middle Pleistocene ndizosowa.Kumene izi zidachitika, zidapezeka m'madontho okhala ndi MSA kumapeto kwa Pleistocene, osati m'magawo oyambira (Table S4) (18).Ngakhale kuti malowa analipo pa ~ 92 ka, nthawi yoyimilira kwambiri ya zochitika za anthu ndi kuyika kwa mafani a alluvial kunachitika pambuyo pa ~ 70 ka, yofotokozedwa bwino ndi mibadwo ya OSL (Chithunzi 2).Tinatsimikizira chitsanzo ichi ndi 25 yosindikizidwa ndi zaka 50 za OSL zomwe sizinasindikizidwe kale (Chithunzi 2 ndi Matebulo S1 mpaka S3).Izi zikuwonetsa kuti mwa zaka 75 zomwe zidadziwika, 70 adachira pambuyo pa 70 ka.Chithunzi 2 chikuwonetsa zaka 40 zomwe zimagwirizanitsidwa ndi zinthu zakale za in-situ MSA, zokhudzana ndi zizindikiro zazikulu za paleoenvironmental zofalitsidwa kuchokera pakati pa beseni lapakati la MAL05-1B/1C (25) ndi malo omwe anali asanasindikizidwe a MAL05-2A kumpoto kwa nyanjayi.Makala (pafupi ndi fani yomwe imatulutsa zaka za OSL).
Pogwiritsa ntchito kafukufuku watsopano wofukulidwa m’mabwinja a phytoliths ndi nthaka micromorphology, komanso deta ya anthu za mungu, makala akuluakulu, zotsalira za m’madzi ndi mchere wopezeka pakatikati pa Malawi Lake Drilling Project, tinakonzanso ubale wa anthu wa MSA ndi Nyanja ya Malawi.Khalani ndi nyengo ndi chilengedwe cha nthawi yomweyo (21).Othandizira awiriwa ndiwo maziko ake omanganso kuya kwa nyanja kuyambira ku 1200 ka (21), ndipo amafananiza ndi mungu ndi zitsanzo za macrocarbon zomwe zidasonkhanitsidwa pamalo omwewo pakatikati pa ~ 636 ka (25) m'mbuyomu. .Ma cores aatali kwambiri (MAL05-1B ndi MAL05-1C; 381 ndi 90 m motsatana) adasonkhanitsidwa pafupifupi makilomita 100 kum'mwera chakum'mawa kwa malo opangira zinthu zakale.Chigawo chachifupi (MAL05-2A; 41 m) chinasonkhanitsidwa pafupifupi makilomita 25 kummawa kwa mtsinje wa Rukulu kumpoto (Chithunzi 1).Paphata pa Chichewa MAL05-2A imasonyeza mmene zinthu zilili padzikoli m’dera la Kalunga, pamene m’kati mwa MAL05-1B/1C sichilandira mtsinje wolunjika kuchokera kwa Kalunga, kotero kuti ukhoza kusonyeza bwino mmene zinthu zilili m’deralo.
Mlingo wa ma deposition olembedwa mu MAL05-1B/1C pobowola wophatikizika unayamba kuchokera pa 240 ka ndikuwonjezeka kuchoka pa avareji yanthawi yayitali ya 0.24 mpaka 0.88 m/ka (Chithunzi S5).Kuwonjezeka koyambirira kumakhudzana ndi kusintha kwa kuwala kwadzuwa kozungulira, komwe kungapangitse kusintha kwa matalikidwe apamwamba pamlingo wanyanja panthawiyi (25).Komabe, pamene orbital eccentricity imatsika pambuyo pa 85 ka ndipo nyengo imakhala yokhazikika, chiwerengero cha subsidence chikadali chachikulu (0.68 m / ka).Izi zinagwirizana ndi mbiri yapadziko lapansi ya OSL, yomwe inasonyeza umboni wochuluka wa kufalikira kwa mafani a alluvial pambuyo pa pafupifupi 92 ka, ndipo zinali zogwirizana ndi zomwe zikuwonetseratu zomwe zikuwonetsa kugwirizana kwabwino pakati pa kukokoloka ndi moto pambuyo pa 85 ka (Zolemba zowonjezera ndi Table S7) .Poganizira za zolakwika zaulamuliro wa geochronological womwe ulipo, ndizosatheka kuweruza ngati maubwenzi awa amasintha pang'onopang'ono kuchokera kumayendedwe obwereza kapena amaphulika mwachangu akafika pachimake.Malingana ndi chitsanzo cha geophysical cha chisinthiko cha beseni, kuyambira ku Middle Pleistocene (20), kufalikira kwa Rift ndi subsidence yokhudzana ndi kuchepa kwachepa, kotero si chifukwa chachikulu cha ndondomeko yopangira mafani omwe tidatsimikiza makamaka pambuyo pa 92 ka.
Kuyambira ku Middle Pleistocene, nyengo yakhala ikuwongolera kuchuluka kwa madzi a m'nyanja (26).Mwachindunji, kukwera kwa beseni lakumpoto kunatseka njira yomwe inalipo kale.800 ka kuzama nyanjayo mpaka kukafika pachimake potuluka masiku ano (21).Polowera kum'mwera kwa nyanjayi, potulukira madziwo ankadutsa m’mwamba mwa madzi a m’nyanjayi pakagwa mvula (kuphatikizanso masiku ano), koma analola kuti besenilo litseke pamene madzi a m’nyanjayo ankatsika pakagwa mvula (27).Kumangidwanso kwa mtunda wa nyanja kukuwonetsa kusinthasintha kowuma ndi konyowa m'ma 636 ka apitawa.Malinga ndi umboni wochokera ku mungu wa zinthu zakale, nthawi ya chilala chambiri (> 95% kuchepetsedwa kwa madzi onse) yokhudzana ndi kutsika kwadzuwa kwanyengo yachilimwe kwadzetsa kukula kwa zomera zomwe zili m'chipululu, ndi mitengo yongokhala m'madzi okhazikika (27).Kutsika (kunyanja) kumeneku kumayenderana ndi mawonekedwe a mungu, kusonyeza kuchuluka kwa udzu (80% kapena kupitilira apo) ndi xerophytes (Amaranthaceae) chifukwa cha msonkho wamitengo komanso kutsika kwamitundu yonse yamitundu (25).Mosiyana ndi zimenezi, nyanjayi ikamafika pamlingo wamakono, zomera zogwirizana kwambiri ndi nkhalango za m’mapiri za mu Africa kaŵirikaŵiri zimafika m’mphepete mwa nyanja [pafupifupi mamita 500 pamwamba pa nyanja (masl)].Masiku ano, nkhalango zamapiri ku Africa zimangowoneka pang'ono pang'ono pamwamba pa 1500 masl (25, 28).
Chilala chaposachedwa kwambiri chinachitika kuyambira 104 mpaka 86 ka.Pambuyo pake, ngakhale kuti nyanjayo inabwereranso pamalo okwera, nkhalango zotseguka za miombo zokhala ndi zitsamba zambiri komanso zosakaniza za zitsamba zinakhala zofala (27, 28).Mtengo wofunika kwambiri wa nkhalango zamapiri ku Africa ndi Podocarpus pine, womwe sunayambe wabwereranso ku mtengo wofanana ndi msinkhu wa nyanja wam'mbuyo pambuyo pa 85 ka (10.7 ± 7.6% pambuyo pa 85 ka, pamene nyanja yofananayo isanafike 85 ka ndi 29.8 ± 11.8% ).Mlozera wa Margalef (Dmg) ukuwonetsanso kuti kuchuluka kwa zamoyo zam'mbuyomu 85 ka ndi 43% kutsika kuposa momwe zidakhalira zam'nyanja zazitali (2.3 ± 0.20 ndi 4.6 ± 1.21, motsatana), mwachitsanzo, pakati pa 420 ndi 345 ka (Supplementary). zolemba ndi ziwerengero S5 ndi S6) (25).Zitsanzo za mungu kuyambira pafupifupi nthawi.88 mpaka 78 ka ilinso ndi mungu wambiri wa Compositae, zomwe zingasonyeze kuti zomera zasokonezeka ndipo zili mkati mwa zolakwika za tsiku lakale kwambiri pamene anthu adakhala m'deralo.
Timagwiritsa ntchito njira yosokoneza nyengo (29) kusanthula deta ya paleoecological ndi paleoclimate ya ma cores omwe adabowoleredwa kale ndi pambuyo pa 85 ka, ndikuwunika ubale wachilengedwe pakati pa zomera, kuchuluka kwa zamoyo, ndi mvula komanso lingaliro lakuchotsa kuneneratu koyera kwanyengo.Yendetsani njira yoyambira ~ 550 ka.Zamoyo zomwe zasinthazi zimakhudzidwa ndi mvula yodzaza ndi nyanja komanso moto, zomwe zimawonekera chifukwa cha kusowa kwa zamoyo ndi zomera zatsopano.Nyengo yamvula yomaliza itatha, zinthu zina za m’nkhalango zokha zinayamba kumeranso, kuphatikizapo nkhalango za kumapiri za ku Africa zomwe sizingapse ndi moto, monga mafuta a azitona, komanso nkhalango za m’madera otentha zomwe sizingapse ndi moto, monga Celtis (Supplementary text and Figure S5) ( 25).Kuti tiyese lingaliro ili, tidatengera momwe madzi a m'nyanja amachokera ku ostracode ndi authigenic mineral substitutes monga zosinthika zodziyimira pawokha (21) komanso zodalira monga makala ndi mungu zomwe zingakhudzidwe ndi kuchuluka kwa moto (25).
Kuti tiwone kufanana kapena kusiyana pakati pa zosakanizazi nthawi zosiyanasiyana, tidagwiritsa ntchito mungu wochokera ku Podocarpus (mtengo wobiriwira), udzu (udzu), ndi azitona (gawo losagwirizana ndi moto la nkhalango zamapiri za ku Africa) pofufuza principal coordinate (PCoA), ndi miombo (gawo lalikulu la nkhalango lero).Pokonzekera PCoA pa malo osakanikirana omwe amaimira nyanja ya nyanja pamene kuphatikiza kulikonse kunapangidwa, tinayang'ana momwe mungu umasinthira pokhudzana ndi mvula komanso momwe ubalewu umasinthira pambuyo pa 85 ka (Chithunzi 3 ndi Chithunzi S7).Asanakwane 85 ka, zitsanzo za gramineous-based aggregated to youma, pomwe zitsanzo za podocarpus zidaphatikizana kunyowa.Mosiyana ndi izi, zitsanzo pambuyo pa 85 ka zimaphatikizidwa ndi zitsanzo zambiri pamaso pa 85 ka ndipo zimakhala ndi mitundu yosiyanasiyana, zomwe zimasonyeza kuti mapangidwe ake ndi achilendo kwa mvula yofanana.Udindo wawo mu PCoA umasonyeza mphamvu ya Olea ndi miombo, zomwe zimayanjidwa pansi pazifukwa zomwe zimakhala zowotcha.M'zitsanzo pambuyo pa 85 ka, Podocarpus pine anali wochuluka mu zitsanzo zitatu zotsatizana, zomwe zinachitika pambuyo pa nthawi yapakati pa 78 ndi 79 ka.Zimenezi zikusonyeza kuti mvula itayamba kugwa, nkhalangoyo ikuoneka kuti inayambiranso kwa nthawi yochepa isanagwe.
Mfundo iliyonse imayimira chitsanzo chimodzi cha mungu pa nthawi yoperekedwa, pogwiritsa ntchito malemba owonjezera ndi chitsanzo cha zaka mu Chithunzi 1. S8.Vector imayimira mayendedwe ndi kusintha kwakusintha, ndipo vekitala yayitali imayimira njira yamphamvu.Pansi pa nyanjayi imayimira kuchuluka kwa madzi a m'nyanjayi monga kuyimira mvula;buluu wakuda ndi wapamwamba.Mtengo wapakati wazinthu za PCoA umaperekedwa pambuyo pa 85 ka (diamondi yofiira) ndi data yonse yochokera kumadzi ofanana ndi nyanja isanakwane 85 ka (diamondi yachikasu).Pogwiritsa ntchito zidziwitso za 636 ka yonse, "mulingo woyeserera wa nyanja" uli pakati pa -0.130-σ ndi -0.198-σ pafupi ndi eigenvalue wapakati pa PCA.
Kuti tiphunzire za ubale pakati pa mungu, mlingo wa madzi a m'nyanja ndi makala, tinagwiritsa ntchito nonparametric multivariate analysis of variance (NP-MANOVA) kuyerekeza "chilengedwe" chonse (choyimiridwa ndi matrix a data a mungu, mlingo wa madzi a m'nyanja ndi makala) kale. ndipo pambuyo pa kusintha kwa 85 ka.Tidapeza kuti kusiyanasiyana ndi kusiyanasiyana komwe kumapezeka m'matrix a datayi ndizosiyana kwambiri zisanachitike komanso pambuyo pa 85 ka (Table 1).
Deta lathu lapadziko lapansi la paleoenvironmental kuchokera ku phytoliths ndi dothi la m'mphepete mwa Nyanja ya Kumadzulo ndizogwirizana ndi matanthauzidwe otengera nyanjayi.Izi zikusonyeza kuti ngakhale kuti nyanjayi ili ndi madzi ochuluka kwambiri, malowa asinthidwa kukhala malo okhala ndi nkhalango zowirira komanso udzu wamitengo, monganso masiku ano (25).Malo onse omwe amawunikidwa pa phytoliths kumadzulo kwa beseni ndi pambuyo pa ~ 45 ka ndipo akuwonetsa chivundikiro chochuluka cha matabwa chosonyeza kunyowa.Komabe, amakhulupirira kuti zambiri mwa mulch zimakhala ngati nkhalango zotseguka zomwe zimadzaza ndi nsungwi ndi udzu wamantha.Malingana ndi deta ya phytolith, mitengo ya kanjedza yosagwira moto (Arecaceae) imapezeka m'mphepete mwa nyanja, ndipo imakhala yosowa kapena kulibe m'malo osungiramo zinthu zakale zakale (Table S8) (30).
Nthawi zambiri, kunyowa koma kutseguka kumapeto kwa Pleistocene kumathanso kutengedwa kuchokera ku terrestrial paleosols (19).Dongo la m'nyanja ndi dothi la carbonate lochokera ku malo ofukula zinthu zakale a Mudzi wa Mwanganda likhoza kutsatiridwa mpaka ku 40 mpaka 28 cal ka BP (yomwe poyamba inali Qian'anni) (Table S4).Dothi la carbonate pabedi la Chitimwe nthawi zambiri limakhala zigawo za nodular calcareous (Bkm) ndi argillaceous ndi carbonate (Btk), zomwe zimasonyeza malo okhazikika a geomorphological bata ndi kukhazikika kwapang'onopang'ono kuchokera ku fan of alluvial yofika patali Pafupifupi 29 cal ka BP (Zowonjezera mawu).Dothi lokokoloka, lolimba la laterite (mwala wa lithic) wopangidwa pa zotsalira za mafani akale akuwonetsa malo otseguka (31) ndi mvula yamphamvu yanyengo (32), kuwonetsa kukhudzidwa kosalekeza kwa malowa.
Thandizo pa ntchito ya moto pakusinthaku zimachokera ku zolemba zamakala zazikulu zobowola, ndipo kulowetsedwa kwa makala kuchokera ku Central Basin (MAL05-1B/1C) kwachuluka kuchokera pafupifupi.175 makadi.Chiwerengero chachikulu cha nsonga zimatsata pakati pa pafupifupi.Pambuyo pa 135 ndi 175 ka ndi 85 ndi 100 ka, madzi a nyanja adachira, koma nkhalango ndi zamoyo zamtundu sizinabwererenso (Zolemba zowonjezera, Chithunzi 2 ndi Chithunzi S5).Ubale pakati pa kuchuluka kwa makala ndi kutengeka kwa maginito kwa matope a m'nyanja ungathenso kuwonetsa mbiri yakale yamoto (33).Gwiritsani ntchito deta kuchokera ku Lyons et al.(34) Nyanja ya Malawi ikupitiriza kuononga malo omwe adawotchedwa pambuyo pa 85 ka, zomwe zikutanthawuza mgwirizano wabwino (Spearman's Rs = 0.2542 ndi P = 0.0002; Table S7), pamene matope akale amasonyeza mgwirizano wosiyana (Rs = -0.2509 ndi P < 0.0001).M'chigwa chakumpoto, pachimake chachifupi cha MAL05-2A chimakhala ndi nangula wakuya kwambiri, ndipo waung'ono wa Toba tuff ndi ~ 74 mpaka 75 ka (35).Ngakhale kuti ilibe malingaliro a nthawi yayitali, imalandira zolowetsa mwachindunji kuchokera ku beseni kumene deta yofukulidwa m'mabwinja imachokera.Zolemba zamakala zakumpoto zakumpoto zikuwonetsa kuti kuyambira chizindikiro cha Toba crypto-tephra, kulowetsedwa kwa makala owopsa kwawonjezeka pang'onopang'ono panthawi yomwe umboni wofukulidwa m'mabwinja umapezeka kwambiri (Chithunzi 2B).
Umboni wa moto wopangidwa ndi anthu ukhoza kusonyeza kugwiritsiridwa ntchito mwadala pamlingo wa malo, kuchuluka kwa anthu komwe kumayambitsa kuyatsa kochulukira kapena kukulirapo pamalopo, kusintha kupezeka kwamafuta podula nkhalango zapansi panthaka, kapena kuphatikiza kwazinthu izi.Osaka amakono amagwiritsa ntchito moto kuti asinthe mphotho zopezera chakudya (2).Zochita zawo zimakulitsa kuchuluka kwa nyama, kusunga mawonekedwe azithunzi, ndikuwonjezera kusiyanasiyana kwamafuta komanso kusiyanasiyana kwa magawo otsatizana (13).Moto ndiwofunikanso pazochitika zapamalo monga kutentha, kuphika, chitetezo, ndi kucheza (14).Ngakhale kusiyana kwakung'ono pakuyika moto kunja kwa mphezi zachilengedwe kumatha kusintha katsatidwe ka nkhalango, kupezeka kwamafuta, komanso nthawi yowombera.Kuchepetsa kwamitengo yamitengo ndi mitengo yapansi panthaka ndikotheka kukulitsa kukokoloka kwa nthaka, ndipo kutayika kwa mitundu yosiyanasiyana ya zamoyo m'derali kumagwirizana kwambiri ndi kutayika kwa madera a nkhalango za ku Africa (25).
M'mabwinja a m'mabwinja a MSA isanayambe, kulamulira kwa moto kwa anthu kwakhazikitsidwa bwino (15), koma mpaka pano, kugwiritsidwa ntchito kwake ngati chida choyang'anira malo kumangolembedwa muzinthu zochepa za Paleolithic.Izi zikuphatikizapo ku Australia.40 ka (36), Highland New Guinea.45 ka (37) mgwirizano wamtendere.50 ka Niah Cave (38) m'chigwa cha Borneo.Ku maiko a ku America, pamene anthu anayamba kulowa m’chilengedwechi, makamaka m’zaka za m’ma 20 ka (16), kuyatsa kochita kupanga kunkaonedwa kuti n’kumene kunkachititsa kuti zomera ndi zinyama zisinthe.Zotsatirazi ziyenera kuzikidwa paumboni woyenerera, koma pankhani ya kuphatikizika kwachindunji kwa mbiri yakale, geological, geomorphological, ndi paleoenvironmental, mkangano wa causality walimbikitsidwa.Ngakhale kuti deta yam'madzi yam'madzi a m'mphepete mwa nyanja ya Africa yapereka kale umboni wa kusintha kwa moto m'mbuyomu pafupi ndi 400 ka (9), apa timapereka umboni wa chikoka cha anthu kuchokera kuzinthu zofukulidwa zakale, paleoenvironmental, ndi geomorphological data sets.
Kuzindikirika kwa moto wopangidwa ndi anthu m'mabuku a paleoenvironmental kumafuna umboni wa zochitika zamoto ndi kusintha kwa nyengo kapena malo a zomera, kutsimikizira kuti kusintha kumeneku sikunanenedweratu ndi nyengo zokha, komanso nthawi / malo apakati pakati pa kusintha kwa moto ndi kusintha kwa anthu. (29) Apa, umboni woyamba wa kuchuluka kwa kukwera kwa ma MSA ndi kufalikira kwa mafani mu nyanja ya Nyanja ya Malawi kunachitika chakumayambiriro kwa ntchito yokonzanso zomera.85 makadi.Kuchuluka kwa makala pachimake cha MAL05-1B/1C kumawonetsa momwe madera amapangira makala ndikuyika, pafupifupi 150 ka poyerekeza ndi mbiri yonse ya 636 ka (Zithunzi S5, S9, ndi S10).Kusintha kumeneku kumasonyeza kuthandizira kofunikira kwa moto pakupanga mapangidwe a chilengedwe, omwe sangathe kufotokozedwa ndi nyengo yokha.M’malo amoto wachilengedwe, kuyatsa kwa mphezi kumachitika kumapeto kwa nyengo yadzuwa (39).Komabe, ngati mafutawo ndi ouma mokwanira, moto wopangidwa ndi anthu ukhoza kuyatsidwa nthawi iliyonse.Pamlingo wa zochitika, anthu amatha kusintha moto mosalekeza potola nkhuni pansi pa nkhalango.Chotsatira cha mtundu uliwonse wa moto wopangidwa ndi anthu ndi chakuti ukhoza kuchititsa kuti zomera zambiri ziwonongeke, zomwe zimatha chaka chonse, komanso pamiyeso yonse.
Ku South Africa, kale kwambiri pa 164 ka (12), moto unkagwiritsidwa ntchito potenthetsa miyala yopangira zida.Kumayambiriro kwa zaka za m'ma 170 (40), moto unkagwiritsidwa ntchito ngati chida chophikira ma tubers owuma, kugwiritsa ntchito moto mokwanira m'nthawi zakale.Mawonekedwe Opambana (41).Kuwotcha kwamalo kumachepetsa chivundikiro chamitengo ndipo ndi chida chofunikira posungira udzu ndi malo okhala ndi nkhalango, zomwe ndizomwe zimafotokozera zachilengedwe cholumikizidwa ndi anthu (13).Ngati cholinga cha kusintha kwa zomera kapena khalidwe la nyama ndi kuonjezera kutentha kopangidwa ndi anthu, ndiye kuti khalidweli likuyimira kuwonjezeka kwa zovuta za kulamulira ndi kutumiza moto ndi anthu oyambirira amakono poyerekeza ndi anthu oyambirira, ndipo zimasonyeza kuti ubale wathu ndi moto wadutsa. kusintha kwa kudalirana (7).Kusanthula kwathu kumapereka njira yowonjezereka yomvetsetsa kusintha kwa kugwiritsidwa ntchito kwa moto ndi anthu ku Late Pleistocene, ndi zotsatira za kusintha kumeneku pa malo awo ndi chilengedwe.
Kukula kwa mafani a Late Quaternary alluvial m’dera la Karonga kungakhale chifukwa cha kusintha kwa nyengo yoyaka moto m’nyengo ya mvula yomwe imagwa kuposa mvula, zomwe zikuchititsa kuti phirili likokoloke.Zomwe zachitikazi zitha kukhala kuchulukana kwamadzi komwe kumachitika chifukwa cha chipwirikiti chomwe chachitika chifukwa cha moto, kukokoloka kopitilira muyeso kwa kumtunda kwa madambo, komanso kukula kwa mafani amtundu wa alluvial mdera la piedmont pafupi ndi nyanja ya Malawi.Izi zingaphatikizepo kusintha kwa dothi kuti muchepetse kulowa mkati, kuchepetsa kuuma kwa pamwamba, ndi kuonjezera madzi osefukira chifukwa cha kusakanikirana kwa mvula yambiri komanso kuchepa kwa chivundikiro cha mitengo (42).Kupezeka kwa matope kumayamba bwino pochotsa zophimbazo, ndipo pakapita nthawi, mphamvu ya nthaka imatha kuchepa chifukwa cha kutentha komanso kuchepa kwa mizu.The exfoliation of topsoil kumawonjezera sediment flux, yomwe imayendetsedwa ndi fani woboola pakati kudzikundikira kunsi kwa mtsinje ndi imathandizira mapangidwe ofiira dothi pa zimakupiza woboola pakati.
Zinthu zambiri zimatha kuwongolera momwe malo amayankhira pakusintha kwamoto, zomwe zambiri zimagwira ntchito pakanthawi kochepa (42-44).Chizindikiro chomwe tikugwirizanitsa pano ndi chodziwikiratu pamlingo wa nthawi ya millennium.Kuwunika ndi kusinthika kwamalo kumawonetsa kuti ndi kusokonekera kwa zomera komwe kumayambitsidwa ndi moto wamtchire mobwerezabwereza, kuchuluka kwa deudation kwasintha kwambiri pamillennium time scale (45, 46).Kusowa kwa zolemba zakale za m'madera zomwe zimagwirizana ndi kusintha komwe kumawonedwa mu mbiri ya makala ndi zomera kumalepheretsa kukonzanso zotsatira za khalidwe laumunthu ndi kusintha kwa chilengedwe pamagulu a anthu omwe amadya udzu.Komabe, nyama zazikuluzikulu zodyera udzu zomwe zimakhala m'malo otseguka zimathandizira kuti zisawonongeke komanso kupewa kuwononga zomera zamitengo (47).Umboni wa kusintha kwa zigawo zosiyanasiyana za chilengedwe sikuyenera kuyembekezera kuchitika nthawi imodzi, koma kuyenera kuwonedwa ngati mndandanda wa zotsatira zowonongeka zomwe zingachitike kwa nthawi yaitali (11).Pogwiritsa ntchito njira yolimbana ndi kusintha kwa nyengo (29), timaona zochita za anthu ngati chinthu chofunikira kwambiri pakusintha dziko lakumpoto kwa dziko la Malawi pa nthawi ya Late Pleistocene.Komabe, zotsatirazi zitha kukhazikitsidwa pacholowa choyambirira, chosadziŵika bwino kwambiri cha kuyanjana kwa anthu ndi chilengedwe.Chiwongolero cha makala chomwe chinawonekera m'mbiri ya paleoenvironmental isanafike tsiku lakale kwambiri la zofukulidwa pansi lingaphatikizepo gawo la anthropogenic lomwe silimayambitsa kusintha kwa chilengedwe monga momwe zalembedwera pambuyo pake, ndipo sizimaphatikizapo madipoziti omwe ali okwanira kusonyeza molimba mtima ntchito ya anthu.
Zidole zazifupi, monga za kufupi ndi Nyanja ya Masoko ku Tanzania, kapena matope ofupikitsa a Nyanja ya Malawi, zimasonyeza kuti kuchuluka kwa mungu wa udzu ndi misonkho ya m’nkhalango zasintha, zomwe zimadziwika kuti zaka 45 zapitazi.Kusintha kwanyengo kwa ka (48-50).Komabe, kungoyang'ana kwanthawi yayitali kwa mbiri ya mungu wa Nyanja ya Malawi > 600 ka, pamodzi ndi malo akale akale pafupi ndi nyanjayi, ndizotheka kumvetsetsa nyengo, zomera, makala, ndi zochitika za anthu.Ngakhale kuti anthu amatha kuonekera kumpoto kwa nyanja ya Nyanja ya Malawi asanakwane 85 ka, pafupifupi 85 ka, makamaka pambuyo pa 70 ka, amasonyeza kuti derali ndi lokongola kuti anthu azikhalamo pambuyo pa chilala chachikulu chomaliza.Panthawiyi, kugwiritsa ntchito moto kwatsopano kapena kopitilira muyeso ndi anthu mwachiwonekere kumaphatikizana ndi kusintha kwanyengo kuti kumangenso ubale wachilengedwe> 550-ka, ndipo pomaliza adapanga malo oyambilira asanachitike ulimi (Chithunzi 4).Mosiyana ndi nthawi zakale, mawonekedwe a nthaka amateteza malo a MSA, omwe ndi ntchito ya ubale wobwerezabwereza pakati pa chilengedwe (kugawa kwazinthu), khalidwe laumunthu (machitidwe a ntchito), ndi kuyambitsa mafani (kuyika / kuyika malo).
(A) Pa.400 ka: Palibe munthu yemwe angadziwike.Chinyezicho n’chofanana ndi masiku ano, ndipo nyanjayi n’njokwera kwambiri.Chivundikiro cha arboreal chosiyanasiyana, chosayaka moto.(B) Pafupifupi 100 ka: Palibe zolembedwa zakale, koma kukhalapo kwa anthu kumatha kuzindikirika chifukwa cha kuchuluka kwa makala.Mikhalidwe yowuma kwambiri imapezeka m'madzi owuma.Mwala nthawi zambiri umakhala wowonekera ndipo matope a pamwamba amakhala ochepa.(C) Pafupifupi 85 mpaka 60 ka: Madzi a m'nyanja amawonjezeka ndi kuwonjezereka kwa mvula.Kukhalapo kwa anthu kumatha kupezedwa kudzera m'mabwinja pambuyo pa 92 ka, ndipo pambuyo pa 70 ka, kuwotchedwa kwa mapiri ndi kufalikira kwa mafani a alluvial kudzatsatira.Pakhala pali mitundu yochepa chabe ya zomera zolimbana ndi moto.(D) Pafupifupi 40 mpaka 20 ka: Kulowetsa makala achilengedwe m'dera lakumpoto kwawonjezeka.Mapangidwe a alluvial mafani anapitiriza, koma anayamba kufooka kumapeto kwa nthawi imeneyi.Poyerekeza ndi mbiri yakale ya 636 ka, nyanjayi imakhala yokwera komanso yokhazikika.
Anthropocene imayimira kuchulukirachulukira kwa machitidwe omanga omwe apangidwa zaka masauzande ambiri, ndipo kukula kwake ndikwapadera kwa Homo sapiens yamakono (1, 51).M'masiku ano, ndikuyambitsa ulimi, malo opangidwa ndi anthu akupitirizabe kukhalapo ndikukula, koma ndizowonjezera za machitidwe omwe anakhazikitsidwa panthawi ya Pleistocene, m'malo mosokoneza (52).Zambiri zochokera kumpoto kwa Malawi zikusonyeza kuti nthawi ya kusintha kwa chilengedwe ingakhale yaitali, yovuta komanso yobwerezabwereza.Kusinthika kumeneku kukuwonetsa chidziwitso chovuta cha chilengedwe cha anthu amasiku ano komanso kusinthika kwawo kukhala mitundu yomwe ili padziko lonse lapansi masiku ano.
Malinga ndi ndondomeko yofotokozedwa ndi Thompson et al., kufufuza pa malo ndi kujambula kwa zinthu zakale ndi makhalidwe a cobblestone pa malo ofufuza.(53).Kuyika kwa dzenje loyesa ndikufukula kwa malo akuluakulu, kuphatikizapo micromorphology ndi phytolith sampling, kutsata ndondomeko yofotokozedwa ndi Thompson et al.(18) ndi Wright et al.(19).Mapu athu a geographic information system (GIS) potengera mapu a Malawi geological survey of the region akuwonetsa kulumikizana bwino pakati pa Bedi la Chitimwe ndi malo ofukula zakale (Chithunzi S1).Kalekale pakati pa maenje oyesera a geology ndi ofukula zakale m'dera la Karonga ndikutenga zitsanzo zazikulu kwambiri (Chithunzi S2).Kafukufuku wa geomorphology wa Karonga, zaka za geological and of archaeological survey akuphatikiza njira zinayi zazikuluzikulu zowunikira: kafukufuku wa anthu oyenda pansi, maenje oyesa zakale, maenje oyesera a geology ndi kufukula mwatsatanetsatane malo.Pamodzi, njirazi zimalola kutsanzira kuwonekera kwakukulu kwa bedi la Chitimwe kumpoto, chapakati, ndi kumwera kwa Karonga (Chithunzi S3).
Kufufuza kwapamalo ndi kujambula kwa zinthu zakale ndi miyala yamtengo wapatali pamalo ofufuza oyenda pansi motsatira ndondomeko yofotokozedwa ndi Thompson et al.(53).Njirayi ili ndi zolinga zazikulu ziwiri.Choyamba ndikuzindikira malo omwe zikhalidwe zachikhalidwe zawonongeka, ndikuyika maenje oyesera ofukula m'mabwinja okwera m'malo awa kuti abwezeretse zikhalidwe za chikhalidwe mu situ kuchokera kumalo okwiriridwa.Cholinga chachiwiri ndikulemba mwalamulo kugawa kwa zinthu zakale, mawonekedwe awo, ndi ubale wawo ndi gwero la miyala yapafupi (53).Pa ntchitoyi, gulu la anthu atatu linayenda mtunda wa 2 mpaka 3 mamita kwa makilomita okwana 147.5, kudutsa mabedi ambiri a Chitimwe omwe anakokedwa (Table S6).
Ntchitoyi idayang'ana koyamba pa Mabedi a Chitimwe kuti achulukitse zitsanzo za zinthu zakale, ndipo kachiwiri idayang'ana magawo amizere ataliatali kuchokera kugombe la nyanja kupita kumapiri omwe amadula magawo osiyanasiyana amatope.Izi zikutsimikizira mfundo yofunika kwambiri yoti zinthu zakale zomwe zili pakati pa mapiri akumadzulo ndi gombe la nyanja zimangogwirizana ndi bedi la Chitimwe kapena matope aposachedwa a Late Pleistocene ndi Holocene.Zinthu zaluso zomwe zimapezeka m'madipoziti ena sizipezeka pamalopo, zimasamutsidwa kuchokera kumadera ena, monga momwe zimawonekera kuchokera ku kuchuluka kwake, kukula kwake, ndi kuchuluka kwa nyengo.
Dzenje loyesera zofukulidwa m'mabwinja ndi kukumba kwa malo akuluakulu, kuphatikizapo micromorphology ndi phytolith sampling, kutsata ndondomeko yofotokozedwa ndi Thompson et al.(18, 54) ndi Wright et al.( 19, 55 ).Cholinga chachikulu ndikumvetsetsa kugawidwa mobisa kwa zinthu zakale komanso matope ooneka ngati fan m'malo okulirapo.Zinthu zakale zimakwiriridwa mozama m'malo onse a Mabedi a Chitimwe, kupatula m'mphepete, pomwe kukokoloka kwayamba kuchotsa pamwamba pa dothi.Pakafukufuku wamwamwayi, anthu awiri adadutsa Mabedi a Chitimwe, omwe adawonetsedwa ngati mapu a geological map aboma la Malawi.Anthuwa atakumana ndi mapewa a matope a Bedi a Chitimwe, anayamba kuyenda m’mphepete mwa nyanja, kumene ankatha kuona zinthu zakale zimene zinakokoloka kuchokera m’matopewo.Popendekera zofukulidwazo m'mwamba pang'ono (3 mpaka 8 m) kuchokera kuzinthu zakale zomwe zikusokonekera, kufukulako kumatha kuwulula malo omwe ali pamalopo poyerekeza ndi matope omwe ali nawo, popanda kufunikira kofukula mozama mozungulira.Maenje oyesera amayikidwa kuti akhale 200 mpaka 300 mita kutali ndi dzenje lotsatira, potero amatenga kusintha kwa dothi la bedi la Chitimwe ndi zinthu zakale zomwe zilimo.Nthawi zina, dzenje loyesera lidawulula malo omwe pambuyo pake adakhala malo okumba mozama.
Maenje onse oyesera amayamba ndi sikweya ya 1 × 2 m, kuyang'ana kumpoto-kum'mwera, ndipo amakumbidwa m'magawo ang'onoang'ono a 20 cm, pokhapokha ngati mtundu, mawonekedwe, kapena zomwe zili mumatope zikusintha kwambiri.Lembani zinthu za sedimentology ndi nthaka ya matope onse ofukulidwa, omwe amadutsa mofanana ndi sieve yowuma ya 5 mm.Ngati kuya kwa kuyika kukupitilira kupitilira 0,8 mpaka 1 m, siyani kukumba mu imodzi mwa masikweya mita ndikupitiliza kukumba ina, ndikupanga "sitepe" kuti mutha kulowa m'magawo ozama bwino.Kenaka pitirizani kukumba mpaka thanthwe lifike, osachepera masentimita 40 a matope osabala a m'mabwinja omwe ali pansi pa zinthu zakale, kapena kukumba kumakhala kosatetezeka (kwakuya) kosatheka.Nthawi zina, kuya kwake kumafunika kukulitsa dzenje loyesa mpaka mita lalikulu lachitatu ndikulowa mu ngalandeyo masitepe awiri.
Maenje oyesera a geological awonetsa kale kuti Mabedi a Chitimwe nthawi zambiri amawonekera pamapu a geological chifukwa chamitundu yofiira.Zikaphatikiza mitsinje yayikulu ndi matope a mitsinje, ndi matope amtundu wa alluvial, sizimawoneka zofiira nthawi zonse (19).Geology Dzenje loyesera linafukulidwa ngati dzenje losavuta lomwe linapangidwa kuti lichotse matope osakanikirana kuti awonetsere pansi pa nthaka.Izi ndizofunikira chifukwa bedi la Chitimwe limakokoloka kukhala phiri lophiphiritsira, ndipo patsindepo pali matope omwe agwa, omwe nthawi zambiri sapanga ziwalo zomveka bwino kapena mabala.Choncho, zinthu zakale zokumbidwa pansi mwina zinachitikira pamwamba pa bedi la Chitimwe, mwina panali kukhudzana kwapansi pansi pakati pa bedi la Chitimwe ndi bedi la Pliocene Chiwondo lomwe lili m’munsimu, kapena kunachitika pamene matope a m’mphepete mwa mtsinjewo ankafunika kulembedwa (55).
Zofukula zakale zofukulidwa m'mabwinja zimachitidwa m'malo omwe amalonjeza misonkhano yambiri ya zida za mwala mu-situ, nthawi zambiri zochokera pamayenje oyesera kapena malo omwe chiwerengero chachikulu cha zikhalidwe za chikhalidwe chikhoza kuwoneka chikugwedezeka kuchokera pamtunda.Zotsalira zazikulu zofukulidwa zachikhalidwe zidapezedwa kuchokera kumagawo a sedimentary ofukulidwa mosiyana mu lalikulu la 1 × 1 m.Ngati kachulukidwe wa zinthu zakale ndi wapamwamba, gawo lokumba ndi 10 kapena 5 cm spout.Zinthu zonse zamwala, mafupa a mafupa ndi ocher zidakoka pakufukula kwakukulu kulikonse, ndipo palibe malire a kukula.Kukula kwa skrini ndi 5mm.Ngati zotsalira za chikhalidwe zitapezedwa panthawi yakukumba, zidzapatsidwa nambala yapadera yojambulira zojambula za bar code, ndipo manambala omwe atulukira pamndandanda womwewo adzaperekedwa kwa zomwe zafufuzidwa.Zotsalira zachikhalidwe zimalembedwa ndi inki yokhazikika, zoyikidwa m'matumba okhala ndi zilembo zachitsanzo, ndi zomangika pamodzi ndi zikhalidwe zina zochokera kumtundu womwewo.Akaunika, zotsalira zonse zachikhalidwe zimasungidwa ku Cultural and Museum Center ku Karonga.
Zofukula zonse zimachitika molingana ndi chilengedwe.Izi zimagawika m'malovu, ndipo makulidwe a malovu amadalira kuchuluka kwa zinthu (mwachitsanzo, ngati kachulukidwe kake kamakhala kochepa, makulidwe a malovu adzakhala okwera).Zambiri zakumbuyo (mwachitsanzo, matope, ubale wakumbuyo, ndikuwona kusokonezedwa ndi kachulukidwe kazinthu) zimalembedwa munkhokwe ya Access.Zonse zomwe zimagwirizanitsa (mwachitsanzo, zopezeka m'magawo, kukwera kwa nkhani, ngodya zazikulu, ndi zitsanzo) zimachokera ku Universal Transverse Mercator (UTM) coordinates (WGS 1984, Zone 36S).Pamalo akulu, mfundo zonse zimajambulidwa pogwiritsa ntchito Nikon Nivo C mndandanda wa 5 ″ station yonse, yomwe imamangidwa pa gridi yapafupi kwambiri kumpoto kwa UTM.Malo a ngodya ya kumpoto chakumadzulo kwa malo okumba zinthu zonse ndi malo a malo okumbirapo Kuchuluka kwa matope akuperekedwa mu Table S5.
Gawo la sedimentology ndi mawonekedwe a sayansi ya nthaka m'magawo onse okumbidwa adalembedwa pogwiritsa ntchito United States Agricultural Part Class Programme (56).Magawo a Sedimentary amatchulidwa kutengera kukula kwa tirigu, angularity, ndi zogona.Zindikirani kuphatikizika kwachilendo ndi zosokoneza zomwe zimagwirizanitsidwa ndi gawo la sediment.Kukula kwa nthaka kumatsimikiziridwa ndi kudzikundikira kwa sesquioxide kapena carbonate mu nthaka yapansi panthaka.Kutentha kwapansi panthaka (mwachitsanzo, redox, kupanga tinthu tating'ono ta manganese) nakonso kumalembedwa pafupipafupi.
Malo osonkhanitsira a zitsanzo za OSL amatsimikiziridwa pamaziko a kuyerekezera kuti ndi ma facies omwe angapangitse kuyerekezera kodalirika kwa zaka zoikidwa m'manda.Pamalo ochitira sampuli, ngalande idakumbidwa kuti ziwonetsere gawo la sedimentary la authigenic.Sonkhanitsani zitsanzo zonse zomwe zimagwiritsidwa ntchito pa chibwenzi cha OSL poyika chubu chachitsulo chosawoneka bwino (pafupifupi 4 cm m'mimba mwake ndi pafupifupi 25 cm m'litali) mu mbiri ya matope.
Chibwenzi cha OSL chimayesa kukula kwa gulu la ma elekitironi otsekeredwa mu makristasi (monga quartz kapena feldspar) chifukwa chokhudzidwa ndi cheza cha ionizing.Zambiri mwa cheza izi zimachokera ku kuvunda kwa ma isotopu a radioactive m'chilengedwe, ndipo pang'onopang'ono zowonjezera zowonjezera m'madera otentha zimawonekera ngati mawonekedwe a cosmic.Ma electron ogwidwa amamasulidwa pamene kristalo ikuwonekera pa kuwala, yomwe imapezeka panthawi yoyendetsa (zeroing chochitika) kapena mu labotale, kumene kuunikira kumachitika pa sensa yomwe imatha kuzindikira ma photons (mwachitsanzo, chubu cha photomultiplier kapena kamera yokhala ndi choyimitsa. coupling device) Gawo lapansi limatulutsa pamene elekitironi imabwerera ku nthaka.Quartz particles ndi kukula pakati pa 150 ndi 250 μm amasiyanitsidwa ndi sieving, chithandizo cha asidi ndi kulekanitsa kachulukidwe, ndipo amagwiritsidwa ntchito ngati ma aliquots ang'onoang'ono (<100 particles) okwera pamwamba pa mbale ya aluminiyamu kapena kubowola mu chitsime cha 300 x 300 mm particles amawunikidwa pa aluminiyamu poto.Mlingo wokwiriridwa nthawi zambiri umayerekezedwa pogwiritsa ntchito njira imodzi yosinthira aliquot (57).Kuphatikiza pakuwunika mlingo wa radiation womwe umalandira ndi mbewu, chibwenzi cha OSL chimafunikiranso kuyeza kuchuluka kwa mlingo poyeza kuchuluka kwa radionuclide mu dothi lachitsanzo chosonkhanitsidwa pogwiritsa ntchito mawonekedwe a gamma spectroscopy kapena neutron activation, ndikuwunika chitsanzo cha cosmic mlingo manda.Kutsimikiza kwa zaka zomaliza kumatheka pogawa mlingo wa maliro ndi mlingo wa mlingo.Komabe, pakakhala kusintha kwa mlingo woyezedwa ndi njere imodzi kapena gulu la mbewu, chiwerengero cha chiwerengero chikufunika kuti mudziwe mlingo woyenera wokwiriridwa kuti ugwiritsidwe ntchito.Mlingo woikidwa m'manda umawerengedwa pano pogwiritsa ntchito chitsanzo chapakati cha nyengo, ngati chibwenzi cha aliquot chimodzi, kapena ngati chibwenzi chamtundu umodzi, pogwiritsa ntchito chitsanzo chosakanikirana (58).
Ma laboratories atatu odziyimira pawokha adasanthula OSL pa kafukufukuyu.Njira zatsatanetsatane za labotale iliyonse zikuwonetsedwa pansipa.Nthawi zambiri, timagwiritsa ntchito njira ya regenerative kuti tigwiritse ntchito OSL kukhala ndi ma aliquots ang'onoang'ono (makumi ambewu) m'malo mogwiritsa ntchito kusanthula kwambewu imodzi.Izi zili choncho chifukwa panthawi yoyesera kukula kwatsopano, chiwerengero cha kuchira kwachitsanzo chaching'ono ndi chochepa (<2%), ndipo chizindikiro cha OSL sichimadzaza pamtunda wa chizindikiro cha chilengedwe.Kugwirizana kwapakati pa labotale ya kutsimikiza kwa zaka, kugwirizana kwa zotsatira mkati ndi pakati pa mbiri yoyesedwa ya stratigraphic, ndi kugwirizana ndi kutanthauzira kwa geomorphological kwa zaka za 14C za miyala ya carbonate ndizo maziko akuluakulu a kafukufukuyu.Laboratory iliyonse idayesa kapena kukhazikitsa mgwirizano umodzi wambewu, koma mosadalira adatsimikiza kuti sichinali choyenera kugwiritsidwa ntchito mu kafukufukuyu.Njira zambiri ndi ndondomeko zowunikira zomwe zimatsatiridwa ndi labotale iliyonse zimaperekedwa muzowonjezera ndi njira.
Zinthu zakale zamwala zomwe zapezedwa pofukula zoyendetsedwa (BRU-I; CHA-I, CHA-II, ndi CHA-III; MGD-I, MGD-II, ndi MGD-III; ndi SS-I) zimatengera ma metric system ndi mtundu. makhalidwe.Yezerani kulemera ndi kukula kwakukulu kwa chogwirira chilichonse (pogwiritsa ntchito sikelo ya digito kuyeza kulemera kwake ndi 0.1 g; kugwiritsa ntchito Mitutoyo digito caliper kuyeza miyeso yonse ndi 0.01 mm).Zotsalira zonse zachikhalidwe zimagawidwanso molingana ndi zopangira (quartz, quartzite, mwala, ndi zina), kukula kwambewu (zabwino, zapakati, zolimba), kukula kwambewu, mtundu, mtundu wa kotekisi ndi kuphimba, nyengo / kuzungulira m'mphepete ndi kalasi yaukadaulo. (zokwanira kapena zogawanika) Miyendo kapena ma flakes, zidutswa za flakes / ngodya, miyala ya nyundo, mabomba ndi zina).
Pakatikati pake amayezedwa motsatira kutalika kwake;m'lifupi mwake;m'lifupi ndi 15%, 50%, ndi 85% ya kutalika;makulidwe apamwamba;makulidwe ndi 15%, 50%, ndi 85% kutalika.Miyezo idachitidwanso kuti awone kuchuluka kwazomwe zili pachimake cha minofu ya hemispherical (radial ndi Levallois).Ma cores onse osasunthika komanso osweka amagawidwa molingana ndi njira yokhazikitsiranso (pulatifomu imodzi kapena nsanja zambiri, ma radial, Levallois, etc.), ndi zipsera zowoneka bwino zimawerengedwa ≥15 mm ndi ≥20% ya kutalika kwapakati.Zipsera zokhala ndi zipsera za 5 kapena zochepa za 15 mm zimatchedwa "mwachisawawa".Kuphimba kwa cortical kwa chigawo chonse chapakati kumalembedwa, ndipo kufalikira kwa kotekisi kwa mbali iliyonse kumalembedwa pakatikati pa minofu ya hemispherical.
Tsambalo limayezedwa molingana ndi kutalika kwake;m'lifupi mwake;m'lifupi ndi 15%, 50%, ndi 85% ya kutalika;makulidwe apamwamba;makulidwe ndi 15%, 50%, ndi 85% kutalika.Fotokozani zidutswazo molingana ndi magawo otsalawo (ozungulira, apakati, otalikirana, ogawanika kumanja ndi kugawanika kumanzere).Kutalikirako kumawerengedwa pogawa kutalika kwa kutalika ndi m'lifupi mwake.Yezerani kukula kwa nsanja, makulidwe, ndi ngodya yakunja ya nsanja ya kagawo kosasinthika ndi zidutswa zoyandikana, ndikuyika nsanja molingana ndi kuchuluka kwa kukonzekera.Lembani kuphimba kwa cortical ndi malo pazigawo zonse ndi zidutswa.Mphepete zakutali zimayikidwa molingana ndi mtundu wa kutha (nthenga, hinge, ndi foloko yapamwamba).Pagawo lathunthu, lembani nambala ndi mbali ya chipsera pagawo lapitalo.Mukakumana, lembani malo osinthidwa ndi kuukira motsatira ndondomeko yokhazikitsidwa ndi Clarkson (59).Mapulani okonzanso adayambika pazophatikiza zambiri zakukumba kuti ziwone njira zobwezeretsera komanso kukhulupirika kwa malo.
Miyala yopangidwa ndi miyala yomwe inapezedwa m'maenje oyesera (CS-TP1-21, SS-TP1-16 ndi NGA-TP1-8) imafotokozedwa motsatira ndondomeko yosavuta kusiyana ndi kukumba kolamulidwa.Pachipangidwe chilichonse, zizindikiro zotsatirazi zinalembedwa: zopangira, kukula kwa tinthu, kuphimba kotekisi, kalasi ya kukula, kuwonongeka kwa nyengo / m'mphepete, zipangizo zamakono, ndi kusunga zidutswa.Zolemba zofotokozera za matenda a flakes ndi ma cores amalembedwa.
midadada yathunthu ya matope inadulidwa kuchokera m'zigawo zofukulidwa m'mabwinja ndi ngalande za geological.Miyala imeneyi anaiika pamalopo ndi mabandeji a pulasitala kapena mapepala a m’chimbudzi ndi tepi yoikamo, kenako n’kupita nayo ku Geological Archaeology Laboratory ya pa yunivesite ya Tubingen ku Germany.Kumeneko, chitsanzocho chouma pa 40 ° C kwa maola osachepera 24.Kenako amachiritsidwa pansi pa vacuum, pogwiritsa ntchito chisakanizo cha utomoni wa polyester wosatulutsidwa ndi styrene mu chiŵerengero cha 7: 3.Methyl ethyl ketone peroxide amagwiritsidwa ntchito ngati chothandizira, osakaniza a resin-styrene (3 mpaka 5 ml / l).Mukasakaniza utomoni, tenthetsani chitsanzo pa 40 ° C kwa maola osachepera 24 kuti muwumitse kusakaniza.Gwiritsani ntchito macheka a matailosi kuti mudulire nyemba zowumitsidwa kukhala zidutswa za 6 × 9 cm, kuziyika pa galasi la galasi ndikuzipera mpaka makulidwe a 30 μm.Magawo omwe adatsatiridwawo adawunikidwa pogwiritsa ntchito scanner ya flatbed, ndikuwunikidwa pogwiritsa ntchito kuwala kokhala ndi polarized ndege, kuwala kozungulira, kuwala kowoneka bwino, komanso kuwala kwabuluu ndi maso amaliseche komanso kukulitsa (× 50 mpaka × 200).Mawu ofotokozera ndi kufotokozera kwa zigawo zoonda amatsatira malangizo ofalitsidwa ndi Stoops (60) ndi Courty et al.(61).Dothi kupanga carbonate tinatake tozungulira anasonkhanitsa kuchokera kuya> 80 masentimita kudula pakati kuti theka akhoza impregnated ndi kuchitidwa mu magawo woonda (4.5 × 2.6 cm) ntchito muyezo sitiriyo maikulosikopu ndi microscope petrographic ndi cathodoluminescence (CL) Research maikulosikopu. .Ulamuliro wa mitundu ya carbonate ndi wosamala kwambiri, chifukwa mapangidwe a carbonate opangidwa ndi nthaka amagwirizana ndi malo okhazikika, pamene mapangidwe a carbonate apansi amadziimira okha pamwamba kapena nthaka.
Zitsanzo zinabowoledwa kuchokera pamwamba pa dothi lopanga carbonate tinthu tating'onoting'ono tating'onoting'ono tomwe timapanga carbonate ndikudula pakati kuti tifufuze mosiyanasiyana.FS inagwiritsa ntchito ma microscopes odziwika bwino a stereo ndi petrographic a Gulu Logwira Ntchito la Geoarchaeology ndi maikulosikopu a CL a Experimental Mineralogy Working Group kuti aphunzire magawo opyapyala, onse omwe ali ku Tübingen, Germany.Zitsanzo zazing'ono za ma radiocarbon adabowoleredwa pogwiritsa ntchito zobowoleza zolondola kuchokera kudera losankhidwa lazaka pafupifupi 100.Theka lina la tinthu tating'onoting'ono tating'onoting'ono ndi 3 mm m'mimba mwake kuti tipewe madera omwe ali ndi recrystallization mochedwa, ma mineral inclusions olemera, kapena kusintha kwakukulu pakukula kwa makristasi a calcite.Protocol yomweyi siyingatsatidwe kwa zitsanzo za MEM-5038, MEM-5035 ndi MEM-5055 A.Zitsanzozi zimasankhidwa kuchokera ku zinyalala zotayirira ndipo ndi zazing'ono kwambiri kuti sizingadulidwe pakati kuti zikhale zopyapyala.Komabe, maphunziro a magawo opyapyala adachitidwa pazitsanzo zofananira za micromorphological za matope oyandikana nawo (kuphatikiza timinofu ta carbonate).
Tinapereka zitsanzo za chibwenzi za 14C ku Center for Applied Isotope Research (CAIS) ku yunivesite ya Georgia, Athens, USA.Chitsanzo cha carbonate chimachita ndi 100% phosphoric acid mu chombo chothamangitsidwa kuti chipange CO2.Kutentha kwapang'onopang'ono kwa zitsanzo za CO2 kuchokera kuzinthu zina zomwe zimachitikira komanso kutembenuka kwamphamvu kukhala graphite.Chiŵerengero cha graphite 14C/13C chinayesedwa pogwiritsa ntchito 0.5-MeV accelerator mass spectrometer.Fananizani chiŵerengero cha zitsanzo ndi chiŵerengero choyezedwa ndi oxalic acid I muyezo (NBS SRM 4990).Carrara marble (IAEA C1) imagwiritsidwa ntchito ngati maziko, ndipo travertine (IAEA C2) imagwiritsidwa ntchito ngati mulingo wachiwiri.Chotsatiracho chikufotokozedwa ngati peresenti ya carbon yamakono, ndipo tsiku losatchulidwa losawerengeka limaperekedwa zaka za radiocarbon (zaka za BP) zisanafike 1950, pogwiritsa ntchito theka la moyo wa 14C wa zaka 5568.Cholakwikacho chatchulidwa ngati 1-σ ndipo chikuwonetsa zolakwika zamawerengero ndi zoyeserera.Kutengera ndi δ13C mtengo woyezedwa ndi isotope ratio mass spectrometry, C. Wissing of the Biogeology Laboratory ku Tubingen, Germany, inanena za deti la magawo a isotopu, kupatulapo UGAMS-35944r yoyezedwa pa CAIS.Chitsanzo 6887B chinawunikidwa mobwerezabwereza.Kuti muchite izi, tambani chitsanzo chaching'ono chachiwiri kuchokera ku nodule (UGAMS-35944r) kuchokera kumalo opangira sampuli omwe akuwonetsedwa pamtunda wodula.The INTCAL20 calibration curve (Table S4) (62) yogwiritsidwa ntchito kumwera kwa dziko lapansi idagwiritsidwa ntchito kukonza magawo amlengalenga a zitsanzo zonse ku 14C mpaka 2-σ.